4. WARTHOGS, BUSH PIGS AND SOFT TICKS AS NATURAL RESERVOIRS
African swine fever can lead to high mortalities in domestic pigs while
being asymptomatic in the natural suid reservoir hosts (Jia et al.,
2017). Wild pigs (warthogs and bush pigs), and soft ticks of the
genus Ornithodoros serve as natural reservoirs in ASFV
transmission (Costard et al., 2013). Wild pigs including warthogs and
bush pigs may be persistently infected generally developing asymptomatic
infections, often referred to as the sylvatic cycle (Kimberling and
Teegarden, 1979). Young warthogs may develop a transient viremia to
infect new ticks without developing clinical disease, and adult warthogs
may be resistant to the pathogenic effects of the virus although the
virus can be often extracted from their lymph nodes (Penrith, 2009).Soft
ticks from the genus Ornithodoros are responsible for the transmission
of ASFV in the environment and acts as a main source of infection
(Burrage, 2013). Even though, soft ticks like Ornithodoros moubata
and O. erraticus have been reported to be involved in the sylvatic
transmission cycle of the virus in Africa and Europe respectively,
several other species of Ornithodoros (O. moubata, O.
sonrai, O. coriaceus , O. turicata , O. parkeri ,
and O. puertoricensis ) have also been confirmed as the biological
vectors for transmission of ASF (Frant et al., 2017). Infection from the
wild pigs to the domestic population is largely dependent on ticks of
the Ornithodoros species than infections through contact between wild
and domestic pigs (Costard et al., 2009). Apart from soft ticks, biting
flies (Stomoxys spp.) have shown to be capable of transmitting
the disease into the swine population (CSFPH, 2019).