Data collection: Data was collected based on key informant
interviews of government and pig traders’ union officials at the market
sites. Data collected were: average weekly population of pigs in the
markets. Towns and villages from where pigs are brought into the markets
and locations where the pig purchased are transported to. Government
regulations in the markets and attached slaughter slabs and the fate of
pigs unsold on at the market. Data on the average number of pigs
slaughtered at the slabs were also collected.
Field observation: Due to poor records at the selected LPMs,
observations of activities of the value chain actors (traders, farmers,
transporters) and slaughter slab operators were carried out using a
checklist. These include pre-entry inspections of pigs going in and out
of the market site, mode of transportation of the pigs, holding
facilities at the markets e.g pens, activities of the slaughter slab
operators, and access of people and other animals to the market sites.
Others include common breeds of pigs at the market, estimated age of
pigs brought to the market, sanitation, and hygiene at the market sites.
To carry out this aspect of the study, arrival at market sites was from
7 am to 8 am depending on location to maximize observation of
activities, sample collections, and travel time back to the laboratory.
At least 2 cycles of visits were planned per month for data and sample
collection.
Figure 1 : Map of Northern part of Nigeria, showing the movement
of pigs from towns and villages into the four selected live pigs markets
Figure 2 : Map of Nigeria showing movement and outflows of pigs
from four selected pig markets to various destinations in the country
Sample size determination and collections: From April 2019- Feb
2020, October-November, 2020 samples were collected at the Dawaki,
Katsit, Numan, and Pandam pig markets in Nigeria. With a population of
7million pigs, the minimum recommended sample size for such a population
using a confidence level of 95% and a margin of error of 5% gives a
calculated sample size of 384 (Dohoo et al., 2009). The samples
were collected using a convenient sampling method, based on the
cooperation of the pig traders and slaughter slab operators. The samples
collected were whole blood, tissue, and sera samples. 5mls of blood in
heparinized and plain sample bottles were collected from pigs at LPMs
and their slaughter slabs. Tissue samples (liver, spleen, and mesenteric
nodes) were collected in labelled sample bottles from all pigs
slaughtered at the slaughter slabs within the premises of the LPMs.
Criteria for sample collection at the slaughter slab was pigs bought at
LPMs, pigs from external sources were excluded. Both apparently healthy
and sick pigs were sampled. Sample collection was disrupted between
March 2020 and September 2020 due to COVID-19 lockdown restrictions in
Nigeria.
Detection of African swine fever antibodies : Sera samples
collected were analyzed using commercially available ID Screen ASF
Indirect kit (IDVet, Grabels, France) specific for the presence of
antibodies against ASFV p32, p62 , and p72 proteins
according to the manufacturer´s instructions.
Detection of African swine fever virus. Total DNA was extracted
from whole blood and homogenized tissue samples using the Qiagen Mini
kit (Qiagen, Hilden Germany) following the manufacturer’s protocol. A
257 bp region corresponding to the C-terminal region of the B646gene encoding the p72 major capsid protein was amplified using
the diagnostic primers PPA1 and PPA2 as previously reported to confirm
the presence of the ASFV genome (Aguero et al., 2003).