title: Surveillance of feral swine for Trichinella spp. and Toxoplasma gondii in the USA and host-related factors associated with infection.
abstract: Trichinella spp. and Toxoplasma gondii are important zoonotic parasites that infect warm blooded animals and humans worldwide. Among domesticated food animals, pigs are the main host for Trichinella spiralis. Pigs, chickens, sheep, and goats are known to be infected with T. gondii at varying rates, depending on husbandry. Infections in wildlife with these parasites are generally higher than in domesticated species. Feral swine act as reservoirs of infection in the sylvatic ecosystem for Trichinella spp. and T. gondii, acting as sources of infection for peridomestic carnivores whose home ranges overlap with domestic pigs. Feral swine can have direct contact with non-biosecure domestic pigs, presenting opportunity for direct disease transmission through cannibalistic behavior. Determination of the prevalence of Trichinella spp. and T. gondii infection in feral swine is needed to understand the risk of transmission of these parasites to domestic pigs. A cross-sectional serological survey was conducted between 2006 and 2010 to estimate the antibody prevalence of Trichinella spp. and T. gondii and risk factors associated with infection in feral swine in the USA. Serum samples were tested from 3247 feral pigs from 32 states; results are reported from 26 states. Maximum entropy ecological niche modeling and spatial scan statistic were utilized to predict the geographic range and to examine clusters of infection of Trichinella spp. and T. gondii in feral pigs. The seroprevalence of antibodies to Trichinella spp. and T. gondii was 3.0% and 17.7%, respectively. Species distribution modeling indicated that the most probable distribution areas for both parasites was similar, concentrated primarily in the South and the Midwest regions of the USA. A follow up survey conducted during 2012-2013 revealed that 2.9% of 984 sampled feral swine were seropositive for Trichinella spp., and 28.4% were seropositive for T. gondii. Three hundred and thirty (330) tongues were collected from the 984 sampled animals during 2012-2013; 1.81% were tissue positive for T. spiralis muscle larvae; no other genotypes were found. The potential exists for introduction of these pathogens into domestic herds of non-biosecure domestic pigs as a result of increasing overlap of the range of feral pigs with non-biosecure domestic pigs production facilities in the USA.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA. Electronic address: dolores.hill@ars.usda.gov.
authors.forename: D E
authors.initials: DE
authors.lastname: Hill
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Dubey
authors.affiliation: United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, 4101 LaPorte Ave, Fort Collins, CO 80521, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Baroch
authors.affiliation: United States Fish and Wildlife Service, 595 Yazoo Refuge Road, MS 38748-9729, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Swafford
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA.
authors.forename: V F
authors.initials: VF
authors.lastname: Fournet
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA.
authors.forename: D
authors.initials: D
authors.lastname: Hawkins-Cooper
authors.affiliation: National Pork Board, 1776 NW 114th St., Clive, IA 50325, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: Pyburn
authors.affiliation: United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, 4101 LaPorte Ave, Fort Collins, CO 80521, USA.
authors.forename: B S
authors.initials: BS
authors.lastname: Schmit
authors.affiliation: National Academy of Sciences, 500 5th Street N.W., Washington, D.C., 20001, USA.
authors.forename: H R
authors.initials: HR
authors.lastname: Gamble
authors.affiliation: United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, 4101 LaPorte Ave, Fort Collins, CO 80521, USA.
authors.forename: K
authors.initials: K
authors.lastname: Pedersen
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Ferreira
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Verma
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Ying
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD, 20705-2350, USA.
authors.forename: O C H
authors.initials: OC
authors.lastname: Kwok
authors.affiliation: Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
authors.forename: H
authors.initials: H
authors.lastname: Feidas
authors.affiliation: Department of Anatomy and Physiology of Farm Animals, Agricultural University of Athens, 75 Iera Odos, Votanikos, Athens 11855, Greece.
authors.forename: G
authors.initials: G
authors.lastname: Theodoropoulos
mesh_terms: D000818:Animals; D000835:Animals, Wild; D000909:Antibodies, Helminth / Q000097:blood; D000913:Antibodies, Protozoan / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D005843:Geography; D006801:Humans; D008297:Male; D016036:Seroepidemiologic Studies; D034421:Sus scrofa; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000469:parasitology; D014122:Toxoplasma / Q000276:immunology* / Q000302:isolation & purification; D014124:Toxoplasmosis, Animal / Q000453:epidemiology* / Q000469:parasitology; D014234:Trichinella / Q000276:immunology* / Q000302:isolation & purification; D017160:Trichinella spiralis / Q000276:immunology / Q000302:isolation & purification; D014235:Trichinellosis / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D014481:United States / Q000453:epidemiology; D015047:Zoonoses
chemical_list: D000909:Antibodies, Helminth; D000913:Antibodies, Protozoan
keywords: Feral swine; Geographic distribution; Risk factors; Spatial scan statistic; Toxoplasma gondii; Trichinella