Comments on: DDT is sometimes the best answer http://www.bloggernews.net/120937 High-quality English language analysis and editorial writing on the news. Thu, 26 Nov 2009 17:40:32 +0000 http://wordpress.org/?v=2.3.3 By: andrewew http://www.bloggernews.net/120937#comment-1236393 andrewew Tue, 19 May 2009 23:52:15 +0000 http://www.bloggernews.net/120937#comment-1236393 You are misreading history: despite what you may read on the websites of many conservative wingnuts, DDT has never been banned from malaria control. It's true that efforts to control malaria in developing countries waned in the 80s 90s and early 2000s, but restrictions on DDT--real or imaginary--were not the main factor. Wars and civil unrest in Africa, the rise of mosquito resistance to DDT and other insecticides, the rise of resistance of the malaria parasite to previously effective drugs, expansion of irrigation, and the loss of interest in fighting malaria by countries that had once generously funded malaria control efforts--these are the root causes for the resurgence of malaria in recent years. DDT it's never been banned for vector control, it has indeed been banned for agricultural use. But this actually increases it's effectiveness against malaria, since its use in agriculture was driving the development of mosquito resistance. So no, hysteria over DDT didn't ever kill people, if anything it saved lives by ending it's use in agriculture. You also mentioned the issue of cost effectiveness of DDT vs alternatives, and this is a real issue, but the debate here is based more on perceptions and assumptions than on hard data. There is actually very little data on the cost effectiveness of DDT vis a vis alternatives, and the little that does exist does not take into all the external costs associated with DDT use. Still, the few rigorous studies that have been published show that on a cost-per-case-averted basis, DDT is no cheaper than other pesticides or distribution of insecticide treated nets. There is a belief among many policy makers particularly in Africa that DDT is the cheapest, but this belief stems almost entirely from DDT being familiar--it was the pesticide of choice in many countries before their national malaria control programs disintegrated, so naturally in restarting these programs DDT is the first thing they want to use. But current information does not support the cost-effectiveness of DDT. You are misreading history: despite what you may read on the websites of many conservative wingnuts, DDT has never been banned from malaria control.

It’s true that efforts to control malaria in developing countries waned in the 80s 90s and early 2000s, but restrictions on DDT–real or imaginary–were not the main factor. Wars and civil unrest in Africa, the rise of mosquito resistance to DDT and other insecticides, the rise of resistance of the malaria parasite to previously effective drugs, expansion of irrigation, and the loss of interest in fighting malaria by countries that had once generously funded malaria control efforts–these are the root causes for the resurgence of malaria in recent years.

DDT it’s never been banned for vector control, it has indeed been banned for agricultural use. But this actually increases it’s effectiveness against malaria, since its use in agriculture was driving the development of mosquito resistance. So no, hysteria over DDT didn’t ever kill people, if anything it saved lives by ending it’s use in agriculture.

You also mentioned the issue of cost effectiveness of DDT vs alternatives, and this is a real issue, but the debate here is based more on perceptions and assumptions than on hard data. There is actually very little data on the cost effectiveness of DDT vis a vis alternatives, and the little that does exist does not take into all the external costs associated with DDT use. Still, the few rigorous studies that have been published show that on a cost-per-case-averted basis, DDT is no cheaper than other pesticides or distribution of insecticide treated nets. There is a belief among many policy makers particularly in Africa that DDT is the cheapest, but this belief stems almost entirely from DDT being familiar–it was the pesticide of choice in many countries before their national malaria control programs disintegrated, so naturally in restarting these programs DDT is the first thing they want to use. But current information does not support the cost-effectiveness of DDT.

]]> By: Nancy Reyes http://www.bloggernews.net/120937#comment-1236316 Nancy Reyes Tue, 19 May 2009 23:17:48 +0000 http://www.bloggernews.net/120937#comment-1236316 I agree. We need a sophisticated way to stop mosquitoes, not just DDT. But a lot of countries couldn't afford the alternatives (and some still can't), and the scientists who were behind the ban on DDT twenty years ago stayed silent while malaria deaths soared. The hysteria over DDT killed people, and I don't want it to happen again. I agree. We need a sophisticated way to stop mosquitoes, not just DDT.

But a lot of countries couldn’t afford the alternatives (and some still can’t), and the scientists who were behind the ban on DDT twenty years ago stayed silent while malaria deaths soared.

The hysteria over DDT killed people, and I don’t want it to happen again.

]]> By: andrewew http://www.bloggernews.net/120937#comment-1235456 andrewew Tue, 19 May 2009 16:53:00 +0000 http://www.bloggernews.net/120937#comment-1235456 You've created a false dichotomy: The question is not as simply as, "Do we spray DDT or do we let people die of malaria." The more complicated question that the scientists you criticize are trying to answer is: "Given its toxicity and the availability of alternatives, how big of a role should DDT play in malaria control?" The fact is that DDT one of 12 chemicals that can be used for Indoor Residual Spraying (IRS); IRS is just one of many strategies available for vector control; and vector control is just one aspect of effective malaria control--the others being prompt diagnosis, treatment with effective drugs, and in some cases use of prophylactic drugs. So, faced with all these alternatives--most of which do not have the same toxicity and ecotox issues that DDT has--and the dwindling effectiveness of DDT (due to resistance) should DDT be on the frontline of malaria control, or should it be as a last resort? That's what's going here. No one is suggesting that we should let people continue to die of malaria. Quite the opposite, these scientists and the WHO are only suggesting that rather than depending on DDT, we should instead shift to less toxic and more effective methods. You’ve created a false dichotomy: The question is not as simply as, “Do we spray DDT or do we let people die of malaria.” The more complicated question that the scientists you criticize are trying to answer is: “Given its toxicity and the availability of alternatives, how big of a role should DDT play in malaria control?” The fact is that DDT one of 12 chemicals that can be used for Indoor Residual Spraying (IRS); IRS is just one of many strategies available for vector control; and vector control is just one aspect of effective malaria control–the others being prompt diagnosis, treatment with effective drugs, and in some cases use of prophylactic drugs. So, faced with all these alternatives–most of which do not have the same toxicity and ecotox issues that DDT has–and the dwindling effectiveness of DDT (due to resistance) should DDT be on the frontline of malaria control, or should it be as a last resort? That’s what’s going here. No one is suggesting that we should let people continue to die of malaria. Quite the opposite, these scientists and the WHO are only suggesting that rather than depending on DDT, we should instead shift to less toxic and more effective methods.

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