DDT

: For other uses, see DDT (disambiguation).

DDT and malaria

Malaria infects between 300 million and 500 million people every year. The World Health Organisation estimates that around 1 million people die from malaria every year. Most of those deaths (90%) occur in Africa and mostly in children under the age of 5. The economic impact includes costs of health care, working days lost to sickness, days lost in education, decreased productivity due to brain damage from cerebral malaria, and loss of investment and tourism (Tren & Bate, 2004).

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Most of the prior use of DDT was in agriculture. Current use for disease control require only a small fraction of the amounts used previously and is much less likely to cause environmental problems. Such limited use of DDT has not become ineffective due to resistance in areas where it is used inside homes. Swaziland, Mozambique and Ecuador are other examples of countries that have very successfully reduced malaria incidence with DDT. However, its use has been greatly limited in many other countries due to reluctance by aid agencies in the developed world to fund DDT spraying and opposition from Western environmental groups. (Africa fighting malaria FAQ, 2005).

Related Topics:
Swaziland - Mozambique - Ecuador

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There are insecticide alternatives to DDT, and Vietnam is often mentioned as a country that has seen a continued decline in malaria cases after involuntarily switching from DDT in 1991. However, Vietnam's neighbour Thailand has continued to use DDT and has a much smaller malaria rate despite similar conditions. The insecticide alternatives are generally more expensive, which limits their use in poor nations and in situations where anti-malarial efforts are already underfunded. It is doubtful that they are more environmentally friendly or as efficient, easy to use and safe for humans as DDT.

Related Topics:
Vietnam - Thailand

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However, in some areas DDT has lost much of its effectiveness, especially where outdoor transmission is predominant form, like in India. "The declining effectiveness of DDT is a result of several factors which frequently operate in tandem. The first and the most important factor is vector resistance to DDT. All populations of the main vector, An. culicifacies have become resistant to DDT. The excito-repellent effect of DDT, often reported useful in other countries, actually promotes outdoor transmission" (Current Science 85 1532-1537http://www.ias.ac.in/currsci/dec102003/1532.pdf) (pdf file)

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In the period from 1934-1955 there were 1.5 million cases of malaria in Sri Lanka resulting in 80,000 deaths. After an extensive anti-mosquito program with DDT there were only 17 cases reported in 1963 and the program was halted. Malaria later rebounded to 600,000 cases in 1968 and the first quarter of 1969. Some proponents of DDT consider this an example of environmentalism trumping public well-being even though the use of DDT was ended more due to the lack of continuing need than due to environmental concerns. Spraying with DDT was resumed but many of the local mosquitoes had acquired resistance to DDT in the interim, presumably because of the continued use of DDT for crop protection, and so it was not nearly as effective as it had been previously. Switching to the more-expensive malathion in 1977 reduced the malaria infection rate to 3,000 by 2004. A recent study notes, "DDT and Malathion are no longer recommended since An. culicifacies and An. subpictus has been found resistant." (Malaria Journal 2005 4:8http://www.malariajournal.com/content/4/1/8)

Related Topics:
Sri Lanka - Malathion

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In many African nations, the problems resulting from malaria are viewed as greater than the potential dangers of DDT. After South Africa stopped using DDT in 1996, the number of malaria cases in KwaZulu Natal province rose from 8,000 to 42,000 cases. By 2000, there had been an approximate 400 percent increase in malaria deaths. Today, thanks to DDT, the number of deaths from malaria in the region is less than 50. South Africa could afford and did try newer alternatives to DDT but they proved less effective (Tren & Bate, 2004). Uganda also began permitting its use in anti-malarial efforts despite a threat that its agricultural products to Europe could be banned as a result. (EU warns Uganda over plans to use DDT to fight malaria, 2005). The country states it cannot achieve its development goals without first eliminating malaria with DDT. The GDP shows a striking co-relation between malaria and poverty, where malaria is estimated to reduce per capita growth by 1.3 percent per annum. (Lirri & Ntabadde, 2005).

Related Topics:
South Africa - KwaZulu Natal - Uganda

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Malaria cases increased in South America after stopping DDT use. Only Ecuador, which has continued to use DDT, has seen a reduction in the number of malaria cases in recent years http://www.cdc.gov/ncidod/eid/vol3no3/roberts.htm. Other mosquito-borne diseases are also on the rise. Until the 1970s, DDT was used to eradicate the Aedes aegypti mosquito from most tropical regions of the Americas. The reinvasion of Aedes aegypti since then has brought devastating outbreaks of dengue fever, dengue hemorrhagic fever, and a renewed threat of urban yellow fever (Bate, 2001).

Related Topics:
South America - Ecuador - Aedes aegypti - Dengue fever - Dengue hemorrhagic fever - Yellow fever

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One old study that actually shows that lives were saved due to banning agricultural use of DDT has been published in the scientific literature: "Correlating the use of DDT in El Salvador with renewed malaria transmission, it can be estimated that at current rates each kilo of insecticide added to the environment will generate 105 new cases of malaria." (Agricultural production and malaria resurgence in Central America and India, Chapin, Georgeanne & Robert Wasserstrom, Nature, Vol. 293, 1981, page 183).

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Donor organizations have often refused to fund public health DDT programshttp://www.fightingmalaria.org/faq.php. Many countries have been coming under pressure from international health and environment agencies to give up DDT or face losing aid grants: Belize and Bolivia are on record admitting they gave in to pressure on this issue from the US. Agency for International Development. http://www.cid.harvard.edu/cidinthenews/articles/nr_051401.html. In 1977 environmental groups sued to ban exports of DDT, after which many countries could no longer obtain any. The World Bank extended $165 million dollars to India's malaria sufferers, but specified that no DDT could be used. Dozens of other countries, where massive numbers of malaria deaths continue to occur, also cannot receive financial aid unless they agree to control mosquitoes by not using DDT. In 1986 Secretary of State George Schultz telegraphed orders to all embassies stating that "The U. S. cannot, repeat cannot, participate in programs using any of the following: (1) lindane, (2) BHC, (3) DDT, or (4) dieldrin." http://www.fightingmalaria.org/research.php?ID=26&month=

Related Topics:
Lindane - BHC - DDT - Dieldrin

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Nevertheless, one insecticide supply company states on its website:

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:DDT still not banned for malaria control

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:DDT is still one of the first and most commonly used insecticides for residual spraying, because of its low cost, high effectiveness, persistence and relative safety to humans.

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:...

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:In the past several years, we supplied DDT 75% WDP to Madagascar, Ethiopia, Eritrea, Sudan, South Africa, Namibia, Solomon Island, Papua New Guinea, Algeria, Thailand, Myanmar for Malaria Control project, and won a good reputation from WHO and relevant countries' government.

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A recent editorial in the British Medical Journal, argues that the campaign against malaria is failing, that use of DDT should be increased, and that donor organizations should abandon their reluctance to fund such programs since DDT has "a remarkable safety record when used in small quantities for indoor spraying in endemic regions".http://bmj.bmjjournals.com/cgi/content/full/328/7448/1086

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