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Climate Change and Malaria  - Indur Goklany - with response from Sir David King
Indur Goklany offers some fascinating insights into climate change, malaria, poverty and development. Sir David King, the UK Government's chief scientific adviser gives a predicable response.

The Real Obstacles to Sound Treatment of AIDS in Poor Countries  - Roger Bate & Richard Tren
Writing for the American Enterprise Institute's Health Policy Outlook, Bate and Tren explore some of the reasons for low drug access in poor countries. Despite promises of cheap or free antiretroviral drugs, Bate and Tren argue that access to treatment in poor countries is abysmally low because of a lack of infrastructure, political indifference, excessive bureaucracy and taxes and tariffs.

South Africa's War Against Malaria - Lessons for the Developing World  - Richard Tren & Roger Bate
The Cato Institute published Richard Tren and Roger Bate's analysis of South Africa's recent history with malaria control. They argue that its policy on DDT use and Artemesinin based combination therapy provide excellent examples for other malarial countries.

SA's Leading Malaria Researchers Support DDT Use  -
South Africa’s leading malaria control experts, researchers and doctors support and endorse the use of the insecticide DDT to control malaria. Their statement is released in light of recent claims that DDT is harmful to human health and should be removed from South Africa’s malaria control programme.

South African Malaria Data  - SA Dept of Health
November 2003 - the malaria statistics show that malaria is still well under control in South Africa. A recent epidemic in the Limpopo Province was primarily caused by late spraying and poor case management.

South Africa Malaria Data  - SA Dept of Health
The latest data on malaria cases and deaths from South Africa show that the country's policy of indoor residual spraying with DDT (among other insecticides) and the use of artemesinin based combination therapy is working. KwaZulu Natal, traditionally the province with the worst malaria and the centre of the recent epidemic has only recorded 1 malaria death this year!

South Africa Malaria Statistics  - Dept of Health
The 11th Dept of Health Malaria Update shows the latest number of confirmed cases and deaths from malaria in the three malarial provinces of South Africa.

Saving Lives Today and Tomorrow  - Dr. Roger Bate
This paper analyses trends in drug development using data from the drug industry association, the Pharmaceutical Research and Manufacturers of America (PhRMA). Worryingly, the findings suggest that far fewer AIDS drugs are in development compared to several years ago, and at a time when drug development for other communicable diseases is increasing. There are several probable explanations for this phenomenon, but the least benign is the likelihood that continual pressure group and media attacks on the industry over pricing of drugs in Africa has reduced incentives for development of new AIDS medicines

South African Malaria Update  - SA Dept of Health
The latest malaria update from the Directorate of Communicable Diseases.

Emerging Infectious Diseases

Letter

Malaria Control and Public Health


To the Editor: Malaria continues to cause disease and death in millions of persons living in areas of the world where it is endemic, despite 4 decades of research on vaccines, new drugs, and alternative methods of control. Still, by far the most effective method for reducing and controlling the impact of this disease is indoor residual spraying (IRS) of insecticides. The most cost-effective and safe insecticide has been, and in many instances still is, dichlorodiphenyltrichloroethane (DDT). This intervention is continually under scrutiny, and we address these issues in this letter.

Chen and Rogan (1) claim that DDT causes reduced duration of lactation and increased incidence of preterm births, and they posit that DDT used for malaria control would do as much harm as good. The validity of their arguments requires substantial evidence of a causal relationship between DDT and adverse consequences of DDT IRS for malaria control.

Chen and Rogan dismiss a field study on births and duration of lactation in South African mothers, some of whom occupied houses sprayed with DDT for malaria control (2). However, if claims of large numbers of adverse health effects of DDT IRS are correct, then the study should have detected large differences between DDT-exposed and unexposed populations. According to Chen and Rogan, the median duration of breast feeding could be as low as 3–4 months when mothers are exposed to high levels of DDT. Thus, a cross-section of breast feeding infants in the DDT-exposed population should, on average, have been considerably younger than in the unexposed population. In fact, the average age of breast feeding infants was slightly greater in the DDT-exposed population (8.3 months versus 7.7 months). For both populations, only an insignificant fraction of mothers could not donate milk. Furthermore, twice the level of dichlordiphenylethylene (DDE, metabolic breakdown product of DDT) that is claimed to cause reduced duration of lactation in humans has no adverse affect on lactation in rats (3). The authors of the South African study (2) report no difference in rates of stillbirths between the sprayed and unsprayed areas.

The National Institute of Environmental Health Sciences study (4) reported a causal association between DDT and preterm and small-for-gestational-age births but this has not been replicated for African births. The study was not based on a random population of births, and no explanation is offered for including diverse categories of births in the study population.

An earlier study in Sri Lanka presented data on deaths attributed to malaria and to premature births years before DDT was used and years when DDT IRS was used in 21 districts (5). Districts varied greatly in levels of malaria endemicity. After DDT was introduced in 1946, levels of IRS in 21 districts were commensurate with levels of endemic malaria. After 1946, malaria deaths declined greatly and the reduction was greatest where DDT usage was highest. During the same period, deaths attributable to premature births increased slightly. Investigators attributed this to "improvements in reporting and diagnosis rather than any declines in the health of expectant mothers, which on all other criteria showed improvement." (5). Spearman's correlation analysis for 21 districts shows that the increase in premature birth deaths was slightly greater in areas with less malaria and DDT use. Thus, the evidence does not support the idea that the reported increase in premature births was a side effect of DDT use. In any case, the increase in deaths attributable to premature births was orders of magnitude less than the reduction in deaths directly caused by malaria and other conditions indirectly related to malaria (5).

Similar major benefits of DDT use were seen in Guyana, where in 2 to 3 years, near elimination of malaria halved maternal deaths and reduced infant deaths by 39% (6). Anemia-associated deaths in pregnant females were reduced from 10 to 2.3 per 1,000 adult deaths (7). There was no offset of infant deaths attributable to adverse effects of DDT. Data from Guyana are particularly relevant to the present issue because malaria control was entirely due to DDT, i.e., drug treatments were not included (7). Health improvements related to DDT use accounted for 21% to 56% of increased population growth in Guyana during the post war years (5).

In summary, these data from South Africa, Sri Lanka, and Guyana are clearly contrary to the claims of Chen and Rogan (1) that ill effects of DDT on maternal health and infant survival would counterbalance the beneficial effect of malaria control. Their claim that alternative chemicals are cheaper than DDT is incorrect (8). Recent data on pyrethroid-treated bed nets are encouraging for situations in which sustained provision of spray pumps and trained spray teams are not feasible. However, even the best results with these nets do not match those obtained in the past with IRS, e.g., the suppression of malaria infection in Zanzibar from holoendemic levels to <5% (9).

In recent years, programs in South Africa and Madagascar (10) that again started IRS with DDT have greatly reduced malaria and malaria-related deaths. DDT is still needed and research is required to improve its use. The Stockholm Convention on Persistent Organic Pollutants specifically allows continued public health use of DDT.

Donald Roberts,*Comments Christopher Curtis,† Richard Tren,‡ Brian Sharp,§ Clive Shiff,¶ and Roger Bate#
*Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA;  †London School of Hygiene & Tropical Medicine, London, United Kingdom; ‡Africa Fighting Malaria, Sandton, South Africa; §Medical Research Council, Durban, South Africa; ¶Johns Hopkins University, Baltimore, Maryland, USA; and #Africa Fighting Malaria, Washington, D.C., USA

Suggested citation for this article: Roberts D, Curtis C, Tren R, Sharp B, Shiff C, Bate R. Malaria control and public health (replies). Emerg Infect Dis [serial on the Internet]. 2004 Jun [date cited]. Available from: http://www.cdc.gov/ncidod/EID/vol10no6/03-0787_03-0116.htm

References

  1. Chen A, Rogan WJ. Nonmalarial infant death and DDT use for malaria control. Emerg Infect Dis. 2003;9:960–4.
  2. Bouwman H, Reinecke AJ, Cooppan RM, Becker PJ. Factors affecting levels of DDT and metabolites in human breast milk from Kwazulu. J Toxicol Environ Health. 1990;31:93–115.
  3. Kornbrust D, Gillis B, Collins B, Goehl T, Bupta B, Schwetz B. Effects of 1,1-dichloro-2,2bis[p-chlorohenyl]ethylene (DDE) on lactation in rats. J Toxicol Environ Health.  1986;17:23–36.
  4. Longnecker MP, Klebanoff MA, Zhou H, Brock JW. Association between maternal serum concentration of the DDT metabolite DDE and preterm and small-for-gestational-age babies at birth. Lancet. 2001;358:110–4.
  5. Newman P. Malaria eradication and population growth, with special reference to Ceylon and British Guiana. School of Public Health, Ann Arbor, Michigan, The University of Michigan, Bureau of Public Health Economics, Research Series No. 10. 1965; p. 259.
  6. Giglioli G. Eradication of Anopheles darlingi from the inhabited areas of British Guiana by DDT residual spraying. J Natl Malar Soc. 1951;10:142–61.
  7. Giglioli G. Changes in the pattern of mortality following the eradication of hyperendemic malaria from a highly susceptible community. Bull World Health Organ. 1972;46:181–202.
  8. Walker K. Cost-comparison of DDT and alternative insecticides for malaria control. Med Vet Entomol. 2000;14:345–54.
  9. Curtis CF, Mnzava AEP. Comparison of house spraying and insecticide-treated nets for malaria control. Bull World Health Organ. 2000;78:1389–400.
  10. Romi R, Razaiarimanga A, Raharimanga R, Rakotondraibe EM, Ranaivo LH, Pietra V, et al. Impact of the malaria control campaign (1993–1998) in the highlands of Madagascar: parasitological and entomological data. Am J Trop Med Hyg. 2002;66:2–6.

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