5. EPIDEMIOLOGICAL CYCLES OF ASF
The epidemiology of ASF was described as comprising four independent
epidemiologic cycles (i) sylvatic (ii) tick-pig (iii) domestic and (iv)
wild boar-habitat cycle (a newly discovered cycle in Europe) (Chenais et
al., 2018). The sylvatic cycle, mostly restricted to African continent,
is maintained between Ornithodoros ticks and natural reservoirs
(warthogs and bush pigs) that are resistant to the ASFV and usually do
not develop any clinical disease (Plowright et al., 1994; Guberti et
al., 2018). In the tick-pig cycle, the virus is transmitted among
domestic pigs through ticks serving as a reservoir and allowing the
virus to persist locally in the environment (Wilkinson, 1984). In the
domestic cycle, the virus is transmitted among domestic pigs or from pig
products to domestic pigs without the involvement of natural reservoirs
(Chenais et al., 2019).The wild boar-habitat cycle is a newly described
cycle in Central and Eastern Europe while investigating the
epidemiological pattern of ASF infections in wild and domestic pig
population (Chenais et al., 2018).This newly evolved epidemiological
cycle involves wild boar (Sus scrofa ), the wild boar habitat and
their carcasses for the maintenance and transmission of ASFV to domestic
pigs (Chenais et al., 2018). The wild boar-habitat cycle may describe
the possibilities of new infections in areas with wild boar population
and in the interspaces between wild and domesticated swine habitat such
as a Wildlife Sanctuary or a National Park.