Submitted to: International Journal for Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/5/2007
Publication Date: 6/1/2008
Citation: Dubey, J.P., Velmurugan, G.V., Ulrich, V., Gill, J., Carstebseb, N., Sundar, N., Kwok, O.C., Thulliez, P., Su, C. 2008. Transplacental toxoplasmosis in naturally-infected white-tailed deer: isolation and genetic characterization of Toxoplasma gondii from foetuses of different gestational ages. International Journal for Parasitology. 38:1057-1063. Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts 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 undercooked meat from infected animals and food and water contaminated with oocysts. Toxoplasmosis causes mortality in many species of animals in the zoos, especially wallabies. Scientists at the Beltsville Agricultural Research Center report prevalence of T,. gondii in deer from Iowa and Minnesota.. The results will be of interest to biologists, parasitologists, and veterinarians
Technical Abstract: Clinical toxoplasmosis is most severe in congenitally-infected hosts. In humans, transmission of Toxoplasma gondii from the mother to the foetus is considered to be most efficient during the last trimester of pregnancy but clinical congenital toxoplasmosis is more severe if the transmission occurs during the first trimester. However, there are no data on the rate of congenital transmission of T. gondii with respect to gestational age in any host during natural infection. In the present study, attempts were made to isolate T. gondii by bioassay in mice inoculated with foetuses of 88 naturally-exposed white-tailed deer from Iowa and Minnesota. Viable T. gondii was isolated from foetuses of six of 61 deer in early pregnancy (45-85 days of gestation) and foetuses of nine of 27 deer in mid gestation (130 -150 days) of a gestational period of seven months. Five of these 15 isolates were from pregnant deer had no detectable antibodies to T. gondii in the modified agglutination test. Results indicate that transmission of T. gondii is more efficient in later stages of pregnancy and the foetus can become infected even before the dam becomes seropositive to the parasite. The 15 T. gondii isolates obtained from fetal deer were PCR-RFLP genotyped using polymorphisms at 10 nuclear markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and an apicoplast marker Apico. Five genotypes were revealed. The most common genotype was Type II, commonly found in humans in North America and Europe suggesting the possible link of transmission from game animals to humans.