Thursday, November 17, 2005

Spray the Anopheles...and Darn the Consequence Later !

The efficacy of DDT (bis[4-chlorophenyl]-1,1,1-trichloroethane, or Dichlorodiphenyl trichloroethane) as an insecticidal has never been in doubt, and its uses against malaria, typhus, and other vector-borne diseases have been well documented. The eradication of endemic malaria in North America and Europe has been attributed to the use of DDT against anopheles mosquitos.

Philip Coticelli and Richard Tren of Africa fighting Malaria, "an NGO which seeks to educate people about the scourge of Malaria and the political economy of malaria control", in their publications in the South Afrcian Mail and Guardian and Business Day, urged the use of widespread DDT in malaria endemic areas of Africa.

I also recognize and appreciate the well written prose on Chippla’s Weblog and Black Looks further re-echoing and championing the cause on the Blogoshere.

These efforts are understandable given that the insecticide was banned in Europe and North America largely because of ecological considerations, and not because of negative effects on humans. What has not been well documented is the health risk of widespread use of DDT.

It is prudent to consider and examine some of the documented toxic effects of DDT, for its use is not entirely without consequences, even if scientific data has not been unequivocal in demonstrating them.
The widespread use of DDT is toxic and could adversely affect reproductive health in men and women exposed to it?

A prolonged exposure to DDT (even when used at the recommended concentration) increases the risk of pre-term births and earlier weaning of newborns (shortened breast feeding duration)?
These are not trival side effects, but ominous possibilities that are yet to be clearly ruled out by clinical studies. Contrary to what many pundits claimed, a recent publication* in The Lancet , an international medical science journal of high repute, suggests these conditions and others may indeed occur following prolonged exposure to DDT.

If one considers the pros and cons of DDT use, it can be argued that the deaths attributable to malarial infection in Africa far outweigh the deaths that can potentially result from DDT toxicity.

The answer is not without some ambiguity.

Infants and children in general carry a disproportionate burden of malaria mortality (deaths), just as they would if DDT toxicity increases the risk of pre-term births and early weaning. Then what of the potential poor reproductive health component of DDT toxicity? This is an unparallel negative score against DDT.

It is apparent that the countries that successfully used DDT to eradicate the malaria many decades back had some common characteristics: they had the political will, solid infrastructures, and deep pockets to finance the intervention. It is even doubtful, in my opinion, that their intervention would have been so successful if they had not taken a multi-systemic approach that included pharmacotherapy, environmental engineering and control, and extensive publicity and awareness drive, etc.

Malaria endemic regions of Africa should do the same and focus on building sustainable, robust, well-designed, and long-lasting public health interventions against malaria and its vector, and at the same time institute infrastructures to monitor the efficacy and the potential toxic effects of DDT.

The question is: Are we ready to do what it takes to control or even eradicate malaria? Or all we want to do is spray the bloody anopheles mosquitos and darn the consequence later?

Going by historical precedence, it seems more like the latter.


*Walter Rogan and Aimin Chen are Epidemiologists with the United States National Institute of Environmental Health Sciences, North carolina. They are the authors of the article mentioned in this post. Their article is a review of 148 publications and studies on DDT.

Here is the full citation to their paper:

Rogan WJ, Chen A.
Health risks and benefits of bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT).
Lancet. 2005 Aug 27-Sep 2;366(9487):763-73.