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Evidence supporting the continued availability of DDT as an option for malaria control

Evidence supporting the continued availability of DDT as an option for malaria control. Chris Curtis London School of Hygiene & Tropical Medicine, London WC1E 7HT, email: chris.curtis@lshtm.ac.uk.

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Evidence supporting the continued availability of DDT as an option for malaria control

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  1. Evidence supporting the continued availability of DDT as an option for malaria control Chris Curtis London School of Hygiene & Tropical Medicine, London WC1E 7HT, email: chris.curtis@lshtm.ac.uk

  2. DDT is sprayed on inside surfaces of walls and ceilings of houses to kill resting adult mosquitoes, not for outdoor spraying of mosquito breeding sites • If illegal selling of DDT to farmers can be prevented it does not enter outdoor food chains; • On this basis use of DDT for disease vector control was accepted nem.con. in negotiations leading to the Stockholm Convention on Persistent Organic Pollutants

  3. Evidence about DDT and human health • Indian and Brazilian DDT spraymen showed no higher prevalence of diseases than other men of the same age; • DDT derivatives found in breast milk where anti-malaria spraying is carried out in S.Africa; • American serum samples and corresponding pregnancy histories from the 1950s show a correlation of DDT derivatives with probability of premature birth; However:- • Compared with before the DDT anti-malaria campaign in Guyana, maternal and infant health improved greatly during the campaign and after successful malaria eradication; Conclusion:- if DDT causesany harm, this is greatly outweighed by its benefits when effectively used against malaria

  4. Italy and Romania

  5. Indoor residual spraying in southern Africa

  6. Zanzibar in the 1950s-60s • DDT spraying (combined with treatment of malaria cases with chloroquine to which there was then no resistance) reduced very high endemicity to only 5% of children infected over a 10 year period; • unfortunately the project was then terminated when eradication seemed imminent; • nevertheless, the reduction achieved was far greater than any of the recent results with insecticide treated nets.

  7. Madagascar highlands

  8. In India in the 1930s there were about 75 million malaria cases/yr, but in the 1960s DDT spraying reduced this to about 100,000 (99.8% reduction) – a FAR greater reduction factor than has yet been achieved with treated nets • Laboratory tests on Indian mosquitoes now show considerable DDT resistance • However:- data of S.N.Sharma (2005 J Vec Borne Dis 42: 54) show that, provided a high % of the houses in a village are sprayed, DDT is still very effective in reducing mosquito vector populations and malaria; • Indian made DDT is much cheaper, per house sprayed, than imported alternative insecticides; lower costs mean more communities can be covered from a limited budget for disease control.

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