6.4 Availability of wildlife reservoirs and their habitat
AFSV is maintained in a stable equilibrium with its wildlife hosts,
warthogs and soft ticks of Ornithodoros species, in a unique ecological
niche (Netherton et al., 2019). Though
the sylvatic cycle
of ASFV in warthogs contrasts
with the domestic cycle
in swine,
yet, in both
instances, soft
ticks of the genus Ornithodoros in warthog burrows and domestic
pigpens serve as biological hosts and vectors (Calisher and Fenner,
2000). The wildlife reservoirs, warthogs are native to Africa and often
found in abundance (de Jong et al., 2017).The Common warthog
(Phacochoerus africanus ) is widely distributed over sub-Saharan
Africa, and expanded its geographic range to West Africa eastwards to
Eritrea and Ethiopia, southward through eastern Africa, and over much of
southern Africa to southern Angola, Botswana, and Mozambique to
northeast South Africa (de Jong et al., 2017). The Desert warthog
(Phacochoerus aethiopicus ) is presently known only from
south-eastern Ethiopia, western Somalia, and in central and eastern
Kenya (d’Huart et al., 2011). Since warthogs are confined mostly to
Africa, outbreaks of ASF recorded outside the continent (recent
outbreaks in Europe and Asia including India) raises questions about the
involvement of sylvatic cycles, but might have arises through other
means of disease dissemination such as infected pig-derived products and
circulation of Ornithodoros species across the borders. However,
distribution of warthogs (desert warthogs in particular), is largely
unstudied for which further field surveys are needed to better determine
geographic limits, area of occupancy, abundance and the impacts of
various human/livestock-raising activities on distribution and abundance
(d’Huart et al., 2011). There are also limited investigations on
bushpigs to understand their contribution in the epidemiology of ASF and
the interactions between these natural hosts and domestic pigs
(Ravaomanana et al., 2011).