General Epidemiology
tsmith | December 17, 2007 In my field, many things that cause the average man-on-the-street to get a bit squeamish or squicked are rather commonplace. My own studies include two types of bacteria that are carried rectally in humans (and other animals), so I spend an absurd amount of time thinking about, well, shit, and the lifeforms that inhabit it and collectively make up our normal gut flora. The vast majority of these species don't harm us at all, and many are even beneficial: priming our immune system; assisting in digestion; and filling niches that could be colonized by their nastier bacterial brethren.
It…
tsmith | December 10, 2007Still playing end-of-year catch-up with grants and manuscripts so posting will be sporadic, but I'd be remiss not to mention this story regarding presidential candidate Mike Huckabee's past views on HIV/AIDS:
In 1992, Huckabee wrote, "If the federal government is truly serious about doing something with the AIDS virus, we need to take steps that would isolate the carriers of this plague."
"It is difficult to understand the public policy towards AIDS. It is the first time in the history of civilization in which the carriers of a genuine plague have not been isolated from the general population…
tsmith | November 30, 2007Since its discovery, only a few countries have really been affected by Ebola. The virus has surfaced multiple times in the Democractic Republic of Congo, in Sudan, in Gabon, and now in Uganda. This country was last hit (and hit hard) by Ebola in 2000, when an outbreak there caused at least 425 cases, and killed more than half of those it infected. Now it's currently causing yet another outbreak, just weeks after the outbreak in the DRC was confirmed to have ended--and the strain that's causing this one seems to be distinct from the four known types of virus we've seen to date. More after…
tsmith | November 19, 2007 It still amazes me sometimes what viruses are capable of doing. I've written a number of times about one virus in particular, the human papilloma virus (HPV). This is the virus implicated in cervical cancer, and it also plays a role in head and neck cancers. There are a number of different strains of HPV--some of them are oncogenic (cancer-causing), while others cause more benign infections, such as warts.
A related virus in rabbits also causes a type of warts, which can replicate out of control and form horny growths (indeed, this is the likely origin of the jackalope myth). Humans…
tsmith | November 15, 2007Two recent stories highlight the good and the bad when it comes to infectious disease prevention.
The good
Death rates for vaccine-preventable diseases are at an all-time low:
The study, by the Centers for Disease Control and Prevention in Atlanta, and published in The Journal of the American Medical Association (link), is the first time that the agency has searched historical records going back to 1900 to compile estimates of cases, hospitalizations and deaths for all the diseases children are routinely vaccinated against.
In nine of the diseases, rates of death or hospitalization…
tsmith | November 9, 2007 Tuberculosis in humans is most commonly caused by Mycobacterium tuberculosis, a slow-growing, waxy, rod-shaped bacterium. Transmitted primarily via the air when an infected individual coughs or sneezes, it's estimated that a third of the world is infected with this agent, which causes approximately 2 million deaths every year. Though most infections are asymptomatic, infection is becoming increasingly deadly, due both to the spread of highly antibiotic-resistant strains and due to the increasing number of individuals with both HIV and TB.
While M. tuberculosis is primarily a human…
tsmith | November 8, 2007 Both Mike and Revere have new posts up documenting swine as a new threat to human health (beyond the pork chops and bacon), via carriage of methicillin-resistant Staphylococcus aureus in these animals. Several papers have been published recently documenting high rates of MRSA carriage in swine in the Netherlands, and also have documented transmission of this bacterium from swine to humans. However, even more worrisome to me than the Dutch publications is a new one out in Veterinary Microbiology, showing high rates of MRSA in Canadian swine--and guess where we import about 9 million hogs…
tsmith | November 6, 2007 I've written a post or two (or a dozen) discussing science journalism--the good, the bad, and, mostly (because they're the most fun), the ugly. There was this story about how blondes "evolved to win cavemen's hearts." Or this one that completely omitted the name of the pathogen they were writing about. Or this one, where a missing "of" completely changed the results being discussed.
I ran across another glaring example yesterday, dealing interestingly enough with one of my favorite topics: chocolate, and bringing in an "omics" prospective to it.
The news story covered a recent…
tsmith | November 5, 2007 I wrote about an emerging mosquito-borne virus with the strange name of chikungunya in a pair of posts last year. This is a virus that was first discovered more than 50 years ago, but as far as arthropod-borne viruses ("arboviruses") go, it's been a minor player for most of that time, as other arboviruses such as yellow fever, dengue, and West Nile caused more disease and death than chikungunya. However, the virus began to rapidly spread beginning in ~2004, causing around a quarter million infections on the island of La Reunion in the Indian Ocean before moving on to cause smaller…
tsmith | November 4, 2007Welcome to this month's edition of Pediatric Grand Rounds! Sit back with a cup of mulled cider and enjoy the best of the past month:
Revere at Effect Measure tells the tale of Streptococcus pneumoniae serotype 19A--a serotype that's not included in the current vaccine, but has increasingly found as a cause of ear aches in children.
Of course, in addition to ear infection, 'tis the season for influenza. As such, it's timely that Highlight Health, Walter emphasizes the importance of influenza vaccination.
My own addition to this month's carnival touches on similar themes: how kids'…
tsmith | October 23, 2007It's only taken 30 years, but information about Ebola in nature is finally starting to snowball. First, after almost 15 years of disappearing from the human population, Ebola returned with a vengeance in the mid 1990s, causing illness in 6 separate outbreaks in Gabon, Ivory Coast, Democratic Republic of Congo (DRC), and South Africa (imported case) between 1994 and 1996. As doctors and scientists rushed in to contain the outbreaks, they were also able to collect viral samples, and trap animals and insects in the area, searching for a reservoir for the virus. In this decade, there have been…
tsmith | October 18, 2007 A few news stories hit my inbox all at once yesterday--and the combination of them doesn't bode well for childrens' health; more after the jump.
First, despite several years now of banging the drum for having kids vaccinated against influenza, they're still being overlooked when it comes to pandemic planning:
Children would likely be both prime spreaders and targets of a flu pandemic, but they're being overlooked in the nation's preparations for the next super-flu, pediatricians and public health advocates reported Wednesday.
The report urges the government to improve planned child…
tsmith | October 9, 2007Following a new PNAS paper regarding the strange facial cancers in Tasmanian devils, I have a post on the topic up over at Correlations. (Be sure to check out the Correlations homepage too!)
tsmith | September 29, 2007In another case of TV shows being prescient, abuzz here at other Scienceblogs is this story, which sounds like a bad B movie: " 6 die from brain-eating amoeba in lakes." The amoeba in question is a species of naegleria, which was featured on the medical drama House last year. According to the article:
Beach said people become infected when they wade through shallow water and stir up the bottom. If someone allows water to shoot up the nose -- say, by doing a somersault in chest-deep water -- the amoeba can latch onto the olfactory nerve.
The amoeba destroys tissue as it makes its way up…
tsmith | September 24, 2007Busy week; working on getting a grant and a manuscript revision out the door. In the meantime, Jake has a post on abstinence-only versus "abstinence-plus" education, and why neither is working that well, and Orac discusses a topic I want to get to but it's one of those long 'n' involved posts I don't have a lot of time for right now: the reliability of epidemiological studies.
tsmith | September 20, 2007One of the organisms I work with is the group B streptococcus, Streptococcus agalactiae ("GBS"). This is a relative of the bacterium that causes strep throat. Typically, GBS causes disease in the very young and older age groups; it's one of the most common causes of meningitis in newborns, for instance. This has dropped some in recent years, as obstetricians have implemented procedures to screen expectant mothers to see if they're carrying GBS (as about a quarter of healthy adults do), and then provide antibiotics to carriers during labor (thereby preventing infection of the baby during…
tsmith | September 18, 2007...They make be spreading disease.
British hospitals are working on keeping that in check by implementing a new dress code:
British hospitals are banning neckties, long sleeves and jewelry for doctors -- and their traditional white coats -- in an effort to stop the spread of deadly hospital-borne infections, according to new rules published Monday.
Hospital dress codes typically urge doctors to look professional, which, for male practitioners, has usually meant wearing a tie. But as concern over hospital-born infections has intensified, doctors are taking a closer look at their clothing.
"…
tsmith | September 17, 2007 Regular readers may have seen me mention on occasion my father's rather large family. My dad is the youngest of a family of 13 children--12 of whom survived to adulthood. Before my dad was born, he lost a brother to complications from infection with chicken pox; he had a severe infection and developed a fatal secondary pneumonia at just a year old. This was back in the early 1940s, prior to the widespread use of modern antibiotics and certainly long before vaccination for chicken pox. Still, despite the availability of effective chicken pox vaccines today, people still knowingly…
tsmith | September 13, 2007Clostridium difficile is an emergent bacterium. A close relative of the bacteria that cause tetanus and botulilsm (Clostridium tetani and Clostridium botulinum, respectively), C. difficile is an intestinal bacterium that can cause colitis. C. difficile has until recently been a fairly rare cause of disease, and then only typically within a hospital setting. However, the emergence of a new, highly virulent strain of the bacterium a few years ago, coinciding with an increase in the rate of serious infections it caused, put this pathogen on the map. And like methicillin-resistant…
tsmith | September 11, 2007...so claims this headline. Only the story screws it up.
The article highlights this dissertation research by Charles Courtemanche at Washington University in St. Louis. Courtemanche's thesis is that the rise in gas prices causes more people to walk, ride bikes, or take public transportation (which they'd also have to walk to), as well as eat at home instead of going out; therefore higher gasoline prices can result in a thinner population. Sounds plausible. I won't get into all the details of his research (the .pdf is available from the above link for anyone interested), but just by…