Category Archives: Bogus!
Spoilers! Ebola worries are non-existent for us in South Central Pennsylvania. However, according to an email I received this week might lead one to believe that the risk is far, far worse. A notice to staff, faculty, and students at York College requires that anyone planning on traveling anywhere outside of the United States through the beginning of March 2015 self identify themselves to the Health Center, and monitor their temperature for the 3 week Ebola Hemorrhagic Fever incubation contagious period. The notice also contains several editorialized Ebola facts, which unfortunately convey a sense about the risks of contracting Ebola virus that are perhaps a bit exaggerated.
A posting in the Atlantic Monthly gives a concise summary of our current understanding. There is no indication today, and there never has been, any evidence to support the hypothesis that Ebola viruses can be transmitted between humans via any indirect means. Ebola virus is what is known as an enveloped virus, and contains a genome made of RNA; consequently, intact virus particles with these characteristics are unable to survive in an infectious state outside of a mammalian host. As a result, in contrast to many bacterial pathogens, inanimate objects (fomites) in the environment are very poor reservoirs for these types of viral pathogens, although virus shed via sneezing does pose a temporary risk.
The one study that examined the possibility of airborne transmission found that transmission between infected pigs and non-human primates can occur in specialized situations. This study has a big caveat (and indeed was followed up with an additional study to address this), in that in pigs Ebola virus has a hugely significant lung involvement, resulting in massive amounts of the virus in respiratory secretions. This doesn’t happen in primates, which show mainly hemorrhagic disease. The followup study looking at primate to primate aerosol transmission found no infection between test animals. Because of the very nature of Ebola virus in comparison to many respiratory viruses, we are not likely to see a change in these properties.
What about the risk to York College community members who are planning on traveling overseas in the near future? The Centers for Disease Control and Prevention and the Pennsylvania Department of Health remain the best sources of information to assess the risks of this scary disease to the general public. The CDC in fact has a page devoted to precautions that are recommended for college students planning travel abroad. All of these precautions are directed towards travel to those countries where the Ebola outbreak is occurring (Guinea, Liberia, Sierra Leone). The CDC also has a page which clearly indicates epidemiological risks for contracting Ebola virus for use in evaluating whether an individual has potentially been exposed. Class 4–No Identifiable Risk is indicated for persons traveling to a country without widespread Ebola virus transmission–this includes travel anywhere besides Guinea, Liberia, and Sierra Leone. Persons traveling to the Democratic Republic of the Congo should practice enhanced precautions, however the CDC risk assessment is very low for travel there. The Pennsylvania Department of Health echoes all of the CDC guidelines, and as of 27 October 2014, is monitoring a total of 105 residents of the Commonwealth who are considered “at some risk” for exposure to Ebola virus, due to recent travel to one of the afflicted countries. These individuals are being monitored for potential exposure to Ebola by local and state health officials. As indicated on the PA Department of Health page, travel into Pennsylvania from any other international origin is NOT considered a risk factor for Ebola exposure.
There is an awful lot of poorly cited information circulating and straight out disinformation about this epidemic at present. Advocating unwarranted steps in screening for potential exposure when the risk is non-existent creates an atmosphere of uncertainty, and this can be damaging in the long run. I urge all BIO230 students to follow the links they see on the Internet, and check to see whether they represent experimentally-supported science, or merely reflect someone’s opinion.
I spotted this article in the Health Section of the New York Times; an extensive retrospective study published in the journal Clinical Infectious Diseases has found no correlation between receiving the seasonal influenza vaccine and developing the serious neurological condition Guillain-Barré Syndrome (GBS). This finding gave me great joy, and also gives me an opportunity to link back to one of my favorite Rage Stroke®-inducing BIO230 postings. The possibility for correlation arose from the 1976 Swine flu vaccine, in which the Centers for Disease Control and Prevention reported a slightly increased risk for developing GBS following receiving that vaccine, with the risk being approximately 1 case of GBS per 100,000 vaccine doses. This measurable increase led to a moratorium and reformulation of the vaccine.
An extensive investigation by the Institutes of Medicine (IOM) confirmed the increased risk of developing GBS with the 1976 influenza vaccine, and although several theories were put forth to explain the potential correlation, the cause remains unclear. One possibility hypothesized in the IOM study linked above suggests that the clear association between developing GBS and infection with the bacterium Campylobacter jejuni might be to blame. Campylobacter is an ubiquitously distributed organism, however it does infect chickens, and eggs are used to produce the influenza virus used to produce the vaccine. The increased incidence of GBS with that year’s vaccine therefore might have been due to contaminating Campylobacter antigens present in the killed vaccine preparation.
The study described in the New York Times article recounts an extensive retrospective analysis of patients from a California health care system, and data examined covered more than 30 million person-years worth of medical records. In that data set, 415 cases of Guillain-Barré were observed for a total annual incidence of approximately 1 in 90,000 people in the population, a number that is very much in line with what is reported by the CDC. Out of those 415 confirmed cases, 25 of them had a reported influenza vaccine in the 6 weeks prior to developing GBS symptoms. Most of the cohort had received a flu vaccine at some point in their medical history, but had additionally had a large variety of other vaccines. The researchers recognize that the very limited number of GBS cases in relation to the large number of records examined limits the statistical power of their analysis, however no apparent correlation between first receiving a seasonal influenza vaccine and then developing GBS could be demonstrated. The researchers further affirm that during the 1976 outbreak there was a causal link between the swine flu vaccine and developing GBS, but as vaccine formulations have been modified, no further link exists. The much more likely culprit causing Guillain-Barré Syndrome is an underlying infection, most likely due to Campylobacter, which can be easily prevented by properly cooking food and washing your hands.
A news alert is making the rounds through the popular press these days; I noticed it on the tech blog io9.com in a summary with the provocative title “Hand soap is killing you.” The article references a paper published in the highly regarded medical journal Proceedings of the National Academy of Sciences. I haven’t read the article beyond the abstract (it is behind a paywall at pnas.org), but the abstract does summarize the methods and results sufficiently to be able to make some educated conclusions about the risks of antibacterial soaps.
Researchers at the University of Colorado, and at the University of California-Davis examined the effects of the common antibacterial compound triclosan on muscle function in mice and fish. Triclosan is a chlorinated derivative of phenol that is widely used for its antibacterial and antifungal abilities. It affects microorganisms by inhibiting the biosynthesis of fatty acids, and in low concentration exhibits significant bacteriostatic properties. It itself it is not significantly toxic to mammals, except when it is present in surface waters in the environment it can degrade to form dioxins, which are carcinogenic to a wide range of species. According to my bottle of Dawn brand antibacterial dish detergent, triclosan is the active ingredient present at a concentration of 0.1% weight/volume, or 0.7 grams of triclosan per 24 ounce bottle.
The PNAS paper uses two animal model systems and one in vitro tissue culture system to examine the physiologic effects of triclosan on muscle cells. In the mouse model, triclosan was administered intraperitoneally via injection at a concentration of at least 12.5 mg per kg of body weight, and was assessed by measuring grip strength following exposure. In the fish model, triclosan was present in the water at a concentration greater than 0.52 µM, and was assessed by measuring swimming performance. Finally, in an isolated myotube tissue culture model, triclosan was present at micromolar concentrations, and the effects were assessed by measuring the ability of the cells to respond to stimuli. Read the rest of this entry
On the next episode of House, one of the Princeton-Plainsboro staff doctors becomes the patient of the week. However, he does not trust House’s team, and wants the man himself to make the treatment call. House and Wilson are on a road trip, so the team has to make the patient believe that House is calling all of the shots. Just the sort of strategy that House would admire! Will it work? Find out Monday at 9, then Tuesday for a recap! Read the rest of this entry
Only about a month of episodes left in the series before House rides off into the sunset. This week on House, the team takes on the case of a man who starts crying blood. The hijinks half of the episode is provided by House’s efforts to retain the services of his favorite “companion.” My quick Google searching for “tears of blood” turns up a variety of hits, most pointing at recent head trauma as the cause of the condition. Others remain a mystery! Back Tuesday morning, with the diagnosis recap and episode spoilers!
Full disclosure: I did not get to watch the episode this evening, as we only have one television, and my daughter wanted to watch Eureka, so I will rewatch House when it pops up next week On Demand. I did go through the episode recap on the Fox.com website however. As I surmised, head trauma was the very first diagnosis, and was discounted in about 2 seconds due to no evidence of head trauma. The patient Henry exhibits a number of recurring symptoms including respiratory “crackles,” liver failure, neurological dysfunction, and a fever spike.
A number of diagnoses are considered and discounted in turn: a sinus thrombosis, drug abuse, clostridial bacterial infection, and finally meningitis. It is this last diagnosis that turns out to be correct when House recognizes “a strange looking teapot” as a Neti Pot, a device that is designed to spray water into the sinus cavities in order to relieve allergy symptoms. House concludes that Henry has primary amoebic meningoencephalitis, due to infection with the protozoan pathogen Nagleria fowlerii, which was the point that I had to haul out the “Bogus” tag, due to the producers’ choice in trotting out an already extremely rare infectious disease for a second time on the show. The patient was put onto the anti-protozoan medication metridnazole to resolve the infection.
Nagleria infections are not common in the United States, with just 32 infections over the past 10 year period. Most cases of Nagleria infection occur during the summer months, particularly in the Southern tier states, as the organism is normally found in warm bodies of water and is acquired when people dive into the water forcing water into the nasal cavities. The seasonal and geographical associations make it extremely unlikely that two cases would occur in New Jersey, in mid-April (the last episode featuring Nagleri fowlerii aired almost exactly 6 years ago.)
The Centers for Disease Control Nagleria website does specifically include instructions how to minimize risks of infection using Neti Pots, so presumably this mode of transmission has been documented, but my quick search of Pubmed did not turn up any relevant hits, so I think it is safe to assume that the risk of acquiring amoebic meningoencephalitis via nasal irrigation is pretty minimal. The CDC’s recommendation for eliminating the risk is to use distilled water during irrigation or water that has been filtered to remove organisms, and to wash the device between uses.