Regional level risk factors associated with the occurrence of African swine fever in West and East Africa

Abstract

BackgroundAfrican swine fever (ASF) causes severe socio-economic impacts due to high mortality and trade restrictions. Many risk factors of ASF have been identified at farm level. However, understanding the risk factors, especially wild suid hosts, determining ASF transmission at regional level remains limited.MethodsBased on ASF outbreak data in domestic pigs during 2006–2014, we here tested, separately for West and East Africa, which risk factors were linked to ASF presence at a regional level, using generalized linear mixed models.ResultsOur results show that ASF infections in the preceding year was an important predictor for ASF presence in both West and East Africa. Both pig density and human density were positively associated with ASF presence in West Africa. In East Africa, ASF outbreaks in domestic pigs were also correlated with higher percentages of areas occupied by giant forest hogs and by high-tick-risk areas.ConclusionsOur results suggest that regional ASF risk in East Africa and in West Africa were associated with different sets of risk factors. Regional ASF risk in West Africa mainly followed the domestic cycle, whereas the sylvatic cycle may influence regional ASF risk in East Africa. With these findings, we contribute to the better understanding of the risk factors of ASF occurrence at regional scales that may aid the implementation of effective control measures.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1953-z) contains supplementary material, which is available to authorized users.

Ecological niche modeling and distribution of Ornithodoros hermsi associated with tick-borne relapsing fever in western North America

“…One program, Maxent, consistently outperforms other ENM models [ 29 , 30 ] and was developed specifically for data with low sample-sizes of presence-only locations [ 31 , 32 ]. Initially designed to evaluate the potential distribution of endangered and threatened species, Maxent has been used extensively to model the distribution of numerous arthropods, including soft ticks that vector important disease-causing pathogens [ 33 – 35 ]. The specificity of suitable living conditions for ticks make O .…”

Seroprevalence and epidemiology of African Swine Fever (ASF) in Burkina Faso

“…In the present study, the seroprevalence of ASF virus infection varied according to the province or region during the study period. Indeed, a significantly higher prevalence (22.6%) was recorded in the Central region compared to the Hauts-Bassins region (3.3%) during [13,[22][23][24].…”

Epidemiology of African swine fever in Africa today: Sylvatic cycle versus socio‐economic imperatives

“…The role of other wild African suids, if any, is likely to be incidental because their habits differ from those of warthogs and are unfavourable for an association with Ornithodoros ticks (Jori & Bastos, ; Jori et al., ). A recent model based assessment of risk factors for ASF outbreaks in Africa suggested that the giant forest hog, Hylochoerus meinertzhageni , is an important threat at regional level for ASF in East Africa (Huang, Langevelde, Honer, Naguib, & Boer, ). However, this hypothesis can most likely be discounted as only one historical record of ASF infection in a true giant forest hog ( H. m. meinertzhageni ) has ever been reported (Heuschele & Coggins, ) and this subspecies is declining, having likely disappeared from Burundi and Rwanda, and occurring in fragmented populations in other East African countries (d'Huart & Reyna, ).…”

“…The authors of the model admitted that the role for giant forest hogs in East Africa would likely be an indirect one, requiring that the forest hogs would infect other wild suid species and/or O. moubata complex ticks, both of which are improbable. Assumptions that ASF infection is the norm in African wild suids and Ornithodoros ticks in endemic areas and that there is an association between all the African wild suid species and the tick vectors may have led to an erroneous outcome of the model for East Africa, which correctly indicated that, in West Africa, ASF is associated with increasing domestic pig and human populations (Huang et al., ).…”