Introduction
Trading livestock through live animal markets is an important part of
the economy of many developing countries (Fèvre et al., 2006; Leslie et
al., 2015; Perry et al., 2005). Demand for live pigs is high in
pig-producing areas of Nigeria, because these animals play a vital role
in the culture and tradition of the people as they are used for
celebrations and festivities (Fasina et al., 2010). Pig marketing in
Nigeria consists largely of live animal sales which are acquired from
multiple sources either directly from farmers at farm gates or fellow
traders at live pig markets (LPMs) (Ajala & Adesehinwa, 2008; Weka et
al., 2021). Hence, LPMs are hubs for the congregation of animals from a
wide range of locations some of which are reporting outbreak diseases.
In addition, poor biosecurity practices, limited government regulation,
and poor infrastructure enhance the ease of disease spread at these
markets. Likewise, the trading and movement of sick pigs have been
identified as a crucial pathway to the spread of transboundary diseases
like African swine fever (ASF) in endemic countries such as Nigeria
(Costard et al., 2013; Olugasa & Ijagbone, 2007). Pig husbandry system
in Nigeria is differentiated into mostly free-roaming/extensive,
semi-intensive and intensive pig production systems in pig producing
areas in Northern Nigeria and intensive commercial/ communal pig estates
in Southern Nigeria (Bourn et al., 1994, Ajala et al., 2006; Saka et
al., 2010; Nwanta et al., 2011). In Nigeria, farmers restock their farms
from LPMs and there have been reports of ASF outbreaks in pig farms
following introduction of pigs from these markets. Also, due to high
demand and need for better prices by farmers and traders, pigs reared in
the northern parts of Nigeria are transported to southern parts of the
country, the majority of such transactions is via LPMs. ASF is a lethal
transboundary disease of pigs caused by the ASF virus (ASFV) which is
the only member of the genus Asfivirus and familyAsfarviridae (Dixon et al., 2020). The disease is endemic and
restricted to countries in sub-Saharan Africa, but due to the highly
transboundary nature of ASFV, the disease has spread to domestic and
wild pigs in Europe, Asia, and Oceania (Penrith, 2020; Sauter‐Louis et
al., 2020). Genetic typing of the virus is based on characterization of
the p72 capsid protein of B646L , the full length of the p54 ofE183L, and further differentiation using the central variable
region of B602L (Bastos et al., 2003; Gallardo et al., 2009).
Based on the p72 p rotein capsid, 24 genotypes of ASFV have been
identified, most of which are restricted to East and Southern Africa
(Bastos et al., 2003; Quembo et al., 2018). Genotyping methods are
important tools for tracing the origin of ASFVs and quickly
differentiate or related virus strains during ASF outbreaks
(Malogolovkin et al., 2015a). The serogrouping-identification method can
be used to further discriminate ASFV strains. Based on this method, 8
ASFV serogroups have been identified based on the EP402R gene
encoding the CD2V protein (Malogolovkin et al., 2015a). ASF was first
introduced into Nigeria in 1997 via the trading of pigs by communities
along the international border with the Benin Republic (Odemuyiwa et
al., 2000). Thereafter, the disease spread to other pig-producing areas
of the country through livestock trading routes (Fasina et al., 2010;
Luka et al., 2016; Owolodun, et al., 2010a). ASFV genotype I was the
only circulating genotype in Nigeria, until recently when genotype II
was introduced into the country (Adedeji et al., 2021). Despite the
importance of live pig markets (LPM) in the pig value chain in Nigeria,
there are no extensive studies on the role of these markets in the
epidemiology of ASF in Nigeria (Fasina et al., 2010; Luka et al., 2016;
Owolodun, Bastos, et al., 2010). Though, previous studies have detected
ASFV and swine influenza virus in a live pig market in Nigeria (Dennis
et al., 2019; Luka et al., 2016; Meseko et al., 2014). However, these
studies involved only one pig market with limited information on
activities and pig movements in and out of the market. Studies in
Nigeria have revealed that live bird markets play an important role in
the ecology and epidemiology of Avian influenza in Nigeria (Coker et
al., 2014; Fusaro et al., 2009; Sulaiman et al., 2021). Similarly, it
has been reported that livestock farmers in Nigeria sell their animals
through live animal markets to mitigate economic losses during disease
outbreaks (Bolajoko et al., 2019). This further emphasizes the
importance of live animal markets in the epidemiology of transboundary
livestock diseases in Nigeria. This study assessed the role of LPMs as
hotspots for transmission and continuous spread of ASFV in Nigeria