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Success of Larval Source Management in urban Africa

October 10, 2013 - 15:15 -- William Jobin

Dear Colleagues,

I am pleased to send you this brief summary of our most recent and interesting African Malaria Dialogue, held during a luncheon meeting on Wednesday 9 October at the Harvard School of Public Health in Boston.

A major theme during the recent Dialogue was the success of classical methods of Larval Source Management for suppressing malaria in urban Africa. Examples were presented on the positive impact of simple drainage and larviciding in urbanized Maputo, in Dar es Salaam, and in western Kenya. Also a recent WHO Manual on Larval Source Management was noted to have reported improved water management for suppressing malaria in urban Khartoum. Local economic value of the labor-intensive measures of ditching and larviciding was also noted, especially important for these countries with high unemployment rates. The Dialogue was attended by the former US Ambassador to Lesotho, as well as a dozen faculty and students from Bentley, Boston and Harvard Universities, and from the Massachusetts Institute of Technology and the Worcester Polytechnic Institute.

Drainage in Maputo, Mozambique

The former US Ambassador, Bob Loftis, recounted his earlier experience at the US Embassy in Maputo in regard to drainage programs for suppressing malaria. USAID had assisted the Maputo municipal government to construct emergency drains during a series of intensive tropical cyclones. Although the drains were aimed primarily at the threat of cholera epidemics, the health authorities were gratified to see an immediate drop in malaria transmission, during the time that the emergency drains were kept in operating condition. The emergency drains were dug primarily by hand labor, with picks and shovels. However the following year when the drains were neglected, the transmission of malaria returned to previous high levels in Maputo.

The economic value of malaria suppression in Mozambique was confirmed in comments by Bill Jobin, who had analyzed recent World Bank data showing that each additional dollar spent by USAID to suppress malaria in Mozambique correlated with an increase in Gross Domestic Product of $41, a remarkable return on the investment. These figures indicated that Mozambique would find investment in permanent drainage works in Maputo to be economically rewarding, despite high initial costs. It was pointed out that crews would also be needed for annual clearing of the drains.

Larviciding in Dar es Salaam, Tanzania

The host for the Dialogue at Harvard, Marcia C. de Castro, also reported the successful suppression of malaria in Dar es Salaam by a community-based larviciding program which started with pre-treatment surveys in 2004. After 4 years of expansion of the larviciding to cover 15 urban wards, malaria prevalence was reduced from 20% to 2%. This was a labor-intensive program, benefiting the large number of unemployed people in the local population. De Castro also noted that annual cleaning of existing drains in Dar would be equally valuable for suppressing malaria transmission.

Jobin also noted the economic value of malaria suppression in Tanzania, using recent data from USAID and the World Bank. Each additional dollar invested in suppressing malaria in Tanzania correlated with an increased GDP of $28, again a remarkable return.

Water management in Western Kenya and Khartoum

De Castro noted that similar positive experiences with Larval Source Management had been observed in urban areas in Western Kenya. In addition the recent WHO publication on Larval Source Management indicated the value of improved water management and drainage in Khartoum, Sudan. These experiences in Africa indicated that in urban Africa, the current WHO and USAID malaria suppression programs could produce more durable benefits by adding Larval Source Management to their current ephemeral methods, which are effective for only a few weeks, at most.

Artemisia

In addition, Pamela Weathers of the Worcester Polytechnic Institute described her success in using whole plant preparations of Artemisia annua for treating malaria infections. Several organic compounds which are normally removed from the harvested plants during drug preparation are in fact helpful in attacking the malaria parasite, when left in the medication. She has had success in mice studies with the whole plant preparations, and will soon conduct human studies. Pam also indicated that she has seen reports currently in press about successful human studies recently completed in Africa.

Bill Jobin
Coordinator for African Malaria Dialogue