Student guest post: A taste of Lyme

Student guest post by Kyle Malter

In many areas of the country there is a vile blood sucker that lurks in our forests, our parks and even our backyards.  What concerns us is not what this creature takes but rather what it leaves in our body after it bites us:  corkscrew shaped bacteria called spirochetes and with the name Borrelia burgdorferi.  When the bacteria invade our bodies and cause problems along the way we call it Lyme disease.

It is Lyme, not “Lymes” disease, and here’s how it got that name. In the early 1970’s a large number of cases emerged involving children with a “bulls-eye” rash followed by arthritis and they were concentrated in a small area in and near Lyme, Connecticut.  Initially, the cause of the disease was unknown.  A clue to the mystery was that most of the kids lived near a wooded area.  After more investigation, ticks that feed on deer were identified as likely suspects.  The medical community learned that the “deer tick” transmitted the spirochete bacteria which was likely infecting the children and causing symptoms.  A researcher named Willy Burgdorfer helped identify the organism and in honor of his contribution the bacterium was named Borrelia burgdorferi. [1]  Wouldn’t it be fun to have a nasty bacteria named after you?

Signs of Lyme disease can vary from a mild rash to serious pain and disability. If infected, a “bull’s-eye” rash occurs in most people because of the inflammation left in the trail of the migrating bacteria. They move from the bite site away leaving the classic target appearance.  When this bug spirals though your joints, organs and tissues it can cause damage and a wide range of symptoms including fever, headache, lethargy, stiffness and general soreness.   In some cases, more serious and long-term problems with swollen joints, arthritis, Bell’s palsy, and even heart disease can result.   The symptoms can come and go and may last a lifetime.  [1] This is one serious problem if you have the disease-spreading tick in your environment.  Most people refer to the species as the “deer tick” or the “black-legged tick” although the proper name is Ixodes. Don’t forget about your dogs either.  They are also commonly infected in endemic states, can get permanent arthritis, and can rarely even die from the disease. [2]

Lyme disease has been diagnosed in all 50 states but is heavily concentrated in the northeast and upper Mid-West. [3] Approximately 96% of cases come from only 13 states. [4] CDC data by state, maps and disease forecast models show a clearly increasing trend.  Why such a steep increase in the number of cases?  There are probably many reasons.  First, surveillance is probably higher now than it was 15 years ago.  We simply weren’t looking for it as much then.  Another contributor is the increased population of the white-footed mouse in some regions. [5] This rodent is a reservoir for the bacteria meaning they harbor the bug until the tick larva come for a meal.  They are like a bank filled with Borrelia ready for every tick to make a withdrawal.  Once the tick has the bug in its gut, it is a loaded gun.

The recent increase in the white-footed mouse population may be the result of a cascade of events. “Change one thing. Change everything.”[6] Ohio reported two recent “banner years” for acorn production with a 36% increase in white oak acorns between 2011 and 2012.[7] A more abundant supply of “mouse food” in the way of acorns could result in more mice because they replicate much more efficiently.  More white-footed mice means more banks filled with Borrelia.  Ticks have a much better chance of making a withdrawal with every meal.  More ticks with Borrelia means more animals and humans infected.   So that’s how more acorns could mean more Lyme disease.

If you are unsure if Lyme bacteria are in your area just ask your dog.  Some studies suggest that dogs that live in your area may be able to predict your risk level. [8] [9] [10]  For those in the northeast and upper Mid-West you don’t have to ask.  It is ubiquitous in these parts of the country. Veterinarians in many non-endemic states are now screening dogs yearly to see if they have ever been infected with Borrelia.   If some dogs in your region are positive you should be more vigilant.  The CDC will keep track as well so check their Lyme page annually.

Preventing Lyme disease can be a very big challenge.  For dogs, very effective vaccines are available to protect them. [11] [12] So if this is such a potentially devastating disease in people why don’t we have a vaccine for humans?  Well, we did.  In the late 1990’s a vaccine was approved by the FDA to aid in the prevention of Lyme disease in humans.  While the safety and efficacy during the approval studies were good, there were skeptics and strong opponents in the public and medical community.  Some people claimed that the vaccine caused Lyme disease rather than prevent it.  Ultimately, the vaccine manufacturer withdrew it from the market citing poor demand. [12] Allen Steere, the man who discovered Lyme disease, also led one of the SmithKline Beecham (SKB) Lyme vaccine trials.  He said, “the withdrawal of the SKB vaccine . . . represents the most painful event in our Lyme disease history . . . the vaccine was really withdrawn because of fear and lawsuits, not because of scientific findings” [13]  Some advocates are attempting to rekindle efforts to make a vaccine for Lyme disease available again while others are opposed to the idea.

Tick prevention is our best strategy to prevent Lyme disease. Without a tick bite you cannot get Lyme disease.  In fact, even if an Ixodes tick bites you, it takes at least 24-48 hours of attachment to transmit the bacteria into your body. The National Institutes of Health suggest that you follow their fashion advice and tuck in your shirt into your light colored pants, tuck your pants into your socks and then put tape around the bottom. [1] I’ve never seen this method utilized in a public place but I’m sure you will end up on the “People of Wal-Mart” site if you try it.  The CDC recommends pyrethrins on your clothing and DEET on your skin and clothing to repel ticks. [4] The EPA also has a nice online tool.  Check yourself everyday for ticks during peak months.  Deer ticks are tiny so take some time and inspect your nooks and crannies.  The nymph stage, the second smallest tick in this picture,  is the one that usually infects people.  Again, don’t forget about your dog. While he can’t give you Lyme disease, he is also susceptible to it. Ask your veterinarian which flea and tick preventative is right for your pets.

Kyle picture

Lyme disease is no longer just a Lyme, Connecticut problem.  If it is not yet in your backyard, it could be soon. Lyme disease can have lifelong, debilitating consequences. Arm yourself with information and your body with tick protection.  We are not defenseless.  Protect yourself.   Protect your dog.  Please.

References:

[1] NIH Website http://www.niaid.nih.gov/topics/lymedisease/understanding/pages/intro.aspx

[2] Littman MP. Lyme nephritis. J Vet Emerg Crit Care (San Antonio). 2013 Mar-Apr;23(2):163-73

[3] Smith BG, Cruz AI Jr, Milewski MD, Shapiro ED. Lyme disease and the orthopaedic implications of lyme arthritis. J Am Acad Orthop Surg. 2011 Feb;19(2):91-100

[4] Centers for Disease Control and Prevention www.CDC.gov

[5] National Science Foundation http://www.nsf.gov/news/special_reports/ecoinf/lyme.jsp

[6] Townsend, Tracy A., “Change One Thing, Change Everything: Understanding the Rhetorical Triangle” (2013). Rhetoric Unit. Paper 3.

[7] Ohio DNR http://www.ohiodnr.com/home_page/NewsReleases/tabid/18276/EntryId/3033/Acorn-Mast-Survey-Results-Show-Increases-for-White-Red-Oaks.aspx

[8] J M Lindenmayer, D Marshall, and A B Onderdonk.  Dogs as sentinels for Lyme disease in Massachusetts. American Journal of Public Health November 1991: Vol. 81, No. 11, pp. 1448-1455.

[9] Olson, Canines as Sentinels for Lyme Disease in San Diego County, California, Journal of Veterinary Diagnostic Investigation March 2000 vol. 12 no. 2 126-129

[10] Faith D. Smith, Rachel Ballantyne, Eric R. Morgan, Richard Wall Estimating Lyme disease risk using pet dogs as sentinels Comparative Immunology, Microbiology and Infectious Diseases, Volume 35, Issue 2, March 2012, Pages 163–167

[11] Levy et al. Use of a C6 ELISA test to evaluate the efficacy of a wholecell bacterin for the prevention of naturally transmitted canine Borrelia burgdorferi infection. Vet Ther. 2002 Winter;3(4):420-4

[12] Aronowitz RA. The rise and fall of the lyme disease vaccines: a cautionary tale for risk interventions in American medicine and public health. Milbank Q. 2012 Jun;90(2):250-77.

[13] Steere, A.C. 2006. Lyme Borreliosis in 2005, 30 Years after Initial Observations in Lyme Connecticut. Wien Klin Wochenschr 118(21–22):625–33.

[14} http://medicineworld.org/stories/lead/7-2010/protection-against-ticks-that-carry-lyme-disease.html

Student guest post: Unintended Consequences

Student guest post by Naomi Kirschenbaum

Although we can never know, there are estimates in the range of 15,000 displaced pets in the wake of 2005 Hurricane Katrina.  Many of the dogs found their way to shelters and homes in our community around the Monterey Bay in California.  As a local veterinarian the most notable observation I saw was how it “seemed” that so many were heartworm positive.  Six years later we have a published study finding a 48.8% prevalence of heartworm in these dogs.

This story is an example of a few important lessons.  First, how things seemed to me, in my clinical practice turned out to be 48.8% of the dogs, not all.  (Of course in our area we may have had a different subset of positive dogs, but I thought, in general, they were nearly all heartworm positive). Secondly, how long it takes for a study to be done and published.  In this case the study I referenced has a six year interval between the event and publication of data examining an aspect of concern.

Now, let’s step into the present.  I’m currently taking courses for a Masters in Public Health at the University of Iowa to branch out from my basic training in veterinary medicine.

Yesterday, in a course I’m taking we had a lecture on a group of zoonotic diseases, Trypanosomes.  This group of little single celled organisms, protozoans, causes problems all over the world.   In Africa it causes, Sleeping Sickness, in Latin America, Chagas’ disease.  We don’t hear a lot about it here in North America.

What came to my attention was a disease described in dogs, here, in the U.S. caused by one in this group called Leishmania.  Dogs are a known reservoir in areas where these diseases are endemic but these U.S. reports starting in the late 1990’s were in two breeds with whopping over representation, specifically Foxhounds1 and Neapolitan Mastiffs.

That’s weird, I thought.  I’ve been a small animal veterinarian for a long time and those are not two very common breeds.  What’s up?

The first two things you need to know have to do with our basic understanding of where this parasite lives and how it infects mammals.  It has been traditionally thought a mammal becomes infected from the bite of an insect vector (tsetse fly in Africa or sand fly in South America), which is carrying the protozoa.  Also, although this occurs more rarely, you can become infected by direct contact with the blood of an infected animal into your tissue, read blood-to-blood transmission.  This second bit of information will be important later.

As well from studying these outbreaks in Foxhounds, one research group received a donated pregnant bitch they new was infected which allowed them to examine the puppies and look to see if they were also infected.  They found Leishmania in the puppies.  This lends evidence of transmission of the organism from mother to puppies in utero. Their thought is the Leishmania protozoan circulates in the mother’s blood and crosses over the placenta to infect the developing fetuses.

An important point here is the novel idea that transmission of the infection can be vertical and DOES NOT REQUIRE A VECTOR.  This would mean you could sustain the parasite in a mammal population where it has never lived before and would not normally be expected to be able to live.

This disease is endemic in parts of Europe and these two breeds, although fairly rare here in the U.S., often are imported from Leishmania endemic areas to be incorporated into U.S. breeding stock lines.   These imported dogs are very valuable and key to their breeding programs.

The work done showing vertical transmission from mother to pup suggests we can establish the infectious agent in a host indefinitely.  So far we are lucky and the areas where these dogs live don’t have vector insects readily available.  I wouldn’t count on that lasting too long.  Between global travel and climate change alone, and if historical record of disease spread with so many other zoonotic infectious agents is any guide, it’s really, likely, just a matter of time.

So a final concern, more immediate, goes back to that second route of traditional transmission I described above, the direct contact, blood-to-blood infection.   Here’s the thing.  These dogs, the Foxhounds and Neapolitan Mastiff’s that are infected are breeding dogs.  Breeding dogs, by definition, are sexually intact.  Dogs that have their “parts” can more often get into scrapes (read: fights).  When dogs fight they really can tear each other up.  The fighting often occurs around the head, neck and ears.  All fight wounds bleed, a lot.  Ears especially bleed like stuck pigs.

People try to break up the fighting dogs.  People get bitten all the time doing this.  (Read: Do not try to break up fighting dogs yourself, but that’s another essay of it’s own).  The dog blood that is all over the dogs is now all over you.  You have an open bite wound.  The dog’s blood now is mingling with your tissue and blood.  You now have Leishmania.  This is the problem.

The good news is if you are immune-competent you should mount a good response to this insult and have a very good likelihood of clearing the infection.  It will require a significant effort calling upon both arms of your immune systems, the cellular and the humoral.  Unfortunately you will not be immune to reinfection should another exposure event occur.  The bad news is if you are in anyway immune compromised, not so good.  You are likely to get clinical illness.

I guess our best hope at this point in time is to help breeders see the need and importance of choosing disease free dogs.  Encourage them to buy and bring only dogs that they have tested and know are free of Leishmania into the U.S.  I know breeding for phenotype and working characteristics and abilities is the holy grail of breeders, but can’t we do it looking at the bigger picture, the greater good?

1Monti, Dean (June 2000). “Hunters hounded as leishmaniasis is diagnosed in Foxhounds”. J Am Vet Med Assoc 216 (12): 1887, 1890.

“Rabid” by Bill Wasik and Monica Murphy

Rabies is a disease without a public relations firm. In developed countries, human disease is incredibly rare–we see typically one or two deaths from rabies each year. In contrast, lightning is responsible for about 60 deaths each year. However, worldwide, rabies is another matter. Today is World Rabies Day, a reminder that 55,000 people still succumb to this virus every year–most of them in impoverished regions of Africa and Asia. While cases in the U.S. are typically due to wildlife exposure (rabid bats or even beavers or rabid kitten), infected dogs remain the main vector of infection in most rabies-endemic countries.

In a new book, “Rabid”, Bill Wasik and Monica Murphy have penned an ambitious history of rabies. It’s subtitled, “A cultural history of the world’s most diabolical virus,” and this emphasis makes Rabid unique. Indeed, while the recognition of the rabies virus is just a bit over a hundred years old, Wasik and Murphy trace the infection back to antiquity. The first half of the book is, as promised, a cultural history–4,000 years of literature references to rabies, hydrophobia, “rage” disease, and dog- and bat-borne contagion in places as far-flung as various mythologies (Greco-Roman, Christian, and Egyptian, to name a few); medical literature from Aristotle to Pasteur; and even the vampire myths from medieval times up to Sesame Street’s Count. Wasik and Murphy explore the animal metaphors used for millenia and examine them through the lens of rabies infection, as well as colorfully explain the various (mis)understandings of the virus and rabies epidemiology in ancient texts. Though Rabid is certainly a pop-science book, many portions of the book wouldn’t be out of place in various literature, history, and even religion classes, which again lends to the book’s eclectic flavor.

The latter half of the tale, then, focuses more narrowly on the science of rabies, covering Pasteur’s work toward a vaccine; the (rather late) discovery of bats as the ultimate reservoir of the virus; the challenge to mount vaccination campaigns in resource-poor areas, and the lingering fear of rabies to this day, which is sometimes justified and sometimes not. They also cover the controversy over the Milwaukee protocol as a treatment for symptomatic rabies, and the problem of rabies control.

Finally, Wasik and Murphy note that even today, almost 130 years after the development of the rabies vaccine, control of rabies among the biggest human source of disease–infected dogs–is almost as poor in some places as it was during pre-vaccine England. The methods to control it are, in some cases, also equally barbaric. The introduction of rabies into Bali in 2008 led to a mass cull of dogs, shooting many in the street. Eventually, a science-based vaccination strategy was adopted and seems to be helping, but not before well over 100,000 dogs were culled and several hundred people had been killed by the virus. Rabies may be an ancient disease, but it is a scourge that is still threatening us where government lacks the will and the funding to beat back “the world’s most diabolical virus.”

What you don’t see can hurt your cat…and you too

This is the second of 16 student posts, guest-authored by Eileen Ball.

The beauty of dogs and cats as companions is that we don’t have to raise them to go out into the world and be successful.  As pet parents we can set the household “rules” according to what works for us and get on with enjoying our pets; hopefully for many years.   According 2011-2012 APPA National Pet Owners Survey cats have now surpassed dogs as the most common household pets in the United States.  Despite this fact  the same survey reports that in 2010 only 30% of US veterinary patients were cats.  As a companion animal veterinarian I find these statistics alarming and I fear that many well-intentioned pet owners are simply unaware of the risks that can accompany the joys of cat ownership.

A common perception is that indoor cats don’t need veterinary care.  In this sentence there two big factors that need to be addressed.  The first, and for me the most obvious, is that indoor cats need veterinary care too!  In a bit I’ll get to explaining that even without outdoor threats,  such as motor vehicles and big dogs, indoor cats and their owners face almost as many dangers as their outdoor brethren.    The other part of the eleven word sentence at the start of this paragraph that requires definition is the concept of “indoor cat.”    During my ten years as a practicing veterinarian I had many a conversation with an owner that started with the question “Is Fluffy indoor or outdoor?”  Followed by the owner confidently responding “indoor.”  As we moved forward in our discussion and I asked more about how Fluffy spent her day I’d often learn that Fluffy had access to the yard or deck and often spent long periods of time there.  There were alternative versions of the discussion where Fluffy didn’t physically go outside but the dog did as well as scenarios where mice, birds or bats came indoors even though they weren’t invited.  The reality is that In order for a cat to be considered 100%  indoor it would need to live in a biosphere.

So why should you take your indoor cat to the veterinarian on at least a yearly basis?   The first and most important reason is that your cat has the potential to carry parasites and diseases that can be transmitted to you and your family.  These include but are not limited to:  hookworms, roundworms, fleas, ticks, ringworm and Rabies.  According to the CDC approximately 14% of the US population has been infected with a type of roundworm called Toxocara.  Indoor cats are a potential source of exposure as they generally use litter boxes and they frequently contact surfaces such as countertops, bathroom vanities, kitchen tables and bedding.  Many cat owners have the misunderstanding that because their cats do not go outdoors they are not at risk.  This is simply not true.  There are lots of indoor/outdoor parasite sources such as mice, rats, other pets and people.  Hookworm and roundworm infections are easily and safely prevented with a variety of medications.  Your veterinarian can run a simple fecal test to see if your cat is infected with these or other parasites.  Another concern for cat owners is the transmission of a type of bacteria called Bartonella.   In most cases infected cats will show no symptoms, although in some it may cause gum disease, conjunctivitis (swollen membranes around the eyes) or respiratory disease.  Bartonella can spread from cats to humans.  It is the causative agent of Cat Scratch Disease in people.  Cats often get this bacteria from fleas and they can transmit it to humans via bites and scratches.  While parasites and Bartonella are a significant risk for healthy humans in those who don’t have a fully functioning immune system the risk is magnified even further.

The most important disease that you can protect your indoor cat from is Rabies.  This is a virus that is spread via saliva and is almost always deadly.  Rabies infection is common in skunks, raccoons, foxes and bats.  A bat getting into the house through an open window or a chimney is a very real risk for any animal or person in your house.  If you should happen to find a bat in the house with your cat (or other pets) you must assume that they were bitten.  Because of the thick fur that cats have it can be impossible to see a small bite wound.  Depending on local laws you may be required to vaccinate your cat for Rabies every 1-3 years.

There are other conditions such as ringworm and toxoplasmosis that cats can have without showing any signs.  People with healthy immune systems are not likely to show symptoms if they are exposed to these parasites but for others with HIV, cancer, pregnancy or a suppressed immune system serious consequences can occur.  When I think of ringworm without symptoms I always recall one of my patients, Miss Kitty, who was loved and adored by her entire family.  Miss Kitty and her humans were originally from Hawaii and had moved to Virginia where I was in practice.  Since Miss Kitty couldn’t travel from mainland US to Hawaii without quarantine the relatives in Hawaii decided to come to Virginia for Christmas.  Miss Kitty’s human grandmother happened to have breast cancer and was undergoing radiation.  The family had a great holiday.  Shortly after her return to Hawaii the grandmother developed circular, itchy scabs on her skin.  Her MD diagnosed it as ringworm and asked if she had any pets.  The grandmother said “no” and the MD presumed she had picked it up from the environment and started treating her.  It was a couple months later in conversation with Miss Kitty’s owner that I’d inquired about the holiday visit and the grandmother’s health.  Miss Kitty’s owner described the wonderful time that they’d had and mentioned that the grandmother had enjoyed the trip except for her persistent skin lesions.  A bell went off in my head and I decided to test Miss Kitty’s hair for ringworm.  Sure enough even though she’d never had a problem with her skin Miss Kitty was positive for ringworm.  Based on the species we cultured the grandmother’s MD was able to change treatment and get her skin cleared up quickly.

Finally, as most people who have shared their lives with both dogs and cats will agree, cats are not small dogs.  While the process of domestication for both dogs and cats has been ongoing for thousands of years it is estimated that the dog started the process 9-10,000 years before the cat.  For this reason cats tend to display a “survival of the fittest” instinct that we don’t see in dogs. Because of this instinct cats generally aren’t transparent when they don’t feel well.  Some cats are prone to chronic heart, thyroid  and kidney diseases that can often be detected with a thorough examination and some bloodwork.  Although most of these chronic conditions can’t be cured, with good veterinary guidance they can be well managed and allow you to share many happy years with your cat.

If your cat hasn’t been to the veterinarian in awhile I hope you will consider scheduling an appointment.  This can not only make life longer and better for your cat it can also protect you and your family from serious disease.

References:

American Pet Products Association 2011-2012 Pet Owners Survey

http://www.americanpetproducts.org/pubs_survey.asp

http://www.cdc.gov/parasites/toxocariasis/epi.html

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002581/

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002310/

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002411/

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001661/

http://catvets.com/cfpandpractitionersearch/

Bartonella Spp. In Pets and Effect on Human Health,  Chomel et al. Vol. 12 number 3, March 2006,  www.cdc.gov/eid