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Posts Tagged Infectious disease

Lemons and Lyme: Bogus tests and dangerous treatments of the Lyme-literati

Tick

It’s that time of year when every day I can expect to see at least one patient with a concern about Lyme disease. In Lyme-endemic regions such as Western Massachusetts, where I practice pediatrics, summer brings a steady stream of children to my office with either the classic Lyme rash (erythema chronicum migrans, or ECM), an embedded tick, a history of a tick bite, or non-specific signs or symptoms that may or may not be due to Lyme disease. Sometimes the diagnosis is relatively straightforward. A child is brought in after a parent has pulled off an engorged deer tick, and there is a classic, enlarging ECM rash at the site of the bite. More often the presentation is less clear, requiring detective work and science-based reasoning to make an informed decision and a diagnostic and therapeutic plan based on the best available evidence. Depending on the story, the plan may include immediate treatment without any testing (as in the straightforward case described above), immediate testing without treatment pending test results, or waiting as we watch and see how a rash progresses before doing anything. An example of this latter course of action would be when a patient comes in with a pink swelling at the site of a new tick bite. In this case, it may not be clear if the swelling is a Lyme rash or simply a local reaction to the bite, a much more common occurrence. The classic ECM rash (an enlarging, red, circular, bull’s-eye rash at or near a tick bite) typically develops 1-2 weeks after a tick bite, but can occur anywhere from 3-30 days later. It then expands and darkens over another 1-3 weeks before fading. This classic rash is not the most common rash of Lyme disease, however, as it occurs in only about 30% of cases. Instead, the rash may be uniformly pink or red (or even darker in the center) without the target-like appearance, or may be a linear rash, expanding outward from the tick bite site. In the case of a patient who comes in with a vague, pink swelling within a day few days of a tick bite, we will typically wait and see what happens to the rash. If it is a local reaction, it will likely resolve within another few days. With Lyme disease, the rash will continue to enlarge and declare itself as an ECM rash. Another unclear and not uncommon situation is when a patient comes in with non-specific symptoms such as fatigue, musculoskeletal pains, and headache. If warranted by the history and the physical exam, we may in this case order Lyme testing. This may not give us an answer even if the patient has Lyme disease, because results are often negative in the first few weeks of the disease. In this case, if symptoms persist or evolve, we will repeat the testing in another few weeks at which point true Lyme disease will test positive and can then be treated. The good news is that the treatment of Lyme disease, particularly in the early, localized phase of the disease, is extremely safe and effective with a 14-day course of antibiotics. The testing is also relatively straightforward, with very good sensitivity and specificity when performed correctly. And this is where the bad news comes… (more…)

Posted in: Diagnostic tests & procedures, Science and Medicine

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Measles gets a helping hand

In a recent post I shared a bit of my personal, near-death experience with measles during the US epidemic of 1989-1991. As I describe in that post, I contracted a very serious measles infection at the end of medical school, and was highly infectious when I interviewed for a residency position at Seattle Children’s Hospital. Like others my age who received an ineffective, killed measles vaccine between 1963 and 1967, I had not been adequately protected. The MMR vaccine was not yet available, and no boosters were recommended at the time. Unfortunately, though my measles titers (a test of immunity to measles) were checked when I entered medical school, the school’s student health department failed to notice or respond to the results – I was not immune and did not receive a booster dose at that time, as I should have. That mistake was huge, and could have cost me my life. It also caused me to potentially sicken many vulnerable children during my tour of the hospital, as well as others I may have inadvertently exposed during the window of communicability as I walked the streets of Seattle. The Department of Health had to be called to trace all of my steps and attempt to track down and protect any potential contacts.
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Posted in: Epidemiology, Medical Ethics, Politics and Regulation, Public Health, Science and Medicine, Vaccines

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Vaccines work. Period.

Over my blogging “career,” which now stretches back nearly nine years, and my hobby before that of engaging in online “debates” on Usenet newsgroups back before 2004, I developed an interest in the antivaccine movement. Antivaccinationism, “antivax,” or whatever you want to call it, represents a particularly insidious and dangerous form of quackery because it doesn’t just endanger the children whose parents don’t vaccinate them. It also endangers children who are vaccinated, because vaccines are not 100% effective. The best vaccines have effectiveness rates in the 90%-plus range, but that still leaves somewhere up to 10% of children unprotected. Worse, because herd immunity requires in general approximately 90% of the population and above to be vaccinated against a vaccine-preventable disease to put the damper on outbreaks, it doesn’t take much of a degradation of vaccination rates to put a population in danger of outbreaks. That’s why, even though overall vaccine uptake is high in the US, we still see outbreaks, because there are areas with pockets of nonvaccinators and antivaccinationists who drive vaccine uptake down to dangerous levels. We’ve seen this in California and elsewhere. Other countries have observed even more dramatic examples, the most well-known being the way that fear of the MMR vaccine stoked by Andrew Wakefield’s bad science and the fear mongering of the British press led MMR uptake to plummet. The result? Measles came roaring back in the UK and Europe, from having been considered under control in the 1990s to being endemic again by 2008.

As much as I get chastised by concern trolls for saying this, to antivaccinationists it really is all about the vaccines. Always. They blame autism, other neurodevelopmental conditions, and a wide variety of chronic diseases on vaccines, without evidence that there is even a correlation. They even falsely blame sudden infant death syndrome (SIDS) on vaccines, even though there is no evidence of an association and, indeed, existing evidence suggests that vaccines likely have a protective effect against SIDS more than anything else. No matter what happens, no matter what the evidence says, antivaccinationists will always find a way to blame bad things on vaccines, even going so far as to claim at times that shaken baby syndrome is a misdiagnosis for vaccine injury.

One thing, however, that is often forgotten, is that they also do their utmost to downplay the beneficial effects of vaccines. One such tactic is for antivaccinationists to claim that the pertussis vaccine doesn’t work because we are seeing resurgences of pertussis even in the face of high vaccine uptake. For example, another common trope is what I like to refer to as the “vaccines didn’t save us” or the “vaccines don’t work” gambit, in which it is pointed out that the introduction of vaccines doesn’t correlate tightly with drops in mortality from various diseases. Julian Whitaker even used this gambit when he debated Steve Novella. The fundamental flaw in this trope neglects the contribution of better medical care to the survival of more victims of disease, which decreased mortality. If you look at graphs of disease incidence you will see a profound and powerful effect of the introduction of vaccines on specific vaccine-preventable diseases. In other words, vaccines work. (more…)

Posted in: Epidemiology, Public Health, Vaccines

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Outbreaks

There have been, in the last 20 years, natural, or perhaps unnatural, experiments that have helped shed light on the efficacy of vaccines.  Many societies, for reason of political unrest, religion, or a lack of understanding of science and medicine have seen the rates of vaccination decline and, with that decline, an increase in the cases of vaccine-preventable diseases.

Infectious disease spread in populations is not simple.  Hygiene, nutrition, access to health care, and education all play a role in the spread of communicable diseases.  Vaccines have been critical in driving the rates of vaccine preventable illnesses to almost zero, but they are not the only intervention in our armamentarium. (more…)

Posted in: Public Health, Vaccines

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A Not-So-Split Decision

For those who battle tirelessly against the never ending onslaught of anti-vaccine propaganda, misinformation, and fear, there was great news the other day from Merck. The pharmaceutical company, and maker of the MMR vaccine against measles, mumps, and rubella, has decided not to resume production of the individual, or “split”, components of the vaccine. A Merck representative made the announcement during a meeting of the CDC Advisory Committee on Immunization Practices (ACIP) on Tuesday. During previous ACIP meetings, science experts on that committee presented compelling arguments against  continued, large scale production of the monovalent components of the MMR vaccine, which were echoed by scientists in Merck’s vaccine division. In a moment, I’ll discuss the arguments against the split vaccine, and why this is so important a decision. First, some background on the issue of splitting the MMR.
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Posted in: Science and Medicine, Vaccines

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