6.1 Population density of domestic pigs
Among the livestock species, pigs find an important place in Indian economy as it not only contributes to the livelihood security of rural masses but also improves the socio-economic status of the marginal farmers and the weaker section of the society (NRC Pig, 2011).The North-Eastern (NE) region of India mostly comprises of a high proportion of tribal people where backyard pig farming is an integral part of their way of living (Talukdar et al., 2019). Apart from NE India, pig farming has been observed in several states of the mainland such as Jharkhand, West Bengal and Uttar Pradesh specially among the down trodden and tribal population as a backyard subsidiary enterprise (Kumar et al., 2004; Jeyakumar et al., 2014; Chauhan et al., 2016; Sahu et al., 2018). According to the latest livestock census report (2019), the current pig population is 9.06 million (M), the highest being in the state of Assam (2.10 M) followed by Jharkhand (1.28 M), Meghalaya (0.71 M), West Bengal (0.54 M) and Chhattisgarh (0.53 M) (Livestock Census, 2019).Over 70% of the pigs reared in India are of indigenous origin (dahd.nic.in). According to studies related to infectious diseases and group sizes, it has been found out that outbreaks of any disease reached higher prevalence when groups are larger and dense (Nunn et al., 2015). Majority of the marginal families involved in backyard farming usually keeps an average of 2-3 indigenous or crossbred pigs for fattening with zero to minimum inputs in terms of family labour and feeding (Kumar et al., 2007; Patra et al., 2016; Singh et al., 2019). Pig owners, specially from remote and rural settings are observed to show keen interest in small-scale pig farming (10-15 pigs per family) mostly with an aim to get avenues for additional income and savings for their children’s education and medical treatment based on the locally available resources (Chauhan et al., 2016). Even though, pigs maintained in such locations are clustered into smaller groups, the rural households are connected close to each other, thus predisposing the animals to infectious animal diseases and their spread to closely reared/in-contact animals. Therefore, considering the existing high density of domestic pig population in India, there is every chance that ASF might attain an endemic status if not controlled critically.