Conservation, agricultural intensification, and infrastructural development are land-use changes happening across rural parts of eastern and southern Africa. Against the backdrop of climate change, these changes are at the expense of pastoralism and small-scale agriculture. In the Kenyan Rift valley (KRV), these practices are complemented by the creation of community-managed conservancies, while in southern Africa transboundary conservation areas such as the Kavango Zambezi Transfrontier Conservation Area (KAZA) park have been established. These land use changes are meant to improve livelihoods through tourism, employment creation and transportation. However, conservation is associated with increased human-livestock-wildlife interactions and the emergence of arboviral diseases. Other land use changes such as agricultural intensification and major infrastructural development can facilitate the spread of invasive plants which may further influence distribution patterns of arboviruses and their vectors. We therefore intend to use a One health approach to evaluate the effect of these landscape changes on arboviral disease.
Research Regions: Namibia and Kenya
Keywords: Virology, Ecology of Land Use
How do pastoralists and agro-pastoralists perceive the growing risk of zoonotic arboviral diseases and is this linked to socio-ecological transformations?
How do major land use and biodiversity changes influence arboviral disease emergence and risk?
Do invasive plants influence life history traits of disease vectors and subsequently their competence?
Our methodological approach relies on a combination of field and laboratory analyses. Diverse traps are used to collect mosquito vectors in conserved areas (with varying vegetation and elephant densities) and in agricultural areas (with and without invasive plants present). Mosquito species are identified to species based on morphological criteria. Samples are screened for arbovirus infections using broad-range generic RT-PCR assays followed by molecular characterization of detected viruses. Longevity of vectors and host meal analyses (blood and plant meal sources) are also investigated.
Key Findings from Phase I
We found that elephant densities in KAZA affected mosquito species composition as well as mosquito densities. Similarly, in the KRV land-use changes caused by invasive plants like Parthenium, Prosopis and Lantana had a strong effect on mosquito community composition. Several pathogenic arboviruses, like West Nile virus that can cause encephalitis in humans were found in Cx. univittatus mosquitoes in KAZA. In total, we detected ten strains of WNV which grouped in two different phylogenetic clades. Our data indicate that two different variants were simultaneously circulating in Namibia and suggest that WNV may contribute to unknown disease aetiologies. In addition, novel orthobunya- and orbiviruses that are likely to cause malformations and abortions in livestock, were detected in mosquitoes and midges in KAZA. The presence of such a great variety of infectious pathogens may be responsible for high levels of uncertainties in shaping the future.
Guggemos, H., Fendt, M., Hermanns, K., Hieke, C., Heyde, V., Mfune, JKE, Borgemeister, C., Junglen, S. 2021. ‘Orbiviruses in biting midges and mosquitoes from the Zambezi region, Namibia’, Journal of General Virology, vol. 102, no. 9. href="https://doi.org/10.1099/jgv.0.001662">DOI
Guggemos, H., Fendt, M., Hieke, C., Heyde, V., Mfune, JKE, Borgemeister, C., Junglen, S. 2021 Simultaneous circulation of two West Nile virus lineage 2 clusters and Bagaza virus in the Zambezi region, Namibia. PLoS Neglected Tropical Diseases 15(4): e0009311. DOI