Saliva and tear as useful tools for the diagnosis of Toxoplasma gondii in human specimens: a systematic review.

Toxoplasmosis is diagnosed by serology, mainly using invasive specimens such as serum or cerebrospinal fluid. This study aimed to investigate whether saliva and tear samples can be used instead of serum samples to diagnose Toxoplasma gondii. Five English-language databases were checked up to 2021. Other types of non-invasive samples (milk and urine) were excluded from this study. In 15 cross-sectional studies, a total of 4338 saliva samples were examined, out of which 718/3848 (18.66%), 30/200 (15%), and 60/122 (49.18%) samples were positive for anti-T. gondii IgG, IgM, and IgA antibodies, respectively. And for tear samples, a total of 723 samples in cross-sectional studies and 153 cases and 97 controls in case-control studies were included, out of which 199/538 (36.98%) and 155/247 (62.75%) samples were positive for anti-T. gondii IgG and IgA antibodies in cross-sectional studies and 86/128 (67.18%), 1/53 (1.88%), and 78/153 (50.98%) cases and 4/47 (8.51%), 0/47 (0%), and 12/97 (12.37%) controls were positive for anti-T. gondii IgG, IgM, and IgA antibodies in case-control studies, respectively. The results suggested that antibody levels in saliva and tear samples in humans could be useful for the diagnosis of toxoplasmosis, especially ocular toxoplasmosis using tear samples.