Drought-Associated Chikungunya Emergence Along Coastal East Africa

Abstract

Epidemics of chikungunya fever, an Aedes spp.-borne viral disease, affected hundreds of thousands of people in western Indian Ocean islands and India during 2005-2006. The initial outbreaks occurred in coastal Kenya (Lamu, then Mombasa) in 2004. We investigated eco-climatic conditions associated with chikungunya fever emergence along coastal Kenya using epidemiologic investigations and satellite data. Unusually dry, warm conditions preceded the outbreaks, including the driest since 1998 for some of the coastal regions. Infrequent replenishment of domestic water stores and elevated temperatures may have facilitated Chikungunya virus transmission. These results suggest that drought-affected populations may be at heightened risk for chikungunya fever, and underscore the need for safe water storage during drought relief operations.

The Normalized Difference Vegetation Index (NDVI): unforeseen successes in animal ecology

“…Ground measures of moth larval density were found to correlate with a NDVI-based defoliation score in Fennoscandia (Jepsen et al 2009), while de Beurs & Townsend (2008 concluded that NDVI data can be used to monitor insect defoliation on an annual time scale. NDVI was used to generate risk and distribution maps for diseases with arthropod vectors (Kalluri et al 2007), as well as for temporal models of disease outbreaks (Chretien et al 2007). Malaria and other mosquito-borne diseases such as West Nile virus seem to receive the most frequent attention and be particularly amenable to modeling efforts involving spatiotemporal data such as NDVI, due to the close causal link between rainfall and both mosquito abundance and NDVI (Brooker et al 2006, Gemperli et al 2006, Ceccato et al 2007, Britch et al 2008.…”

Tracking epidemic Chikungunya virus into the Indian Ocean from East Africa

“…Chikungunya virus (CHIKV) was responsible for explosive outbreaks during [2004][2005][2006][2007] in the islands of the Indian Ocean and India (Borgherini et al, 2007;Chretien et al, 2007;Mishra & Ratho, 2006). Estimates of the number of affected individuals in the islands of the Indian Ocean have reached several hundred thousand and serological survey data suggest that over 60 % of the regional populations have been exposed to the virus (Sergon et al, , 2008.…”

Serologic Evidence of Arboviral Infections among Humans in Kenya

“…CHIKV IgG was present in a high proportion of samples on the coast and in Kisumu District, indicating continued circulation after (6) 11 (9) 8 (7) 7 (6) 10 (8) 24 (20) Kisumu, lowlands, children (n = 57) 5 (9) 5 (9) 3 (5) 6 (11) 5 (9) 4 (7) 4 (7) 24 (42) Nandi, highlands, children (n = 65) 2 (4) 2 (4) 4 (7) 5 (9) 3 (5) 3 (5) 6 ( the chikungunya fever outbreaks in 1970 21 but before the 2004 coastal epidemic. 28 Flaviviral antibodies were identified in both district sites, although Kisumu District (lowlands) appears to have a greater diversity of arboviruses infecting humans.…”