POTENTIAL OF THE POLYMERASE CHAIN-REACTION IN THE DIAGNOSIS OF ACTIVETOXOPLASMA INFECTION BY DETECTION OF PARASITE IN BLOOD

Blood samples from 54 patients presenting with acute toxoplasmic lymph adenopathy were tested for the presence of Toxoplasma gondii DNA using a nested polymerase chain reaction (PCR). PCR test results of a singl e blood sample obtained 2-23 weeks after onset of illness were positiv e for 19 (35%) of the 54 patients. Nine (53%) of 17 patients were posi tive by PCR when the initial blood sample was collected within th firs t 5 weeks of illness. In 7 of the 19 patients found positive, further blood samples were available, and subsequent clearance of T. gondii DN A from the blood was demonstrated. On the basis of positive findings a mong patients with acute toxoplasmosis and the absence of positive fin dings among 10 uninfected persons and 43 with past Toxoplasma infectio n, a positive PCR result appears to be a helpful indicator of active d isease. However, since only 53% of patients with lymphadenopathy persi sting less than or equal to 5 weeks were positive, a negative PCR resu lt does not exclude recent infection.