Various bacteria
tsmith | June 11, 2007It's been awhile since I picked on the real science journalists (as opposed to we Daily Show-esque "fake news" sites). I don't mean to get down on them too much; I know that there are many out there who do an incredible job, but then there are also ones who write up articles like this one on how "...women in northern Europe evolved with light hair and blue eyes at the end of the Ice Age to stand out from the crowd and lure men away from the far more common brunette."
Ugh.
So especially for you infectious disease types, can you spot a glaring omission in this article: "Meningitis A…
tsmith | June 6, 2007Over at her old blog, Karmen had a nice overview of Deinococcus radiodurans, a fascinating organism that's able to withstand many different extremes: genotoxic chemicals, oxidative damage, high levels of ionizing and ultraviolet radiation, dehydration, and, as the name suggests, incredibly high doses of radiation. (We're talking high--up to 5,000 Gy without breaking a sweat, while it only takes about 10 Gy to kill a human). However, despite 50 years of study, no one's really figured out just how it does it, though some clues (such as higher levels of manganese and low levels of iron) have…
tsmith | June 4, 2007 Syphilis is a disease frequently shrouded in many levels of mystery. It appeared suddenly in Europe in the late 1400s as a highly virulent and often fatal disease, a disease that could give Ebola a run for its money when it comes to sheer grotesque-ness. Victims may be covered with pustules from head to toe, diseased flesh peeled from their bodies, and patients may be in agonizing pain for weeks or months prior to death. However, after this inauspicious beginning, syphilis seems to have become less virulent, and instead shifted in presentation to more of the chronic disease that we know…
tsmith | May 31, 2007Just popping in quickly after I saw Klearchos' comment on the updated tuberculosis post. He notes on his website that the CDC has released additional travel information about the XDR-TB infected patient, including shorter flights made within Europe in addition to the intercontinental flights. However, Klearchos notes:
...there is a big "hole" in the information provided by the CDC since, nobody has answered yet the question about how he moved from Santorini to Mykonos. CDC doesn't say anything about that in its report!!
There is no direct flight between the two Greek islands so he must have…
tsmith | May 31, 2007Today is the kids' last day of school, and just happens to be an early dismissal as well, so I'll be busy with them and not tied to the computer this morning/afternoon. However, there are tons of good things to read elsewhere.
First, Orac has a long-awaited update on the Tripoli Six: the group of nurses and doctors accused of killing children in Libya by deliberately infecting them with HIV. The science exonerated them, but that didn't change the court outcome, and I've not seen updates until now.
Next, Revere writes about the H7N2 influenza outbreak in Wales, reminding us (as as I've…
tsmith | May 30, 2007I blogged earlier about the Georgia man who globe-trotted while infected with XDR-TB. I wrote that post late Tuesday evening, and since then, a number of other details about his case have come to light--and they're not encouraging. In fact, this serves as a nice example of a convergence of a number of areas I've written about before--obviously, the evolution of antibiotic resistance and the terrible position it leaves us in, the politics and policies of quarantine/isolation (and how they'd be enforced), and the global spread of infectious disease, so I figured this would warrant another…
tsmith | May 30, 2007 I blogged back in March about World TB day, the theme of which was "TB anywhere is TB everywhere." We know that someone can simply hop on a plane halfway across the world, and be practically anywhere else on the globe in the span of about a day--and their bacteria and viruses are just along for the ride. This is particularly disconcerting when it comes to respiratory diseases, where fellow airline passengers may be coughing and sneezing all over you, or touching shared objects without washing their hands. This is also a scenario that's known to have spread SARS, and may spread a future…
tsmith | May 24, 2007 Way back in a few editions of Animalcules, several of the submissions mentioned a fungus that was killing frogs. Wednesday at the ASM meeting suggested that there may be a way to protect these amphibians:
First in a petri dish and now on live salamanders, probiotic bacteria seem to repel a deadly fungus being blamed for worldwide amphibian deaths and even extinctions. Though the research is in its early stages, scientists are encouraged by results that could lead the way to helping threatened species like mountain yellow-legged frogs of the Sierra Nevada mountains of southern California…
tsmith | May 23, 2007 Everyone knows about the "butterfly effect": the idea that a butterfly flapping its wings in Brazil could eventually result in the formation of a tornado in Texas by virtue of very small alterations in the initial conditions of a system. Though this description of it is often decried by people who study chaos theory as an inaccurate oversimplification, it's a useful illustration of the tiny perturbations that can have vast effects on a downstream chain of reactions.
When it comes to infectious diseases, climate change may be the beginning, but environmental effects extend much farther…
tsmith | May 21, 2007 I had a strange worry as a kid. I was very scared of getting bit by a tick and developing Rocky Mountain Spotted Fever (RMSF). I know, weird--even for nerdy kids like me, who knows about Rocky Mountain Spotted Fever? How many readers are even familiar with it?
For those who aren't, RMSF is a zoonotic rickettsial disease transmitted by several species of ticks. Though the disease is named after the geographical region where it was first described back in the late 1800s, the bacterium that causes it, Rickettsia rickettsii (an obligate intracellular pathogen), has been found in almost all…
tsmith | May 10, 2007Last month I noted the story of Robert Daniels, a patient with drug-resistant tuberculosis who's been held in isolation in Arizona in order to prevent spread of the deadly pathogen. While some patient's rights advocates have been outraged, Mr. Daniels' treatment pales in comparison to what Mona at Science Notes writes about:
News has broken that the Canadian government continued to require Native Canadian children to attend residential schools where they could learn "civilized," Christian, European ways, for years after they knew that tuberculosis was rampant in those schools, and they…
tsmith | May 1, 2007 A few weeks back during the whole Egnor kerfuffle, I mentioned how important an understanding of evolutionary biology was to many areas of epidemiology, and specifically, for vaccine development and implementation. As one example, I brought up the phenomenon of serotype replacement, which can occur due to the use of what are called "multi-valent vaccines." Essentially, these vaccines include strains of pathogens which are either the most common, or the most likely to cause disease--thereby protecting individuals from infection with these specific serotypes, but not making the recipient…
tsmith | March 30, 2007I don't know if you've seen any of the posts here at Scienceblogs or Panda's Thumb about the Discovery Institute's newest protégé, Dr. Michael Egnor. A professor of neurosurgery at SUNY-Stony Brook, Dr. Egnor has been pontificating on how "Darwinism" has nothing to offer to medicine; and indeed, that evolutionary biology has "hijacked" other fields of study. Mike has already aptly pointed out many of Egnor's strawmen and intellectual dishonesties, so I won't review them all. I've stayed out of the fray until now because I've had limited time and others have been handling it quite ably,…
tsmith | March 24, 2007Mycobacterium tuberculosis infection is as old as civilization. The bacterium infects approximately a third of the world's population--roughly 2 billion individuals. It's estimated that 8 million new cases are contracted each year--around a new infection every second. ~2 million individuals die as a result of TB every year. The bacterium also plays a prominent role in the history of microbiology: it was on March 24, 1882, that Robert Koch announced his discovery of the causative agent of the dread disease tuberculosis:
"If the importance of a disease for mankind is measured by the number…
tsmith | March 15, 2007 When we think of the spread of antibiotic resistance between animals and humans, we tend to think of it going from Them to Us. For example, much of the research over the past 20 years on the sub-clinical use of antibiotics in animal feed has looked how this use of antibiotics as a growth promotant breeds resistant organisms in animals, which can then enter the human population via the food we eat. Along a similar line, I just mentioned Burt's post post on cephalosporin use in cattle and the evolution of antibiotic resistance, where the worry is that use of these broad-spectrum antibiotics…
tsmith | February 14, 2007...some vintage posters raising awareness about the other VD: venereal disease.
(Click on them to go to the original site). A few more highlights below the fold...
And this one, which is better appreciated at larger size so you can read the print:
There are 20 posters in all, plus this syphilis comic book from 1965:
Happy Valentine's Day!
tsmith | February 8, 2007So, I left off on Tuesday noting two things about our normal flora: 1) that in the big picture, we know hardly anything about them; and 2) that one reason we know so little about them is because we've never grown many of them in a laboratory setting--that is, we've never cultured them using our typical tools of the trade.
What's one way to remedy this? Eliminate the need for culture, and take some cues from the microbial ecologists. More on this below.
I've mentioned the term "metagenomics" previously on this blog (see the stories about it here and here). Using this technique,…
tsmith | February 6, 2007 I mentioned in the Introduction to Microbiology and Infectious Disease that many people don't understand the difference between a commensal and a pathogenic organism. I also mentioned that I'd try to write something about microbial ecology. Since I just gave a lecture yesterday on normal human flora in health and disease, now seems as good a time as any to combine these two and discuss just what it means when microbiologists refer to "normal flora" or "commensal organisms," and to talk about the microbial ecology of the human body in a series of posts on this topic.
First, though, a…
tsmith | February 2, 2007Introduction to Microbiology and Infectious Disease
You and your normal flora, Part I
You and your normal flora, Part II
tsmith | February 1, 2007I've mentioned a few times the work of Ignaz Semmelweis in preventing "childbed fever" in new mothers. To recap:
Semmelweis was a physician in Vienna in the 1840s, with an interested in "childbed fever," a leading cause of mortality in women who'd given birth. During this time, he noticed that the mortality rate from this disease in a hospital division where medical students delivered babies was 16%, while in a division where midwives delivered them was ~2%. It was also known that childbed fever was rare when women gave birth at home. Semmelweis thought there was something the med students…