Future Infections

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.

• 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?

• Can we model mosquito abundance and arboviral prevalence under different climate and land-cover scenarios to better predict and possibly prevent future outbreaks of mosquito-borne diseases?

• Semi-structured interviews
• Questionnaires
• Soil and rangeland quality analysis
• Analysis of wildlife diversity and density
• Analysis of arbovirus infection rates in mosquitoes, small mammals and cattle across different land-use types
• Morphological and competence assessment of mosquitos in relation to invasive plant litter
• Spaceborne and drone-based remote sensing 

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.

B02 embraces the CRC concept of bridging boundaries by improving our understanding of how shifting bio-cultural boundaries may facilitate the introduction of vector-borne pathogens into a new environment. The focus is on large-scale land use changes such as conservation, agricultural intensification, and road development that present significant socio-ecological changes. Together with climate change these changes may have unintended side-effects on human and animal health. Emphasis will be on vector abundance/diversity and prevalence of vector-borne zoonotic diseases, and how the creation of conservancies, the accidental introduction and spread of invasive plants (resulting from agricultural intensification), and the construction of roads favour disease emergence. The focus will be on high-risk communities in the KAZA and KRV regions especially pastoral communities and how the resulting ecological and behavioural changes impact rural livelihoods. This work will be in collaboration with CRC projects A01, A02, A04, A05, B01, and C07.