Individual-based network model for Rift Valley fever in Kabale District, Uganda

Authors: SEKAMATTE, MUSA - Uganda Ministry Of Health; RIAD, MAHBUBUL - Kansas State University; TEKLEGHIORGHIS, TESFAALEM - Kansas State University; Linthicum, Kenneth - Ken; Gibson, Seth; RICHT, JUERGEN - Kansas State University; GONZALEZ, J - Kansas State University; SCOGLIO, CATERINA - Kansas State University

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2019
Publication Date: 3/5/2019
Citation: Sekamatte, M., Riad, M.H., Tekleghiorghis, T., Linthicum, K., Britch, S.C., Richt, J.A., Gonzalez, J.P., Scoglio, C.M. 2019. Individual-based network model for Rift Valley fever in Kabale District, Uganda. PLoS One. 14(3):e0202721. https://doi.org/10.1371/journal.pone.0202721.
DOI: https://doi.org/10.1371/journal.pone.0202721

Interpretive Summary: Rift Valley fever (RVF) is a disease which causes significant morbidity and mortality among livestock and humans in endemic regions that include countries throughout Africa and the Arabian Peninsula. This disease has demonstrated the capability to expand into new regions and poses a significant risk for globalization, and could cause substantial economic and public and veterinary health burdens on the US. One potentially effective way to reduce the chance of globalization is to help countries contain outbreaks of this disease where it is currently endemic. Recent RVF activity in Uganda demonstrated that RVFV could spread through livestock movements, and underscored the need to develop effective mitigation strategies to reduce transmission and prevent spread among cattle operations. In this study we simulated RFV virus transmission among cattle in different sub-counties of Kabale District in Uganda using real world livestock data in a network-based model. This model was configured to investigate and quantitatively evaluate the relative impacts of mosquito control, livestock movement regulations, and diversity in cattle populations on the spread of RVF. We concluded that cattle movement should be restricted during periods of high mosquito abundance to control the disease spreading among sub-counties. On the other hand we found that mosquito control would only be sufficient to control the outbreak when mosquito abundance was low. Importantly, simulation results also showed that cattle populations with a higher diversity with regard to indigenous combined with exotic breeds led to reduced numbers of infected cattle compared to more homogenous cattle populations. These findings may contribute immediately to development of national plans to contain RVF in Uganda and other nearby nations where RVF has been observed to spread via cattle movement.

Technical Abstract: Rift Valley fever (RVF) is a zoonotic disease which causes significant morbidity and mortality among ungulate livestock and humans in endemic regions. In the major RVF epizootic regions of East Africa, the causative agent of the disease, Rift Valley fever virus (RVFV), is primarily transmitted by multiple mosquito species in Aedes, Culex, and Mansonia genera during both epizootic and enzootic periods in a complex transmission cycle largely driven by the environment. However, recent RVFV activity in Uganda demonstrated that RVFV could also spread through livestock movements, and underscored the need to develop effective mitigation strategies to reduce transmission and prevent spread among cattle operations. We simulated RVFV transmission among cattle in different sub counties of Kabale District in Uganda using real world livestock data in a network-based model. This model considered livestock as spatially explicit factors in different sub-counties subjected to specific mosquito and environmental factors, and was configured to investigate and quantitatively evaluate the relative impacts of mosquito control, livestock movement regulations, and diversity in cattle populations on the spread of the RVF epizootic. We concluded that cattle movement should be restricted during periods of high mosquito abundance to control the epizootic spreading among sub-counties. On the other hand we found that mosquito control would only be sufficient to control the epizootic when mosquito abundance was low. Importantly, simulation results also showed that cattle populations with a higher diversity with regard to indigenous combined with exotic breeds led to reduced numbers of infected cattle compared to more homogenous cattle populations.