Prevalence of toxoplasmosis in patients infected with tuberculosis; a sero-molecular case-control study in northwest Iran

In this study, we investigated the possible association between TB and Toxoplasma gondii infection. One hundred confirmed TB individuals living in northwest Iran were classified into three subgroups; newly diagnosed patients (NTB), old diagnosed patients (OTB) and multidrug resistance patients (MDR-TB). One hundred healthy subjects in the same age and sex distribution were ethnically matched. Sera samples were screened for anti-Toxoplasma antibodies. Nested-PCR was performed by targeting the B1 and GRA6 genes. The frequency of Toxoplasma infection based on IgG titer was 71.1% in the OTB subgroup and 33% in the control group, indicating significant association between Toxoplasma seropositivity and OTB (P = 0.001). According to phylogenetic network, the type I strain of Toxoplasma was identified in the OTB subgroup (10.1%). We concluded that patients with OTB subgroup are at high risk for acquisition of Toxoplasma infection which could reactivate the latent toxoplasmosis. •Toxoplasma gondii is commonly circulating among tuberculosis patients in northwest Iran.•Chronic tuberculosis patients are at higher risk for acquisition of Toxoplasma infection.•Serological assays should be performed among TB patients, aiming to prevent severe toxoplasmosis.