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Beltsville, MD, United States

Lindsay D.S.,Virginia Polytechnic Institute and State University | Dubey J.P.,Animal Natural Resources Institute
Parasitology | Year: 2011

Researchers have learned much concerning the population biology of Toxoplasma gondii over the past 2 decades. It is now apparent that many atypical genotypes exist besides the typical 3 genotypes (type I, type II and type III) first described from samples from Europe and the United States. These genotypes can differ in pathogenicity and transmissibility from the typical genotypes that have been used in the majority of scientific research over the past 70 years. These differences impact much of what we used to believe as facts about congenital toxoplasmosis (CT) and will be important in developing new recommendations for prevention of CT and the monitoring of women at risk for developing CT. The present review highlights new information on T. gondii genotypes and how this information will change the way we convey information about CT to pregnant women, physicians and students. Copyright © Cambridge University Press 2011. Source

Lopes A.P.,University of Tras os Montes e Alto Douro | Dubey J.P.,Animal Natural Resources Institute | Gargat M.J.,National Institute of Health | Vilares A.,National Institute of Health | And 3 more authors.
Epidemiology and Infection | Year: 2012

Seroprevalence of Toxoplasma gondii infection and associated risk factors were investigated in 401 women of childbearing age from the North of Portugal. Of the 98 (244%) seropositive women, 92 (939%) only had immunoglobulin (Ig)G, two (20%) only had IgM, and four (41%) others had both IgG and IgM. Risk factors for T. gondii infection in women were: engaging in soil-related activities without gloves [odds ratio (OR) 84], consumption of unwashed raw vegetables or fruit (OR 76), and consumption of smoked or cured (non-cooked) processed pork products (OR 25). Most women of childbearing age from the North Portugal are susceptible to primary infection with T. gondii and, therefore, the risk of congenital toxoplasmosis remains high. © Copyright Cambridge University Press 2011. Source

Dubey J.P.,Animal Natural Resources Institute | Ferreira L.R.,Animal Natural Resources Institute | Martins J.,Animal Natural Resources Institute | Mcleod R.,University of Chicago
Parasitology | Year: 2012

Humans and other hosts acquire Toxoplasma gondii infection by ingesting tissue cysts in undercooked meat, or by food or drink contaminated with oocysts. Currently, there is no vaccine to prevent clinical disease due this parasite in humans, although, various T. gondii vaccine candidates are being developed. Mice are generally used to test the protective efficacy of vaccines because they are susceptible, reagents are available to measure immune parameters in mice, and they are easily managed in the laboratory. In the present study, pathogenesis of toxoplasmosis was studied in mice of different strains, including Human Leukocyte Antigen (HLA) transgenic mice infected with different doses of T. gondii strains of different genotypes derived from several countries. Based on many experiments, the decreasing order of infectivity and pathogenicity of oocysts was: C57BL/6 background interferon gamma gene knock out (KO), HLA-A 1101, HLA-A 0201, HLA-B 0702, Swiss Webster, C57/black, and BALB/c. Mice fed as few as 1 oocyst of Type I and several atypical strains died of acute toxoplasmosis within 21 days p.i. Some Type II, and III strains were less virulent. The model developed herein should prove to be extremely useful for testing vaccines because it is possible to accurately quantitate a challenge inoculum, test the response to different strains of T. gondii using the same preparations of oocysts which are stable for up to a year, and to have highly reproducible responses to the infection. © Cambridge University Press 2011. Source

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