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When a shovel is enough to do the job...

June 4, 2010 - 09:57 -- Bart G.J. Knols

Yesterday I gave a talk for the Dialogues house in Amsterdam, which is affiliated to the ABN-AMRO Bank. The audience consisted of people that have no background or experience in malaria. But something funny happened there...

My talk focused on the history of malaria and its control, how the world map of malaria distribution shrunk until the end of the 1960s, and that major successes since have been lacking.


I gave them the DDT story, we talked about bednets, drugs and drug resistance, the usual items you would present to a lay audience.


But then I couldn't resist chipping in the story about Fred Soper, the invasion of Brazil by African malaria mosquitoes, and the massively successful campaign that was waged against it seven decades ago.


This was a turning point in the talk. People started speaking up, were astonished about this story, never thought that something like this was possible. Could malaria elimination really be that simple?


Then I gave them an example of what happened to me in northern Sudan six years ago. Of how simple it can be to control malaria vectors and have a huge impact. By just filling a breeding site with sand.


I guess there is little doubt, based on historical facts, that the tools at hand for vector control (nets and indoor residual spraying) will not be sufficient to eliminate malaria. Ultimately, area-wide tactics that involve source reduction and larval control will have to come into play.


But the strategy needed for larval source modification (LSM) in the context of elimination is still to develop. Who should do it, and how should we do it?


I wonder how MalariaWorld members look at this. Following on from the previous blog about Soper, we welcome your thoughts and ideas.




William Jobin's picture
Submitted by William Jobin on

What is the strategy, who should do it, and how?

Bart you are on a roll! Thanks for your wonderful ideas and thought-provoking points. As you might guess from my lengthy comments below, I have also been working on these questions since about 2005 when I gave up on PMI and WHO in Angola, in disgust.

Your comment about shovels, seems to be asking these questions:

What strategy is needed for larval source modification in the context of elimination?
Who should do it?
And How should we do it?

Those are broad questions that we can all work on.

1. First, let us stay away from words like elimination, eradication and even control. What we can do is fight malaria. We can fight it with an integrated strategy of sustainable methods. Our goal should simply be to reduce transmission. For the continent of Africa at least, a significant reduction, which we can maintain with sustainable methods, is enough to strive for. But elimination or eradication concepts merely distort our planning. They are chimeras, not likely for Africa.

2. For the goal of reduced transmission, our strategy should be integrated and sustainable, thus LSM is another important weapon to be added to the overall strategy. LSM has been neglected partly because the bewildered folk in Geneva cannot imagine anything other than newer and more expensive drugs, or vaccines.

3. Who will do it? Not WHO anymore. When I first worked for WHO in the 1960’s it was a competent organization with a real budget and with all the best people in international health. Because their budget was emasculated in the 1980’s by strong conservative governments, they are now able just barely able to buy light bulbs for their building in Geneva, and except for PAHO, the regional offices are on paper only. So what is our alternative?

4. In Africa, I think we should build directly on the strong countries, where they have demonstrated capabilities and stable, progressing governments. This means South Africa first. Also Senegal in the West and Tanzania and Mozambique in the East. We should work with these countries to support them and expand their national programs. The US PMI has some funds and flexibility, so they might possibly be major players. If not, I think we should go right to the NMCPs in each of the 4 countries above. As they progress, on their own budgets, they can also start training centers for their own personnel, and then for folks from nearby countries with the same language.

5. How should we do it? LSM should be added to the current mix of unsustainable methods. It should include habitat reduction with shovels, and attacks on the larvae with bacillus, fish and biocides. These approaches to LSM require repeated application, except for the shovel work. The biocides worry me too, but the rest can be safely done with a labor-intensive budget. But as Mark Benedict pointed out, larval reduction is subject to the insane effect of density-dependence, where partial reduction in larval density is of no avail, we have to go to the limit. The other challenge to LSM is management of the folks who do the work, and so Soper gives us courage.

6. Continuing the answer to “How?” - the Swiss Cheese sandwich comes in. We want a sandwich made of multiple layers of Gruyere. Admittedly the cheese has holes in it, so one layer does not give complete coverage. But a sandwich with 6-7 layers, each put on slightly askew, can give us complete coverage. To illustrate: a mass-treatment program with drugs will miss the people away on vacation or on nomadic trips or visiting the big city. But if we do LSM around their town, and help some of their neighbors plaster and screen their houses, and spray the houses of some other neighbors, and give accurate diagnoses and rapid drug treatment in the local markets, we will thus gradually knock a growing hole in the transmission. So we need multiple methods, especially the permanent measures such as habitat elimination and house screens.

7. The size and shape of a budget for this strategy of transmission reduction is modest, with gradual expansion based on success and on budget realities of the country.

8. We have to divest ourselves of the fantasies about huge initial dollar inputs from Gates or others. A budget like that is distorted by the dream about eradication, and is a chimera for Africa. If malaria is important for South Africa, they will make national budget commitments. The same is true for Senegal, Tanzania and Mozambique.

9. The fight against malaria must be based on a sustainable and affordable strategy, one stable country at a time, gradually expanding according to budget realities. It thus becomes a realistic strategy, a program that we can carry out, not a fantasy.

Bill, still hopeful

William Jobin Director of Blue Nile Associates

Bart G.J. Knols's picture
Submitted by Bart G.J. Knols on

Thanks for your lengthy response and valid contributions to this and other blogs. Let me respond to your 9 points:

1. I respect your views on this, and gauging from your extensive experience, this may indeed be the case. My opinion differs somewhat, in that I maintain the belief that as long as we have not really tried an integrated approach that includes rigorous larviciding, that we don’t know if this is feasible.

2. In agreement.

3. Seeking out the right partners is the next (critica) step. I honestly think that it should first be the government/population of a carefully selected part of Africa that considers this a worthwhile approach to try out. The more locally this can be orchastrated and executed, the more likely the chance of success.

4. In line with my views mentioned above. Personally I feel that a proof-of-principle may be the most we can opt for at this stage, and the selection of a target area should be done on the basis of a careful evaluation. I have discussed with others the option of bringing together a party of people interested in this approach, people with long-standing experience in Africa, to discuss this.

5-9. All in agreement.

Thanks very much for continued insight into this matter. Much appreciated!

Submitted by Jaime Chang on

Malaria elimination is possible. There's proof of it... there are many former malaria endemic areas where public health and development made transmission stop. There is also areas where these two elements can not really take the merit for stopping malaria transmission.
For me, the problem is that many don't read the small letters, and there is a risk in starting running behind the flag of elimination without being prepared to do so (e.g. surveillance systems working almost perfectly), and incurring in opportunity costs they can not afford.

This said, any malaria prevention and control program should be an integrated one, and LMS should be part of it as much as possible. In some locations LMS could need to be implemented on small bodies of water, in others it could involve larger ones. As you write, a careful evaluation is needed before deciding on implementing LMS. Sure enough, it may not be feasible in some places and may not an option in others.

In Peru, we have been working in the introduction of intermittent rice irrigation for malaria control (IRI). We started with empiric observation in the early 90s (the Peruvian coast is basically a desert crossed for mostly seasonal rivers); and the most raw data analysis (i.e. showing correlation index for number of malaria cases and number of hectares cultivated with rice at country level was 0.84, and 0.95 for a department in the coast where rice is a leading crop). Later we found literature reporting IRI in Portugal (1930s) and China (2000s).

Adopting an ecosystem approach to malaria prevention and control, the next thing we did was a feasibility study that showed that introducing IRI was feasible from the economic, agriculture/agronomic, social, and cultural points of view, and that rice pads were 92% of water surface available as breeding sites. We had done before a study on the Economic impact of malaria in Peru. Based on these studies, in late 2005 an initiative (not a project, i.e. a movement with a goal but not rigid or fully funded as a project) was started to introduce IRI for malaria control in the Region of Lambayeque, based on a multi-sector based agreement led by the Regional Government with the participation of Ministries of Health and Agriculture, farmers associations, cooperation agencies, etc.

(Note: IRI consists in a technical package including IRI itself, use of certified seeds, and improved use of agrochemicals)

We are now working at 4 regions (Peru is divided in Regions), and already on a stage aiming to region-wide scaling up. Results consistently show -in intervened rice fields- a 80%+ decrease in production of malaria vectors, 25%-50% decrease in water used for irrigation, a 50%-80% decrease in amount of pesticides and of fertilizer used, and a 10%-25% increase of productivity. In sum, a rare win-win situation for health, economics, and environment.

It must be added that although it started as an activity significantly financed by international cooperation (USAID/Peru), now it is led and it is almost entirely financed by the Ministry of Health and Regional Governments (exception is a project supported by the International Development and Research Centre - Canada).

Results with IRI have led to have it included as part of Regional Development policies (a strong reason for that being the decrease in water utilization) and to modify agriculture regulations (if IRI is applied, rice cultivation is allowed in the 500 meter band around villages).

We continue working on the scale up needed to attain effective decrease of risk for malaria transmission at population level.

I hope you find this of interest.