Although I have presented these ideas previously, I found a new way of explaining the concepts which I hope you will find easier to understand, or to disagree with!
10 November 2014
THE SUCCESSFUL ENVIRONMENTAL PATHWAY TO PERMANENT MALARIA SUPPRESSION
At the recent African Malaria Dialogue, held at MIT in Cambridge, Massachusetts, we spent some time examining the two major pathways toward malaria suppression which have been pursued historically. One was the failed Chemical Pathway followed by the WHO Global Malaria Eradication Program. The other was the successful Environmental Pathway to Permanent Malaria Suppression followed by many temperate and sub-tropical countries, starting with the southern states of the USA, the Tennessee Valley Authority, Puerto Rico, Italy, Israel and Turkmenistan, as well as all the European countries. This successful Environmental Pathway has involved three major steps, ending with a final Exit Strategy. We have learned from sad experience that one should not start a war without an Exit Strategy. Unfortunately the current WHO, RBM and USPMI strategies have not followed the successful Environmental Pathway, nor do they have an Exit Strategy.
Three Steps of the Successful Environmental Pathway
What is the successful Environmental Pathway? The First Step starts with an emphasis on simple environmental methods of drainage and habitat reduction which permanently eliminate breeding sites for anopheline mosquitoes, and also emphasizes improved human housing by preventing access by mosquitoes at night, primarily through installation of metallic screens on doors and windows, and closing eaves and other openings.
This First Step was taken by the successful countries at the beginning of the Twentieth Century, continuing to mid-century, when transmission had been drastically reduced. In most of these countries transmission was by then restricted to summer-time malaria, and only in lowlands. Although financial difficulties and program interruptions caused by war and the Great Recession were severe and sometimes interrupted the control efforts, malaria transmission remained in check because the methods used had been permanent in nature.
Second Step with DDT and chloroquine
By mid-century, DDT and chloroquine became available, to be used in the Second Step. This Second Step caused an immediate reduction of transmission to very low levels, everywhere. The cost and effort from application of these drugs and biocides in the Second Step was minimized both geographically and temporally because of the slow but permanent reduction in transmission from the First Step. Adding this Second Step did not interfere with the permanent gains made during the First Step.
Economic and Industrial Development
We have shown recently that suppression of malaria has dramatic economic benefits, with returns in subsistence agricultural economies of 3:1 or greater. Thus the Second Step in these countries led to economic gains which easily offset the costs of the First and Second Steps, and led to industrial development which made possible the Third Step – the Exit Strategy.
The Second Step and economic development also resulted in expansion of the scope of the Environmental Pathway by making the suppression of malaria a holistic effort by the entire developing society. Thus improvements in education, general health services, housing, roads, telephones, community development and political stability reinforced the reductions in malaria transmission from every aspect of society, as described by Snowden in his book on the conquest of malaria in Italy. Simple improvements in literacy in the population increased the effectiveness of all public health campaigns, especially the malaria suppression program. Improved roads and telephones made all operations of the Ministry of Health more efficient, reaching even remote villages.
Third Step, Electricity, and the Exit Strategy
This Third Step came as part of the overall economic and industrial development which occurred in these countries in the latter half of the Twentieth Century, especially the provision of widely available and affordable electricity. This made it possible for people to sleep in closed houses during the malaria season, using small electric fans. Once people could sleep comfortably in closed rooms, the mosquitoes could no longer transmit the malaria parasite, and the disease was doomed. Malaria disappeared from the USA and Europe about 1950, from Puerto Rico in 1960, from Italy in 1956 and from Turkmenistan in 1965. Especially in the Tennessee Valley of the USA, in Puerto Rico and in Turkmenistan, the construction of hydroelectric dams was a major factor in making electricity available in rural areas previously beset by malaria.
Failed Chemical Pathway
In contrast, the GMEP was based on the hubris of newly created drugs and biocides and made the mistake of taking the First Step on the Chemical Pathway. But the GMEP used only these synthetic chemicals because they offered such fast and seductive results. However the cost of these methods was very high because no attempts had been made to first reduce the geographic or temporal extent of transmission. Also, unlike the permanent methods used in the Environmental Pathway, these ephemeral control methods also had to be re-applied every year. Furthermore these chemical efforts were generally applied by outside and single-minded agencies which disregarded other aspects of development of the country. There were no improvements in literacy nor in roads, nor in political stability. Thus as soon as financial problems or resistance occurred, transmission resumed. The GMEP collapsed in 1969.
How can we prevent a similar collapse now?
It is disturbing that the current malaria programs of RBM, WHO and the USPMI are blindly following the narrow pathway of the Chemical Approach, without an Exit Strategy. What do you think will happen? How can we prevent a collapse similar to that of the GMEP?