Tuesday, October 30, 2007

How not to be part of the problem

Good, timely article in the NYT today about MRSA and antibacterial . . . umm . . . stuff.

MRSA: methicillin-resistant Staph. aureus, which caused, apparently, 19,000 deaths in the last year, 2 recently in healthy high schoolers.

antibacterial stuff: soaps, toys, cutting boards, etc. that have been impregnated with triclosan (an antibiotic) to prevent bacterial growth.

There is no direct epidemiological link between the two, but lab tests seem to indicate that over-use of the latter can lead to the former. (Interesting side note: should we reject a theory for lack of epi back-up, even though it works in the lab? Even when we also reject theories for lack of lab back-up, even when there's a statistical link in epi studies? Are we biased in our trust of the two methods?) Do we over-use the stuff?

If you want to control bacterial growth on stuff, as the article suggests, alcohol-based cleaners work better. If you want to control bacterial growth on your hands, ditto, but soap and water works too. Just in case, lets be sensible.

Thursday, October 18, 2007

Geniuses can be stupid, too

James Watson has been known to say stupid things about women, but now he's added Africans -- apparently, he thinks there's no reason for them to be as smart as Caucasians. After all, tests have proven it!

Much as I generally don't agree with Stephen Jay Gould, just read The Mismeasure of Man. Tests don't measure IQ (or IQ doesn't measure intelligence, if you prefer). We have to acknowledge that cultural familiarity plays a role in both questions and answers. I'm sure that an African-created IQ test would show the same differences . . . in the opposite direction.

Tuesday, October 16, 2007

Food is a right

I hadn't seen anything worth the trouble of writing in a while, but apparently I missed World Food Day. It's good to see so many countries coming out in support of food as a human right (after all, if life is a right, food has to be a right). My one question: where was the US and why didn't we hear about this?

Wednesday, October 10, 2007

The oracle and Delphi

Yes, Taubes strikes another blow at the epidemiologic stronghold! This time, though, he has a point . . .

Namely, people can be influenced by a strong opinion, especially if they aren't certain and/or multiple people express the same opinion. Peer pressure by any other name . . . it can certainly affect any study that requires expert opinions to fill data gaps.

That's why there's this great thing called the Delphi method. Basically, a survey is sent to a panel of experts (or they are interviewed, whatever your method). They are asked to answer a series of questions. Those answers are compiled for each question (range and mean for numerical data, lists for qualitative answers) and sent back to the panel with a fresh copy of the same survey. The experts can then change their answer based on what other people answered without one loud voice dominating. This process is repeated a few times, simulating discussion. Et voila! a consensus is reached in which everyone has an equal voice. A friend of mine used this method in his MS research and it worked quite well.

The price of free things

Health agencies are starting to focus on giving away bed nets in Africa.

If you've been reading this for a while, you know how I feel about giveaways -- they cause dependency and ruin local producers/merchants! No hand-outs!

Except . . . giving away bed nets seems to be equivalent to giving away vaccines: bed nets actually have a protective effect on the community if used by a sufficient number of residents. First, really?--cool! Second, public health issues are actually considered to be areas in which the well-being of all benefits from public funding. Just like vaccines, it's in the public interest to provide bed nets to those who can't afford them.

So why the debate? Well, there are always a few small government advocates who want everything to be in the private sector. Also, some people don't like to let go of an idea once they get hold of it. I was once told that the correct answer to any question asked by an epidemiologist is 'it depends'. For the people who still cling to the concept that giving away free goods is the least cost-efficient development scheme, add this caveat: only if the societal benefit of the giveaway is less than the societal cost. In this case, that assumption fails, so we must change our stance and encourage bed net giveaways.

Tuesday, October 09, 2007

Can we even trust epidemiology?

Another class assignment! In this case, just forcing me to do a more thorough review of an article I meant to review anyways. Here it is:

What level of proof is necessary to make a claim? That seems to be the question Taubes is asking in “Do we really know what makes us healthy.” I would posit that a more appropriate question would be ‘how do we interpret our claims?’

Taubes doubts the validity of epidemiological arguments based on his understanding of statistics as “tools . . . that may be unreliable” and “circumstantial evidence” that should be barely trusted, and only until clinical evidence is available. In one sense, he is right: as a science based on probabilities, epidemiology can be done badly and misused, with results that are untrustworthy. What about epidemiology done right? Sampling biases still exist: healthy users, atypical study subjects, compliance. Diagnostics are imperfect and that can bias results. Some confounders are unknown or immeasurable. However, dealing with these issues is one of the purposes of peer review. Taubes claims that the first report is untrustworthy simply because it lacks that peer review, ignoring the review process that is required to make that report. Any report published without peer review is indeed suspect, but that is true in any field. To re-quote John Bailar, “The appropriate question is not whether there are uncertainties about epidemiologic data, rather, it is whether the uncertainties are so great that one cannot draw useful conclusions from the data.”

The problem may come, not from the science itself, but from the understanding and application of the results. Taubes quotes an editorial from the New England Journal of Medicine on the role of the media in this debacle, namely, that the lay media interprets studies wrong. Rather than seeing an association as it is, they insist on a causative – it’s just easier to report. When a majority of these causations fail to materialize (although the associations may still be present), Taubes suggests they should reject epidemiology as an untrustworthy source.

Rejecting epidemiologic studies on the whole because a majority have been refuted is not a sensible choice. For example, many movies and even more books have poor to dismal ratings from tough critics; should I then reject all such media because the majority are considered bad? I would rather focus on the good, even if they are in the minority. That, of course, requires close, skeptical reading on the part of the science reporters.

Taubes champions the experimental study as the savior of epidemiologic conclusions. After all, if we can prove that the epidemiologists were right, we can ‘trust’ them (for a certain value of trust). However, one of the older studies he cites is ethically questionable (Goldberger trying to infect himself and colleagues) and the new studies he considers have plausibility problems of their own (H.R.T. studies choosing different subject types). In many cases, experimental studies are simply not possible, as Taubes admits. Why, then, does he end with a suggestion to wait for clinical trials to back up the epidemiologic associations?

The main problem with this entire debate, however, is the differing viewpoints. Taubes writes to inform the individual readers, who will try to apply the results of epidemiologic studies to their own lives. As any epidemiologist knows, those studies are not meant to predict individual results. To an individual, population-level data is a step removed. Maybe the problem comes simply in the application, stepping down to the micro what is meant to be macro – in other words, the ecologic fallacy.

Friday, October 05, 2007

It could happen here?

Think I wasn't accurate about the UK being a little unlucky? Well, turns out their most recent FMD problem could happen here, too.

Just so you know. I mean, if I'm going to stay up at night worrying, why shouldn't you?

Wednesday, October 03, 2007

Unlucky? Unlikely

Somebody asked Slate.com why British cattle get so many diseases.

Ummm . . .

Let's talk about information bias. To be specific, diagnostic bias and reporting bias. The UK has a fantastic diagnostic service. The UK also reports any diseases it finds. Therefore, the UK reports a lot of disease outbreaks. In sub-Saharan Africa, which has 75% of the world's disease burden according to a recent lecture I attended, there is no money for diagnostic services, so even strict reporting (which is unlikely) wouldn't lead to a lot of outbreak reports. Ditto for Southeast Asia -- diagnostics are lacking and reporting is low. China, on the other hand, probably has good diagnostic services; they don't report many outbreaks because they choose not to report what they find.

The reporting bias is an important point. On Promed, outbreaks in some countries are reported by the OIE or the country involved; outbreaks in other countries are reported by field workers or locals. If we only consider outbreaks in countries where reporting is through official channels, those (few) countries will look disease-ridden compared to the rest.

Okay, there may be some luck (or lack) involved in the case of the UK. I'm not sure Heathrow is a bigger international hub than Schipol or LAX. I'm not sure the UK has a bigger smuggling problem. They just got unlucky with FMD.

In the case of BSE, though, we got lucky that it happened in the UK. They diagnosed it (and fixed it) faster than most countries could have. Think SARS or avian influenza, but with no obvious animal link -- how long would it have taken Thailand to figure it out or China to tell us about it?

Monday, October 01, 2007

Zoonotic diseases? From livestock? You're kidding, right?

This is a serious problem; urban agriculture is a growing segment of the livestock industry in many low-income countries with large, sprawling cities. Especially with the lack of good water treatment facilities or sewage control -- the sewers were one of the biggest gains in public health in human history, so what happens if we don't have them and we have all sorts of livestock spreading manure in our cities? In traditional systems, we didn't have this problem because animals were kept out on ranges. Of course, the animal caretakers had issues to deal with . . . and still do . . . but now consumers are at risk.

This doesn't even address the issue of free-ranging animals in urban areas (cattle in India, poultry and small ruminants in many other areas). They could spread disease directly, as well as from their waste. No solutions from me, sorry -- this is a sticky issue that needs a lot of attention.
FAO sees disease threat from increase global meat production
By Janie Gabbett on 9/18/2007 for Meatingplace.com
Increase global meat and poultry production to meet escalating demand has pushed production closer to urban areas, increasing the risk of animal to human disease transmission, according to the United Nations' Food and Agriculture Organization (FAO).

"The risk of disease transmission from animals to humans will increase in the future due to human and livestock population growth, dynamic changes in livestock production, the emergence of worldwide agro-food networks and a significant increase in the mobility of people and goods," FAO said in a policy brief titled "Industrial Livestock Production and Global Health Risks."

It warned the risk of pathogen transfer is increased by: animal movement; the concentration of confined animals; and the waste produced by large animal houses.

With global pig and poultry production growing the fastest, the FAO cited a trend towards industrialized livestock production replacing traditional systems in developing countries, most notably in Asia, South American and parts of Africa.

It also raised concerns that most chickens and turkeys in industrialized nations are now produced in houses with 15,000 to 50,000 birds and that both poultry and pig production rely on significant animal movement.

The FAO called on meat producers to: apply basic biosecurity measures, refrain from building production sites too close to human settlements or wild bird populations, regularly clean and disinfect farms, control staff and vehicles movement and train employees in biosecurity.

A long-overdue study

What are the international trade barriers to US beef, and how do they effect the industry?

Are you kidding? Haven't they done this before now?!?! For all I know, of course, this is just a duplication of somebody's thesis that never got read . . .

ITC to investigate international trade barriers on U.S. beef
By Tom Johnston on 9/17/2007 for Meatingplace.com

The U.S. International Trade Commission said on Friday it launched a probe into the effects of international trade restrictions on U.S. beef.

The ITC investigation follows a request by the Senate's Finance Committee, which lamented the economic impact of restrictions by Japan and South Korea on the U.S. beef industry. (See Senator wants audit of Asian barriers on U.S. beef on Meatingplace.com, Aug. 8, 2007.)

The commission said it would provide an overview of the U.S. and global markets for beef, as well as information on animal health, sanitary, and food safety measures facing U.S. and other major beef exporters. It will also will render information on other barriers to U.S. beef exports in major foreign markets, including high tariffs, quotas and import licensing and distribution systems, as well as analyze their economic effects.

The ITC is slated to submit its report to the Senate's Finance Committee on June 6, 2008. It will hold a public hearing related to the investigation at 9:30 a.m. Nov. 15, 2007. Requests to appear should be filed with the Secretary, United States International Trade Commission, 500 E Street SW, Washington, D.C. 20436, by 5:15 p.m. Oct. 18.

Sensible classes? Real-world ideas? Yes, thank you.

I know, I've been away for a little while (busy, sick, etc), but I've built up a backlog of articles to comment on, so here goes:

MIT apparently started classes in basic technologies that could be used in countries with infrastructure or supply issues. Simple, useful ideas for heating, cooking, powering, processing -- this is exactly the sort of thing more development agencies should be doing.

Now, if only we could get the classes held on-site . . .