MALARIA: African Countries Debate Using DDT in Anti-Malaria Efforts

July 12, 2011 : Sanday Chongo Kabange : Lusaka, Zambia

African Countries Debate Using DDT in Anti-Malaria Efforts : Some propose using pesticide in tightly controlled conditions

Photo: VOA - A. Fortier

African children watch a play on malaria prevention at the Mbosse health clinic.

The chemical pesticide DDT has been banned by most countries for use in agriculture, but some continue to use it indoors to kill insects that carry malaria.
In Zambia, it’s an important part of the government’s malaria control program, and the controlled use of DDT spray has led to a reduction in malaria cases over the years.
Other African countries are facing a rise in the number of cases and several African governments are considering the carefully monitored use of DDT as part of their strategy against the disease.
In Malawi, for example, the Department of Health may undertake a DDT spray program in malaria prone-areas.
There is no doubt that DDT is very effective in killing mosquitoes. The problem lies in what other effects DDT may have on human health, wildlife, environment, horticulture and crops.
Malawi’s secretary of health, Chris Kang’ombe, was part of a delegation that visited Zambia to learn how the use of DDT has helped reduce malaria there.
Kang’ombe is convinced that DDT can help reduce the spread of malaria in Africa -- if handled under controlled conditions by trained personnel and monitored by government agencies.
He says, “DDT is used for indoor spraying. It is used to only spray within, inside the house, dwelling houses. What we have learnt (from Zambia) and we know from our experience here (in Malawi), the other chemicals [are active for] up to about two or three months, whereas with DDT you are talking of six months plus. So in terms of “residue effect,” it (DDT) is better, and also eventually the cost of indoor spraying…will be much cheaper, more cost effective than using other chemicals. “
While authorities in Malawi are still considering using DDT in malaria control, a thorny issue has arisen.
The Tobacco Control Commission is against the idea of using the pesticide. Tobacco is the mainstay of Malawi’s economy, and there’s fear that Western consumers will not buy it if there are any traces of DDT on the crops. So the commission will likely require careful monitoring if Malawi is to start using DDT in malaria control.
Similar views are shared by Uganda’s Network on Toxic Free Malaria Control. The network is against the use of DDT as a malaria control strategy.
“We have no law specifically for DDT,” says Network Secretary General Ellady Muyambi . “ We have no trained manpower. We do not have equipment in terms of transportation facilities, in terms of storage facilities, in terms of disposal facilities, in terms of laboratories for chromatography. We do not have the capacity. We are still relaying on donor funding and we are saying why can’t our country use its own resources to deal with its own problems, especially these ones like malaria.,” says Muyambi.
Also involved in the DDT debate is Kenya, another country debating whether to use the pesticide.
Shrikant Bhatt professor of medicine at the University of Nairobi in Kenya explains why the controlled use of DDT should be reintroduced. “We are almost getting defeated by the pandemic that is occurring due to malaria. [Anti-malarial] drugs are gaining resistance [to the parasite]. You know we have very few drugs which we can use as effective means of controlling malaria. So, I think we do not have any option but to reintroduce DDT in a limited way, [like] spraying DDT indoors or using it in endemic areas we should be able to contain the malaria pandemic,” he explains.
The International Centre for Insect Physiology and Ecology (ICIPE), also based in Kenya, is taking different approach.
John Githure a researcher at the centre says “ICIPE is largely concentrating on how we can come up with innovative ways or even using available products to kill the mosquitoes at larval stage. “
One such product uses soil-dwelling bacteria called bacillus thuringiensis, or BTi.
Githure says ,”we are trying to introduce that in Africa and ICIPE have of course gone ahead to construct a demonstration factory that will be able to at least make the product BTi available, affordable and accessible to the community to use for mosquito control.”
Meanwhile, the government and various organizations including Melinda and Bill Gates Foundation are encouraging free distribution of insecticide-treated mosquito nets and sleeping under bed-nets as short term measure for malaria control.
http://www.voanews.com/english/news/africa/pan/African-Countries-Debate-Using-DDT-in-Anti-Malaria-Efforts--125426193.html

MALARIA: Old socks and yeast to lure mosquitoes

Maina Waruru: 1 December 2010
  Flickr/Jory: Old socks: a tool for malaria control?

[NAIROBI] A worn sock and a bottle of fermenting yeast could provide a cheap and effective trap for mosquitoes, according to a study.
Scientists testing ingredients for traps outside huts in western Kenya found that they could lure many mosquitoes away from their human targets using these simple components. Mosquitoes follow carbon dioxide (CO2) gas because it is breathed out by animals, on whom they feed — in the case of humans, transmitting diseases such as malaria and dengue in the process. Scientists already use traps baited with industrially produced CO2 to capture mosquitoes for study.

But scientists, from Wageningen University in the Netherlands, the University of Nairobi in Kenya and the Kenya-based International Centre for Insect Physiology and Ecology (icipe), wanted to see if they could produce a cheaper, household version. The scientists baited some traps with the usual, industrially produced CO2. They baited others with CO2 produced by fermentation when yeast is mixed with a sugar solution. Both options were tested in a variety of settings including 'semi-field' trials, and full field trials — where traps were hung under the eaves of four huts in Lwanda, a rural village in western Kenya, whose occupants were sleeping under bednets. Nylon socks that had been worn by two of the scientists — to ensure they contained "human foot volatiles" — were added to some of the traps, with clean nylon socks added to others as controls. The top performing traps were those containing a combination of CO2 derived from the yeast mixture and worn socks.
In the semi-field trials, unbaited traps caught only five per cent of the mosquitoes that were released; worn socks alone trapped 43 per cent, and the combination of a worn sock and yeast-produced CO2 trapped nearly 80 per cent of released mosquitoes.
In Lwanda, where the trials were conducted among the naturally occurring mosquitoes, the results showed a similar pattern.
The scientists believe that the yeast may release other gases in addition to CO2, when it ferments, that are similar to other gases that humans produce.
Traps made using socks and yeast solution could, they say, "significantly reduce costs and allow sustainable mass-application of odour-baited devices for mosquito sampling in remote areas".
While producing CO2 from yeast using a bottle sugar and water is easy and possible in every African home, more research is needed to determine exactly what chemicals from the human scent attracted mosquitoes, said Wolfgang Schmied, one of the team, whose work was published in Malaria Journal (25 October).
"The idea is not to stop closing windows or using bednets," Schmied said, "but the traps could become an additional building block in an encompassing mosquito control programme if they became cheap and effective enough".
Albert Otieno of icipe's human health division, who was not involved in the research, said that yeast-based traps could be made for less than US$6 dollars since yeast is easy to obtain and used bottles can be used as apparatus.
http://www.scidev.net/en/news/old-socks-and-yeast-to-lure-mosquitoes-1.html