Submitted to: Veterinary Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/6/2006
Publication Date: 10/1/2006
Citation: Dubey, J.P., Bhaiyat, M.I., Macpherson, C.L., De Allie, C., Chikweto, A., Kwok, O.C., Sharma, R.N. 2006. Prevalence of Toxoplasma gondii in rats (Rattus norvegicus) in Grenada, West Indies. Veterinary Parasitology. 92:1107-1108. 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.Scientists at the USDA Agricultural Research Service and University in Grenada, West Indies report the prevalence of Toxoplasma antibodies in rats from Grenada.The results will be of interest to biologists, parasitologists, and veterinarians.
Technical Abstract: Cats are important in the natural epidemiology of Toxoplasma gondii because they are the only hosts that can excrete environmentally-resistant oocysts. Cats are considered to become infected with T. gondii by ingesting infected tissues and they often prey on birds and rodents. During 2005 a total of 238 rats (Rattus norvegicus) were trapped in Grenada, West Indies and their sera along with tissue samples from their hearts, and brains were examined for T. gondii infection. Antibodies to T. gondii were assayed by the modified agglutination test (MAT, titer 1:40 or higher) and were found only in two (0.8%) of 238 rats. Brains and hearts of all rats were bioassayed in mice. T. gondii was isolated from the brain and the heart of only one rat which had a MAT titer of 1:320. All the five mice inoculated with the heart, and the five mice inoculated with the brain tissue of the infected rat remained asymptomatic and tissue cysts were found in their brains. Genetically, the isolates of T. gondii from the heart and the brain were identical and had the genotype III using the SAG1, SAG2, SAG3, BTUB and GRA6. These data suggest that rats are not important in the natural history of T. gondii in Grenada.