Aetiology

Well, this is not a question, but a call for people who teach science and have blogs to write something related to science education and send me the permalinks for the next Carnival of Education (next Wednesday, April 12).

Posted by: coturnix | April 5, 2006 11:28 AM

A random bird flu question:

A friend of mine (not a specialist in infectious diseases, nor am I) mentioned that we won't know how dangerous the virus is until antibody studies are done in regions where confirmed cases have occurred. The idea being that until then we won't know whether only a few people have been infected but the virus is unusually dangerous once you've got it, or whether a potentially larger number of people have been infected but just never felt sick enough to seek professional medical care. Since if you just feel average flu symptoms you'll probably just stay in bed for a few days.

Is that at all accurate (Ihaven't been following the story closely)?

Just wondering.

Posted by: PLW | April 5, 2006 11:33 AM

A friend of mine (not a specialist in infectious diseases, nor am I) mentioned that we won't know how dangerous the virus is until antibody studies are done in regions where confirmed cases have occurred. The idea being that until then we won't know whether only a few people have been infected but the virus is unusually dangerous once you've got it, or whether a potentially larger number of people have been infected but just never felt sick enough to seek professional medical care. Since if you just feel average flu symptoms you'll probably just stay in bed for a few days.

Well, mostly. "Dangerous" isn't exactly a scientific term. What we don't know until those types of studies are done is the actual mortality rate of the virus--how many of those who are infected die. For instance, right now with H5N1 it's estimated to have about a 50% mortality rate--half of those infected, die. But if asymptomatic or milder infections are missed, then the denominator becomes much larger, and the mortality rate indeed would go down. I have discussed this previously here (more posts on this topic by following the links in that post). From what I understand, though, a few small studies looking for seroprevalence to H5N1 haven't found much evidence of those milder infections.

Posted by: Tara | April 5, 2006 12:33 PM

Asked this before, but would appreciate an epidemiologist's opinion on the infamous "catapult the corpses of those killed by plague" at the Siege of Kaffa by the Tartars in 1346, as recounted second-hand here.

Two things seem to make this "Early biological warfare" implausible as the actual cause of plague entering Kaffa:

1) Fleas would have left the corpses shortly after death
2) One would expect that the primary transmission of pneumonic plague would be person-to-person instead of via fleas as the vector.

What's the opinion of academic epidemiologists on this? If it is an urban legend, it'd be nice to see it overturned.

Posted by: Urinated State of America | April 5, 2006 5:14 PM

there was an interesting story in the UK recently about 6 volunteers in a drug trial who were injected with a new monoclonal antibody and suffered severe immune reactions leading to organ failure. All the men became severely ill and two were in intensive care for about a month.

I was hoping someone on scienceblogs would write about it - here is a link if Tara is interested...

http://www.guardian.co.uk/medicine/story/0,,1733552,00.html

Posted by: mark c | April 7, 2006 6:17 AM

Tara says:

USA--apologies for not answering you; I'd pretty much agreed with what Dave said here and so didn't have much to add. I don't know that there's any consensus opinion among epidemiologists on the issue; it's difficult to sort out legend from fact in cases like those, but at least from articles I've read written by either historians of science who specialize in infectious disease, or by microbiologists/epidemiologists, I don't know of any who really think the corpses spread the plague into the city.

Yes, there are two ways to get pneumonic plague. The primary vector is via breathing in plague contaminated particles from someone else who already has it. But you can also get it via a case of bubonic plague which later invades the lungs of the same person and can develop into the pneumonic form.

So here, I'm thinking that bubonic plague infected rats from the seige encampments made their way inside the walls to infect some individuals in the town with the bubonic form, and some of these untreated (or poorly treated) cases developed into the pneumonic form. From there the spread was rapid person-to-person. But the rats kicked it off, not the corpses. In my opinion.

P.S. I like the banner idea, but have the artistic ability of a dead plague infected rat myself. Hope someone rises to the challenge, as I'm sure they will.

Posted by: Dave S. | April 8, 2006 4:38 PM