Development and Assessment of a Geographic Knowledge-Based Model for Mapping Suitable Areas for Rift Valley Fever Transmission in Eastern Africa

Abstract

Rift Valley fever (RVF), a mosquito-borne disease affecting ruminants and humans, is one of the most important viral zoonoses in Africa. The objective of the present study was to develop a geographic knowledge-based method to map the areas suitable for RVF amplification and RVF spread in four East African countries, namely, Kenya, Tanzania, Uganda and Ethiopia, and to assess the predictive accuracy of the model using livestock outbreak data from Kenya and Tanzania. Risk factors and their relative importance regarding RVF amplification and spread were identified from a literature review. A numerical weight was calculated for each risk factor using an analytical hierarchy process. The corresponding geographic data were collected, standardized and combined based on a weighted linear combination to produce maps of the suitability for RVF transmission. The accuracy of the resulting maps was assessed using RVF outbreak locations in livestock reported in Kenya and Tanzania between 1998 and 2012 and the ROC curve analysis. Our results confirmed the capacity of the geographic information system-based multi-criteria evaluation method to synthesize available scientific knowledge and to accurately map (AUC = 0.786; 95% CI [0.730–0.842]) the spatial heterogeneity of RVF suitability in East Africa. This approach provides users with a straightforward and easy update of the maps according to data availability or the further development of scientific knowledge.

Sero-prevalence of brucellosis, Q-fever and Rift Valley Fever in humans and livestock in Somali region, Ethiopia

“…The ability of RVF to spread outside traditionally endemic countries, even out of the African continent lies in the fact that large ranges of arthropod vectors are capable of transmitting the virus. The presence of a wide range of hosts and vector species, and the epidemiological characteristics of RVF, had led to concerns that epidemics may occur in previously not described regions like Ethiopia [33]. In other East and central African countries such as Kenya, inter-epizootic/epidemic cases are increasingly documented for the past 10 years [34–37].…”

High seroprevalence of Rift Valley fever phlebovirus in domestic ruminants and African Buffaloes in Mozambique shows need for intensified surveillance

“…The high prevalence of antibodies to RVFPV in the central and south Mozambique as compared to the north, may be related to climatic factors, water availability and landscape, which likely influence the amplification and spread of RVFPV in the east and southern African countries [40,49]. …”

“…The difference in seroprevalence between buffaloes in Sofala (Marromeu Reserve and Gorongosa National Park) and those in Tete (Tchuma-tchato Special Conservation Area) may be associated with climatic events and factors related to the landscape that influence the type, distribution and the density of potential RVFPV mosquito vectors species [49,62]. …”

Individual-Based Network Model for Rift Valley Fever in Kabale District, Uganda, to Guide Mitigation Measures: A One Health Model

“…

20 21 22 higher diversity with regard to indigenous combined with exotic breeds led to reduced numbers of infected 40 cattle compared to more homogenous cattle populations. 41 42 Rift Valley fever (RVF) is a zoonotic mosquito-borne disease caused by Rift Valley fever virus (RVFV;43 Phlebovirus: Bunyaviridae) that severely affects ungulate livestock and wildlife but can also affect humans in 44 RVF-endemic regions of sub-Saharan Africa and parts of the Arabian Peninsula [1,2]. The potential extreme 45 economic, and public and veterinary health burdens of epizootics/epidemics of RVF have been described 46 extensively [3].

…”

“…43 Phlebovirus: Bunyaviridae) that severely affects ungulate livestock and wildlife but can also affect humans in 44 RVF-endemic regions of sub-Saharan Africa and parts of the Arabian Peninsula [1,2]. The potential extreme 45 economic, and public and veterinary health burdens of epizootics/epidemics of RVF have been described 46 extensively [3].…”