Going out with a Bangs: Control of Human Brucellosis by means of an Animal Vaccine

This is the thirteenth of 16 student posts, guest-authored by Jessica Ludvik. 

One Disease, Many Species

Brucellosis, more commonly known as undulant fever in humans or bangs disease in cattle, is one of the oldest bacterial scourges of livestock-producing nations, especially those in which the animals live in close proximity with the human population.  The disease is caused by bacteria of the genus Brucella.  Within this category are many species of bacteria, each almost exclusive to a particular animal species.  A few of the most common seen in veterinary and human medicine today are listed in Table 1.  Of these, all but B. ovis has been shown to be transmissible to humans [1].

Why Should I care about Brucellosis?

            The presence of Brucellosis in a region is catastrophic to the economy and animal and human health.  In many livestock species, the bacteria elicits its major effects on the reproductive system, leading to late term abortions and stillbirths in females, weak newborns leading to death soon after birth, and inflammation of the testicles and testicular abscesses in males [2].  Abortion storms of 30-80% have been documented in cattle herds infected by B. abortus [2].  B. abortus and B. melitensis are the most common of the strains associated with human infection, and the World Health Organization (WHO) estimates that 500,000 new cases of human cases of human Brucellosis occur annually, making it the most common zoonotic disease in the world [3].  Its importance has earned it a spot on the Center for Disease Control’s (CDC) 2012 list of Nationally Notifiable Conditions.  To view this list visit the CDC’s website at http://www.cdc.gov/osels/ph_surveillance/nndss/phs/infdis.htm.

Symptoms include fever, profuse sweating, headache, fatigue, depression, loss of appetite, irritability, cough, chest pain, and upset stomach [1].  It can also affect bones and joints causing arthritis [1].  If untreated, symptoms may recur after a latent period of many years [1].  For the official case definition, click http://www.cdc.gov/osels/ph_surveillance/nndss/casedef/brucellosis_current.htm. 

What’s the Risk?

            Most human cases of Brucellosis are a result of occupational exposure to the bacteria [2].  It can penetrate mucus membranes of the digestive or respiratory tract, or can enter through skin wounds or abrasion after contact with reproductive fluids, aborted fetus or placenta, or aerosolized particles from the aforementioned [2].  Brucellosis can also be contracted by people via accidental injection with the cattle vaccine or by ingestion of unpasteurized dairy products of infected animals [2].

Most people diagnosed with Brucellosis recover fully with treatment, which usually consists of a six to eight week antibiotic regimen [4].  Less than 2% of untreated individuals die, however chronic complications such as endocarditis and meningitis may occur [2].

On the Global Scale….

Figure 1: Worldwide incidence of human Brucellosis [5] Click to enlarge.

As the major mode of human infection is through direct contact with infected animals otr through the consumption of products from those animals, the most logical means of disease prevention in the human population has been through the prevention of the disease in animals.  Many developed regions such as North America, Australia, and Northern Europe have dramatically reduced the prevalence of brucellosis in livestock through widespread vaccination efforts [5].  The United States Department of Agriculture (USDA) implemented an eradication program in 1934, which involved the testing and identification of diseased animals, slaughter of infected animals, and trace back and investigation of their herds of origin [2].  In 1951, Animal Plant Health Inspection Services (APHIS) made compliance of all states mandatory [2].   Currently, RB51 vaccine is the standard in cattle and Rev-1 vaccine in goats.  Both of these are attenuated live vaccines, which are strains of bacteria that cause a similar but less severe infection in the vaccinated individual, so the animal’s immune system will respond to and eliminate the agent.  Immune cells then remember the bacteria, so that if the animal is exposed to the wild type strain of bacteria, it will destroy it before it becoming infected.  One of the advantages of the RB51 vaccine that has helped to make testing for the disease effective is that the vaccine strain lacks a specific surface molecule that the wild type strain of bacteria possesses, so tests can distinguish between diseased cattle and those vaccinated with RB51 [1].  The Program has decreased the number of infected herds in the US from 124,000 in 1957, to 2 as of December 2003 [2].  These vaccines are not approved for human use, and as mentioned before may actually cause clinical illness if accidently injected into the handler [1].

In February of 2008, all States in the US were classified as disease-free [6].  In September of that year however, the states of the Greater Yellowstone Area (GYA), Montana, Wyoming, and Idaho lost their disease-free status [6].  For more information on this, see APHIS’s website at http://www.aphis.usda.gov/newsroom/content/2009/10/printable/brucellosis_concept_paper.pdf.  What was the source of the infections that triggered this revocation?  Brucellosis is endemic in the herds of elk and bison in the area.  8-60% of elk herds and 11-75% of bison herds were positive for B. abortus by serologic tests [7].  Studies of mapping the molecular profiles of the isolates from this area show that cattle are more likely to be infected by elk than bison, and indicate that there may be a possibility of transmission between cattle and feral pigs, though it is unclear of the direction [7].  These wild reservoirs pose another significant barrier to the complete eradication of the disease in the US.

In the Future

The issue of wildlife reservoirs for Brucellosis will need to be addressed to prevent transmission of the disease to people, especially those at particularly high risk of infection by this route, such as hunters, hikers, and campers.  Some proposed strategies include the daunting tasks of selectively culling bison herds and vaccinating elk and bison [7].

Control of human Brucellosis through vaccination of livestock has been successful thus far because it virtually eliminates our exposure to the infectious agent, so it is a sort of indirect prevention. But how will we prevent disease outbreak should we be exposed by a different means?  There is no human vaccine for Brucellosis, it can be aerosolized, and it only takes 10-100 organisms to cause disease in humans [1].  All these characteristics make it a possible agent of bioterrorism [1].  Although the mortality rate is low, the morbidity rate is high, so an outbreak would cause a tremendous consumption of money and resources to treat the affected, and a dramatic decrease in workforce and morale. Control of human Brucellosis is another area in which we must not allow ourselves to fall victims to our own success.  We must continue to support the vigilant monitoring and livestock vaccination efforts and encourage efforts in the development of a vaccine that is safe and effective for use in humans.

 References

[1]         Ficht, TA, and LG Adams. Brucellosis. Vaccines for Biodefense and Emerging and Neglected Disease. Elsevier Inc. 2009. Ch 42.

[2]         http://www.cfsph.iastate.edu/DiseaseInfo/disease.php?name=brucella-abortus&lang=en. Accessed 9 June, 2012.

[3]         Atluri, VL, MN Xavier, MF de Jong, AB den Hartigh, RM Tsolis. Interactions of the Human Pathogenic Brucella Species in Their Hosts. Annual Review of Microbiology. 2011. 65:523-41.

[4]         Solis Garcia del Pozo, J, J Solera. Systematic Review and Meta-Analysis of Randomized Clinical Trials in the Treatment of Human Brucellosis. PloS One. 2012. 7(2):e32090.

[5]         Pappas, G, P Papadimitriou, N Akritidis, L Christou, EV Tsianos. The New Global Map of Human Brucellosis. Lancet Infectious Disease. 2006. 6:91-99.

[6]        http://www.aphis.usda.gov/newsroom/content/2009/10/printable/brucellosis_concept_paper.pdf. Accessed 9 June, 2012.

[7]         Higgins, J, T Stuber, C Quance, WH Edwards, RV Tiller, T Linfield, J Rhyan, A Berte, B Harris. Molecular Epidemiology of Brucella abortus Isolates from Cattle, Elk, and Bison in the United States, 1998 to 2011. Applied Environmental Microbiology. 2012. 78(10):3674-84.

Coexisting with Coyotes

This is the twelfth of 16 student posts, guest-authored by Stanley Corbin.

Disease in wildlife is an important concern to the health and safety of humans and domestic animals. The expanding growth of our nation and resultant land use changes with urbanization has resulted in a shrinking habitat and fragmentation for all animals, including humans. The effects of ecological disruption are universally recognized and adversely effects wildlife through multiple mechanisms.

Hand it to the coyote (Canis latrans) for its ability to exist with humans. The resilience of this animal can be attributed to its natural instincts, remarkable intelligence and survivability. Opportunistic is another word that can be used to define them. Once an animal roaming the mid-west prairies, their territory has expanded throughout the North American continent and beyond. Coyotes demonstrate their wily nature by meeting the challenges of the American landscape.  

Progression of coyote range expansion throughout North America and Mexico. (7) Click to enlarge. 

Precise population estimates of coyotes in the United States are not available and unclear at best. However, to put it in perspective, the California Department of Fish and Game estimates a population range of  250,000  to 750,000 animals.(1)  The greater metropolitan area of Chicago estimates home to between 200-2000 coyotes. (3) The coyote population in New York during the summer is approximately 20,000-30,000. (2)  In March 2010, a lone coyote led a police chase through lower Manhattan, deep in New York City.

Coyotes can thrive in suburban settings and even some urban ones creating a concern for public health. A study by wildlife ecologists at Ohio State University yielded some surprising findings in this regard. Researchers studied coyote populations in Chicago over a seven-year period (2000–2007), proposing that coyotes have adapted well to living in densely populated urban environments while avoiding contact with humans. They found, among other things, that urban coyotes tend to live longer than their rural counterparts. (3)

As with most all wild animals, the coyote population represents a reservoir for diseases. Zoonotic (animal to human) diseases in particular are on the rise, comprising 75% of emerging infectious diseases. Viruses, bacteria, fungi, internal and external parasites, and other pestilence are only the headings for what’s out there.

Fortunately, the rabies virus is rather uncommon in coyotes as reported. The only exception was the 1974-1998 rabies epizootic (epidemic in animals) in south Texas. The world’s largest wildlife oral rabies vaccine (ORV) drop, 11.6 million doses covering over 189.6 square miles, was performed beginning in 1995 and led to the total elimination of the domestic dog-coyote (DDC) variant by 2006. (4) A study performed by the USDA, APHIS, Wildlife Services, National Wildlife Research Center concluded; “In Texas, the use of the ORV stopped the northward spread and led to the progressive elimination of the DDC variant of rabies in coyotes”. (5) This campaign was a win for our tax dollars as well. The economic evaluation study yielded “total estimated benefits of the program approximately ranged from $89 million to $346 million, with total program costs of $26,358,221 for the study period”. This represents benefit-cost ratios that ranged from 3.38 to 13.12. (5)

Coyote rabies surveillance reported by the Center for Disease Control (CDC) for 2010 declared 10 confirmed cases. None of these cases were DDC variant, which remains non-detected from the populations. The raccoon variant and skunk variant represented 8 (AL, GA, NC, NJ, NY, NYC) and 2 (CA, CO) cases respectively. (6)These coyote rabies cases were diagnosed from New York City (1) on the east coast to California (1) in the west, confirming the widespread distribution of this terrestrial carnivore. An interesting fact that comes from this data is that the coyote is not a player in the zoonotic rabies front. From a public health concern, a human has a significantly greater chance of contracting the disease from the backyard domestic cat.

Canine Distemper Virus is an enzootic disease (prevalent in an animal population) in the coyote. The neurological form is rightfully confused with a rabies infection as the two appear similar clinically. Humans are not susceptible to the disease, however it is highly contagious to dogs. Greater Yellowstone Park has a dynamic management study to assist with the surveillance of the disease enzootic in the parks coyote population.

The parasitic disease Sarcoptic mange is what gives the animal the “mangy” look. Caused by the mite Sarcoptes scabei, the disease in humans is called Scabies. Severely affected coyotes are unsightly and are perceived as threatening by their appearance. The compromised condition may explain the increased frequency of nesting and scavenging in suburban areas, especially in daylight hours. Coyotes with extensive mange infections are not considered aggressive as concluded by The Cook County, Illinois, Coyote Project.(7) Human infections from animal sources are short-lived and self-limiting due the highly host species-specific nature of the bug.

A recent hot epidemiological study conducted in Santa Clara County, California, identified coyotes as a wildlife reservoir for a disease caused by Bartonella vinsonii subsp. Berkhoffii .(8) The disease in humans is characterized by endocarditis, an inflammation of the interior lining of the heart. The study was prompted by the coyote bite of a child who developed symptoms compatible with Bartonella infection. Among 109 coyotes sampled, 31 animals (28%) were found to be bacteremic and 83 animals (76%) had Bartonella vinsonii seropositve antibodies. The disease is thought to be transmitted by insect vectors (ticks, biting flies, fleas), however further studies are necessary to elucidate additional modes of transmission to humans.(8) Bartonellosis in domestic cats is commonly called “cat scratch fever”, caused by a different species variant of Bartonella. The role coyotes play in this emerging infectious zoonose and public health concern are yet to be resolved.

Additional diseases exist in the coyote populations warranting public health attention. Anyone concerned with coyote interaction and communicable diseases will need to seek information relative to their geographical location. The ubiquitous nature of this animal and the corresponding diseases posing risks to humans and domestic animals respectively are regionally specific.

Coyotes are here to stay. Most every state (excluding Hawaii) has a control program in effect to manage the public health risks and deprivation to human welfare. The Humane Society of the US has issued techniques to resolve coyote conflict and how to discourage coyotes.  Project Coyote champions innovative solutions to live in peace with the coyote despite differences, especially in terms of human policy. (9) A collaborated and integrated management approach is required to maintain a balance of needs for this specie of animal and humans. Wildlife specialist Jeffery Green summarizes; “regardless of the means used to stop damage, the focus should be on damage prevention and control rather than elimination of coyotes”. (10)

Pet owners need to adapt to coyote presence and take precautionary measures in securing their animal’s health and safety. Routine core vaccinations and other preventative health care are effective in stopping the transmission of nearly all the important diseases from the coyote to a pet animal.

Coyote attacks on humans are rare; the coyote human avoidance factor is responsible for the low incidence. In the cases of human attacks, approximately 30% were reported as humans feeding coyotes. (8) Additionally, greater than 50% of the human attack cases were in California, (8) where coyotes have a longer history of habituation with humans.

A person who sees a coyote should feel lucky since they avoid humans and are mostly invisible.

The most important advice to prevent human exposure is: do NOT feed coyotes and ensure your environment is NOT coyote friendly. Any attempt to domesticate or habituate the coyote will surely be a kiss of death for its existence. Survival of coyotes is dependent on living side by side but not together with humans.

The “tricksters still run wild and provoke all sorts of all-too-human difficulties, pitting the spirit of the wild against the sturdy values of our American farmers and their need to protect livestock. Somehow we need both”. (11)

Our Canadian neighbors at The Royal Canadian Geographical Society  conclude; “the more we cut down habitat and build, the happier the scavenging and opportunistic coyote”. (12)

As they say in Texas, “when the human population fails, cockroaches and coyotes will survive”. (13)

References:

  1. L.A. County Department of Animal Care and Control website. Accessed June 15, 2012. Available at: http://animalcare.lacounty.gov/coyote.asp
  2. New York State Department of Environmental Conservation website. Accesses June 15, 2012. Available at: http://www.dec.ny.gov/animals/9359.html
  3. World Science website: Thriving under our noses, stealthily: coyotes.  Accessed June 13, 2012. Available at:  http://www.world-science.net/othernews/060105_coyotefrm.htm
  4. Texas Department of State Health Service website. Accessed June 12, 2012. Available at: http://www.dshs.state.tx.us/idcu/disease/rabies/orvp/statistics/
  5. Stephanie A. Shwiff, PhD; Katy N. Kirkpatrick, BS; Ray T. Sterner, PhD. Economic evaluation of an oral rabies vaccination program for the control of a domestic dog-coyote rabies epizootic: 1995-2006. JAVMA, Vol.233, No.11, Dec.1, 2008. Available at http://www.avma.org/avmacollections/rabies/javma_233_11_1736.pdf
  6. Jesse D. Blanton, MPH; Dustyn Palmer, BA; Jessie Dyer, MSPH; Charles E. Rupprecht, VMD,PhD. Rabies surveillance in the United States during 2010. Vet Med Today: Public Veterinary Medicine. JAVMA, Vol. 239, No. 6, September 15, 2011. Available at: http://avmajournals.avma.org/doi/pdf/10.2460/javma.239.6.773
  7. The Cook County, Illinois, Coyote Project website. Accessed June 13, 2012. Available at: http://urbancoyoteresearch.com/Coyote_Project.htm
  8. Chang CC, Kasten RW, Chomel BB, Simpson DC, Hew CM, Kordick DL, Heller R, Piedmont Y, Breitschwerdt EB. Coyotes (Canis latrans) as the reservoir for a human pathogenic Bartonella sp.: molecular epidemiology of Bartonella vinsonii subsp. Berkhoffii infection in coyotes from central coastal California. J Clin Microbiol. 2000 Nov; 38 (11): 4193-200. Available at: http://www.ncbi.nlm.nih.gov/pubmed/11060089
  9. Project Coyote website. Accessed June 15. 2012. Available at: http://www.projectcoyote.org/programs.html
  10. Jefferey S. Green, Urban Coyotes: Some Summary Thoughts. Proceedings of the 12th Wildlife Damage Management Conference (D.L. Nolte, W.M. Arjo, D.H. Stalman, Eds. 2007
  11. Shake-Spear’s Bible.com website; Coyote: An Instant Classic. Post by Roger Strirtmatter, October 25, 2011. Accessed June 13, 2012. Available at: http://shake-speares-bible.com/2011/10/25/coyote-an-instant-classic/
  12. The Royal Canadian Geographical Society website. Accessed June 13, 2012. Available at: http://www.canadiangeographic.ca/wildlife-nature/?path=english/species/coyote/2
  13. Personal correspondence; James Wright; Tyler Texas. Retired Texas Department of State Health Service official.

A Query about Q fever –Answers to the Questions you should ask

This is the tenth of 16 student posts, guest-authored by Jean DeNapoli. 

I own a small back yard flock of sheep and lambing season is the most exciting and rewarding time of the year.  Nothing is more enjoyable than watching a lamb who takes a few wobbly steps and nurses for the first time as her mother nickers encouragement.  Within a day, the lamb will be playing, bucking, running, and exploring her world.

Despite the pastoral wonders of the season, lambing is also inherently stressful.  I must constantly check the barn to monitor for birthing problems and help out when necessary.   This help might include repositioning a lambs stuck in the birthing canal, pulling a lamb when the ewe is unable to push it out herself, and cleaning the face and airway of a newborn when its mother is too exhausted to follow through on her own.  Shepherds all over the world share the same experiences that I do.  But what many of them don’t know is that they are probably being exposed to Q fever.

When the disease was first recognized it was given the temporary name Query fever (since very little was understood about it).  We now know it is caused by a bacteria called Coxiella burnetii.  It is found word wide and it is estimated that 15-20% of all cattle, sheep and goats have been exposed to it.  The livestock rarely show signs of illness, but it can contribute to reproductive problems such as abortions.

In an infected animal, the organism can be found in milk, urine, and feces.  But the greatest concentration of bacteria is in the amniotic fluid and placenta.  Ticks can spread the disease, but much more frequently, it is passed directly to other animals at the time of birth.  It can develop into a long lasting spore-like form and can then contaminate dust and be carried by the wind.  Q fever is very easily spread and it takes only one organism to cause disease!

Q fever is zoonotic; it can be passed from animals to people.  When people become infected, they may have fevers, headache and weakness.  Fortunately, the fatality rate is low (<2%).  But some people, especially pregnant women and those with heart disease or who are immune deficient, end up with a more chronic and severe disease.  Q fever may also cause pre-term delivery or miscarriage if women become infected while pregnant.

I am not only a shepherd, but I am a veterinarian and it surprises me that few shepherds (at least the hobby farmers I know) discuss Q fever or take the recommended precautions.  In research facilities, Q fever is a biosafety 3 organism (on a scale of 1-4), requiring special laboratory containment precautions. To put this in perspective, other level 3 organisms include tuberculosis, anthrax, SARS, and yellow fever.  Yet many farmers routinely assist in births without any thought to their own health.

Q fever is fairly common and can be difficult to detect in healthy animals, so experts recommend treating all sheep as if they are infected.  Pregnant women or women who may become pregnant should avoid working with sheep at lambing time.  Other people at increased risk (people with impaired immune systems and heart valve abnormalities) should also stay away from the barn at lambing time.

Shepherds should wear disposable gloves when assisting lambing or handling newborn lambs.  Masks should also be worn, especially in dusty conditions.   Farmers should not eat or drink in the barn and should clean their footwear and wash their hands when leaving the barn.

Clothes have also been shown to carry the organism and they are capable of causing infection in people handling the laundry.  Therefore, high-risk people should not handle clothing that has been worn in the barn until it has been cleaned.

Farmers should use good sanitation when handling birthing materials and bury or compost the placentas.  Birthing areas should be cleaned frequently and in a way that will not cause excessive dust.  It is very important that farmers understand biosecurity precautions in general and specific Q fever prevention protocols to keep themselves, their families and their neighbors safe.

Shepherds should also work closely with their veterinarian to keep their flock as healthy as possible.   In the event of an abortion, the fetal material (placenta) should be submitted to the veterinary diagnostic laboratory for testing.

But what if you are not a farmer, do you need to be concerned?  Well, you should at least be aware of the disease.

Although usually associated with farm animals, dogs and cats may also transmit Q fever to people, most commonly at and around the time of birth.  Again, people who are most susceptible should avoid association with pets at those times.  Coxiella burnetii has been found in milk, so dairy products should be properly pasteurized before being consumed.

The organism is easily transmitted through the air (it is even considered a possible bioterrorism risk for this reason).  The Netherlands had a recent outbreak of Q fever in people living close to goat farms due to unintentional airborne transmission.  However, the people who generally are at the greatest risk are farmers, veterinary workers and researchers.  They are the people most likely to be near animals giving birth or handling the organism during the course of their daily work.

With education and reasonable safety precautions, a visit to the barn does not have to be a risky event.  Through the simple sharing of information, we can keep future generations of farmers safe, healthy, and productive.

References:

Prevalence of Coxiella burnetii infection in domestic ruminants:  A critical review.  Raphael Guatteo, Henri Seegers, Ann-Freida Taurel, Alain Joly, Francois BeaudeauVeterinary Microbiology 149 (2011) 1-16

Q Fever:  Current State of Knowledge and Perspectives of Research of a Neglected Zoonosis.  Sarah Rebecca Porter, Guy Czaplicki, Jacques Mainil, Raphael Guatteo, and Claude Saegerman.  International Journal of Microbiology Volume 2011 (p 1-22)

Eurosurveillance, special issue on Q fever, vol. 17, 19 January 2012

New York Department of health Q fever facts sheet (2011) http://www.health.ny.gov/diseases/communicable/q_fever/fact_sheet.htm

World Organization for Animal Health (OIE) fact sheet on Q fever (2011) http://www.oie.int/fileadmin/Home/eng/Media_Center/docs/pdf/Disease_cards/Q-FEVER-EN.pdf

Center for Disease Control (CDC) Q fever information (2011) http://www.cdc.gov/qfever/index.html

Public Health Agency of Canada pathogen safety data sheet for Q fever (2010) http://www.phac-aspc.gc.ca/lab-bio/res/psds-ftss/coxiella-burnetii-eng.php

Health Protection Agency Q fever information for farmers (2010) http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/1210834106356

University of Florida IFAS Extension, The Herd Health Handbook for Goat Producers:  Biosecurity at the Farm Level, Ray Mobley and Carmen Lyttle-N’guessan.  (2009) http://edis.ifas.ufl.edu/famu006

Wyoming State Veterinary Laboratory, Q fever fact sheet (2004) http://www.uwyo.edu/wyovet/disease-updates/2004/files/qfever.pdf

Institute for Biosecurity, Saint Louis University School of Public Health, Q fever fact sheet (2001) http://www.bioterrorism.slu.edu/bt/quick/qfever01.PDF

Eurosurveillance Q Fever in the Netherlands: an up date on the epidemiology and control measures, W van der Hoek, et al. (2010) http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19520

Photographs are courtesy of Laura Cowperthwaite and Triple J Farm.

Wait, the infamous “Black Death” still plagues the United States?

This is the eighth of 16 student posts, guest-authored by Michelle Formanek. 

For many of us in the scientific world, particularly budding infectious disease epidemiologists like myself, the Plague (or, more dramatically, the “Black Death”) is a prime example of the rapid and devastating spread of an infectious disease. So devastating, in fact, that it wiped out nearly one-third of the population in Europe in the mid-1300’s. That’s roughly equal to 25 million people. It then persisted and has caused various outbreaks throughout history, most notably the Great Plague of London in which 1 in 5 residents died.

So why should be care about the Plague today? Isn’t that old news?

While I will go into more detail about the history of the plague a little later, I first want to mention what prompted me to write about what many people consider to be a no-longer-relevant disease. In order to gauge modern perceptions of the plague, I took a very unofficial survey of friends and family from various backgrounds about what they knew about the Plague. While the knowledge base ranged quite a bit, most were very surprised to hear that we still have cases of the Plague here in the United States.

Yes, you heard me right. The Plague still exists in the United States.

Of course, due to increased knowledge and antibiotic therapy, we no longer see the sweeping epidemic that caused so much turmoil throughout history. Nevertheless, an Oregon man is currently suffering from a rare case of the “Black Death.”

According to reports, a stray cat bit the unidentified man while he was trying to pull a mouse away from the cat. (I won’t even begin to speculate as to why this man was attempting to steal a mouse away from what was likely a very hungry stray cat, but that’s another story.) Several days later the man began to feel ill and presented to the hospital with symptoms typical of the Plague. These included fever, swollen lymph nodes and stomach pain. It has since progressed to bleeding mouth, nose and anus, and dying tissue.  Although the CDC has yet to confirm the diagnosis, all signs point to the Plague.

Only 10-15 people report becoming ill with the disease each year in the United States; this man is the fifth person in Oregon since 1995.

The Plague is caused by the bacterium Yersinia pestis., a rod-shaped bacillus that can live in various species of animals including rats, mice, squirrels, cats, prairie dogs, camels, and rabbits, among others. Yersinia pestis can then be transferred to humans through direct contact with infected animals, bites from fleas that have previously fed on infected animals (this is most common), or human-to-human through the air. Historically, the high population of small rodents and their flea friends in urban areas were attributed to the rapid spread of the disease.

While the Bubonic plague may be the most well known form of the disease, there are actually three different types of the Plague.  The Bubonic plague is the most common form and is characterized by buboes – painful, swollen lymph nodes – in the groin, armpit or neck. Septicemic plague occurs when the bacteria begins to spread in the bloodstream. Lastly, the most infectious form of the disease is Pneumonic plague. This advanced stage strikes when the bacteria can be passed from person to person through airborne droplets coughed up from the lungs. Bubonic plague is fatal roughly half the time, while Septicemic and Pneumonic are almost uniformly fatal without antibiotic treatment.

The man in Oregon was first believed to be suffering from Bubonic plague, but is now beginning to show signs of Septicemic plague, meaning it has entered his bloodstream and is able to reach all different parts of the body.  Luckily, antibiotics are effective in the treatment of the Plague if given early enough. Without antibiotics, 1 in 7 people infected end up dying.

So you may be asking yourself, as I did, where a deadly disease like this came from in the first place. The puzzling start of the epidemic went something like this:

“The Black Death arrived in Europe by sea in October 1347 when 12 Genoese trading ships docked at the Sicilian port of Messina after a long journey through the Black Sea. The people who gathered on the docks to greet the ships were met with a horrifying surprise: Most of the sailors aboard the ships were dead, and those who were still alive were gravely ill. They were overcome with fever, unable to keep food down and delirious from pain. Strangest of all, they were covered in mysterious black boils that oozed blood and pus and gave their illness its name: the “Black Death.” The Sicilian authorities hastily ordered the fleet of “death ships” out of the harbor, but it was too late: Over the next five years, the mysterious Black Death would kill more than 25 million people in Europe–almost one-third of the continent’s population.”

Unfortunately, the cause of the disease was not discovered until 1894, long after it swept through Europe with alarmingly high death rates. People had their ideas about what was causing the Black Death, but no one could actually figure it out. Some believed it was the spirit escaping the eyes of a sick man and infecting the nearest healthy person, others believed it was God’s way of punishing those who had sinned.  Citizens were so panicked that they went to extreme lengths to avoid contracting the disease, even so far as to completely abandon loved ones who got sick. More details here.

As mentioned before, antibiotics can be extremely effective in fighting this bacteria. As of right now, the Oregon man is still fighting for this life, but thanks to modern medicine, his chances of living are fairly high. The man likely contracted the disease from the cat; however, the cat died shortly after and its remains have since been sent to the CDC for testing.  Who knew that a stray cat in the Northwest U.S. could have possibly been harboring bacteria that once had the potential to wipe out entire cities. Fortunately, modern medicine is on our side.

So is the re-emergence of the Plague something that we should really be concerned about? Probably not. But it never hurts to be informed.

References:

http://www.cdc.gov/ncidod/dvbid/plague/index.htm

http://ocp.hul.harvard.edu/contagion/plague.html

http://science.nationalgeographic.com/science/health-and-human-body/human-diseases/plague-article/

http://www.cbsnews.com/8301-504763_162-57452519-10391704/oregon-man-diagnosed-with-black-death-plague/

http://www.mayoclinic.com/health/plague/ds00493/dsection=symptoms

http://www.cdc.gov/ncidod/dvbid/plague/bacterium.htm

http://www.cdc.gov/ncidod/dvbid/plague/qa.htm

http://www.who.int/mediacentre/factsheets/fs267/en/

http://www.history.com/topics/black-death

Is Chagas Disease Really The New AIDS Of The Americas?

This is the seventh of 16 student posts, guest-authored by Joshua Pikora.

Recently an article published in PLoS Neglected Tropical Diseases titled Chagas Disease: “The New HIV/AIDS of the Americas” caused a stir in the media receiving coverage through Fox News and The New York Times among others.  This article, as the title indicates, claims that Chagas disease is the new AIDS of the Americas and likens the current situation of Chagas disease to that of the first two decades of the AIDS epidemic, but is that truly the case1?  The argument that I gained from the article is that the early decades of the AIDS epidemic and Chagas disease affected similar demographics of people, and that the current number of AIDS patients and Chagas disease patients with cardiomyopathy in the Americas are similar.  The argument that the populations are similar is that both diseases affected those living in poverty, that do not have access to medical care, and hidden populations homosexuals in the case of AIDS and immigrants in the case of Chagas1.  Also the numbers of those living with AIDS and Chagas disease with cardiomyopathy cited in the article are similar with 2-5 million people with cardiomyopathy and roughly 3 million people with AIDS1.  Additionally the article also argues that they are both chronic conditions, are expensive to treat and are stigmatizing1.  While this is a compelling argument I believe that the differences between the two diseases outweigh these similarities, and these similarities alone do not warrant declaring Chagas disease the “new” AIDS.  In my opinion the article is well written, and puts together a case to support their claim, but while I do not mean to discredit the article, or to imply that Chagas disease is not a serious disease and should not be addressed, I disagree that it is as big of a problem as AIDS is, and was in the early decades of the epidemic.

Beyond simple differences between the disease like that Chagas disease is caused by a protozoan and AIDS is cause by a virus I have several problems with the claim that Chagas disease is the “new” AIDS of the Americas.  My first problem with the claim is that, in my opinion, in order for something to be the “new” AIDS, AIDS itself must be dealt with first, and as the article makes clear, AIDS is still a problem in the Americas with 1.6 million people living with AIDS in Latin America and the Caribbean, and 1.2 million living with AIDS in the US1.   The second issue I have with the claim is that it includes North America.  The article states that 8-9 million people are living with Chagas disease in Latin America compared to 300,000 in the US, with most of them being immigrants and vector transmission being rare in the US1,2.  While I would agree that Chagas disease is a serious problem in Lating America that needs more resources, I still would not compare it to AIDS as the two have very different levels of burden, and need to be addressed in different ways based on transmission.

The article does point out that Chagas disease and AIDS do share some modes of transmission, but they also have some unique modes as well.  Both AIDS and Chagas disease can be transmitted from mother to child vertically, and through blood transfusions1.  However, according to the article the rate of vertical transmission of  Trypanosoma cruzi 5%-10% pales in comparison to that of untreated HIV which is 15%-40%, though the rates of vertical transmission of HIV when antiretrovirals are being used is only 1%-2%1.  In the case of blood transfusions the US has screened for T. cruzi since 2007 and HIV since 1985 and blood banks in Latin America also screen for T. cruzi2,3.  Though AIDS and Chagas disease do share these modes of transmission they also have vastly different modes.  Chagas disease is primarily a vector born disease, using triatomine bugs as vectors, with transmission occurring by the bug’s feces getting into the site where the bug bit the host2.  There is also evidence of Chagas disease being transmitted through food contaminated with the feces of infected triatomine bugs1.  On the other hand AIDS can be sexually transmitted, and can be transmitted by using needles that have been used by an infected person3.

The article does describe several ways in which AIDS and Chagas disease are different.  The first of these is based on the differences in morbidity and mortality between the two diseases.  The article cites that annual deaths and lose of DALYs in the Americas is five times greater for AIDS than it is for Chagas disease, which shows a clear gap between the two1.  Another difference the article points out is that while AIDS is almost always fatal, only 20%-30% of people with Chagas disease will develop cardiomyopathy, displaying another gap between the diseases1.  A third difference that the article states between Chagas disease and AIDS is the number of medications available for the diseases.  While there are no medications that cure AIDS there are a number of antiretrovirals available to use as treatment, whereas there are medications available that can cure Chagas disease if caught early these medications are few in number and are infective against the chronic form1.  The amount of time that the medications need to be taken also differs between the diseases, with antiretrovirals being needed for life for AIDS patients, and medication for Chagas disease needing to be taken for one to three months1.

While both AIDS and Chagas disease are serious disease and Chagas disease is a particularly important issue that needs to be addressed in Central and South America, I do not believe that it is appropriate to call Chagas disease the “new” Aids of the Americas or even of Latin America.  Whether the title of the article was a ploy for attention or an honest belief may never be known, but hopefully this media attention can increase the awareness of Chagas disease and efforts to contain it, without distracting from the still important issue of AIDS.

Works Cited

1. Hotez PJ, Dumonteil E, Woc-Colburn L, Serpa JA, Bezek S, et al. (2012) Chagas Disease: “The New HIV/AIDS of the Americas”. PLoS Negl Trop Dis 6(5): e1498.

2. Zieve, David. “Chagas Disease.” Pubmed Health. U.S. National Library of Medicine, 15 Sept. 2010. Web. 17 June 2012. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002348/.

3.  Dugdale, David. “AIDS.” Pubmed Health. U.S. National Library of Medicine, 9 June 2011. Web. 17 June 2012. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001620/.

Spotlight on Nasty Parasites: Echinococcus granulosus

This is the fifth of 16 student posts, guest-authored by E. Jane Kelley.

Did you know that some dogs might have a tapeworm in their small intestine that can cause the development of large cysts in people’s livers, lungs, and brains? This is not very common in the United States currently, though there are cases reported periodically (2), but in some areas of the world it is a huge problem. An infection that can spread from animals to humans or vice-versa is called a zoonotic infection.

The tapeworm is called Echinococcus granulosus and the cystic disease it causes is called hydatid disease (http://www.cdc.gov/parasites/echinococcosis/) .  Human beings are considered a “dead-end” host because they are not usually the host of the parasite. The most common life cycle of the tapeworm involves dogs as the definitive host (which means that the adult tapeworm lives in their intestine) and sheep as the intermediate host (which means that they have the immature stage of the parasite, called a metacestode, in their bodies). As you can imagine, this means that this infection is more common in areas of the world where there is extensive sheep-raising. There are other definitive hosts (such as foxes, wolves, coyotes, wolves and cats) and there are other intermediate hosts (cattle, goats, deer, rabbits, and rodents for instance), but the dog-sheep cycle is globally the most important as far as human disease.

Back to the life-cycle: the adult tapeworm is small and lives quite innocuously in the small intestine of the dog, not usually causing any problem for the dog. Tapeworm eggs are shed in the dog’s feces and, in the usual scheme of things, are ingested by sheep as they graze. The eggs develop into an immature stage of the parasite, which travels in the bloodstream from the small intestine to other organs such as liver and lung. After a while, the immature stage develops into a cyst in the liver and/or lung and the life cycle is complete when a dog eats organs from a dead sheep. In most cases, multiple small cysts (3-4 cm in diameter and they are fluid-filled) develop in the liver or lung of the sheep, but, remarkably, affected sheep do not usually show any clinical signs and the cysts are found at slaughter.

Sometimes humans ingest the eggs accidentally (this parasite is spread by what is called fecal-oral transmission from the dog to the human, use your imagination, enough said) and the cysts can form in the liver, lung, brain or other places in the human. In human beings, the infection tends to result in a single large cyst rather than multiple small cysts like the sheep. These can take years to develop and can become very large (20 cm in diameter or more). Some cysts in the liver do not cause problems, but cysts in the lung may cause respiratory problems such as coughing and shortness of breath and cysts in the brain are not good for obvious reasons. The treatment is surgical removal of the cyst.

Again, we don’t have much problem with hydatid disease in this country currently but there is potential for it to become more prevalent. It was believed to have been introduced in the early 1900s with infected livestock. Interestingly, the infection initially established itself in a domestic dog/domestic pig cycle (not sheep) in the east (8) and by the 1920s was in Mississippi, Louisiana, Tennessee, and Arkansas. By the 1970s, it was fairly prevalent in the sheep-raising areas of the west (Utah, Arizona, California, and New Mexico)(4) and there is a cervid (elk, moose, deer) cycle in wildlife in Canada, Alaska, and Minnesota (6). Recently in Montana and Idaho, approximately 60% of gray wolves sampled had adult tapeworms in their intestine and cysts were found in organs of elk, mule deer, and a mountain goat (5).

Let’s focus on Utah for a moment. Echinococcus granuosus was believed to have been introduced into the state in 1938 in sheep dogs from Australia (3). Sanpete County in central Utah is the area where most of the sheep-raising went on (and still does). In the 1970s Echinococcus granulosus was endemic in sheep and dogs in central Utah. Endemic means that the disease is constantly present in a certain area. About 25-30% of the dogs were infected and 13% of sheep carcasses examined had cysts (1,7). In addition, during this time period, there were several human cases. The close contact between sheep-herders and their families and the sheep dogs and sheep kept the cycle going. Also, the sheep were range sheep with common grazing allotments and contact with other dogs and sheep. Control measures such as proper disposal of dead sheep, hand-washing, regular deworming of the dogs and educating the families were implemented and greatly decreased the incidence of infection in dogs, sheep and people (1,3,7). However, there are occasional cases still in Utah so either control measures were not 100% effective and/or there is a wildlife reservoir of infection (such as coyotes). There have been 3 cases in humans reported to the Utah Department of Health since the 1970s and multiple liver and lung cysts were found in a slaughtered sheep in 2008.

In some areas of the world, such as China (11), Echinococcus granulosus is a serious and increasing public health concern. In China, it is considered an emerging or re-emerging disease (a disease that was at a low level but is recently causing many more infections). Eradication of hydatid disease has been achieved in some island countries such as Iceland, New Zealand and Tasmania (10). It is certainly an easier task to control infection on a relatively small island with a single government than in other areas. Control of infection involves measures previously mentioned such as  regular deworming of dogs, proper disposal of sheep and cattle carcasses, stray dog control, education about the importance of hand-washing, and elimination of wildlife reservoirs if present. This is not as easy as it sounds and requires long term commitment which may be a problem in countries with economic and political unrest. For example, in Kazakhstan (a country in central Asia), after independence from the Soviet Union in 1991, social and economic changes have brought about changes in animal husbandry (from large collective farms to smaller farms with closer contact between people, dogs, and livestock) such that incidence of Echinococcosis has been increasing in people, dogs, and livestock (9).

In the United States, hydatid disease is less likely to become a serious problem because we have a relatively stable government and the infrastructure for the handling of carcasses and stray dog control. However, there are parts of the country where this still exists and, I don’t know about you, but I don’t relish the thought of having a huge cyst in my liver or brain. For those of you who kiss your dogs, have you seen what dogs eat?  Add this disease to the list of reasons that it’s not a good idea.  Don’t let your dogs defecate in children’s playgrounds because small children are not very discerning about what goes in their mouth.

References:

  1. Barbour AG, Everett JR, Andersen FL, et al. Hydatid disease screening: Sanpete County, Utah, 1971-1976. Am J Trop Med Hyg 1978 Jan; 27: 94-100.
  2. Bistow BN, Lee S, Shafir S, et al. Human echinococcosis mortality in the United States, 1990-2007. PLos Negl Trop Dis 2012 Feb; 6: e1524.
  3. Crellin JR, Andersen FL, Schantz PM, et al. Possible factors influencing distribution and prevalence of Echinococcus granulosus in Utah. Am J Epidemiol 1982 Sep; 116: 463-474.
  4. Donovan SM, Mickiewicz N, Myer RD, et al. Imported echinococcosis in southern California. Am J Trop Med Hyg 1995 Dec; 53: 668-671.
  5. Foreyt WJ, Drew ML, Atkinson M, et al. Echinococcus granulosus in gray wolves and ungulates in Idaho and Montana, USA. J Wildl Dis 2009 Oct; 45: 1208-1212.
  6. Himsworth CG, Jenkins E, Hill JE, et al. Emergence of sylvatic Echinococcus granulosus as a parasitic zoonosis of public health concern in an indigenous community in Canada. Am J Trop Med Hyg 2010 Apr; 82: 643-645.
  7. Loveless RM, Andersen FL, Ramsay MJ, et al. Echinococcus granulosus in dogs and sheep in central Utah, 1971-1976. Am J Vet Res 1978 Mar; 39: 499-502.
  8. Pappaioanou M, SchwabeCW, Sard DM. An evolving pattern of human hydatid disease transmission in the United States. Am J Trop Med Hyg 1977 Jul; 26: 732-742.
  9. Shaikenov BS, Torgerson PR, Usenbayer AE, et al. The changing epidemiology of echinococcosis in Kazakhstan due to transforming of farming practices. Acta Trop 2003 Feb; 85: 287-293.
  10. Torgerson PR, Budke CM. Echinococcosis- an international public health challenge. Res Vet Sci 2003 Jun; 74: 191-202.
  11. Yang YR, McManus DP, Huang Y, et al. Echinococcus granulosus infection and options for control of cystic echinococcosis in Tibetan communities of Western Sichuan Province, China. PLos Negl Trop Dis 2009 April; 3: e426.

Atypical Typhus

This is the third of 16 student posts, guest-authored by Mary Egan.

Murine typhus has been in the news recently in Austin, TX, where in May of this year, two people were found to be positive and one died.  This rings a number of alarm bells for me, since I live in Texas, and specifically in Austin.  I know of another Austin veterinarian who got sick with murine typhus in 2008, when it was first noticed in Austin and investigated by the CDC.  I was also working as a relief vet at the Town Lake Animal Center, the municipal shelter, and at the Austin Humane Society, the main nonprofit adoption shelter which has a feral cat Trap-Neuter-Return surgery clinic, when the CDC investigators came to Austin.  They collected blood samples on local animals and also fleas.  Of course, at that time I wasn’t particularly interested in public health, just shelter medicine, and it didn’t really register.  Now I wish I could’ve gone back and tagged along to see more of what they were doing!

Murine typhus is an odd and off the radar disease.  It doesn’t help that murine and typhus are both words with multiple meanings.  Murine is a word that refers to mice, in Latin, murinus, or mouse, in Latin, mus.  It is also a type of eye drops and also a brand of ear wax remover.  How putting mice in your eyes or ears helps them is a mystery to me.  Murine also sounds very similar to marine, so it’s not unreasonable to start picturing typhus near the ocean, which is an odd coincidence, since murine typhus actually occurs primarily in coastal areas.

Typhus itself is a confusing word.  It comes from the Greek, and means hazy, which is how your brain feels if you’re infected.  It is not the same as typhoid fever, which is caused by Salmonella typhi, a bacteria that can cause food borne illness resulting in diarrhea and vomiting.  This is not that.

The typhus we are interested in is a tiny bacteria from the family Rickettsia.  And of course there is more than one type of typhus, to confuse the issue further.  Epidemic typhus is the ancient disease that has been a major player in history.  It was first noted in the Spanish blockade of Granada in 1489, and then killed more of Napoleon’s army than the Russians.   This is Rickettsia prowazekii, which is carried on lice and affects humans.  This is the typical typhus.  If you ever read just “typhus” it is referring to this type of typhus.  It has also been called jail fever, since many old jails were breeding grounds for lice, and the prisoners were more likely to die of infection than be hung for their misdeeds.  This typhus can cause a rash, fever, severe headache, joint pain, kidney failure, delirium, stupor, and even death in 10-60% of cases if it’s not treated.  A blood test will show if there are antibodies to typhus if you go to your doctor with these signs.  There is an effective treatment, a course of antibiotics that kills the rickettsia, and supportive care depending on how far along the disease had progressed.  It is possible for the agent to go underground, and then reappear later in life.  Then it is called Brill-Zinsser disease and is often a very mild form of epidemic typhus, still treated with antibiotics.

The typhus that showed up in Austin is murine typhus, also called Rickettsia typhi, and it is carried on fleas and primarily affects rats.  This is also called endemic typhus because it is pretty much always present on rats in the environment.  Humans historically get it as a side product of coming into contact with rats carrying the infected fleas.  This disease is usually not as severe as epidemic typhus, but can still cause all the same signs and symptoms, and rarely can lead to death if not treated.  Less than 2% die of murine typhus if it is not treated with antibiotics.

Murine typhus has a worldwide distribution, but in the United States it is usually seen near coastal areas in California, Hawaii, and Texas.  The 2008 cases were odd that they were in Austin, in central Texas.   In the previous 25 years, there had only been four cases total.  In 2008 there were 13 cases in the four months from March to July, and a total of 33 cases by October.  Of these, 70% of the people infected were hospitalized with myalgia, severe headache, and fever, and the most severe cases were treated for pneumonia, kidney failure, and coagulopathy.   There were no deaths.  This outbreak showed that aside from the normal rat-flea cycle, there are likely other cycles that involve domestic and feral cats, opossums, dogs, and the fleas that live on them.  And consequently, the fleas that live on domestic cats and dogs then live in the yards and homes of their owners, and then can live on the owners themselves.

The cases were clustered in the central Austin area, with a large percentage coming from one zip code that contains a large portion of the exceedingly popular Town Lake Hike and Bike Trail used by over 20,000 people daily, and the smaller but more wild Shoal Creek Trail.  There have been reports of coyote sightings and suspected killings of family pets in this zip code.  So there is ample space for wildlife within this urban environment.  This also means there are plenty of hosts for fleas.  And Austin in general and this neighborhood in particular is known for a slightly hippy, crunchy granola lifestyle preferring organic and natural everything, with easy access to the outdoors and hiking trails.  It is not surprising this outbreak occurred in this area.

So what does all this mean?  Diseases which were previously uncommon are now becoming more common due to changes in lifestyle.  People want to live close to nature and have trails to walk their dogs.  There is nothing wrong with that.  It’s the parasite hitchhikers their pets pick up and bring home that’s the problem.  And changes in behavior where dogs are now not only in the house, but often in the bed with their owners, means that those fleas have a chance to bite humans.  That doesn’t mean you shouldn’t walk your dog on the trail.  But it does mean you need to use protection.  Spray yourself and your clothes with a flea killing insecticide such as DEET when out walking.  Wear boots, long pants, and long sleeved shirts.  Use appropriate flea control on your pets.  Kill fleas in your yard or home with appropriate premises control measures.  It’s great to be one with nature, you just don’t want that nature to bite back with a case of murine typhus.

Bibliography

1.  Adjemian J, Parks S, McElroy K, Campbell J, Eremeeva ME, Nicholson WL, et al. Murine typhus in Austin, Texas, USA. Emerg Infect Dis. 2010 Mar.   Accessed June 13, 2012.  Available at: http://wwwnc.cdc.gov/eid/article/16/3/09-1028.htm

2.  James C.  Two cases of typhus in Travis County.  KXAN web site.  Accessed June 13, 2012.  Available at: http://www.kxan.com/dpp/news/local/austin/2-cases-of-typus-in-travis-county

3.  Typhus.  Wikipedia website.  Accessed June 13, 2012.  Available at: http://en.wikipedia.org/wiki/Typhus.

4.  Murine typhus.  Texas Department of State Health Services website.  Accessed June 13, 2012.  Available at: http://www.dshs.state.tx.us/idcu/disease/murine_typhus/information/

5.  Conlon J.  The historical impact of epidemic typhus.  Accessed June 13, 2012.  Available at: http://entomology.montana.edu/historybug/typhus-conlon.pdf.

6.  Google map of 78703 zip code.  Google maps website.  Accessed June 13, 2012.  Available at: http://maps.google.com/maps?oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&q=78703&um=1&ie=UTF-8&hq=&hnear=0x8644b55c47d7dc5f:0x717c8b7186632905,Austin,+TX+78703&gl=us&ei=i7DTT9vPJsLQ2AX54riFDw&sa=X&oi=local_group&ct=image&ved=0CHQQtgM

7.  Gonzales R.  Santa Ana announces flea-borne typhus alert.  Orange County Register website.   Accessed June 13, 2012.Available at: http://www.ocregister.com/news/santa-356066-control-typhus.html

8.  Roving pack of coyotes mauls pets.  KXAN website.  Accessed June 13, 2012.  Available at: http://www.kxan.com/dpp/news/local/austin/roving-pack-of-coyotes-maul-pets

Bugs in your berry juice

This is the first of 16 student posts, guest-authored by Riva Ben-Ezra.

Acai fruit comes from the Brazilian Amazon forests and is one of the main dietary staples of the native population.  It has been touted as having potent antioxidant properties 1,2 as well as being a stimulant for weight loss3, a cancer cure and an anti-aging miracle drug.  Whether these claims are true or not remains to be seen4,5; however the FDA has clamped down on Acai products claiming to perform health benefits without classifying themselves as drugs (see here, here and here).

Something that the FDA has not taken into consideration, however, is the presence of triatomines in Acai juice.  Triatomines are blood-sucking insects that have been found in South America (mainly Brazil), Texas and Mexico.6 These bugs can carry a protozoan parasite called Trypanosoma cruzi, which is the causative agent for Chagas disease.6  Chagas disease is considered a “Neglected Disease” by the CDC because:

These infections are considered neglected because relatively little attention has been devoted to their surveillance, prevention, and/or treatment.

Chagas disease can be divided into two phases: acute and chronic.  In the acute phase, the most common symptoms are fever and swelling where the parasite feces entered the patient.  The chronic phase is hallmarked by the development of cardiomyopathies, arrhythmias, and megaesophagus or megacolon. 6 The disease can “hibernate” in the body and re-activate during times of stress or immunosuppression.   The WHO estimates that 10,000,000 people worldwide have been infected with Trypanosoma cruzi, and the CDC estimates that approximately 300,000 of those people are living in the United States.  The most common methods of becoming infected include:

  • being bitten by a triatomines insect
  • receiving a contaminated blood transfusion
  • transferring it through the placenta to a fetus
  • receiving a contaminated organ transplant, and
  • ingesting contaminated food

Since 2009, the last option mentioned above was considered to be rare.  However, in the past three years, several studies have been published confirming the transmission of Chagas disease through contaminated food in Brazil, Venezuela and Colombia (not the US).7  The suspected or confirmed culprits include acai juice/paste, orange juice, guava juice, sugarcane juice, and other (unknown) meal items.7  An epidemiological trace-back to discover the source of the protozoa on infected food revealed the presence of feces from either triatomine bugs or other animals such as opossum, marsupial or rodent8 9 already infected with the protozoa7.  From observing the processing of Acai fruit and sugar cane, it was revealed that conditions are frequently unsanitary and that there are many instances when the triatomine bugs are ground up with the fruit to make juice.10  In 2007, the Brazilian authorities drafted a guidance document to control foodborne transmission of Trypanosoma cruzi, but as evidenced by the data above, there is little compliance with these recommendations.7
Triatomine bug

Triatomine bug, Trypanosoma cruzi vector, defecating on the wound after taking a blood meal.

 Source: http://dpd.cdc.gov/dpdx/HTML/ImageLibrary/TrypanosomiasisAmerican_il.htm

So, given the fact that people can and do become infected with Trypanosoma cruzi through eating contaminated fruit and other foods, and given the fact that the WHO, EFSA, and the CDC all recognize that oral transmission of Chagas disease is an emerging infectious disease, how have our regulators addressed this risk?

The simple answer is: not at all.

In the United States, fruit juice must be processed under a food safety system called HACCP- Hazard Analysis and Critical Control Points.  HACCP requires the manufacturer to identify the possible hazards associated with the production of this food, and preventing those hazards from being present in the final product.  The FDA’s Guidance for Industry: Juice HACCP Hazards and Controls Guidance was published in 2004 as a response to an outbreak of E. coli 0157:H7 in apple juice11,12.  It states:

The HACCP regulation requires you to use treatments capable of consistently achieving at least a 5-log reduction (using ten as the base number) in the level of the pertinent microorganism in your juice…The “pertinent microorganism” is the most resistant microorganism of public health significance that is likely to occur in the juice and is the pathogen that you must target for the 5-log pathogen reduction treatment (21 CFR 120.24(a)). By choosing the most resistant pathogen as your target, you are also treating the product for all other pathogens that are less resistant to the means of treatment.  One way to identify the pertinent microorganism for your juice is to consider whether there have been any illness outbreaks associated with this type of juice, and what microorganisms have caused the outbreaks. If certain pathogens have been demonstrated, i.e., through outbreaks, to be potential contaminants in certain juices, then the pertinent microorganism for your process typically should be one of these pathogens.

Sounds good, however further on it lists the various hazards that may be present in fruit juice, and it does not include the protozoan parasite Trypanosoma cruzi.  It also does not require pasteurization for all fruit juices, the only known method to destroy Trypanosoma cruzi.10  The FDA permits other methods to create a 5-log reduction such as high-pressure, UV radiation, or surface sanitation; none of which have been shown to be effective in destroying Trypanosoma cruzi.

The CDC published an article entitled “Preventing Health Risks Associated with Drinking Unpasteurized or Untreated Juice” on their web site.  Their recommendations are as follows:

Untreated (raw) juice has not been treated in any way to kill pathogens that may be present. This type of juice may be found in the refrigerated sections of grocery stores, health-food stores, cider mills, and farm markets. Another form of untreated juice is untreated cider. One way to make this cider safer is to heat it to at least 170° F. Prepackaged, untreated juice must bear a warning label that looks similar to this one:

sign

To minimize health risk, young children, the elderly and people with weakened immune systems should not consume packaged juice that bears the above warning label or any other form of juice that is known to be untreated (e.g. untreated juice served by the glass at a roadside cider stand). Anyone who wishes to reduce their risk may follow this recommendation.
If it is unclear that a juice has been treated to destroy harmful bacteria, avoid drinking it.

This is definitely a step in the right direction-however, not only high-risk individuals can become infected with Trypanosoma cruzi, and the recommendations should reflect that.

Looking at other countries, we find a variety of responses.

The Codex General Standard for Fruit Juices and Nectars does not include any reference to pasteurization or other treatment to control the transmission of Trypanosoma cruzi in fruit juice.  The Code of Hygienic Practice for Fresh Fruits and Vegetables does address the general notion of prevention of contamination during harvesting and storage.

 

The Australia New Zealand Food Authority discussed the possibility of requiring orange juice to be pasteurized or to require a label stating that the product is unpasteurized as in the US, and recommended similar requirements as the FDA in 2001.  As of 2008, however, the Fruit Juice Standard does not require any form of pathogen reduction treatment or labeling.

 

The European Union, similar to Australia, does not have any requirement for pathogen reduction treatment or labeling within their legislation.  They do require HACCP for all factories manufacturing fruit juice and with that should be the listing of the presence of Trypanosoma cruzi as a hazard to be eliminated.

 

The Canadian Food Inspection Agency published the “Code of Practice for the Production and Distribution of Unpasteurized Apple and Other Fruit Juice/Cider in Canada” which addresses the possibility of fecal contamination of the fruit used to make juice and outlines procedures to minimize the presence of microbial contamination in the final product.  It also requires manufacturers to label unpasteurized products as such.  In their Holiday Food Safety Tips for consumers, they write:

  • When making punch or serving cider, check the product label to make sure the juice or cider has been pasteurized.
  • If the juice or cider has not been pasteurized, bring it to a rolling boil and then cool before serving.
  • Unpasteurized fruit juice and cider may contain bacteria like Salmonella and E. coli that can cause serious illness, especially in children, seniors and people with weakened immune systems.

Again, similar to the CDC recommendations, they do not address the fact that healthy people can become infected with Trypanosoma cruzi by drink unpasteurized juice.

Returning to Acai berries, what is the take-home message for you, the consumer?

 

  • Make sure you only drink pasteurized juice.
  • Don’t use skin products with Acai berries in them unless the product has undergone a heat treatment.
  • Don’t accept claims that Acai berries cure disease.
  • When travelling to Latin and South America, be sure to eat food from a reliable source and do not eat fruit that has not been pasteurized.

 

 

Sources:

1. Lichtenthler R, Rodrigues R, Maia JGS, Papagiannopoulos M, Fabricius H, Marx F. Total oxidant scavenging capacities of euterpe oleracea mart. (açaí) fruits. Int J Food Sci Nutr. 2005;56(1):53-64.

2. Jensen G, Wu X, Patterson K, et al. In vitro and in vivo antioxidant and anti-inflammatory capacities of an antioxidant-rich fruit and berry juice blend. results of a pilot and randomized, double-blinded, placebo-controlled, crossover study. J Agric Food Chem. 2008;56(18):8326-8333.

3. Udani J, Singh B, Singh V, Barrett M. Effects of açai (euterpe oleracea mart.) berry preparation on metabolic parameters in a healthy overweight population: A pilot study. Nutrition journal. 2011;10:45-45.

4. Are some of the more exotic berry types, such as goji and açaí berries, better for health than the more common berries such as strawberries, blueberries and raspberries? Mayo Clinic health letter. 2010;28(11):8-8.

5. Marcason W. What is the açaí berry and are there health benefits? J Am Diet Assoc. 2009;109(11):1968-1968.

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Holy influenza, batman!

Typically when we think of flying things and influenza viruses, the first images that come to mind are wild waterfowl. Waterbirds are reservoirs for an enormous diversity of influenza viruses, and are the ultimate origin of all known flu viruses. In birds, the virus replicates in the intestinal tract, and can be spread to other animals (including humans) via fecal material.

However, a new paper expands a chapter on another family of flying animals within the influenza story: bats.

I’ve written previously about the enormous diversity of microbes that bats possess. This shouldn’t be surprising–after all, bats are incredibly diverse themselves, encompassing about a fifth of all known mammalian species. Though rabies is probably the most famous bat-associated virus, other viruses that have been isolated from bats include Nipah and Hendra viruses, SARS coronavirus, Chikungunya virus, Japanese and St. Louis encephalitis viruses, Hantaan virus (a relative of the Sin Nombre hantavirus), and filoviruses, among many others. And of course, a bat->pig->human cross-species infection ended up being a plot line in the recent movie, Contagion (modeled after Nipah virus). However, bats still remain chronically under-studied, despite the fact that they can carry so many potential human pathogens.

This new research expands our knowledge of bat viruses a bit. The authors examined 316 bats from eight locations in Guatemala in 2009-10. Rectal swabs were obtained and screened for influenza virus using molecular methods (looking for influenza virus RNA). Three of the samples tested positive, and all were from little yellow-shouldered bats (Sturnira lilium). This could indicate some clustering and transmission of the virus within bat colonies–and indeed, two of the bats were from the same area in the same year (2009). However, the third bat was captured in 2010 at a location 50 km away from the other two, suggesting that the virus may be more widespread than in just one colony.

When we discuss the epidemiology of influenza viruses, we talk about two genes: the HA gene, which encodes the hemagglutinin protein and allows the virus to bind to host cells; and the NA gene, which encodes the neuraminidase protein and allows the virus to leave an infected cell and spread to others. This is where the “H1N1” or “H5N1” nomenclature come from. The novel bat virus was a completely new H type–type 17 (provisional, they note, pending further analyses). The NA gene was also highly divergent, but they are awaiting further analyses to more definitively classify this gene. (Currently there are 9 recognized types of NA genes).

Though they weren’t able to culture out the flu viruses, the authors did do some molecular work suggesting that these novel bat viruses could combine with human viruses and form a functional recombinant virus. What implications could this have for human health? Well, hard to say. We still know very little about all the implications of any distinct type of avian influenza virus, or swine influenza virus, much less something completely foreign like bat flu. It’s interesting that, like birds, influenza virus in bats was found in the intestine (though lung samples were also positive). Can it cause an intestinal infection as well as an upper respiratory infection (the latter being more common in other mammal species)? Does it cause any signs of disease in infected bats at all? If they can get this bat virus to grow, all sorts of interesting lines of research are just waiting.

The article also mentions that seroepidemiological studies are currently being carried out to better understand the epidemiology of bat flu. Looking at PubMed, there is one reference to some similar studies carried out in the early 1980s, but I can’t access anything beyond the title. There also is a report of H3N2 influenza in bats in Kazakhstan, but that article is in Russian and also not readily available. Either way, everything old is new again, and it looks like interest in bat influenza has resurfaced after a 30-year lull. Who knows what else we’ll find lurking out there as interest continues to increase in the wildlife microbiome.

Reference

Suxiang Tong, Yan Li, Pierre Rivailler, Christina Conrardy, Danilo A. Alvarez Castillo, Li-Mei Chen, Sergio Recuenco, James A. Ellison, Charles T. Davis, Ian A. York, Amy S. Turmelle, David Moran, Shannon Rogers, Mang Shi, Ying Tao, Michael R. Weil, Kevin Tang, Lori A. Rowe, Scott Sammons, Xiyan Xu, Michael Frace, Kim A. Lindblade, Nancy J. Cox, Larry J. Anderson, Charles E. Rupprecht, & Ruben O. Donis (2012). A distinct lineage of influenza A virus from bats PNAS Link.

Is the HPV vaccine “weak science?” (Hint: no)

Oh, Discover. You’re such a tease. You have Ed and Carl and Razib and Phil and Sean, an (all-male, ahem) cluster of science bloggy goodness. But then you also fawn over HIV deniers Lynn Margulis and Peter Duesberg. Why can’t you just stick with the science and keep the denial out?*

But no, now they’ve let it spill into their esteemed blogs. I was interested to see a new blog pop up there, The Crux, a group blog “on big ideas in science and how these ideas are playing out in the world. The blog is written by an outstanding group of writer/bloggers and scientist/writers who will bring you the most compelling thoughts throughout the world of science, the stuff most worth knowing.” Sounds ok, let’s see what stories are up…oh, one on HPV! Right up my alley. And hey, a woman! Bonus.

*Reads story*

Ohhhhh, it’s actually one on HPV vaccine misinformation, written by the author of the fawning Duesberg article referenced above. Faaantastic.
Continue reading “Is the HPV vaccine “weak science?” (Hint: no)”