|PROWELL, MARY - Beltsville Veterinary Hospital|
Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2012
Publication Date: 2/1/2013
Citation: Dubey, J.P., Prowell, M. 2013. Ante-mortem diagnosis, diarrhea, oocyst shedding, treatment, isolation and genetic typing of Toxoplasma gondii associated with clinical Toxoplasmosis in a naturally-infected cat. Journal of Parasitology. 99:158-160.
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 under-cooked meat from infected animals, as well as food and water contaminated with oocysts. Cats are rarely sick during the time of oocyst shedding, and diagnosis of clinical toxoplasmosis is rarely made in live cats. Here, the authors report shedding of Toxoplasma oocysts and clinical diagnosis in a cat antemortem. The results will be of interest to biologists, parasitologists, and public health workers.
Technical Abstract: Toxoplasma gondii infections are common in humans and other animals but clinical disease is relatively rare. It is unknown whether the severity of toxoplasmosis in immunocompetent hosts is due to the parasite strain, host variability, or to other factors. Recently, attention has been focused on the genetic variability among T. gondii isolates from apparently healthy and sick hosts. Whether T. gondii genetic makeup plays a part in the pathogenesis of clinical feline toxoplasmosis is uncertain because little is known of genetic typing of strains associated with clinical feline toxoplasmosis. A 6- mo-old domestic male cat was hospitalized with because of lethargy, anorexia, fever, and diarrhea. Numerous (6 million in 1 sample) T. gondii oocysts were found in feces of the cat and antibodies to T. gondii (titer 1:800) were found in its serum by the modified agglutination test. The cat was medicated orally with Clindamycin for 10 days, and became asymptomatic after 10 days and discharged from the hospital. Viable T. gondii (designated TgCatUs3) was isolated from feces (oocysts) by bioassays in mice. Genetic typing using the DNA extracted from the brains of infected mice and 10 PCR-restriction fragment length polymorphism (RFLP) markers revealed Type II allele at the SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, PK1 loci, and Type I at the L358, and Apico loci, therefore this isolate belongs to the ToxoDB PCR-RFLP genotype #4, which is grouped into the Type 12 lineage that is dominant in wildlife from North America. To our knowledge this is the first T. gondii isolate characterized genetically from a sick cat in the USA.