Tropical Health Matters

William R Brieger (wbriege1@jhu.edu) and Gilbert Burnham (gburnha1@jhu.edu) of The Johns Hopkins Bloomberg School of Public Health, Department of International Health presented ideas about mapping and integration of neglected tropical diseases and malaria interventions at the Malaria World Congress, Melbourne, Australia, July 2018

Overview: Lymphatic Filariasis (LF) and Malaria share a common vector in sub-Saharan Africa. Mass Drug Administration (MDA) is a strategy that is common to both diseases. Where the diseases overlap there is the potential opportunity to coordinate both vector control and MDA to achieve synergy in program results. The example of Burkina Faso, supplemented with information from Ghana, serves as an example of what could be integrated and what actually happens.

Background: Thirty years ago then veterinary drug, ivermectin, was found effective in controlling neglected tropical diseases (NTDs), specifically two human filarial diseases: onchocerciasis and lymphatic filariasis (LF). The drug manufacturer donates 300 million treatments annually to eliminate both diseases. Since then, annual community based mass drug administration (MDA) efforts have resulted in millions of treatments in endemic countries and great progress has been made toward elimination of transmission. Through observation and experimentation, ivermectin was found to kill malaria carrying mosquitoes when they bite people who have taken ivermectin making it a useful tool for vector control.

CHWs in Burkina Faso demonstrating how to measure height to determine ivermectin dosage

Community Health Workers’ Role: Current research is examining how dosing and timing of treatments may impact national malaria vector control efforts. Comparing maps between malaria and LF can be a starting point for adapting ivermectin MDAs for malaria vector control. Burkina Faso MDAs are operationalized by community health workers (CHWs) who are part of a national program that provides treatment for common illnesses and also conducts village level onchocerciasis and LF MDAs. Vector Control with Long Lasting Insecticide Treated Nets In most of rural Africa, malaria and lymphatic Filariasis are co-endemic and share the same anopheles mosquito vector.

However, that does not mean that there is a coordinated effort to plan distribution of LLINs despite the fact that the intervention meets the needs of both disease control efforts. The current NTD programs in Burkina Faso and Ghana focus on Preventive Chemotherapy (PCT) delivered through Mass Drug Administration (MDA). Vector Control is seen as essential in areas co-endemic with LF, Loa loa and Malaria – mapping helps identify priority areas for vector control.

Vector Control by Chance: In Ghana, the NTD/LF elimination program was unaware of the LLIN coverage data available in the NMCP housed in an adjacent building. This illustrates the lack of collaboration between the two programs. Thus where — and if — vector control benefits the reduction of both diseases, it is often by chance where LF is concerned.  The International NGO, The Carter Center, may be the only one that includes vector control as part of its programming for both malaria and LF in Nigeria. This practice should be replicated by other partners and country programs where possible.

Mass Drug Administration: MDA is the major strategy for control of five PCT diseases in the NTD program, and LF is one of those. Currently MDA anti-malarial drugs has been considered in limited situations in countries where there are areas that have very low transmission In the future countries may consider research that shows mosquitocidal effects of Onchocerciasis and LF MDAs with ivermectin. Otherwise for malaria, a special intervention called Seasonal Malaria Chemoprevention (SMC) is used in an MDA-like approach to reach young children in the African Sahel during high transmission months. In both cases, existing cadres of (usually volunteer) community health workers are the front line providers of MDA.

Burkina Faso LF Map from ESPEN: Mapping shows 10 of 70 health districts are currently doing LF MDA, though all have done it. Thus CHWs in all districts are experienced in ivermectin MDA. The malaria map shows that two-thirds of districts have a malaria incidence of 400/1000 or more while 14 have lower incidence. There is an overlap between current LF MDA districts and higher incidence malaria districts Both LF and Malaria Program Coverage can be seen to overlap in [program maps.

Ghana CHWs explain how they conduct MDA

Ghana Experiences: Ghana provides a contrasting example. There five regions in central Ghana that are mostly non-endemic for LF but do have moderate malaria transmission In the south two regions with former LF MDA activity overlap with higher malaria endemicity While four northern regions have lower malaria parasite prevalence, they do have current and recent LF MDAs Community Directed Distributors work with LF MDA in Ghana

Conclusions: Malaria elimination will need a mix of strategies to be successful. Therefore, it is not too early for malaria and NTD program managers, as well as their respective donors, to begin comparing maps to identify possibilities for adapting ivermectin MDAs for malaria vector control. Even though one endemic disease is nearing control or elimination, the infrastructure put in place to accomplish this can be mobilized for other disease control efforts – as long as we map where interventions and resources have been targeted.

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