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Global Health, Infectious Disease

R.I.P., DDT: Now, how to bury malaria?

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After the publication of Rachel Carson’s explosive book Silent Spring in 1962 launched the environmentalist movement, DDT – a demonstrably, even uniquely, effective anti-mosquito agent – was banned in the 1970s, The ban may well have brought the bald eagle back from the brink of extinction.

It may not have been so kind to people. Malaria, caused by a mosquito-borne parasite, made a steady comeback in many parts of the world where it had been on the road to eradication. (In 2006 the World Health Organization, in a major policy shift, once again backed DDT’s use for eliminating the scourge.)

A flurry of studies and commentaries (1, 2, 3, 4, 5, 6) on the current global malaria situation were published in The Lancet today. That situation is not pretty.

Because malaria has by and large been eliminated in developed countries, we don’t think about it much. Think about this: the disease kills more than 860,000 people annually. And that’s a drop in the bucket compared with the estimated 247 million – million! – separate cases contracted every year by living, breathing human beings, more often than not children.

At this moment, the closest thing to an effective malaria vaccine is still in development and appears to be only 50 percent effective. Better than nothing, but not great.

DDT is not mouth-wash. Sprayed in excess, as it was back in the early post-war years, it piles up and disrupts the environment. Used carefully, it has no equal as a pesticide. At this point, of course, a heavyweight DDT offensive against malaria-carrying mosquitoes is unlikely to fly very far or very fast.

But, back in 1990, Stanford immunologist Leon Rosenberg, PhD, who died in July of this year, had an unconventional idea for ridding humanity of the malaria parasite:

Because this organism undergoes numerous changes in the course of its life cycle, the development of a malaria vaccine is a challenge. Rosenberg’s concept was to produce a vaccine not against malaria, but against the mosquitoes carrying it. Injecting ground-up ticks into cattle had been shown to raise a strong enough immunological response in the ruminants to be lethal to ticks; Rosenberg reasoned that the same procedure – injecting humans with ground-up mosquitoes – would produce an analogous result. While this wouldn’t prevent contracting malaria from a mosquito that carried it, it would – by killing the mosquito – stop it from infecting anyone else. Such a vaccine, were enough people to receive it, could over the long run substantially reduce the transmission of the disease to humans. Rosenberg, however, was unable to corral the enormous resources necessary to test and develop such a vaccine, and the idea went unfulfilled.

Maybe it’s time to take that idea seriously.

Photo by Wellcome Images

10 Responses to “ R.I.P., DDT: Now, how to bury malaria? ”

  1. Ed Darrell Says:

    It’s useful to recall that WHO changed no position in 2005 and 2006, with regard to DDT. DDT has always been a tool in the toolbox of Who malaria fighters.

    The difficulty is that DDT is no miracle worker against malaria, certainly not by itself, and now not even in conjunction with massive government efforts to improve health care to diagnose and treat malaria effectively and quickly.

    Did you see the earlier article in Lancet about the possible undercounting of malaria deaths in India? That was important for at least two reasons: First it indicates that we don’t know enough about the effects of malaria, especially in areas where poor people concentrate without great medical care, and especially in areas where health care information is not tracked scrupulously.

    But second, when we realize that India is the world’s largest producer and user of DDT, using more DDT annually than the rest of the world put together, we must look at continuing malaria problems as hard proof that DDT is no panacea. Were DDT the magic powder some claim, India should have no malaria at all, judging by the scale of DDT use.

  2. Marje Hecht Says:

    Meanwhile, one child in Africa dies every 30 seconds of malaria. It would be more effective to promote the use of DDT for indoor residual spraying, to stop the spread of malaria. This works, even when mosquitoes are resistant to DDT, because DDT repels mosquitoes. A vaccine would be nice, but use of DDT can immediately begin to prevent deaths. For more information, see
    the DDT articles at http://www.21stcenturysciencetech.com

  3. PeterG Says:

    Do they know how many gene pairs the malarial virus is? 6,000 pairs! It is impossible to make a vaccine——–that is why one has been promised every 5 years for the last 40 years. On the other hand the way DDT is currently used in indoor spraying is quite effective and safe. Due to it’s long acting effect very little needs to be applied. Once or twice a year is all that is needed. ” According to WHO, extensive research and testing has shown that DDT, if well-managed, is safe and effective for indoor spraying as a tool to combat malaria transmission. The tests, says WHO, show that indoor spraying is safe for both humans and animals. Indoor spraying means applying DDT to walls and the roofs of houses and domestic animal shelters. It destroys the malaria-carrying mosquitoes that land on the surfaces of walls and roofs. This preventive measure can reduce malaria transmission by up to 90%.”

    One thing that I’ve noticed is that the main claim by the environmentalists is that DDT doesn’t work anymore in killing insects such as mosquitoes, bedbugs etc. They use the ” resistance argument. ” This argument for me doesn’t hold any water from what I’ve learned about “behavioral resistance”, from what Dr. Ronald R. Roberts says about it. From what I see it has nothing to do with the insects dying from DDT toxicity but it is actually about the repellent action that is DDT’s actual function. It provides “spatial repellency ” so that the insects get disoriented and avoid the area. Looks to me like the environmental movement early on created a non-sequitur of the term “resistance” by linking it with death. Thus creating a new fake meaning that implied ” resistance to dying.” So that if they didn’t die from DDT it meant that the had evolved an immunity to it. While all along it had nothing to do with killing them that made DDT effective. It’s repellency not death that is the real meaning of resistance in the case of DDT.

    They go on to cite studies of insects saying that the insects mutated years ago through a ” knockdown-type nerve insensitivity mechanism. ” And conclude that DDT by being widely used in the past that now it has likely predisposed the insects such as mosquitoes and especially the bedbugs to resistance through the neuronal insensitivity mechanism. Considering the outcry of people on the magnitude of the bedbug problem in the US, they are hammering in this myth that DDT doesn’t kill the bedbugs. Well DDT was never supposed to kill the insects in the first place. This ” knockdown-type nerve insensitivity mechanism ” has nothing to do with DDT’s repellent activity. No matter how the insects mutates it always remains repelled by DDT. So this would apply to bedbugs also. The environmental movement’s incessant drumbeat keeps everyone focused on how DDT won’t kill mosquitoes and bedbugs meanwhile sidestepping and diverting attention away from the fact of DDT’s repellency property.

    So it looks like this ” behavioral resistance ” or spatial repellency is the key attribute of DDT. And that this was erroneously interpreted to be that the mosquitoes had adapted and were now resistant to being killed by DDT. When the fact is that they are repelled by DDT which is why it is so effective in the control of malaria. Now this repellent action works on all the insects not just on mosquitoes. So I think this is a good time to test DDT again for it’s repellent action against the bedbug problem here in the U.S. The bedbugs do not have to be killed by the DDT but just repelled by it so that they are no longer able to feed on the human blood. So they starve to death. And because DDT is long acting and cheap and safe it seems to be the ideal solution to the bedbug problem. Dr. Rutledge has a new documentary called ” 3 Billion And Counting” documenting what the malaria situation is all about. If you are interested see his highly informative website on this matter on http://www.3billionandcounting.com
    If you would like to read Dr. Ronald R. Roberts entire Senate testimony were he describes in detail why DDT is so effective and safe. Go to this link below.

    http://epw.senate.gov/hearing_statements.cfm?id=246769

  4. Bruce Goldman Says:

    With regard to Ed Darrell’s thoughtful comments, I’ll stick with the wording “major policy shift” (I didn’t say “reversal”) on WHO’s part. See this September 2006 New York Times article: http://www.nytimes.com/2006/09/16/world/africa/16malaria.html.

    That the cessation of DDT spraying in developing countries led to a massive malaria resurgence is hard to dispute. Sri Lanka is a textbook example. Please see this July 2000 Nature Medicine commentary, written by authors who are far more credentialed than I can ever hope to be: http://www.malaria.org/attarannaturemed.html.

    Marje Hecht and PeterG’s comments speak eloquently for themselves. In response to PeterG’s remark about the difficulty of developing a vaccine against malaria, I would add only that it’s even worse than he says: Those 6,000-odd genes are expressing themselves in wildly varying combinations over the course of the malarial parasite’s life cycle, forcing any vaccine to hit the moving target constituted by its ever-shifting surface antigens . All the more reason to consider Leon Rosenberg’s brilliantly quixotic proposal: Forget the parasite, and wipe out the mosquito it rode up in. Does an anopheles-free world sound all that bad?

  5. PeterG Says:

    Thank you Bruce. In response to Ed Darrell mentioning the article in Lancet about the possible undercounting of malaria deaths in India. I would like to include a very relevant article which came out last week to this discussion. It quotes the Health Minister from India Dr. Leslie Ramsammy describing the current malaria situation in India.

    Malaria cases rising
    By Stabroek staff
    Published – October 22, 2010
    -Ramsammy urges review of DDT ban

    [Full text of article edited by moderator. See link below.]

    http://www.stabroeknews.com/2010/news/stories/10/22/malaria-cases-rising/

  6. Ellen Says:

    Thank you for this article and information from those who made comments. Have not read the book, but have gone to http://www.3billionandcounting.com and enjoyed the wealth of information supplied there!
    It was my understanding that malaria is getting worse in areas in India that are NOT spraying DDT. And the areas where they do, they have been successful. This is something that we need to know, before saying it is used there, and not working.
    I also enjoyed the article written by the Health Minister from India. It appears that he, like Dr. Rutledge Taylor, are facing uphill battles because we have been conditioned for so long with the junk science surrounding DDT, that folks are having a hard time opening their minds to the truth. It’s sad that the facts that DDT is safe for humans and environment were always known, but governments chose to ban it and spread lies arounding it. I agree with the one commenter .. I feel it was done for population control! Time is up for this scam .. too many folks are wise to the tricks of environmentalists who want to save “insects” and kill humans!

  7. Peter Says:

    I realized that I put some wrong information about that link to the article on “Malaria cases rising.” Dr Leslie Ramsammy is not the Health Minister from India. He is the Health Minister from Guyana, South America.

  8. Ed Darrell Says:

    “That the cessation of DDT spraying in developing countries led to a massive malaria resurgence is hard to dispute. Sri Lanka is a textbook example. Please see this July 2000 Nature Medicine commentary, written by authors who are far more credentialed than I can ever hope to be: http://www.malaria.org/attarannaturemed.html.”

    Except that the number of cases of malaria has been falling constantly, especially since widespread misuse of DDT was stopped — 500 million cases annually in 1970, to 250 million cases a year, today — and malaria deaths have fallen even more, from 4 million deaths annually at the peak of DDT use in 1959 and 1960, to under 900,000 deaths a year today — a reduction of more than 75%.

    Sri Lanka? There was no DDT ban there. Sri Lanka stopped its malaria eradication work, all of it, and malaria roared back as it always will if DDT is used without massive alteration and build-up of medical facilities to treat malaria in human victims.

    Among the chief reasons for the increase in malaria in Sri Lanka was this troubling fact: Mosquitoes there became resistant and immune to DDT.

    When mosquitoes become immune to DDT, spraying more of it has no beneficial effect.

  9. Ed Darrell Says:

    Much more on DDT and malaria, here:

    http://timpanogos.wordpress.com/ddt-chronicles-at-millard-fillmores-bathtub/

  10. Ed Darrell Says:

    Time marches on.

    The malaria report for 2012 from WHO confirms that malaria rates and deaths both continue to drop, largely without DDT. Serious problems continue to vex malaria fighting, chiefly the uneven flow of funds, which now threatens to reduce the distribution of bednets which have proven so much more effective than Indoor Residual Spraying, especially IRS with DDT, in reducing malaria cases and deaths.

    DDT is no panacea, and the continued character assassination of Rachel Carson in particular and environmentalists in general make no one cheer but mosquitoes.

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