What if we killed all the mosquitoes?

It appears that a malaria vaccine will not be available for some time. According to Reuters,

“The world’s first potential malaria vaccine proved only 30 percent effective in African babies in a crucial trial, calling into question whether it can be a useful weapon in the fight against the deadly disease.”

Reading this reminded me of my own illness with malaria at the end of summer.

Back in September I contracted malaria while on a short trip back home in Kenya. Due to malaria’s incubation period I only started feeling sick after I was back in Palo Alto. My illness set off a total freakout at the Stanford Hospital. No less than four medical students, besides the crowd from the infectious disease unit at the hospital, passed by my hospital bed to ask the EXACT same questions (And of course they wanted to keep me overnight. They had an IV drip already installed in my arm. I tried my best to tell the doctor that I didn’t think I needed to be hospitalized to no avail.) The nurse who took my vitals put a mask on my face the moment I told her that I had malaria (I had to restrain myself from reminding her that malaria is not airborne). A week later the Santa Clara county infectious disease office called me to get my details and ask me if I was feeling better – The government wanted to know where and how I got malaria (The grad student in me was fascinated by this level of state capacity).

A few weeks before my Kenya visit I was in Fort Worth, TX. This was at the height of the West Nile virus outbreak that killed dozens of people. At the time the health authorities in the Dallas-Fort Worth area were in the middle of spraying the area to kill all the vectors (mosquitoes). My girlfriend reminded me of the fact that as recent as when her parents were growing up in Grand Prairie, TX much of the American South still had to be sprayed regularly (with DDT) to get rid of disease-bearing mosquitoes.

The reason I recounted these stories is to illustrate the fact that there is an alternative to pouring tons on money on vaccine research or bed nets. Yes, these may result in cool scientific discoveries or provide excellent opportunities for social scientists to get published on their RCT findings. But the reality is that millions of people are still dying.

Instead of asking those living in high disease burden environments to change their behaviors and sleep under mosquito nets, how about we get rid of the mosquitoes??

If it worked in the American South, and many other places, why can’t it work in Africa?

I would very much love to live in a place free of malaria. Because of my age and health, my malaria infection at the end of summer was a mere nuisance – muscle aches, head aches and fatigue. But for millions of children and post-natal mothers across much of tropical Africa malaria is a fatal disease.

But is DDT the answer? Haven’t we been made to internalize the evils of DDT?

It turns out that what we know about DDT might not be the whole truth. As Gourevitch argues, the environmental impact of DDT might have been overblown by the environmentalists.

Writes Gourevitch:

“Around the same time, the U.S. government launched an ambitious DDT-centered malaria eradication project which by the early ’60s had virtually eliminated malaria from Southern Europe, the Caribbean, and parts of East and South Asia. (In India, for example, annual deaths went from 800,000 to zero.) At the time, DDT was thought to be such an effective and useful substance that in 1948, Muller received a Nobel Prize in medicine. “To only a few chemicals does man owe as great a debt as to DDT,” declared the National Academy of Sciences in a report in 1970. “In little more than two decades, DDT has prevented 500 million human deaths, due to malaria.””

Adding that:

“But over the years, mainstream scientific opinion has absolved DDT of many of its supposed sins. Indeed, the Stockholm Convention partially backfired because it brought to light a slew of studies and literature reviews which contradicted the conventional wisdom on DDT. Like nearly any chemical, DDT is harmful in high enough doses. But when it comes to the kinds of uses once permitted in the United States and abroad, there’s simply no solid scientific evidence that exposure to DDT causes cancer or is otherwise harmful to human beings……

Not a single study linking DDT exposure to human toxicity has ever been replicated.”

But even assuming that the effects were as bad as they were claimed to be, shouldn’t we as humans be able to decide on the relative importance of human lives versus bald eagles?

How many children should be allowed to die so that bird watchers can better enjoy their Sunday afternoons?

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12 thoughts on “What if we killed all the mosquitoes?

  1. Gourevitch gets the science wrong. DDT was banned because it kills entire ecosystems — but the ban applied only to agricultural use in the U.S. DDT stopped being the favorite of malaria fighters because about ten years earlier than they predicted, and years earlier than they hoped, the malaria fighters found mosquitoes in Africa were resistant and immune to the stuff, so it ceased being the needed tool to wage all-out war on the disease.

    NAS said DDT was very beneficial, yes — but in that book the scientists called for a rapid phase out, because the harms of DDT are greater than its benefits.

    You can’t kill all the mosquitoes. When they come roaring back, as they always do, malaria comes back, too — unless malaria is cured in all the humans who have the parasites, in the area. Then there would be no pool of disease from which the mosquitoes could draw, and malaria would be wiped out. That’s what we did in the U.S., reducing malaria to an occasional outbreak, years before DDT was even available.

    DDT is still a deadly poison, still kills entire ecosystems, and is increasingly unuseful against malaria.

  2. Ed, many thanks for your comment.

    Of course we cannot kill all the mosquitoes, the title of the post was a rhetorical question.

    On the science of DDT use, I am not an expert so I am not in a position to adjudicate between the two sides. My aim was to opine on the rather lopsided win for the environmentalists over an all-the-above approach to fighting malaria, especially in Africa. Other places – notably tropical Asia – have succesfully eradicated the disease, with efforts that included the killing of mosquitoes with chemicals such as DDT.

    I do not understand why it is only in Africa where we continue to solely rely on a bednet and treatment approach.

    And to be frank, I have been to some places that experienced extensive DDT use and they do not look like nuke wastelands. From a lay perspective, I am no environmental expert, these places look pretty liveable to me.

    I reiterate, your points on the science of DDT are well taken, but the question still stands: When is it ever OK to let people die for the sake of the environment?

  3. As I noted earlier, the National Academy of Sciences, in that report you quote from, said that despite DDT’s value, its harms outweigh its benefits. I’m not sure when we make the decision to poison ourselves to save a few lives in the near term, but that isn’t the question with DDT — it doesn’t cure malaria, it doesn’t work as well as other methods or other pesticides to prevent the spread of the disease.

    We have made tremendous progress against malaria since the DDT advocates ruined it for fighting malaria. At peak DDT use, malaria infected a half-billion human annually, and killed 4 million or more. Today, malaria infections number about 250 million — a reduction of 50% — and malaria deaths hover under a million, usually estimated at under 800,000 per year — a reduction of 75%. Most of that progress comes despite DDT use.

    Tropical Asia? Hmmm. India manufactures and uses more DDT than the rest of the world combined, today. India is one place where malaria appears to be spreading, and the fight seems lost, often. If DDT were magical in the fight against malaria, that could not be so. In Vietnam, meanwhile, the disease has been beaten back through an ambitious campaign of education of people to drain mosquito breeding places around human habitation, and new pharmaceutical regimens carefully delivered to quickly and accurately diagnosed malaria victims.

    India’s case raises another issue of a major hole in the anti-environmentalist rant you almost-reasonably wonder about: The fact that DDT is still manufactured and used in grotesque quantities indicates clearly that there never has been a ban on its use.

    Malaria is a tough problem, a nasty disease, and it remains a scourge to humanity. Whipping environmentalists doesn’t do anything to fight the disease, neither stopping the spread nor curing the victims.

  4. I did not mean to sound like an anti-environmentalist. But while I realize the need to sustainably utilize the environment, I am wary of practices that seek to protect said environment at enormous costs to humans.

    As a Kenyan I have seen it with regard to wildlife protection and with regard to the use of pesticides.

    In nearly all of Africa, the anti-pesticide crusade won a long time ago. There are no large scale government programs to fight malaria this way. What we have instead are aerosol cans that do nothing to stem the tide of malaria.

    I still insist that African governments must seriously consider the use of pesticides to fight malaria instead of putting all their eggs in the treatment basket. Present attempts at prevention and treatment are clearly not working in ending the scourge. Pesticides (in conjunction with treatment) have worked elsewhere and they can work here. And if we have to kill a few wildlife species to get there, so be it.

  5. The secret of WHO’s anti-malaria campaign was discipline in the local public health services — 80% of homes MUST be treated, just 1% lower, and the program fails — and on improvement of health services to do two things while the mosquito population is TEMPORARILY knocked down by DDT. Health services needs to quickly and accurately diagnose malaria, down to the species of the parasite, and then be able to deliver appropriate medicines for an appropriate length of time to wipe out the malaria in the human victim.

    If those things obtain, then when the mosquitoes come roaring back as they always do, there is no pool of infection from which the mosquitoes can draw malaria to spread.

    Kenya has done nothing to improve medical services, you say? I find that hard to believe. But in any case, if that is so, then pesticide use will only exacerbate malaria problems, not reduce them.

  6. My simple (and perhaps simplistic) and last response to this is that Kenyans should not be expected to sleep under bed nets for eternity – especially since many still use the bed nets they get for free for other purposes and end up contracting malaria.

    Surely, is it not too much to ask for a life free of mosquito repellants and bed nets not to mention malaria???

    The current approach to the disease is still a failure because it is too tasking on the potential victims of malaria. That is a fact.

    Despite the stats you cite, tens of thousands of Kenyan kids still die of malaria every year. That is simply unacceptable.

  7. Bed nets are between 50% and 85% effective in preventing malaria, by themselves. DDT is between 25% and 50% effective almost by itself, IF you can treat 80% of all homes in an area and IF you beef up medical care to treat malaria.

    The key, then, is to beef up medical care, and conduct serious educational campaigns to reduce the chances people will be bitten.

    Malaria-free never happens with DDT. Never has, never will.

  8. And that is a big IF. It is one thing to cite stats but quite another to consider the practicalities of implementation. I know this is weird counterfactual but do you seriously think that without pesticides the places that have eliminated malaria would have done so simply through treatment and the use of bed nets (keeping in mind the bed net use rates)?

    Anyway, many thanks for your comments. I like it a lot when I hear from engaged readers like you. Your points are very well taken.

  9. Mr. Opalo, I have read your article and the comments and, your response to the comments. It is disturbing that you hold the view that DDT is the ultimate panacea for the perennial malaria problem in Kenya. This is a nullity as both ITNs (now LLins) and even indoor residual spraying (with DDT or ICON) are basically preventive measures meant to create barriers between humans and the vector. In one of your responses you mention that people cannot sleep under bed nets forever. The same applies to DDT as people spend more time outdoors where mosquito bites are equally intense. People do not live indoors forever. I have also noted the various untruths in your assertations like we do not know a lot of truth about DDT. We today know that DDT would not have an impact on malaria due to the East African mosquitoes having acquired the kdr resistance gene. Resistance to DDT in Northern Uganda and in Lusaka Zambia have reached 60% according to pulished studies. In some cases in Zambia it could reach 90% according to CropLife. This means that cross-resistance (to pyrethroids) is already taking place. In Apac (in Uganda) DDT had not impact on malaria morbidity according to hospital data. You also mention that “places that have eliminated malaria would have done so simply through treatment and the use of bed nets”. Mexico eliminated malaria without use of DDT or pesticides. Key elements of the Mexican experience were personal hygiene, sanitation, bush clearing and malaria treatment. Rowanemslieintern’s comment that “DDT’s effects are not easily quantifiable” is very true simply because we do not have appropriate tools. Currently available tools and protocols simply work on the basis of “the dose makes the poison”. However this cannot work with endocrine disrupting chemicals. It is like attempting to diagnose HIV infection using microscopy. You are wrong that mosquitoes were eliminated in South Americas. There are mosquitoes even in the Tundra region. Nowhere has this ever happened – insects were the first to inhabit the planet and are the last to quit.
    Saoke Nairobi

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