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 identify 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 toxoplasmosis. Using these samples, a PCR test to identify T gondii DNA was developed.

SAMPLE POPULATION

Feline and canine aqueous humor, CSF, serum, and blood samples.

PROCEDURE

Tachyzoites of several strains of T gondii grown in cell culture were added to feline and canine aqueous humor, CSF, serum, and blood samples. Protocols for identifying T gondii DNA by use of the PCR were developed.

RESULTS

The DNA from as few as 10 tachyzoites of T gondii could be identified in feline and canine aqueous humor, CSF, and serum samples. One hundred tachyzoites could be identified in blood samples.

CONCLUSIONS

Toxoplasma gondii can be identified 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 provide a sensitive tool for the antemortem diagnosis of toxoplasmosis and may be most beneficial when used in conjunction with serum antibody titers.