Serum samples, 100 in the total number, were collected from different laboratories in Tehran, Iran and tested for anti-Toxoplasma specific IgG and IgM antibodies using indirect immunofluorescent antibody test (IFAT). Using the IgG (chronic) and IgM (acute) positive samples, the IgG avidity test was performed by ELISA in duplicate rows of 96-well microtiter plates. One row was washed with 6 M urea and the other with PBS (pH 7.2), then the avidity index (AI) was calculated. Sixteen out of 18 (88.9%) sera with acute toxoplasmosis showed low avidity levels (AI≤50), and 76 out of 82 (92.7%) sera in chronic phase of infection showed high avidity index (AI>60). Six sera had borderline ranges of AI. The results showed that the IgG avidity test by ELISA could distinguish the acute and chronic stages of toxoplasmosis in humans.

To perform IgG avidity immunoblotting assay for detection of acute toxoplasmosis, 100 serum samples were collected from Tehran, Iran. The presence of Toxoplasma-specific IgG and IgM antibodies were checked by commercial Trinity kit. Samples were categorized in acute and chronic phases of Toxoplasma gondii infection according to IgG avidity ELISA. IgG avidity immunoblotting was performed, and antigenic bands with molecular weights of 22, 25, 28, 30, 32, 42, 44, 49, 55, 60, 66, 69, 88, 106, 130 and 157 kDa were recognized as low avidity markers. The most prevalent antigen for low avidity was p22. It is concluded that IgG avidity immunoblotting could distinguish acute and chronic phases of T. gondii infection.

Canine visceral leishmaniasis (CVL) is not only a veterinary problem but has also a serious public health importance. Rapid detection of CVL is highly important for control of human visceral leishmaniasis in Iran. This study was aimed to compare the fast agglutination screening test (FAST) with direct agglutination test (DAT) as a standard serological test for the detection of anti-Leishmania antibodies on dog serum samples. DAT and FAST antigens were prepared in the School of Public Health, Tehran University of Medical Science. Altogether, 73 serum samples from Leishmania infantum infection dogs and 74 sera from healthy controls were collected from human VL/CVL endemic and non-endemic areas of Iran, respectively. All the sera were evaluated with both FAST and DAT techniques. A sensitivity of 98.60% (95% CI, 98.57-98.62) and specificity of 78.70% (95 CI%, 69.20-88.20) were found at a 1:160--(cut-off) titer when DAT confirmed cases were compared with healthy control. A good degree of agreement was observed between FAST and DAT (86.8%) by kappa analysis (p < 0.01). In conclusion, this study showed that FAST is very practical and simple diagnostic tool for the sero-diagnosis of CVL in endemic areas of Iran.

Objectives: Toxoplasma gondii is an obligate intracellular parasite that infects a broad range of warm-blooded animals including human. Tachyzoites of T.gondii invade the host cell, replicate and finally lead to the lysis of the cell. T. gondii is associated with congenital infection and it can cause encephalitis, or systemic infection in immunocompromised patients. It is important to know whether the infection is recently acquired or is chronic. Differentiation between acute and chronic infection has a dramatic impact, especially for the developing fetus. In this study, Toxoplasma gondii was detected in acute phase of infection in serum sample of a person who had been accidentally infected with tachyzoites of RH strain in the laboratory. Materials and Methods: Anti-T.gondii IgG antibody was prepared by rabbit immunization with soluble antigen of tachyzoites of RH strain. Capture-ELISA, immunoblotting and PCR were performed in the laboratory. Results: : Antigenemia and parasitemia was detected in serum sample of infected person by capture_ELISA, immunoblotting and PCR techniques respectively. Conclusion: Acute T.gondii infection could be detectable in a short period of time in the sera of infected person.