DETECTION OF TOXOPLASMA-GONDII IN FELINE AND CANINE BIOLOGICAL SAMPLES BY USE OF THE POLYMERASE CHAIN-REACTION

Objective-To develop a polymerase chain reaction (PCR) technique to id entify Toxoplasma gondii DNA in biological samples from cats and dogs. Design-To artificially create samples that would mimic those acquired in a clinical setting from animals with naturally acquired toxoplasmo sis. Using these samples, a PCR test to identify T gondii DNA was deve loped. Sample Population-Feline and canine aqueous humor, CSF, serum, and blood samples. Procedure-Tachyzoites of several strains of T gondi i grown in cell culture were added to feline and canine aqueous humor, CSF, serum, and blood samples. Protocols for identifying Tgondii DNA by use of the PCR were developed. Results-The DNA from as few as 10 ta chyzoites of T gondii could be identified in feline and canine aqueous humor, CSF, and serum samples. One hundred tachyzoites could be ident ified in blood samples. Conclusions-Toxoplasma gondii can be identifie d in feline and canine biological samples by use of the PCR. Clinical Relevance-Correlation of clinical disease to T gondii serum antibodies provides only a presumptive diagnosis of toxoplasmosis. Use of PCR to detect T gondii DNA in biological samples from cats and dogs may prov ide a sensitive tool for the antemortem diagnosis of toxoplasmosis and may be most beneficial when used in conjunction with serum antibody t iters.