The Ministry of Health has confirmed that 12 years after its use was discontinued, DDT is being reintroduced in Indoor Residual Spraying (IRS) for malaria control.
The ministry’s spokesman, Temba Sibanda, says that the plan is to pilot DDT’s re-introduction in one district this October and then scale it up to other districts in subsequent years.
In explaining this development, Sibanda adds that Botswana withdrew use of DDT in 1997 “mainly because of procurement difficulties” since most companies that manufactured it had closed down after its ban in the United States.
Use of DDT in the country started in the early 1950s during the colonial era and was continued by the homegrown government at independence in 1966.
According to Sibanda, Botswana is reintroducing DDT for four reasons: acknowledgement of malaria as a major public health problem; the country’s high vector susceptibility; evidence of reduction in vector susceptibility to pyrethroids which are currently being used; and, evidence of major success in malaria control through use of DDT for IRS in malaria control.
“In 2001, the Stockholm Convention on Persistent Organic Compounds classified DDT as restricted and allowed for its continued use for disease vector control following WHO guidelines. Today WHO actively promotes the use of IRS with DDT. SADC also recommends the use of DDT for IRS and most SADC Member States have been using DDT since 2006 following the SADC Health Ministers decision for the universal use of IRS with DDT as a primary preventive strategy to address malaria in the region,” Sibanda says.
In 1998, WHO’s Malaria Expert Committee recommended continued use of DDT particularly in the poorest endemic countries. The world health body’s position is that ‘premature shift to less effective or more costly alternatives to DDT, without adequate preparation of the capacity of member states (human, technical and financial) will not only be unsustainable but also have a negative impact on disease burden in endemic countries’.
Sibanda states that DDT use for vector control was never banned but that international pressure restricted its implementation in malarious countries.
“Botswana is one of the four countries targeted for malaria elimination and as the country gears for this, it is imperative that we use the best arsenal available to reduce the burden of malaria vector which is DDT,” he says.
Procurement of DDT will not be a problem as the Stockholm Convention on Persistent Organic Compounds permits the production of DDT, but strictly for disease vector control under WHO guidelines.
In Botswana, malaria is mostly prevalent in the northern districts. The districts of Chobe, Gumare, Ngami, Tutume, North-East and Boteti account for 95 percent of the cases and incidence on average. Of these districts, the southern-most have high co-efficients of variability.
The annual average rainfall by district varies from 300 to 600 mm with low values in the south-western districts and higher values in the north, east and in the south-eastern region around Gaborone. Malaria incidence is higher in wetter regions except in the south-eastern region.
Malaria needs minimum temperatures of 18 degrees Celsius and maximum of 32 degrees Celsius to breed and an accumulated rainfall total of 400 millimetres is likely to bring about an epidemic.
In Botswana, incidences of malaria peak during the months of March and April after a two-month lag during the malaria vector populations would have been breeding.