DDT effective in fight against malaria

Oct 17, 2010 News

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– Minister Ramsammy insists

– calls for re-examination of global policies to ban insecticide

The impact of vector-borne diseases, the likes of malaria and dengue, will not be reduced but rather will surge as the effects of climate change materialise further.  And according to Minister of Health, Dr Leslie Ramsammy, the health sector’s struggle against such diseases is likely to fail because of global policies that limit the use of effective tools such as Dichlorodiphenyl Trichloroethane, commonly referred to as DDT. For this reason the Minister said that he calling on the global authorities to re-examine their position on the insecticide.
“My position is that DDT is the most effective and affordable chemical we have to control malaria…further is that the global response to the burgeoning malaria rates in the world should allow for DDT residual spraying.” And it is the Minister’s conviction that the benefits in the use of DDT for public health purposes far outweighs the risk for low-level usage of this chemical. He noted that regulations and policies of industrialised countries and international agencies that block financial assistance to countries for the use of DDT for malaria control should be eliminated.
“It is my view that we should establish a global mechanism for the production and distribution of DDT for prevention and control of malaria, dengue and other mosquito-borne diseases. The low-level usage for public health purposes will not have any environmental impact.”
Guyana continues to encounter malaria as a major public health problem. And while significant progress has been made in the last five years in the prevention and control of malaria in Guyana, the local health sector has had significant problems in sustaining a reduced level of malaria incidences in Guyana in the past 12 months, Minister Ramsammy revealed.
The use of long-lasting insecticide, impregnated bed nets, more training for health workers, and use of better medicines have, however, contributed to an almost 80 percent reduction of malaria between 2004 and 2008. Yet the efforts have stagnated and this year there has been a significant increase in malaria incidences in Guyana, Dr Ramsammy said.
“Clearly, without an effective, long-lasting residual and affordable insecticide to reduce the mosquito population (effective vector control) to break transmission of malaria, the fight against malaria in any country will continue to be a difficult and daunting challenge and success cannot be guaranteed. For many countries, this realisation is a case of déjà vu. In Guyana’s case, we can recall the use of DDT as the insecticide used for indoor residual spray (IRS) in the 1950s which led to the elimination of malaria from Guyana’s coast.”
With the virtual banning of DDT, the pyrethroids have now largely replaced other insecticides including DDT, as the main IRS insecticide, according to the Minister. And mainly because of their short residual life-cycle and biodegradable property, the pyrethroids have been the preferred insecticide for IRS control of mosquito (vector) population, in preference to DDT, Minister Ramsammy added.
But the use of the pyrethroids, he said, has been limited because of their extremely high cost and the need for greater frequency of application when compared to DDT in the hot, humid conditions of the endemic malarious areas which are also far, isolated and difficult to access. These areas are the rich, biodiversity areas of Regions Number One, Seven, Eight, Nine and parts of Two and 10.  Also, they are the areas of Guyana’s forest, mineral deposits and vast water resources and the home of the poor, vulnerable indigenous Amerindians.
It was in recognition of the fact that DDT had some environmental effects that the Stockholm Convention was formulated, and includes special provisions for the phasing out of DDT. The convention however provides for DDT’s continued use for malaria control in countries with specific exemptions.  Thirty-one (31) of the 91 countries that signed the Stockholm Convention requested exemptions for DDT use to control Malaria.  Guyana is listed by WHO as a “recent user” although Guyana was the first country in the Americas to use DDT in 1942 for malaria control.
However, since the Stockholm Convention, the manufacturing of DDT has been severely curtailed, with only a few countries including India and China, still producing it.  Also, while WHO still endorsed and support DDT for Vector Control, transportation of the insecticide is prohibited. There are many other examples of poor international policies relating to DDT that have contributed to morbidity and mortality of mosquito-borne diseases.
Belize, for example in 2000, was threatened by USAID with withdrawal of support if it were to use DDT. Guyana, like many other poor countries needs increased donor funding for not only malaria prevention and control but also for research, and with the present non-availability of DDT – either allowing its availability or the international community providing sustained support for alternative control methods.
However sustained international donor support for vector control activities is not available at this time, Minister Ramsammy revealed. And without such support, the availability of expensive, recommended IRS commodities will remain unreliable and, therefore, the battle against the malaria vector will remain weak, he asserted.
“As Minister of Health, I believe that the almost one million deaths occur because of malaria and the countless other deaths caused by other vector-borne diseases around the world make it an imperative for global authorities to re-think policies relating to DDT. DDT has been an effective tool to control mosquito population in countries around the world before the virtual ban of DDT,” he added.
And according to him, the case against DDT as a harmful environmental chemical is weak compared to the fact that millions are dying and hundreds of millions are sick and disabled, and becoming impoverished because of mosquito-borne diseases. The virtual banning of DDT is a policy that cannot be justified, and as climate change causes a new surge in mosquito population, there is need for Guyana to use all effective vector control chemicals at its disposal.
Between 1955 and 1969, there was a WHO-led campaign to stop malaria and other mosquito-borne diseases. These efforts failed. The new assault against malaria, called the Roll-Back Malaria Program, started in 1998. And according to the Minister, “we must not allow this campaign to suffer the same faith as the previous campaign. But we will fail unless we are willing to use all tools at our disposal. The removal of DDT from the arsenal of tools we can use against mosquito is a not only a foolish policy, but a deadly and impoverishing one.”
He revealed that more than 800,000 persons, including a large number of women and children, die in Africa alone each year, adding that the country loses more than US$100 billion annually because of malaria alone. DDT, he said, can prevent these deaths and reduce the haemorrhaging of financial resources that could be used to lift Africa out of poverty. Similar stories abound in other regions of the world.
And most of the rich countries today had in fact used DDT once to control vectors like mosquitoes, but are today the countries in the forefront of the policies to ban the use of the proven effective chemical in developing countries, Minister Ramsammy highlighted.
He asserted that the battle against malaria will not be won because of DDT alone, adding that the battle against malaria has to be fought on many fronts, including education and awareness, eradication of the vector (mosquito), as well as medically treating against the parasite.

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