Neglected Tropical Diseases and Malaria: The need for mapping

Neglected Tropical Diseases Diseases of poverty and of the poor Neglected in terms of funding and efforts at their control Schistosomiasis Chagas Disease Buruli ulcer STH Onchocerciasis Lymphatic Filariasis Dengue fever HAT Leishmaniasis Trachoma Leprosy

Onchocerciasis

Elimination of onchocerciasis in Africa Prospects – Preventive Chemotherapy – MDA through CDTI Challenges – Loa loa – Determining transmission zones

MDA and elimination

Transmission zones Factors to determine transmission zones based on species distribution – Vector cytospecies identification – The frequency of polymorphic inversions – The identification of non-vector cytospecies in adjacent areas

Species identification in Malawi

Mapping of vector distribution

Chromosomal inversion data Frequency of polymorphic inversions: Maegga et al in press Centromere of chromosome 3

Vector migration issues and determination of a transmission zone (Maegga et al in press)

Man-made ecological changes Wilson et al (2002)

Leishmaniasis

Ghana: first reported in 1999 from 3 sub-districts; Ho/Shia, Kpedze/Vane and Tsito of the Ho District –Burkina Faso Late 1990s till now – Mali Leishmaniasis in Ghana and other West African countries

What is known in outbreak areas Parasite species identified Vector species in some areas identified Others not known but attempts being made All belonged to the genus Sergentomyia, S. simillima, (31%) S. ingrami, (23%) S. africana africana (14%) S. antennata

What is not known What climatic factors led to the series of outbreaks in West Africa? What are the reservoir hosts? Can the situation in the late 1990s be modeled to provide some insight into future outbreaks?

Schistosomiasis

Current maps

Clustering of infection within a community to understand the spatial distribution of disease in order to achieve a better epidemiological analysis towards an effective control strategy for the disease in the community

Need for mapping Water-related development projects: e.g. in Ghana building of a new dam – How is it going to influence prevalence in the new area? – Can this be predicted? Identification of S. bovis/S. haematobium hybrids How does that change the epidemiology? How will that influence the predictive maps already available? Create a household level map of infected cases within the community

Lymphatic filariasis

Need for mapping Why is MDA not working in certain areas of the same country? Can information gathered from such areas be used to develop a predictive map of areas where MDA may not lead to elimination?

Vector-borne Viral diseases: Dengue and Yellow fever Aedes transmitted Emerging especially dengue Impact of climate change Less studied in most endemic countries especially in Africa

Malaria: MARA MAPS

MARA MALARIA PREVALENCE MAP These models analyse the malaria data against some environmental determining factors (such as climate, altitude, vegetation cover, agro-ecological zones, etc.). The level of prevalence is then predicted for the entire country or region, based on the established relationships between malaria prevalence and environmental data

Duration of Malaria transmission season

Current maps None of the maps has entomological information – Different species have different vectorial capacities – Insecticide resistance will influence transmission even in the face of control measures – If data is obtained from area of permanent water body e.g. dam, it will influence the seasonality maps In the era of malaria elimination/eradication these maps are inadequate

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