Abstract:
Pigs are ungulate animals of the genus Suis and family Suidae. They are globally spread but restricted
in certain countries due to religious and cultural beliefs. Pork serves as an important source of protein
(38% of meat consumed in the world). While pig production remains a profitable enterprise, commercial
and particularly the small-scale farmers face huge constraint in this husbandry practice, one of the
most important being bacterial infections and its associated with morbidity and mortality. In this work,
we reviewed the prevalence of bacterial infections in pigs with particular reference to Escherichia coli, a
bacterium that is regularly isolated and can lead to multiple infections in pigs. Literatures were
searched on selected veterinary and biological data bases in 2016 with focus on natural infections and
isolates from natural infections with epidemiological details. Pathotypes, serotypes and serogroups of
E. coli, the country of origin, source, growth stage, age of pigs infected, disease outbreak, the number
of samples and type of samples, numbers and percentage of positive samples and isolates were used
as filters. Pathotypes reported include enterotoxigenic E. coli (ETEC) 66.7%, enterotoxigenic E. coli and
shiga toxigenic E. coli (ETEC and STEC) 14.3%, STEC only (7.9%), enterotoxigenic E.
coli/enteropathogenic E. coli/enteroaggregative E. coli (ETEC/EPEC/EAE) 31.7%. Others were
enterohaemorrhagic E. coli (EHEC), diffusely adherent E. coli (DAEC) (ETEC, EPEC, STEC) and extraintestinal
pathogenic E. coli (ExPEC). Twenty-nine countries with documented records of cases of E.
coli were included with the USA reporting, the highest number followed by China. About 74% of the
samples were taken from farms and others were from samples submitted to research laboratories and
veterinary faculties for necropsy. Serogroups O141, O149, O139, O138, O8 and O9 were most common.
Piglets were most affected (52.3%) followed by weaners (39.6%) and porkers (7.9%) with age ranging
from 1 to 392 days old. A total of 24,854 isolates were considered, 10477 (42.2%) were positives and the
following genes were carried: STa, STb, LT, stx1, stx2, Stx-2e, F4, F5, F6, F18, F41, AIDA, EAST1, eae,
paa and hlyA. The diseases produced by E. coli were neonatal diarrhoea, colibacillosis, post-weaning
diarrhoea and edema disease. The associated risk factors were poor housing, management and feed
changes, extensive use of antibiotics as prophylaxis, overcrowding, and high humidity and temperature
changes. India, USA, Japan, Slovakia, Denmark Sweden and Poland were countries with significant
reports and high detection of virulence factors (72 to 100%).
