Factors Contributing to the Spread of ASF in Asia
Four of the top 10 pork producing countries in the world, namely China, Vietnam, Philippines, and South Korea produce 34,000; 2,250; 1,450 and 1,350 thousand Metric Ton respectively, are in Asia (Statista, 2020). Historically Asian countries were less affected with ASF which may be attributed to the effective sanitary regulation and strict rules for import of animals and animal products (Costard et al., 2013). Periodic outbreak of various viral and prion diseases including BSE, Avian influenza, Classical swine fever has further alerted various Asian countries to strengthen veterinary services (Ozawa et al., 2006).
Recently, outbreaks of ASF are reported in Asian countries including China, Laos, Vietnam, India and is rapidly spreading all over Asia (Table 3) (OIE, 2021). China is the key Asian country for the production and supply of pork globally. There is high risk for the entry of ASF into various other Asian countries through China as it has international trade with various countries of Africa where ASF outbreak have been recently reported (Costard et al., 2013). Furthermore, various cultural events in Asia demand more pork supply that increases the risk of ASFV transmission and ASF outbreaks. Illegal import of pig products also favors the entry and outbreak of disease vigorously (Shih et al., 2005). Movement of live animal and pig products support the condition for spread of the virus at the regional level. Most of the Asian countries practice free ranging pig husbandry system that causes endemic outbreak of ASF. Beside this, existence of wild pigs also favors the potential outbreak of disease since the virus is maintained in wild suid reservoirs. Study of soft tick includingOrnithodoros  (Alectorobius ) spp. is also due essential to better understand the dynamic of spread of disease by these vectors in Asian territories (Ahmed et al., 2007).