Global Warming, DDT, and Malaria

After making significant progress against Malaria in the 1950s and 1960s, the disease is back and, in fact, rates of malaria incidence are increasing in many developing countries. Why?

One answer that has been increasingly common is that global warming is responsible for the rise in malaria. Some scientists have suggested that not only is climate change response for the current upswing but that continued warming temperatures could lead to a resurgence of malaria outside of the tropics. Fortunately such claims don’t hold up to scrutiny.

Although malaria today is thought of as a specifically tropical disease, in fact malaria used to be present pretty much everywhere in the world — as entomologist Paul Reiter told the BBC in September, the first major reported outbreak of malaria in the world occurred in Philadelphia, of all places, in the 1780s. As recently as the 1880s, malaria was a serious problem throughout all of North America and was present as far north as Finland.

Improvements in public health monitoring as well as increases in population density helped largely eliminate the threat of the disease toward the last decade of the 19th century. Thus it’s not too surprising to see malaria increases in cooler, highland countries of Africa such as Rwanda and Kenya. This is especially true when one takes into account the increased efforts at diagnosing and reporting malaria cases in countries such as Rwanda — UNICEF spent millions of dollars in the mid to late 1980s to improve Rwanda’s ability to track malaria cases, and its hardly surprising that Rwanda’s health authorities as a result found more cases of malaria.

The really sad thing about the vector-borne disease/global warming link is just how ill-informed the so-called experts were who made this claim in the Intergovernmental Panel on Climate Change’s 1996 report. As Reiter told the BBC, “The bibliographies of the nine lead authors of the health section show that between them they had only published six research papers on vector-borne diseases.”

Meanwhile, the Save the Children from Malaria Campaign fears that an ongoing anti-DDT campaign by environmental activists is discouraging the use of that pesticide to control malaria. Some countries have stopped using DDT altogether, and those nations have experience increases in malaria according to tropic disease expert Donald Roberts. Roberts notes that in Guyana, for example, malaria incidence increased 12-fold from 1984 to 1991 when that nation reduced its DDT spraying.

While much of the environmentalist fears about DDT are overblown, neither is DDT a magic bullet as disastrous and counter-productive government application of DDT proved in the 1950s and 1960s. DDT is an important tool, but to rid the world of malaria will require governments and non-governmental organizations to use the pesticide wisely.

Source:

Malaria rising as DDT use falls, scientist says. Reuters, November 22, 2000.

Warming ‘not spreading malaria’. The BBC, September 21, 2000.