public health
tsmith | April 13, 2006Orac highlighted here a post over at Vox Populi which doubted the effectiveness of the mumps vaccine, in light of the recent epidemic in Iowa. I was prepared to write a whole post on the math of it, but Mark at Good Math, Bad Math saved me some work. Nevertheless, I have a few things to add after the jump.
As has been mentioned, the given efficacy rate for the mumps vaccine is 95%. This is actually likely a bit high; previous outbreaks have suggested it's more like 85-90% effective, so that as many as 15% of the vaccinated population won't actually be immune. The key to telling whether…
tsmith | April 13, 2006 Okay, so I lied. I was planning to wrap up the emerging diseases and zoonoses series with the post on monkeypox, but I think I'll just continue it as a sporadic event, since a new paper fits into the series perfectly.
I talk a lot here about streptococcus. As regular readers know, there's a good reason for that. Though my main research right now is on Streptococcus agalactiae (group B streptococcus, GBS), I also have a project working on a related organism, Streptococcus suis. As the "suis" name suggests, this is mainly a pathogen of swine. Indeed, it's kind of the pig equivalent of…
tsmith | April 12, 2006 A new study in the journal Pediatrics suggests this common procedure may improve the condition of kids diagnosed with attention defecit/hyperactivity disorder (ADHD). I think it's an excellent case of some true "alternative explanations" for the data.
Creationists often try to validate their position by saying that both they and mainstream scientists start from the same data, but that creationists use their "Bible glasses" to interpret it, while scientists view it through their "evolution glasses." In other words, they're not wrong--it's just a different interpretation of the same data,…
tsmith | April 11, 2006I attended a lecture yesterday given by Patty Quinlisk, Iowa's state epidemiologist. The bad news: there have been over 500 reported cases of mumps as of Monday, April 10, with more cases in neighboring states (30-50 in Nebraska, for example). She did, however, give a bit more history on the epidemic, described below.
The outbreak can be traced back to last December, when 2 cases were found to be IgM-positive for mumps. (IgM is the first type of antibody produced to a new infection; therefore, this is diagnostic of a current infection, whereas looking at a different type of antibody--…
tsmith | April 7, 2006 For the final post of the series, I want to discuss yet another outbreak, this one a bit closer to home: that of monkeypox in the United States in 2003.
First, I should note that "monkeypox" is a bit of a misnomer. Though the virus--a relative of smallpox and cowpox--can infect monkeys (and humans), the reservoir host is likely a rodent. Previously, monkeypox had been found mainly in sub-Saharan Africa, in forested regions. 2 clades of the virus had been identified. One was common in West Africa, and generally didn't cause severe disease when humans became infected with it. The other…
tsmith | April 6, 2006 I've touched on the broad issue of "cultural practices" that can lead to emerging diseases in a few posts already (such as farming practices and cockfighting and avian influenza, or petting zoos and bacterial diseases), but today I'm going to go into a bit more detail with the specific example of the emergence of Nipah virus in Malaysia.
Nipah is a paramyxovirus, in the same family as measles and mumps. The virus was first recognized in 1999, during an encephalitis outbreak in Malaysia that had begun the previous September. The vast majority of the cases had occupational exposure to…
tsmith | April 6, 2006 Again on the zoonoses topic, today's BBC news has an article about cats and "bird flu" (referencing this article in Nature).
The first report of domestic cats dying of the H5N1 virus emerged in Thailand in 2004 when 14 out of 15 cats in a household near Bangkok fell ill and died.
One had eaten a chicken carcass on a farm where there was an outbreak of the virus.
Post-mortem examinations on three of the cats confirmed the presence of H5N1.
Since then, there have been deaths among cats in Indonesia, Thailand and Iraq, where H5N1 appears to be prevalent among poultry.
And the disease is…
tsmith | April 5, 2006 As I mentioned in previous posts, the emergence of new infectious--especially zoonotic--disease isn't limited to poor countries. Exact numbers vary depending on whose estimates you use, but this source puts the number of pet dogs in the United States alone at roughly 63 million, with over 76 million pet cats. This source is almost 10 years old and thus outdated, but we can use it as a ballpark: it claims almost 100 million cattle and calves in the U.S. Similarly, over 60 million hogs; almost 8 million sheep; 2.5 million horses and ponies; 366 million chickens. We have a lot of animals…
tsmith | April 5, 2006...but just haven't had the time to do more extensive write-ups. So, a mini carnival of good stuff:
First, as other Sciencebloggers have noted, Seed is sponsoring a writing contest. $1000 dollar top prize and publication in Seed to the winner.
Cervantes at Stayin' Alive writes about the cost of pandemic preparedness--you might be surprised that it's, well, nothing so far. You get what you pay for?
Joseph has a post on Ebola examining the claims made by Eric Pianka that have received so much attention lately.
Some Ohio infectious disease news: tuberculosis found in illegally-transported…
tsmith | April 4, 2006In addition to all the science of H5N1, several presentations were given discussing communication between scientists and the public (or those who more often communicate with the public--science journalists). As I've written on here before, it's not an easy dance to figure out, for a variety of reasons discussed below.
As anyone who follows science reporting in the mass media knows, it can seem at times that each new study contradicts the last. Something is good for you; yesterday it was bad for you. Something is the new treatment of tomorrow based on early studies; but sorry, it was…
tsmith | April 4, 2006 I mentioned last week that Iowa's suffering from a large outbreak of mumps. An update, from the March 30th Morbidity and Mortality Weekly Report:
In the United States, since 2001, an average of 265 mumps cases (range: 231--293 cases) have been reported each year,* and in Iowa, an average of five cases have been reported annually since 1996. However, in 2006, by March 28, a total of 219 mumps cases had been reported in Iowa, and an additional 14 persons with clinically compatible symptoms were being investigated in three neighboring states (11 in Illinois, two in Nebraska, and one in…
tsmith | April 4, 2006Busy yesterday and today, but I saw a brief mention of a study yesterday that Orac has discussed in more detail today. The study questions whether an "autism epidemic," as frequently cited in the anti-vaccination literature, has really occurred in the United States or not.
So, in nearly all states, as the reporting of autism cases for special education administrative purposes increased, the reporting of mental retardation and learning disabilities declined correspondingly, suggesting that children who once would have been classified as mentally retarded or learning disabled were now more…
tsmith | April 3, 2006 As conferences covering both emerging infectious diseases and emerging zoonoses, influenza H5N1 was obviously a prominent topic of discussion. The big question wasn't really answered--what is the most important mechanism of spread from country-to-country: wild birds, or domestic poultry? The only thing that was clear is that the answer, well, isn't. I know grrlscientist has written extensively about the evidence against wild birds as a vector (using search word "influenza" here brings up many of them; more on her old site), and there certainly was a lot of discussion about farming and…
tsmith | April 2, 2006 Joseph over at Immunoblogging has two posts on Mycobacterium bovis and gives a potential answer to Dave S.'s question here. In post one, Joseph notes (after the fold):
It's interesting to note that Mycobacterium bovis, which infects farmed animals dates back roughly to the time we domesticated animals proving that for a change, we gave one of our pathogens to an animal and not the other way around.
In part two, Joseph discusses mycobacteria in general, and why M. bovis is a threat to farm economies.
Part three discusses the role badgers play (or don't) in the transmission of M. bovis to…
tsmith | April 1, 2006At the risk of starting an infectious cancer/HIV/AIDS fight over at The Loom, I'll point your attention to Carl's post discussing, well, those topics here. He elaborates on a study I mentioned here but didn't delve very much into the science. Zimmer does--check out the link to find out how he relates it to HIV.
tsmith | March 31, 2006 So far this week, I've mostly been talking in generalities--the introductions to the topic, or how the animals we eat or other types of human behavior can put us at greater risk for the emergence of such diseases. Today I want to talk about a more specific example: an ongoing outbreak of a virus called chikungunya.
Chikungunya (from the Swahili word for "stooped walk," or "that which bends up" depending on who you believe, referring to the posture of a person suffering from the disease) is an arbovirus: a virus that is transmitted by insects. In this case, the insect in question is the…
tsmith | March 30, 2006 I mentioned in part 2 of the introduction the role that war plays in the emergence and transmission of infectious disease. Accurate numbers are difficult to come by, but currently, it's estimated that approximately 120 million people worldwide are affected in some way by conflict. In 2003, it was estimated that more than 72 countries were identified as unstable, and various conflicts have resulted in over 42 million refugees and internally displaced people worldwide. War and its concomitant devastation and social upheaval leaves its victims at an increased risk of disease transmission…
tsmith | March 29, 2006From the Bushmeat Task Force:
In Africa, forest is often referred to as 'the bush', thus wildlife and the meat derived from it is referred to as 'bushmeat'. This term applies to all wildlife species, including threatened and endangered, used for meat including: elephant; gorilla; chimpanzee and other primates; forest antelope (duikers); crocodile; porcupine; bush pig; cane rat; pangolin; monitor lizard; guinea fowl; etc.
Some of this can be hunted legally--much of it is not. Though I won't be concentrating on the bushmeat crisis per se (the focus of the Bushmeat Task Force), they note several…
tsmith | March 28, 2006Just FYI, yesterday's New York Times has a piece by Denise Grady and Gina Kolata on avian influenza: How Serious Is the Risk?
tsmith | March 28, 2006I mentioned previously that a new virus had been found that's associated with prostate cancer. Several ongoing studies are finding tons of new species of microbes, and we're learning more about the diversity that is around us every day. And though most of these newly-discovered organisms won't harm us, some just might.
A new study (summarized here points to a calicivirus (genus Vesivirus, a relative of the Norovirus that has gotten much attention recently as the cause of gastroenteritis on cruise ships) as a potential cause of human illness. Vesivirus has an oceanic reservoir and has…