1. INTRODUCTION
African Swine Fever (ASF) is a highly fatal viral infectious disease
that manifests as a haemorrhagic fever in affected pigs (Penrith and
Vosloo, 2009). ASF has been listed as a priority disease in World
Organisation for Animal Health (OIE) owing to its socio-economic
importance and transboundary potential (OIE, 2020a). The first report of
ASF was detected in Kenya as a disease entity distinct from Classical
Swine Fever (CSF) (Montgomery, 1921). Since its first inception, ASF has
spread from its historic range of Africa, to several countries in Europe
(France, Italy, Malta, Belgium and the Netherlands and Iberian
Peninsula) (Penrith and Vosloo, 2009; Blome et al., 2013) and more
recently to Asia (China, Mongolia, Vietnam, Cambodia, Korea, Lao,
Myanmar, Philippines and Indonesia) threatening both domestic and
wildlife conservation (FAO, 2020a). The disease ASF is caused byAfrican swine fever virus (ASFV) of genus Asfivirus and is
currently the sole member of the family Asfarviridae (Alonso et
al., 2018). ASFV infects domestic
and wild
swine (Sus
scrofa ), warthogs (Phacochoerus
africanus; Phacochoerus aethiopicus ) and bush pigs (Potamochoerus
porcus ) (Alonso et al., 2018). ASFV can be transmitted directly during
(i) contact between infected and susceptible pigs (ii) consumption of
the meat from infected pigs (iii) bites of infected soft ticks
(Ornithodoros species), and indirectly(iv) by contact with
fomites contaminated by virus-containing matters such as blood, faeces,
urine or saliva from infected pigs (Penrith and Vosloo, 2009).Clinical
disease of ASF can manifest in multiple ways ranging from peracute
(mortality ~100%) to an asymptomatic infection (Penrith
and Vosloo, 2009). Acute infections are typically characterized by a
high fever, anorexia, lethargy, weakness, recumbency, diarrhoea and/or
constipation, abdominal pain, hemorrhagic signs, respiratory distress,
nasal and conjunctival discharge, and abortions in pregnant females
followed by death within 6-13 days after the onset of clinical signs
(Sanchez-Vizcaino, 2010). Subacute infections are often recorded with
high mortality in young animals and include clinical signs such as
abortion, fever, and transient haemorrhage with death or recovery within
3-4 weeks (Penrith and Vosloo, 2009; Schulz et al., 2017). Chronic
infections are associated with low mortality and clinical signs such as
intermittent or low fever, loss of appetite and depression which might
develop over 2-15 months (Sanchez-Vizcaino, 2010).
India has reported the first outbreak of ASF in the domestic pig
population of two of the North-Eastern states viz. Arunachal Pradesh and
Assam to OIE on the 21st May, 2020 (OIE, 2020b). The
North Eastern Region (NE) of India, owing to its unique geographical
location while sharing international boundaries with China, Bhutan,
Bangladesh and Myanmar bears a constant threat of transboundary emerging
diseases though its porous borders (Barman et al., 2016). Apart from the
first outbreak of ASF in NE India, this region has also reported several
other emerging diseases of pigs such as Porcine reproductive and
respiratory syndrome (Rajkhowa et al., 2015) and PorcineCircovirus -2 infections (Mukherjee et al., 2018).In this article,
the authors will discuss the risk factors/indicators that might favour
the spread of ASF infections in India, its possibilities of
establishment of endemic infections and the control strategies to
prevent future outbreaks.