A High Sensitive Nested PCR for Toxoplasma gondii Detection in Animal and Food Samples

Toxoplasma gondii is a major food and waterborne transmitted parasite world-wide. The tissues and meat samples of many warm blooded animals can contain tissues cysts from chronic toxoplasmosis. Water and vegetable can be contaminated by the parasitic oocysts shed through the feces of infected cats, representing the definitive host of the parasite. A sensitive PCR for Toxoplasma gondii detection is described. The first step amplified the region between the 28S and 18S rDNA in the closely related T. gondii and Neospora caninum; RFLP analysis distinguished the DNA from the two morphologically identical parasites. Although N. caninum is not involved in human transmission, so far, it is important for animal health since is a major responsible for abortion in cattle. The nested PCR was used in a dilution assay in pork sausage samples spiked with T. gondii parasitic DNA. The analysis showed that up to 200fg equivalent to two single parasites only, could be detected. Similar detection limit for T. gondii can be obtained with real-time PCRs, but real time methods need special consumables and expensive equipment.