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About the Author

Bart Knols
Medical Entomologist (Dodewaard, Netherlands)

Bart G.J. Knols (1965) is the Managing Director of MalariaWorld, the world's first scientific and social network for malaria professionals. He is a malariologist with a Masters degree in Biology and a PhD in Medical Entomology from Wageningen University, the Netherlands. He also obtained an MBA degree from the Open University (UK) in 2006, for which he won the prestigious international ‘MBA Student of the Year 2007 Award’ as well as the Alumnus of the Year Award from the Open University. With 11 years of working experience in Africa he has managed large-scale research and vector control programmes on malaria for ministries, international or national research institutions. He has worked for the UN (IAEA) as a programme manager for three years, has served as a consultant for the World Health Organization, and is currently a Board Member of the UBS Optimus Foundation, the second largest charity in Switzerland. He has published over 130 peer-reviewed research articles, has written 16 book chapters, and has served as senior editor on a WHO/IAEA sponsored book on implementation research. In 2007 he co-edited a best-selling book titled 'Emerging Pests and Vector-Borne Diseases in Europe'. He received an Ig Nobel Prize (2006), an IAEA Special Service Award (2006), and in 2007 he became a laureate of the Eijkman medal (the highest award in the field of tropical medicine in the Netherlands). He has been a member of the Royal Dutch Academy of Arts and Sciences since 2004. Bart held an Assistant Professorship at Wageningen University until April '09 with projects across Africa. He currently directs K&S Consulting, a firm he founded in the beginning of 2007.


Malaria: Greenpeace’s tough dilemmas

Published 28th April 2010 - 18 comments - 12467 views -

We campaign for the elimination of toxic chemicals, for nuclear disarmament and an end to nuclear contamination, and against the release of genetically modified organisms into nature” said Gerd Leipold, when he was appointed as International Executive Director of Greenpeace in 2001. A glance at the movement’s website shows that these issues still dominate its agenda.

Now compare this with three ways to control malaria mosquitoes: DDT, genetically-modified mosquitoes, and the Sterile Insect Technique, and you will see why Greenpeace faces some tough dilemmas.


DDTThe insecticide Dichloro-Diphenyl-Trichloroethane (DDT) is perhaps the most controversial pesticide ever used. I wrote about it when I pondered over the question if science can cripple development. There are strong proponents as well as opponents for its use to control malaria mosquitoes in many parts of the developing world by spraying the chemical indoors of houses. Some argue that hundreds of studies have not shown any harmful effects on humans, others claim to have convincing data to the contrary. Some claim that the ban on DDT in the developed world in the 1970s, followed by a strong reduction of its use in the developing world, caused the death of millions of people that could have been protected by the chemical. Others applauded the ban – among them the environmentalist movement.

But all changed with the Stockholm convention on Persistent Organic Pollutants (POPs) treaty that came into effect in 2004. Although it was the intention to completely stop the production of ‘the dirty dozen’, twelve highly toxic and persistent chemicals including DDT, it escaped it and was allowed for continued use inside houses for malaria control. With a ‘free ticket’ in hand, impoverished nations in Africa started using DDT again. Backed by a WHO resolution in September 2006. Today, the global production is 4-5 million kg per year. At least 17 countries in Africa are spraying it, and more are likely to follow.

When I contacted Greenpeace’s headoffice in Amsterdam last week I was told that none of their staff had time to talk to me about DDT. After persisting I talked to Kim Schoppink and she explained that Greenpeace is ‘against the use of DDT’, that ‘DDT is harmful’ and that ‘it causes cancer’. A day later I received a letter from Greenpeace, written by Leipold in 2006, that was more reserved and considered the official stance of the organisation: ‘…we remain focused on the search for long-term solutions to the problem of malaria itself, and not on perpetuating a rather unproductive and divisive debate on the single issue of DDT’.  This followed a statement of Greenpeace scientist David Santillo who condemned US support for DDT spraying in 2006 by saying ‘That certainly raises some quite substantial concerns and if there's substantial funding coming from the US to support that, then that does sound very much like a step in the wrong direction'.

DDT to save African children? Or a ban on it to stop accumulation in the food chain? Greenpeace’s dilemma #1.

Genetically-modified mosquitoes

dnaWith the massive advances in molecular sciences since the 1990s came the idea of introducing genes into mosquitoes that arm them against the pathogens they transmit. These genetically-modified mosquitoes, or GMM, would become ‘refractory’ or incapacitated by expressing molecules that interfere with pathogen development. The World Health Organization, the National Institutes of Health (USA) and the Gates Foundation fuel(led) this research with millions of dollars. Already eight years ago a GMM strain was created of which only 1 in 5 mosquitoes transmitted malaria parasites. All non-modified mosquitoes remained fully susceptible. If indeed a parasite-transmitting population of mosquitoes could be replaced with one that no longer does so, the world could see much less malaria. But that would mean the release of a (human)blood-feeding genetically-modified mosquito into the environment. The fate of which remains largely unknown until it is actually done. Leave it up to Greenpeace to tell us about the risks of introducing organisms in the environment of which scientists have tinkled with their genetic material…

Genetically-engineered mosquitoes may fly one day to control malaria and save the lives of African children, but it will be an introduction of a GM organism in nature: Greenpeace’s dilemma #2.

Sterile Insect Technique

radiationAnother method to wipe out malaria mosquito populations that is currently being developed is the so-called Sterile Insect Technique. By producing millions of males of the target pest insect, sterilising them using radiation, and then releasing them into the wild, pest populations can be reduced or even eradicated. Sterile males will seek out wild females and inseminate them with their radiation-distorted genetic material. The result is that wild females lay eggs that never develop. It is important to note that the released insects are NOT radioactive. But a nuclear source is needed to sterilise all the males before release.

Around the world, the Sterile Insect Technique is being used against pest insects. It is probably the ‘greenest’ of pest control methods, but it relies on radiation sources for sterilising the males: Greenpeace’s dilemma #3.

Last year I was involved in organising a workshop in Venice on genetically-engineered insects. I pressed hard to have Marco Contiero, Greenpeace's EU GMO policy director, join us at the discussion table. In spite of phonecalls and several emails, we never heard from him.

Clearly, Greenpeace is facing some tough dilemmas.

What would you choose if you were Greenpeace? Toxic chemicals, GMM, or Nuclear applications? Remember: Every 30 seconds somewhere in Africa a child succumbs to malaria...



  • Tiziana Cauli on 28th April 2010:

    This is a very interesting post Bart. I guess if we put it this way one can only Greenpeace should reconsider its position. After all it’s human lives we are trying to save. At the same time, environmentalists and other anti-DDT activists - I’m sure Greenpeace is not the only organization who campaigned against its use - are only doing their job when they highlight the risks involved in practices such as the use of pesticides and GMOs. I only find it sad that this dilemma cannot be addressed jointly by scientists and activists in a bid to find an acceptable compromise.

  • Daniel Nylin Nilsson on 28th April 2010:

    In deed, all of these alternatives are controversial. We must fight malaria, but on the other hand, I don’t think anyone would come up with the idea to spray houses in western Europe with DDT.

    All these solutions are attractive in a short hadn perspective, but what if they don’t manage to eradicate malaria now? The long time effects of GMO’s, DDT and radiaton are likely to be just as big a problem. With DDT there is also the issue of resistance. If the mosqitous grow resistant, you have risked peoples health in vain, so I am also very sceptical, even though I realize how important it is to combat malaria.

  • Bart Knols on 28th April 2010:

    @Tiziana. I don’t think that Greenpeace would deliberately deny people the benefit of DDT for malaria control. They simply can’t. But at the same time they argue strongly for its replacement, emphasising the need for alternatives. As long as these alternatives, like the use of genetic engineering or nuclear applications pop up, they face another problem in front of their millions of members who would expect them to argue against these. Truly a big dilemma.

    Hopes that environmentalists and DDT proponents will sit at the same table are slim…

  • Bart Knols on 29th April 2010:

    @Daniel. DDT was widely used throughout Europe, indoors, between the 1950s and the time it was banned in the early 1970s. It is broadly acknowledged that it played a key role in the eradication of the disease in Europe.

    You are absolutely right about the risks of long-term use of DDT. It will, inevitably and shown time and again, lead to resistance. Even this week a report was published of widespread DDT resistance in Ethiopia.

    But then, can we argue that because resistance is inevitable, that we should stop using DDT for as long as it works and saves lives? DDT is cheap and persistent, two ideal characteristics that appeal to Health ministries in developing countries…

  • Uli on 03rd May 2010:

    Thanks for a great post, Bart! It kept me thinking the whole weekend - what a fascinating challenge to find a green, sustainable position on malaria! You are right, there a massive dillemas and our ‘usual’ european political divisions tend to fail when it comes to such questions.
    Two quick comments though: There are fascinating studies by historians about the elimination of malaria from US and Italy, which show that in fact DDT was not as much of a magic bullet as people commonly think. Not only because of resistance. In the USA malaria cases actually started to go down before DDT spraying began. It turned out that what caused the sustainable break in transmission was actually an agricultural bill that made people move farer away from the field and thus mosquitoes…
    Secondly, it is of course true that malaria is a massive health problem in sub-Saharan Africa, which the one child dies every 30 second statistic conveys beautifully. But we also have to keep in mind that there is a difference between non-immune children, and adults in sub-Saharan Africa, where 50% of the population in endemic countries co-habit with parasites at any give time, without necessarily being ill.
    This is of course not to say that malria is not dangerous, or that we should not fight malaria, or not use the techniques mentioned by you. But there might be even deeper dillemas here than the ones you point to so nicely.
    I would love to discuss this more with you! Best, Uli

  • Bart Knols on 03rd May 2010:

    @Uli. Thanks. Your two comments are very important.

    DDT: It is indeed true that the role of DDT has been over-emphasized. In The Netherlands, improved housing conditions, seperation of the barns from human habitation, and the use of synthetic detergents also contributed, as did the overall improved public health system after WWII. So yes, DDT was a component, maybe a significant one, but not the only one.

    On this point, I wrote an editorial for MalariaWorld this week:

    It is indeed true that the situation is complicated because of the little devil we call semi-immunity. Solving the ‘deeper dilemmas’ you point to is based on the determination to eliminate the disease. It can be done, and we have green alternatives to DDT (such as the larvicide Bti) but it depends entirely on the way these tools are used. I don’t think there is a single operation in Africa right now where the credo is ‘We’re here to get rid of malaria and will not leave until the last person is cleared of parasites’. We’re still in the ‘control’ game, not the ‘end-solution’ game…

    As long as this remains the attitude, we will be confronted with more problems, especially when donor fatigue kicks in again, like it did in the 1980s. We need to and we can do it right now. So let’s get on with it. Do you agree?

  • Uli on 03rd May 2010:

    Hey again,
    Thanks for clarifying on DDT. Now I agree with you entirely. (But if we see DDT this way (and add in resistance, costs, and experiments such as Garki, where malaria moved back in very quickly after spraying stopped) allows us to ask if DDT is actually the most cost-effective tool we should invest in? But that’s a side issue.)

    Re semi-immunity, eradication & control: Actually, the people who make funding decisions nowadays have changed back to an eradication paradigm, as am sure you know. So, the world invests in GMM, SIT, vaccines and insecticides to replace DDT. And they do this moreso than to invest in decentralised malaria care (getting RDTs, ACTs and training to rural health workers - MSF has done a beautiful study on this). And to me, not enough attention is paid to actually educating people properly about why it makes sense to use mosquito nets despite the heat etc. We need to get beyond the ‘use a net, it saves from malaria’ if we want to convince people, who have lived with malaria all their lives (and who have their own conceptions & philosophies about disease).
    So I guess, I agree and don’t agree at the same time smile another tough dilemma….

  • Bart Knols on 03rd May 2010:

    @Uli. We’re touching on a discussion that is extending below my blog on Twitter nets:

    In Holland, ask anyone about what TB is or hepatitis, or Q fever, or even HIV: You will be surprised how little is known. Yet, we handle these diseases fairly well. Why? Because there is a centralised, well-coordinated and financed group of professionals and institutions that do what is needed to prevent upsurges of these diseases.

    Awareness is essential, let us not be mistaken about this. But it is not the (shall I say only?) way to eliminate an infectious disease. Eliminating an infectious disease takes a highly structured and rigirous campaign, otherwise you’re wasting funds. I come back to what I said in my blog about Zanzibar, in which I quoted Fred Soper about malaria: ‘There is no such thing as partial success. It is either glorious success, or dismal failure’.

    Would you consider the current focus on nets as a recipy for dismal failure?

  • Uli on 03rd May 2010:

    Nets are a great tool, and I don’t think at all that the focus on nets is a recipe for failure. And you are right, awareness is not necessarily connected to usage, plenty of psychological studies have shown that there is only a weak link between knowledge and action, and between reason, habits and passion (see condoms & HIV). Still I think education in SSA tends to be patronising and assumes that people don’t know, which sells short what is actually going on. However, what I would say is that what your example from the Netherlands shows nicely is how important (mobile) health care systems and infrastructure is! And this I find is one of the neglected aspects in malaria funding today. (a neglect that might well go to the expense of the most removed patients, such as people in conflict zones, refugee camps etc., places compared to which Ifakara looks like paradise)

    And then I think I’m not with Fred Soper, am afraid. I admire his work in Brazil (of course), but hasn’t larviciding also shown that malaria control requires something else too: It requires manpower and careful attention to shifting vector-human habitats and most importantly constant, tideous maagement and control (see urban malaria control in Dar es Salaam with bti).

    I think we should be careful about eradication, end-solutions and glorious success, and start dreaming more about small steps, sustainable solutions and malaria control that is affordable and accessible to the many, now. Because we have the tools for broad-scale successful control. Are GMMs really a good investment for successful malaria control? Convince me.

  • Bart Knols on 05th May 2010:

    @Uli. This discussion is becoming more and more interesting. Let me reply to specific points:

    1) Nets are not a bad thing. And of course, I agree. But, but, but, they are not the solution, and can only be part of the endgame. Nets in themselves will not bring the ‘E’ words (elimination, eradication) any closer. Not now, not in future. If we are to play the endgame, then area-wide control approaches have to come in. So to point 2.

    2) Soper is and was a controversial man. But, but, but, he is one of the few that succeeded. And yes, yes, yes, if you want to eliminate, you will need manpower. Lot’s of it. Yesterday I drove through the streets of Dar es Salaam, and saw hundreds of youngsters sitting around, unemployed. This morning I thought about putting an ad in the newspaper here to recruit 2000 of them to be larval control inspectors. They would be lining up by the thousands the day after tomorrow. Manpower is the least of our problems. And you are right: You need constant and tedious monitoring. Well, if you don’t, you’re wasting your money and time. Remember: we’re no longer in the control game, we’re in the endgame.

    3) Dreaming and small steps belong to the control era. Hard work under the tropical sun, blood, sweat and tears, belongs to eradication 2.0. Larviciding did it in the past, larviciding can do it now.

    4) As for GMMs, I refrain from comments. This approach is still at the bench. If anything, there could be a debate as to whether all the resources for this work are justified. Compared to the overall money that goes into malaria research, the GMM work is peanuts. So, benefit of the doubt for now…

    Thanks for poking me about Soper and other issues. I will write a story about his approach soon. You and I, and anyone in malaria today has no experience with malaria elimination. We need to learn, and Soper is a good starting point, agreed?

  • Uli on 06th May 2010:

    Bart, This is indeed getting more and more interesting!

    I guess I’m sceptical about the e-words and the endgame. Of course I would love malaria to disappear from this planet! But am just not sure if it is really a realistic and achievable hope. Yes, we have made massive progress in many places, and that’s wonderful and needs to be scaled up. But it also needs to be sustained.

    And this is my first doubt: how are we going to sustain the success on the African continent, which is just so much more physically connected than other locations where malaria was eliminated? (These were usually islands or places where malaria was not lurking at the borders, ready to move back in; plus places that managed to achieve socio-economical development at the same time than malaria elimination)

    Secondly, I fear we might put too much money into technology and, crucially, places that are doing relatively well already (with ok health infrastructure and disease surveillance etc), at the expense of thinking creatively about malaria’s heartlands, where mortality is much higher (such as conflict zones, very remote and infrastructurally weak regions - I’m thinking of DRC, Liberia, Sierra Leone, Burundi etc etc). The heartlands are the areas where the battle will be toughest and needs to receive careful attention, more than it does currently I think. In short, geographies of disease matter.

    Thirdly, I am concerned that the current focus on the e-words risks to concentrate funding in a way that might sidestep successful, broad-scale control (very much like Kevin Marsh and Bob Snow have recently argued). And we need to keep in mind that even at the moment - at malaria’s funding highpoint - resources are not enough; and with the economical crisis will realistically not rise - even with an amazing success record.

    And yes, agreed, Soper and larviciding are good starting points! Looking forward to your blog on him….

  • Bart Knols on 08th May 2010:

    @Uli. On point 1 I disagree, on point 2 I fully agree, on point 3 I tend to be in the middle.

    Point1:  Malaria was not just eliminated from islands like Taiwan and the Carribean, it was eliminated from the whole of Europe, Russia, and the USA as well. Those are major areas. Sustenance is no longer a word in the dictionary of elimination. Following the consolidation phase there will be need for surveillance in certain settings, but sustaining control efforts will be a thing of the past… Sustaining malaria control efforts without playing the endgame is the recipe for disaster. We have seen this in the past, see it now, and will see this in future when we loose drugs and insecticides because evolution catches up with our efforts, no matter how good these are.

    Point 2: The malaria heartland, countries stricken by civil war, etc. It will be extremely difficult to have a real go at malaria in these settings. However, if you read Collier’s book ‘The Bottom Billion’, you will see that it is not always bad to focus on countries that are doing better. It has been shown clearly that when a poor country’s neighbour is a country that is on the up, that the poor country is also seeing development. But yes, in certain parts of Africa it will be hard. But then, there are many parts of Africa where malaria should have been eliminated ages ago. The whole of Sudan north of Khartoum, the islands of Sao Tome and Principe, major parts of the Sahel, and so on…

    Point 3: Broad-scale control should not suffer because of ‘e’ activities, I agree. On the economics side, though, elimination will pay itself back, sooner or later, thus the upfront investment is in the end not the maor hurdle. It took some 4 million USD to free the island of Zanzibar of tsetse flies. Over the last 10 years they have accrued economic benefits that will probably outweigh the initial investment. I don’t see this different for malaria. More on Zanzibar in the blog about that (I met with the Permanent Secretary of Health of Zanzibar this week).

    Soper coming soon!

  • Uli on 11th May 2010:

    Hey again, Bart.
    I think we agree mostly on 2 & 3, so just two quick comments below, and then some more thoughts on 1, where I think we do disagree slighlty - but in very intersting ways!

    Re point 2: I agree that it will be much harder to do successful control in those areas. I’m not with Collier, however. I think the ‘trickle-down’ effect has rarely ever worked in development. And I see too many countries, where more prosperous neighbours don’t seem to trigger change (the case I know best is Ghana & Togo). So, I think if we want to think about getting malaria cases down in the more challenging areas, we really need specific approaches that think creatively about the challenges the ecologies of people, mosquitoes and humans pose in a region/locality.

    re 3: I agree it’s a tricky one, and cannot be answered with a total yes or no. I just think there is a danger here that we need to be acutely aware of, and those concerns/doubts might not be expressed enough in the public domain…

    re 1: OK, yes, not all areas that eliminated malaria were islands, and yes some were major areas. But those areas has very different ecologies, epidemiologies and social geographies of malaria than sub-Saharan Africa has (different vectors, less p.falciparum, less supportive climate etc - winter being a major difference). And as we agreed on before, in most areas we had massive, accompanying changes in socio-economic status (USA), health care infrastructure (Italy), and agricultural shifts (machinization & industrialization), which led to an increased distance between vectors and humans, ultimately breaking the cycle of transmission (USA).
    And yes, we are caught in a evolutionary dynamic with emerging resistances - but might there be a different way to reply to this? Instead of using it as a trigger to put on a full-on fight, maybe we might be better off reading with a changed engagement with malaria? Maybe we should put more emphasis on small-scale changes in local agricultural practices that would diminish mosquitoes’ niche? Maybe we should put more emphasis on how to build up the semi-immunity of children and vulnerable groups? .... these are genuine questions, especially with the first one I stray into ur entomological knowledge, and am curious what you think about it? I think my only point is that I have serious doubts that eradication will be doable in sub-Sahran Africa. A person I interviewed some years back, put it this way: “If we are to eradicate malaria in Africa, we first have to eradicate poverty”. I fear she might be right…. Thoughts?

  • Bart Knols on 12th May 2010:

    @Uli. Ref 1: No, I’m afraid we’re not at par. The ecology and transmission potential for malaria that was vectored by African Anopheles was much better in Brasil than it was in its native Senegal. If you read Soper’s book ‘Anopheles gambiae in Brazil, 1930-1940, you will come across some astonishing figures. The oocyst load in Brazil was much higher than that experienced in many places of Africa, so if anything, than Brazil was much worse than many parts of Africa.

    As for winters providing hostile conditions for anophelines in Europe, well, I think we can compare that with the dry season induced by the intertropical convergence zone. Long spells of drought have the same effect on anophelines as a cold dark winter.

    As for your questions: small-scale changes in local agricultural practices maybe feasible, but what would this result in? Changes in disease incidence and prevalence come from reductions of vector density on a log scale. Small changes yield (virtually) nothing and are simply temporary small dents in a sea of misery. I don’t quite see a way to build up semi-immunity in a safe manner, unless we have a vaccine in hand (like the RTSS that’s being tested around Africa at the moment).

    Finally, if you want to do something about poverty, you start by doing something about malaria. In that sense I must agree with the Jeffrey Sachs school of thought. But for argument sake: how would you eradicate poverty by not tackling malaria, knowing that in many parts of Africa significant amounts of the small household budget is spent on just this disease? Drugs, repellents, coils, etc….

  • Uli on 17th May 2010:

    Hi again Bart,

    OK and interesting re Brazil vs Seengal (I need to read the Soper book, clearly). But Brazil and Senegal are more similar in climate than USA, Russis, Italy etc is to SSA, and more importantly Soper was fighting a bounded epidemic and bounded A.gambiae population that had arrived by ships. So, there were less mosquitoes, in a bounded area (and not a huge continent), and they had not adapted to this habitat for hundreds of years yet. So, Brazil might have been worse in some respects and wasn’t in others I would argue.

    And I’m not sure if you can really compare winter with the dry season. In many areas in Africa we have holoendemicity, so transmission all over the year, including in the dry season. There are areas with very dry seasons and droughts, but there are also many (more I would say) areas where transmission does not stop or decrease enough.

    And re poverty: Yes, of course malaria and poverty are intertwinned. And both are terribly resilient (that’s the point I tried to make in the last post), and of course I’m all in for fighting malaria and poverty! I just think we might be better off building up resilience and centering our campaigns around this principle rather than an all-out-war.

    But I think we could keep discussing this forever, and am also not decidedly against elimination attempts… just skeptical about the merits of an eradication campaign….or worried about its unintended side-effects. So, I guess in the end we are not too far apart from each other - mainly, because we would probably agree that one needs highly specific, well-informed and -researched campaigns. Yes?
    Anyways, I hope we’ll meet in person one day and can continue the discussion over a cold Kili or two. Now off to read your new MDG posts smile


  • Bart Knols on 17th May 2010:

    @Uli. All in agreement. Just a bit more about Brasil. The infestation of An. arabiensis in Brasil covered, eventually, 54,000 sq km. This is an area larger than 14 of the smallest African countries. This infestation took 10 years to reach this area, and apparently the African An. arabiensis was feeling quite at home in S America…

    The comparison between dry season and winter. Good point you make about endemicity. What I would argue is that mosquito populations are particularly vulnerable at the end of the dry season, with limited foci of breeding, and therefore more susceptible to control efforts.

    A good dose of skepticism ref elimination is warranted, I agree. Nobody claims this will be easy and it may take several decades. Feachem’s lecture on YouTube is very informative in this regard:

    Thanks for all your insightful comments. And yes, always up for a Kili or 3.

  • Uli on 17th May 2010:

    OK, convinced: I will need to read more about Brazil! Fascinating…. (and I think Argentina might be another great historical case study, Alvarado etc)

    And yes, agreed on your point about the end of the dry season being a vulnerable period and thus great for interventions!

    Thanks for a great discussion! And hopefully sooner or later to be continued over Kili….

  • Bart Knols on 27th May 2010:

    @Uli. My post on Soper is live. Curious to hear your views:

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