WorldChanging On E. coli Spinach

WorldChanging has a great piece called Spinach, Feedlots and Knowing the Backstory. Did you know that E. coli O157:H7, the dangerous strain that is now contaminating spinach, thrives primarily in the digestive tracts of grain-fed feedlot cows? Where does our food come from, anyway?

Friday Random Ten

• Animaniacs, "Parts of the Brain". Sung, of course, by the Brain.
• Linda Beck, "La Tierra Misma". A gentle song in English and Spanish.
• Bruce Cockburn, "My Beat". Impressionistic word painting of a city.
• Collin Raye, "Twenty Years and Change". Definitely the best thing Collin's written so far.
• Mindy McCready, "Guys Do It All the Time". Oh yeah!
• Collin Raye, "Sweet Miss Behavin'" Pun-filled dance tune.
• Peter, Paul and Mary, "500 Miles". I enjoy singing this one.
• Julia Ecklar, "Walkabout". Weird song of disillusionment.
• Jo Dee Messina, "Bye Bye". The boyfriend is history!
• Stephen Longfellow Fiske, "No Easy Answers". A song about homelessness; not Fiske's best.

Should HIV Testing be Routine?

Faced with a room full of premeds, my undergrad statistics professor enjoyed giving us problems like, "If one person in a thousand has a certain disease and the test for the disease gives a positive result X percent of the time if the person has the disease and Y percent of the time if they don't, how many false positives does it give if 100,000 people are tested?" For rare diseases, even very high test accuracy often resulted in more false positives than true ones.

Those old assignments came to mind when I read that the CDC is now recommending HIV testing for all adults and adolescents. This is supposed to reduce spread of the virus and ensure that those infected get anti-retroviral treatment before they actually get sick, but I was worried about false initial positives. Fortunately, the numbers are more favorable here than they were in Stats 13.

About 1% of the US population is estimated to have undiagnosed HIV infection. New rapid tests have a false positive rate of about 0.2% and a false negative rate of about 0.1%. So, screening 100,000 individuals would give 0.999*0.01*100,000=999 true positives and only 0.002*0.99*100,000=198 false positives, a pretty good ratio.

Conclusion? Although it makes sense to opt out of testing if you're sure you have no chance of having HIV, universal screening appears to be a good public health measure and I hope it's implemented quickly.

Nutrition, Solar Design and Buying Local

Now that organic is going mainstream, buying locally grown food has become the hot new trend among environmentally-oriented foodies. While I think the trend can go to entertaining but impractical lengths and some of the arguments in favor of locally grown food do not work, there's no doubt that buying local saves energy, since your veggies don't have to be trucked cross-country. And fresh food just plain tastes better.

There's just one small problem: winter. For those of us in temperate or northern climates, a local diet would be seriously vitamin-deficient -- not to mention boring -- for four to six months of the year. As a South Dakota resident colorfully put it:

If all I bought was local production in the wintertime, I wouldn't be buying anything but meat. I would have the same vitamin-deficient, fruit-deficient, vegetable-deficient diet that people had in the 1800s, when they lived on bread, beans, bacon, and potatoes for 6 months out of the year, and died in their 50s. A flu germ would kill me. If you want vitamin C, you're gonna have to import.

So, is there a way out of this dilemma? Yes, and its name is passive solar design. In one incarnation, described by Tom Philpott in Grist Magazine, this involves combining greenhouses built right into hills with using large barrels of water to store up heat. Another version, which even works in Maine, uses cold frames and varies crops with the seasons. Almost certainly, other possibilities exist that haven't been invented yet.

I do not think it is necessary or desirable to rely entirely on local produce, but it should certainly become more common than it is. (Why is Florida orange juice so common in California? What are California peaches doing here in Georgia?) The big lesson of passive solar design in agriculture is that we shouldn't automatically accept trade-offs between truly desirable things. Very often, we can have our fresh tomatoes and eat them, too.

I'm Back

It's good to be posting again! Past readers will notice the change in my profile -- I officially started graduate school a few weeks ago. Moving to Athens, getting set up and then obtaining my forgotten password from Blogger took far longer than I thought it would. Expect a new post sometime in the next few days. In the meantime, check out my fellow Athenian blogger Wayne at Niches.