Why quarantine for measles is critical…and quarantine for Ebola was not

Measles has come to the happiest place on Earth. As of this writing, a total of 32 cases of measles have been linked to Disneyland visits that took place between December 17th and 20th. About 75% of the cases identified to date were not vaccinated, either because they chose to forgo vaccines or because they were too young, and at least 6 have been hospitalized.

A measles outbreak is a public health disaster, which can cost into the millions of dollars in health resources. You can be sure that public health workers in California and beyond are working overtime trying to identify cases, educate those who were possibly exposed about how dangerous measles can be, and implement practices so that those who may have been exposed to measles don’t further put others at risk. This includes avoiding public places, and practices such as calling ahead to a doctor’s offices so possible cases can be ushered into private rooms rather than languishing in the waiting room. A clinic in La Mesa recently closed because of a potential measles exposure. An unvaccinated South Pasadena woman, Ylsa Tellez, received a quarantine order after her younger sister was diagnosed with measles. Tellez is fighting the order and “taking immune-boosting supplements” instead.

Why such extreme measures on the part of public health?

Measles is highly contagious. It’s spread by air, and so contagious that if an infected person enters a room, leaves, and an unvaccinated person enters the room hours later, they still can contract measles. Remember a few months back, when that figure was circulating showing that Ebola wasn’t particularly easy to spread? Well, measles very much is. The basic reproductive rate for Ebola is around 2, meaning on average each infected person will cause an additional 2 infections in susceptible individuals.

And what’s the reproductive number for measles?

Eighteen. Eight. Teen. I’m not exaggerating when I say that it is literally one of the most contagious diseases we know of.  On average, if you have 10 susceptible individuals exposed to a measles patient, 9 will end up getting sick.

How do we break the cycle of transmission? Vaccination is one way–if one has been vaccinated for measles, chances are very low (but not zero, because nothing is perfect) that they will contract measles. Beyond vaccination, the next-best intervention is to keep those who are infected away from everyone else. The way we do this is by quarantining them.

In public health terms, quarantine specifically refers to the separation of individuals who have been exposed to an infectious agent, *but are not yet ill themselves,* from the rest of society. That way, they’re unable to spread the infection to others. Quarantine makes the most sense when individuals can transmit the infection before they realize they’re sick, which is exactly the case with measles. Infected individuals can spread the virus fully 4 days before the characteristic rash starts to appear, and continue to spread it for another 4 or so days after the rash begins—potentially infecting a lot of people. The problem is, like Ylsa Tellez, they’ll feel fine while they’re out there in the general population. They don’t even have to be coughing or sneezing to spread it (symptoms which can appear prior to the rash)—they can just be breathing (something many of us like to do on a regular basis), and still contaminate their environment with the measles virus.

The difference in transmissibility also makes measles a very different situation from Ebola. Public health officials almost universally condemned quarantine for Ebola exposures, for two reasons: 1) Ebola wasn’t highly transmissible, and  isn’t airborne like measles is; and 2) because Ebola isn’t efficiently transmitted until late in the infection when the patient is very ill and likely bedridden. Quarantining Ebola patients was a political stunt, not a public health necessity.

This is why states have the legal authority to enforce quarantine for infectious diseases: it reduces the risk that asymptomatic, potential disease-spreaders will act as “Typhoid Marys” (another asymptomatic, deadly-disease-spreader), which is in the public interest. And while unvaccinated Tellez feels “attacked” and her mother thinks people are being “not nice” when they demand that Tellez submit to quarantine, their choice not to vaccinate has already put many others at risk of disease and, and is resulting in the quarantine of many other exposed individuals as well. In the 2011 Utah measles outbreak, 184 were quarantined and thousands of contacts traced, at an expense of approximately $300,000. The Disneyland outbreak has already spread into 4 states (California, Utah, Washington, and Colorado). Quarantine is one of our tools to stem the epidemic. In our recent outbreak among Ohio Amish, most willingly submitted to quarantine, and over 10,000 doses of the MMR vaccine were administered. Quarantine is undoubtedly a difficult prospect to face, but perhaps if Tellez and others had been vaccinated in the first place, they, and we, wouldn’t be in this situation.

Student guest post: The Fallacious Fad of Foregoing Vaccinations

It’s time for this year’s second installment of student guest posts for my class on infectious causes of chronic disease. First one this year is by Dana Lowry.

Humans have a long history of illness and death from infectious diseases. It wasn’t until the 1790s that we had a solution. Edward Jenner recognized that milkmaids never contracted smallpox but suffered from a more mild disease, cowpox. Jenner took pus from a cowpox lesion on a milkmaid’s hand and placed it in an incision he made in an eight year-old boy’s arm. He then exposed the boy to smallpox; the boy didn’t contract the disease, proving he was immune. Jenner experimented on several other children, including his own 11-month old son, and his theory of passing on immunity proved to be successful. The Latin term for cow is vacca, which is where Jenner coined the term “vaccine”. Jenner’s discovery eventually led to the eradication of smallpox from the U.S. in 1949 and from the world in 1979. For over a century, vaccines were limited to preventing smallpox but as we know today, vaccines prevent a large number of diseases.

Although many developing countries still suffer from the burden of preventable infectious diseases, the U.S. has greatly increased the life expectancy and quality of life through the use of vaccines. In the 1940s, the U.S. recommended vaccines for diphtheria, pertussis and tetanus; polio was added in the 1950s. In the 1970s, measles, mumps and rubella (MMR) were added to list. Today in the U.S., immunizations are recommended for 17 vaccine-preventable diseases during one’s lifetime and more are available for individuals traveling outside of the U.S. Many of these vaccinations are combined so they can prevent multiple diseases from one series of immunizations. The increase in life expectancy in the 20th century is largely attributable to vaccines. For each birth cohort vaccinated, 33,000 lives are saved, 14 million cases of disease are prevented, healthcare costs are reduced by $9.9 billion and $33.4 billion is saved in indirect costs. The Bill Gates Foundation believes that vaccines are one of the most cost-effective investments in global health, saving about 2.5 million lives each year. One child dies every 20 seconds from vaccine-preventable diseases while tens of thousands of other children suffer from severe illnesses and permanently disabling diseases.

Despite the facts, less and less parents are choosing to vaccinate their children today because of fears that vaccines are unsafe. Much of the controversy started with Dr. Andrew Wakefield, a former British surgeon and medical researcher. Wakefield published a paper in 1998 linking the MMR vaccine to autism and bowel disease. Wakefield’s entire study was found to be fraudulent and the infamous paper was retracted in 2010. But, what got more attention than a retracted science paper was Jenny McCarthy sharing her personal life story of how her son got autism from a vaccine on the Oprah Show. Unfortunately, more moms keep up-to-date with Oprah and popular news rather than science and still do not know the truth behind Wakefield’s falsified study; therefore, the autism myth continues.

Furthermore, parents argue “herd immunity”. If your children are effectively vaccinated then why would I have to worry about mine? First, many vaccine-preventable diseases still exist in other countries and can easily be brought into our country; second, some individuals do not build immunity to the disease even after vaccination. The more and more parents that opt out of vaccinations, the less protection their children have from the rest of the “herd”. Additionally, parents argue that their children should contract diseases “naturally” through the environment to build immunity. Parents don’t fully understand the severity of these diseases because many have been virtually eradicated through the successful use of vaccines. Though some crippling effects of polio still linger, it is rare to come across someone wearing braces or using a wheelchair as a result of a polio infection in the U.S. Many vaccine-preventable diseases can cause death during the initial acute illness and if the individual survives, he or she may be left with chronic effects that last a lifetime. Polio can lead to temporary or permanent paralysis, deformities in the hips, ankles and feet; measles, mumps and varicella can all lead to brain damage and mumps is known to cause deafness; hepatitis B can cause permanent liver damage and even liver cancer. The list of damaging effects goes on and on.

In some areas throughout the U.S., as many as 1 in 20 kindergarteners have not been vaccinated. As the antivaccination fad grows in American so do the infectious disease rates. Measles was said to be eliminated from the U.S. in 2000 but an average of about 60 cases of measles occurs each year, typically from traveling. However, in 2011, there were 17 measles outbreaks in U.S. communities and the number of cases jumped to 222. In 2012, the U.S. had one of the largest pertussis outbreaks in nearly 50 years. Nationwide, over 85,000 vaccine-preventable diseases occur each year. I am not arguing that vaccines have no potential side effects and have never caused adverse effects or even death in children. However, I do think vaccines have done considerably more good than harm. So I urge parents, before deciding to withhold your children from vaccinations, look into the facts and make a decision based on science – not popular news. Although outbreaks of disease have been conquered in the past, many vaccine-preventable diseases remain throughout the world and the U.S. is not immune to future outbreaks.

 

Temple Grandin is wrong on vaccines and autism

Temple Grandin is undoubtedly one of the most famous women with autism of our time. Trained in animal science, Dr. Grandin is a widely read author and noted speaker on autism. April is National Autism Awareness Month, and Dr. Grandin has a new book out, “The Autistic Brain.” Together, this must have seemed like a good time for the New York Times to interview her. Unfortunately, the interview is superficial and not very illuminating, and what Dr. Grandin does say is disappointing. Her take on vaccines and autism, which apparently is elaborated upon in her new book:

Q: In your new book, “The Autistic Brain,” you seriously entertain possible links between vaccines and autism in children, links that scientists have vehemently dismissed.

A: Well, there’s only one vaccine that could possibly be a problem, and that’s the measles-mumps-rubella vaccine. Now that they’ve changed the vaccine, it has fewer antigens, and that would make it a lot safer. But with the old version of the vaccine, I have not yet come across a study that looked at regressives — when a child had some speech but lost it.

Q: There has been a highly emotional battle between mothers of autistic children and the scientists who dispute their theories.

A: I have talked to maybe five or six of those mothers, and that’s the reason I don’t pooh-pooh it. Those mothers have all described the same things. They all have the vaccine, and then they talk about fevers and the weird wailing that started in just a few days. When I brought this up to an expert and asked, “Have you ever studied the regressive group separately?” I got silence.

This is the problem when scientists speak about areas where they’re not experts. I got a lot of flak for my post to my dad addressing vaccines, with people accusing me of being condescending and underestimating his intelligence, but this shows it’s not an intelligence thing at all. (Plus, my dad is plenty intelligent–otherwise why would I bother to write that for him at all?) Grandin is obviously intelligent. She’s also highly educated. She has a PhD in another field. But she’s not an expert in vaccines, as her comments show, and that’s the problem with scientists who speak outside of their area of expertise. Even the very educated amongst us can’t know everything, and it becomes problematic when we use our reputation as scientists to promote something that we don’t have the background knowledge to really understand.

So, Grandin. First, she’s simply wrong about MMR formulation. Perhaps she’s thinking of the DTP vaccine, which now includes an aceulluar pertussis component (“DTaP” or “TDaP”) and therefore has reduced the amount of antigens in the vaccine (not that “excess” antigens are a problem for our immune system, which deals with literally millions of antigens on a daily basis, but that’s another story).

She’s also wrong about studies on regressives. As a scientist, why doesn’t she do her own literature search, rather than “asking experts” and supposedly getting silence? Because she could find several such studies, like this study in the journal Pediatrics or this one in PLoS ONE, if she simply searched.

Her biggest problem, though, isn’t just failure to represent the scientific literature or to understand the MMR vaccine. It’s her over-reliance on anecdote. Simply by the numbers, this correlation between regression and MMR vaccination (or any vaccination) is completely expected. There are currently about 75 million children in the United States. It’s estimated that anywhere from about 1 in 90 to 1 in 50 kids have some kind of autism spectrum diagnosis. Using the higher numbers for the sake of argument and easier math, that’s about 1.5 million kids, and most are diagnosed between the ages of 1 and 5. The first dose of the MMR vaccine is at ~12-15 months of age–when many parents of children with autism are starting to realize that their kids perhaps aren’t communicating like their peers or showing other characteristics of autism, and may think about getting them evaluated. That’s a window of about 1500 days, in which the majority of those 1.5 million kids receive their diagnosis–so averaging a thousand kids a day. Some of those kids will have just gotten shots, and some will have the reactions Grandin mentions–fevers, crying–by chance alone. Some will also wear mismatched socks that day. Some will eat Cheerios for breakfast. But because these aren’t in the news, moms don’t remember the socks, Cheerios, or a thousand other things that their kid did that day that are just as relevant to developing autism as the vaccines they received.

Correlation does not equal causation, and in this case, many, many studies have *disproven* such a link. Talking to “five or six mothers” does not trump years of scientific data looking at many thousands of kids diagnosed with autism, and it’s unfortunate both that Grandin has promoted this type of thinking, and that the New York Times interviewer considered that newsworthy enough to ask Grandin, out of everything else in her book.