Infections of the body politic
NOt so many months ago, London researchers devised genetically engineered mosquitoes in the hope of forging a new weapon against malaria, a killer of 3 million people a year despite every modern effort to control it.
These man-made mosquitoes no longer could harbor the parasite that causes malaria. Researchers reasoned that these customized insects would out-breed their unmodified cousins in the wild, thereby driving malaria into extinction.
It didn’t work. These laboratory creations could not compete against the more vigorous unmodified insects, the researchers reported in February. Their new genes did not last as long as a typical African summer, the malaria mosquito’s normal breeding season. You can almost hear Robert Desowitz sigh: I told you so.
A knowledgeable and irascible veteran of the world’s public health wars, Desowitz is the author of “Federal Bodysnatchers and the New Guinea Virus.” This virus is a cousin of the AIDS virus that he sees as an example of misguided U.S. government efforts to patent disease organisms. He shows even more impatience with efforts to seek high-tech solutions to malaria. The world long has had a way to control the malaria mosquito cheaply and effectively, he believes. Only the corrupt politics of international public health agencies, misguided environmental regulations and, well, willful stupidity prevents its use to save the millions of infants and children who most often fall victim to mosquito-borne diseases.
It’s called DDT.
The infamous pesticide, long banned in most countries for its ill effects on wildlife, remains the single most effective tool against mosquitoes that carry malaria and other lethal plagues, such as West Nile virus, Desowitz believes. As vaccine research falters, DDT may well come back as the public health tool of last resort.
Applied more judiciously than in the 1950s, when indiscriminate spraying drove some species to the edge of extinction, the relatively inexpensive insecticide could be safely used against all mosquito-borne diseases, he says. DDT may be no panacea, but it can work until something better is developed.
Such contrarian thinking about intractable public health problems makes Desowitz’s new book on parasitic diseases compelling reading in this season of severe acute respiratory syndrome and West Nile virus. A Bronx-born, British-educated authority on tropical medicine, he has devoted his life to fighting lethal parasites that cause malaria and sleeping sickness in their human hosts. By and large, epidemiologists and other public health experts are a tight-lipped bunch. So much of their work depends on the approval of local political authorities that these disease detectives tend to keep their complaints and frustrations to themselves.
Not Desowitz. In his fifth nonfiction narrative on tropical diseases, he does not conceal anger or bitterness about how the public health enterprise of modern medicine has lost its way in the struggle against infectious diseases. He is passionate and, at times, near despair describing how United Nations bureaucracies, the greed of pharmaceutical firms, patent laws and scientific arrogance hinder efforts to control these resurging plagues.
He is unusually frank about the daunting challenge nature has set us. The mosquito -- a living hypodermic that injects disease parasites directly into the human bloodstream as it sucks the blood it needs to breed -- has withstood all medical efforts to control it. The parasite itself displays an unusual talent for adaptation and survival honed through eons of evolution.
Yet only a few decades ago, malaria was all but eradicated in regions where it was epidemic, he reminds us. Large-scale sanitation efforts and vast amounts of pesticides had curbed it. The malaria mosquito now is largely immune to pesticides that once controlled it, while the disease parasite itself is increasingly resistant to drugs used to treat it. In many countries, political chaos has disrupted national public health programs.
The disease today is more prevalent than at any other time in history, with more than half a billion new cases reported every year. In Africa, where 90% of all malaria occurs, it kills a child every 30 seconds. In India, the government spends almost half its public health budget combating malaria. To make matters worse, the disease is rebounding in the world’s poorest countries, where there are few financial incentives for pharmaceutical companies to develop new treatments, but unless new control measures are discovered, the death toll is expected to double in the next 20 years, Desowitz warns.
Desowitz is impatient with experimental schemes to cure malaria by redesigning the insects that transmit it. He scorns the equally unsuccessful struggle to create effective vaccines against the disease. Seventy years of tinkering with vaccine schemes, he says, have yielded nothing but intellectual opportunities for ambitious scientists. “The vaccine research is the stuff that National Academy of Science membership is made of, but this research hasn’t saved one child, pregnant woman, traveler or soldier from severe malaria,” he writes. “There are new ways to combat malaria -- new drugs, new impregnated mosquito nets, new understandings of mosquito behavior, new tolerance to spraying residual insecticides -- and the vaccine is not, or may never be, one of them.”
Shortly after Desowitz published this book, scientists announced they had deciphered the complete genetic inheritance of both the malaria parasite and the mosquito. With the human genome also in hand, researchers now can study the complete genetic sequence of a disease parasite, the insect that transmits it and its human host. No one knows how many more years it may take to be translated into new insecticides, effective vaccines, better medicines or genetically engineered insects that break the cycle of disease transmission.
Desowitz hopes such new tools will be useful. Last week, for example, scientists announced that they had sequenced the genome for the coronavirus believed responsible for SARS in only 12 days. Still, there so far is not a treatment.
Optimism -- a professional necessity for all scientists -- has yet to cure a single child dying of malaria. In the interim, Desowitz would certainly argue, it is to the past we must look to save ourselves, not to an uncertain future.
