Prevalence and Characterization of Salmonella Isolated from Feral Pigs Throughout Texas

Abstract

Feral pigs are one of the most abundant free-roaming ungulates in the United States, yet their role in the ecology and transmission of foodborne pathogens is poorly understood. Our objectives were to estimate the prevalence of Salmonella shedding among feral pigs throughout Texas, to identify risk factors for infection, and to characterize the isolates. Faecal samples were collected from feral pigs in Texas from June 2013 through May 2015. Standard bacteriologic culture methods were used to isolate Salmonella from samples, and isolates were characterized via serotyping and anti-microbial susceptibility testing. The prevalence of faecal Salmonella shedding among sampled pigs was 43.9% (194/442), with positive pigs originating from 50 counties. Pigs sampled during fall and summer were significantly more likely to be shedding Salmonella than pigs sampled during winter. High serovar diversity was evident among the isolates, and many of the detected serovars are leading causes of human salmonellosis. The most common serovars were Montevideo (10.0%), Newport (9.1%), and Give (8.2%). Resistance to anti-microbial agents was rare. The burgeoning feral pig population in the United States may represent an emerging threat to food safety.

Infection, colonization and shedding of Campylobacter and Salmonella in animals and their contribution to human disease: A review

“…However, in studies conducted in the United States, no significant seasonal variations were observed in samples collected in harvest‐ready feedlots and poorly productive culled beef and dairy cattle (Brichta‐Harhay et al, ; Kunze et al, ). High bacterial shedding during summer is not only reported in domestic animals but also in wild pigs (Cummings et al, ), and corresponds with an increase in Salmonella infections in humans (Cummings et al, ). Hot conditions as observed in summer in temperate areas favour pathogen survival and virulence and are associated with seasonal changes in human behaviour which increase the interactions between pathogens and humans (Ravel et al, ).…”

“…Salmonella serovars are often isolated in asymptomatic cattle, sheep, pigs, and non‐domestic ruminants and suids (Afema et al, ; Cummings et al, ; Eguale et al, ; Love et al, ; Zishiri, Mkhize, & Mukaratirwa, ). The magnitude and duration of colonization and shedding of Salmonella in animals vary along the different stages of infection or carriage, and not all infected animals shed Salmonella in faeces continuously (Donoghue, Farnell, Cole, & Donoghue, ).…”

Status of Laboratory Biosafety and Biosecurity in Veterinary Research Facilities in Nigeria

“…Most infectious and zoonotic diseases usually start as anthroponoses—transmitted from lower vertebrates (primary sources) to humans. Anthroponoses, such as those involving the highly pathogenic avian influenza viruses, Lassa fever virus, Brucella spp., pathogenic Mycobacterium spp., Bacillus anthracis, Escherichia coli O157:H7, Salmonella spp., and rabies virus [5], [6], [7], [8], [9], [10], [11], [12], typically cause serious health hazards among vast animal populations worldwide with the attendant economic and public health consequences being enormous [13]. The majority of these pathogens are on the Centers for Disease Control and Prevention (CDC) bioterrorism agents list [14].…”

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“…Of 442 feral swine sampled in Texas, 194 animals were found to harbour Salmonella spp. in their faeces and a number of different serovars were detected (Cummings et al., ). These studies were conducted in different regions at different times, further indicating that feral swine are frequently exposed to Salmonella spp.…”

“…The diversity of Salmonella spp. isolates detected in wild boar and feral swine suggests these animals are exposed via numerous routes, which may include livestock farming, waste disposal or via consumption of carcasses (Cummings et al., ). Co‐mingling of wild boar with domestic cattle resulted in much higher levels and greater diversity of Salmonella spp.…”