Is DDT still effective and needed in malaria control?


DDT is an abbreviation for a compound known as dichlorodiphenyltrichloroethane.

  • How Is DDT Used? DDT is used for residual treatment of walls in dwellings in areas where malaria transmission occurs. DDT has been used in malaria control programmes since the late 1940s, often with great success. DDT is particularly useful when used in combination with improvements in housing counditions, such as screening of windows and doors. DDT is less costly than more modern chemicals used for mosquito control, such as the pyrethroids. Thus, in certain cases DDT is affordable while other compounds are not. Remember that malaria occurs in countries that are very often highly strapped for money.
  • How Dangerous is DDT to People? Very few (probably no) human deaths or illnesses have been conclusively linked to proper usage of DDT. On the other hand, proper usage of DDT has prevented many illnesses and deaths that would have occurred as a result of malaria.
  • Are There Regions Where DDT No Longer Works?Anopheles mosquitoes are physiologically resistant to DDT in some regions, and thus DDT is not effective in these areas. Currrent insecticide resistance test data should be used when planning malaria control efforts. Much resistance test data is 15-30 years old, and current resistance test data should be gatbered.
  • Are There Regions where DDT is Still Effective?In some regions. the vectors of malaria are still susceptible to DDT, and the compound remains effective in blocking malaria transmission. An example is control of Anopheles funestus in South Africa.
  • How Is DDT Used for Malaria Control?DDT usage for malaria control involves spraying the walls and backs of furniture in dwellings. These treatments are aimed at adult mosquitoes that come into the dwelling to feed on the occupants. DDT used in this manner also controls leishmaniasis, a disease that can be deadly or disfiguring and that occurs in the Indian subcontinent, Asia, and South America. Robert Desowitz, a noted student of tropical public health, has written about leishmaniasis and malaria in The Malaria Capers.
  • Is DDT Used Outdoors? There are now highly effective biological larvicides [Bacillus thuringiensis israelensis] for larval mosquito control, and outdoor DDT usage is inappropriate.
  • What About the Hazards of DDT? DDT is hazardous to certain wildlife species and should not be used outdoors or in natural areas. DDT toxicity to human beings is low. The appropriate use of DDT is to treat human dwellings and other buildings where mosquitoes enter to bite people.
  • Is There a Moral Dimension to this Question? Yes. Certain countries with high morbidity and mortality rates from malaria have trouble affording high-tech medical treatments or the latest insecticides. If DDT is effective for use against vectors in these regions it should be used to prevent premature death and disability. The preservation of human life is paramount.

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