Global Epidemiology of African Swine Fever
ASF was first reported from East Africa in 1921 and is still present in
the region (Figure 3) (Lubisi et al., 2005). It was also identified in
the southern, central, and West Africa during early 1900s and has been
endemic in the African continent by circulating in one of the three
different transmission cycles (Lubisi et al., 2005). Portugal had the
outbreak of ASF in 1957, the first time outside of Africa
(Sanchez-Vizcaıno et al., 2015) and also in 1959 which was believed to
be imported from Angola where it was established in the Iberian
Peninsula and was only eradicated in 1994 (Mary Louise Penrith, 2009).
Several other outbreaks resulted in Western Europe in the 1970s and
1980s, Sardinia in 1987 where ASF persists, Cuba, Hispaniola (Haiti and
the Dominican Republic) and Brazil in a similar time frame from where it
has been eradicated (Sanchez-Vizcaıno et al., 2015).
The outbreak of ASF in countries of South and North America mainly
occurred in 1980s. Since then, ASF outbreak has not been reported in
American countries. However, there is still threat of ASF outbreak in
both north and south America. Till now, only Australian country, Papua
New Guinea, has reported first outbreak of ASF in 2020 (Mary Louise
Penrith, 2020; World Organisation for animal health (OIE)
, 2020b).
A resurgence in western Africa occurred in 1994 infecting various
nations that were previously unaffected along with the first outbreak in
Kenya in 30 years, an outbreak in ASF free region in Mozambique, and
first outbreak in Madagascar in 1997 (Mary Louise Penrith, 2009).
Countries like Spain, France, Madeira, Italy, and Cuba were infected
from 1960 to 1971, Haiti reported the infection in 1979 and reappearance
was seen in Cuba in 1980 (Wardley et al., 1983). The spread of the ASF
virus can be attributed to three major factors which were: 1) increment
in the pig population and production; 2) reservoir non-symptomatic pig
population; and 3) globalization (Sanchez-Vizcaıno et al., 2015). Since
2007 ASF is seen in the Caucasian region with the outbreak in Georgia
with spread to Armenia, Azerbaijan, and the Russian Federation, Ukraine,
and northwest Russia near the Baltic Sea and Barents Sea (Table 1)
(Sánchez‐Vizcaíno et al., 2019). Subsequently, various outbreaks
occurred in different European, Asian, and Pacific nations on different
years (OIE, 2020b; M. L. Penrith & Vosloo, 2009) (Table 1) (Figure 3).
Nepal has not yet reported the case of ASF. But the recent outbreaks in
the neighboring countries make it susceptible to the outbreaks in near
future mainly due to the open borders with India which could lead into
the transfer of infected products and animals into the nation. The first
case was detected in India in January with a total of 11 confirmed
outbreaks, 9 in Assam and 2 in Arunachal Pradesh, with 10,920
susceptible animals and 4,199 cases (OIE, 2020a). The total death has
been reported to be 3,701 with 14,000 pigs culled in Assam alone (OIE,
2020a). To date China reported 165 outbreaks of ASF since the
conformation of the first outbreak in Liaoning Province on 3 August 2018
with 1,193,000 pigs being culled (FAO, 2020).
The current ASF epidemiological situation shows that Europe holds
maximum outbreak of ASF (66.87%), Asia (32.72%) and Africa (0.41%)
respectively (Table 2) (OIE, 2020b). Asian pig industry is highly
affected by ASF with more than 80% losses compared to that in Europe
(16.86%) and Africa (1.04%). Asian and African countries mainly report
cases of domestic pigs while the European countries also reported a
larger number of the cases of wild boar (Table 2). The increasing trend
in spread of ASF brought a serious threat to animal health, pig
production, and swine population globally and therefore, affect
economies and trade. ASFV remains endemic in many sub‐Saharan countries
on the African continent.