Primary and Nested PCR Amplification of B1 Gene to Confirm Seropositivity of Toxoplasmosis Among Cancer Patients in Sri Lanka.

Toxoplasmosis, caused by the parasite Toxoplasma gondii, affects approximately 30% of the human population worldwide. Reactivation of latent infection in immunocompromised people leads to fatal disease. This study aimed to determine the seropositivity of toxoplasmosis by enzyme-linked immunosorbent assay (ELISA), confirmed by primary polymerase chain reaction (PCR) and nested PCR (nPCR), and validate ELISA against nPCR among a group of cancer patients. Of the 321 participants, six (1.9%) patients were positive for nPCR and both IgG and IgM ELISA tests while 36 (11.2%) and 131 (40.8%) showed evidence of possibly acute and past infection, respectively, and 15 (4.7%) were indeterminate. Among them, 19 (5.9%) nPCR positives would have been ignored as having evidence of past infection. Four (1.2%) patients would not have been treated at all if only ELISA had been performed as they had indeterminate ELISA results. This is the first study that used primary and nPCR with B1 gene amplification for confirmation of toxoplasmosis among cancer patients in Sri Lanka. These findings emphasize the need for confirmatory tests, such as nPCR, particularly in cancer patients who exhibit a weak antibody response. Implementing such tests can aid clinicians in effectively managing these patients, given the rising incidence and mortality rates of cancer in Sri Lanka.