Neglected Tropical Diseases and Malaria: The need for mapping
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Neglected Tropical Diseases and Neglected Tropical Diseases and Malaria: The need for mappingMalaria: The need for mapping
Neglected Tropical DiseasesNeglected 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
OnchocerciasisOnchocerciasis
Elimination of onchocerciasis in AfricaElimination of onchocerciasis in Africa
Prospects– Preventive Chemotherapy– MDA through CDTI
Challenges– Loa loa– Determining transmission zones
MDA and eliminationMDA and elimination
MDA and eliminationMDA and elimination
Transmission zonesTransmission 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 MalawiSpecies identification in Malawi
Mapping of vector distributionMapping of vector distribution
Chromosomal inversion dataChromosomal inversion data• Frequency of polymorphic inversions: Maegga et al in press
Centromere of chromosome 3
Vector migration issues and determination of a Vector migration issues and determination of a transmission zone (Maegga et al in press)transmission zone (Maegga et al in press)
Man-made ecological changes Man-made ecological changes
Wilson et al (2002)
LeishmaniasisLeishmaniasis
• Ghana: first reported in 1999 from 3 sub-districts; Ho/Shia, Kpedze/Vane and Tsito of the Ho District
• 1996-1998 –Burkina Faso• Late 1990’s till now – Mali
Leishmaniasis in Ghana and other Leishmaniasis in Ghana and other West African countriesWest African countries
What is known in outbreak areasWhat 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
Species composition of blood-fed sand flies
38.2%
0.4%26.9%
34.5%
S.simillima
S. ingrami
S. a. africana
S. antennata
73% 69%
27%
0%
0%10%20%30%40%50%60%70%80%
Per
cen
t
Chicken Human Goat Bovine
Host
Total percentages of reactive sand flies feeding on the 4 blood meals
Blood-fed sand flies
What is not knownWhat 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 1990’s be
modeled to provide some insight into future outbreaks?
SchistosomiasisSchistosomiasis
Current mapsCurrent maps
Clustering of infection within a communityClustering 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 mappingNeed for mappingWater-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 filariasisLymphatic filariasis
Need for mappingNeed 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:Vector-borne Viral diseases:Dengue and Yellow feverDengue and Yellow fever
Aedes transmitted Emerging especially
dengue Impact of climate
change Less studied in most
endemic countries especially in Africa
Malaria: MARA MAPSMalaria: MARA MAPS
MARA MALARIA PREVALENCE MAPMARA 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 seasonDuration of Malaria transmission season
Current mapsCurrent 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
Thank youThank you
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