Skip to main content
ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Publications at this Location » Publication #323776

Title: Isolation and genetic characterization of Toxoplasma gondii from naturally infected Canada goose (Branta canadensis) detected two new atypical strains

item VERMA, SHIV - Orise Fellow
item CALERO-BERNAL, RAFAEL - Orise Fellow
item Kwok, Oliver
item Dudley, Michael
item SU, CHUNLEI - University Of Tennessee
item Hill, Dolores
item Dubey, Jitender

Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2016
Publication Date: 5/20/2016
Citation: Verma, S.K., Calero-Bernal, R., Cerqueira-Cezar, C.K., Kwok, O.C., Dudley, M.R., Su, C., Hill, D.E., Dubey, J.P. 2016. Isolation and genetic characterization of Toxoplasma gondii from naturally infected Canada goose (Branta canadensis) detected two new atypical strains. Parasitology Research. 115(5):1767-72.

Interpretive Summary: Toxoplasmosis continues to be a public health problem worldwide. It causes mental retardation and loss of vision in children, and abortion in livestock. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Humans become infected by eating under cooked meat from infected animals and food and water contaminated with oocysts. Why some individuals become ill and even die of toxoplasmosis whereas most remain asymptomatic is largely known. The molecular characteristics of T. gondii I strains is thought to be one factor in the pathogenesis of disease. The interchange (mixing) of T. gondii strains from wildlife and those circulating in domestic animals can change the virulence of the parasite, particularly domestic and wild cats. Some strains of T. gondii are geographic and transport of T. gondii across continents is not fully explained. Migratory birds are thought to contribute to global distribution of the parasite. In the present study, authors genotyped isolates from wild migratory geese hunted in Maryland and found higher genetic diversity than previously known. The results will be of interest to biologists, parasitologists, and veterinarians.

Technical Abstract: Wild birds are important in the epidemiology of toxoplasmosis because they can serve as reservoir hosts, and vectors of zoonotic pathogens including Toxoplasma gondii. Canada goose (Branta canadensis) is the most widespread goose in North America. Little is known concerning T. gondii infection in both migratory and local resident populations of Canada geese. Here, we evaluated the seroprevalence, isolation and genetic characterization of viable T. gondii isolates from migratory population of Canada geese. Antibodies against T. gondii were detected in 12 of 169 Canada geese using the modified agglutination test (MAT, cut-off 1:25). Hearts of 12 seropositive geese were bioassayed in mice for isolation of T. gondii; viable parasites were isolated from 8. One isolate was obtained from a seropositive goose by both bioassays in mice, and by bioassay in a cat; the cat fed infected heart excreted T. gondii oocysts. Additionally, one isolate was obtained from a pool of 4 seronegative (<1:25) geese by bioassay in a cat. The T. gondii isolates were further propagated in tissue culture, and DNA extracted from cell culture derived tachyzoites was characterized using 10 PCR-RFLP genetic markers (SAG1, 5’and 3’SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico). Results revealed five different genotypes; ToxoDB PCR-RFLP genotype #2 in four isolates, genotype #4 in two isolates, and two isolates new genotypes (genotype #266, and #267). Results indicate genetically diverse T. gondii strains circulate in the Canada geese, and this migratory bird can provide a mechanism of T. gondii transmission at great distances from where an infection was acquired.