Bad theories kill people

A column by Jack Woodall in The Scientist addresses what "infectious disease says about humanity's penchant for self-destruction".

Hum. I must confess, I'm not quite sure what his point is, but he gives some wonderful examples of how bad theories kill people.

In an earlier column I related what had happened when a malicious rumor about polio vaccine circulated in one African country in early 2004, and vaccination was halted. The infection has now spread back to 20 countries from which, at great effort and expense, it had been eradicated.

Look at another crippling disease, tuberculosis. The cure requires daily doses of antibiotics for a number of weeks. But in countries where people have to travel far from home to receive health care, as soon as they start to feel better they head for home, not yet cured, carrying back with them bacteria that have survived the treatment and are now resistant, to be spread again in the community.

Doctors keep warning us we need to finish the whole course of antibiotics, and not stop taking them just because we feel better. But we're used to associating symptoms with disease, and we tend to run on the theory that when the symptom goes away, so does the disease.

Look also at HIV/AIDS, the 25th anniversary of which is the subject of a feature in this issue (see p. 36 ). Educated people know how it is spread and what to do about it, but nevertheless get carried away and ignore precautions in the heat of passion. As a wise friend of mine likes to say, "Hormones will always trump neurons." A Swiss teenager who was told her drug-addicted boyfriend was HIV-positive said, "I know he loves me and would never do anything to hurt me." In the face of such emotional responses, what chance do precautions have of succeeding?

Just a few leaps of logic, eh? Theory: He loves me. Evidence: usually not much besides the fact that she has the hots for him. Theory: He'd never do anything to hurt me. Evidence: He loves her, and (lesser included theory) he knows how to keep her from contracting AIDS. The evidence supporting the sub-theory? Not much. The fact that he's HIV-positive makes it hard to have much faith in his ability to prevent infection.

Some scientists have convinced themselves that AIDS is not caused by HIV but by anti-AIDS drugs. Worse yet, they have succeeded in convincing politically powerful figures, setting back AIDS control programs for years as in the case of South Africa. That country's leaders have changed their views, but the damage has been done.

And that's another case where a bad theory kills people.

Turn now to the less-educated majority. When I ran the CDC's dengue lab in San Juan, Puerto Rico, I accompanied sanitary inspectors on their tour of the city to look for mosquito breeding places. We lifted the lid of a rain barrel to find a swarm of mosquito larvae inside. When we showed them to the homeowner, he said, "You gringos all think we are stupid. Don't try to tell me these worms are going to turn into mosquitoes. Get out of my house!"

Bad theory: worms are worms, and worms they'll always be. Better theory: some worms are larval stages of mosquitos, and will grow up to carry dengue fever if you let them.

(Interestingly, the use of the term "gringos" points to a larger theory, which seems to spawn a lot of these bad theories. This theory says, "the white man is out to get us." White people tell people in Puerto Rico that worms will turn into mosquitos. White people tell black Africans that HIV causes AIDS, and the anti-AIDS drugs are a treatment. Woodall doesn't say what the polio vaccine rumor was, but I bet it had something to do with killing off the black population.

Well, according to theory, white people are racist, so they must have some nefarious purpose for saying this, and they think the other races are stupid enough to fall for it. And when they die from the side-effects of their theories, the white men will be right there, still going strong, and great targets for blame.)