By Olumayowa Okediran
Dichloro-Diphenyl-Trichloroethane (DDT), an organochlorine known for its insecticidal properties, is recognized as saving more lives than any other man-made chemical. In recent times, there has been a resurgence of malaria in many places where it had been previously eradicated, leading to increasing death tolls due to malaria. The added threat emerging from the Zika Virus makes the recent ban on the use of DDT sound incredibly ludicrous.
When Swiss scientist Paul Müller developed the pesticide Dichloro-Diphenyl-Trichloroethane (DDT), he was efficiently putting to rest a disease that was killing millions of people annually. DDT is used in indoor residual spraying (IRS) by spraying indoor surfaces with a coating. The coating works by repelling, irritating or killing mosquitoes, thus efficiently preventing transmission of malaria. It was first used on a large scale during the Second World War.
The rise in the use of DDT significantly decreased the incidence of malaria. Malaria death in Italy was reduced to zero in 1948, only three years after DDT was introduced. Malaria cases fell by 33 percent between 1942 and 1946 in South America. In India, malaria cases dropped from 75 million to 50,000 in a decade. Death from malaria was eradicated in Sri Lanka after the use of DDT in 1946, while cases declined from 3 million to just 29 in about two decades. In at least 10 countries, malaria was successfully eradicated.
The effectiveness of DDT in eradicating malaria was later questioned after mosquitoes began to develop some resistance to it. However, Donald Roberts, an entomologist at Tropical Public Health at the Uniformed Services University of the Health Sciences in Bethesda, Maryland, showed that DDT was still effective in repelling mosquitoes thus sustaining its capability to control malaria.
Apart from mosquitoes, DDT was effective against other arthropods that threatened agricultural growth. The U.S Department of Agricultural entomologists demonstrated that DDT was effective against lice, houseflies and other noxious insects. An Egyptian research led by Brigadier General Leon Fox also reported the successful use of DDT to combat small typhus epidemics in Algeria, Egypt and Mexico. Thus, DDTs soared both in pest control and malaria control/eradication.
DDT — A Health Hazard?
The promising rise of the use of DDT for combating malaria witnessed an unprecedented fall when in 1962, Rachel Carson published Silent Spring and stated that the use of DDT was adversely affecting the environment and could pose health hazards. Examples given included the decline in the fish and bird populations due to thinning of eggshells. Some other report suggested that DDT could induce reproductive and neurological defects in birds and fish when it accumulates in tissues of animals. Severe impairment in calves could also be caused when DDT accumulates in cow milk. The argument was capped in Carson’s publication which claimed that DDT could subsequently wipe out human population after contaminating food chains.
This led to significant changes in the world’s fight against malaria with the help of DDT. The United States, after some considerations, banned the use of DDTs in 1972. The U.S Agency for International Development, along with other western nations, discontinued support for the use of DDT and pressured recipient nations of their aid to stop its use. In 1989, The World Bank and the World Health Organization followed suit by creating the Roll Back Malaria program which focused on alternatives to insect controls methods such as bed nets, personnel training and drug therapies.
The Rise of Malaria Infections
Sadly, it took thousands of lives before countries who discontinued use of DDT in combating malaria realized their folly. Malaria returned in places where it had been eradicated. South Africa’s switch from DDT initially witnessed some degree of success, but it was only a few years before it announced its return to the use of DDT, after an unprecedented rise in cases of malaria infections. Uganda, Kenya and Zimbabwe also returned to the use of DDT as alternatives were not as efficient in combating the disease. The World Health Organization called for the reintroduction of IRS in 2006, scrambling to achieve its aim of eradicating malaria by 2015 in the Millennium Development Goals. It was added that regions that were significantly threatened by malaria such as Sub-Saharan Africa may continue to use DDTs. Its Roll Back Malaria program was recognized as an abysmal failure after spending so much on inefficient methods of controlling malaria.
It can thus be inferred that contradictory to Rachel Carson’s claims, the eradication of DDTs is more of a threat to human existence than the use of it.
With the new threats of the deadly Zika Virus, a brother plasmodium carried by mosquitoes, and the obvious need to combat malaria heads on as a threat to human welfare, how many people must die of mosquito related diseases while this debate on DDTs continues?
Olumayowa Okediran is a socio-economic and political commentator, nonprofit consultant and entrepreneur.