Evaluation of Different Serodiagnostic Methods of Toxoplasmosis in Pregnant Women and Immunodeficient Patients.

Sucila Thangam, G (2008) Evaluation of Different Serodiagnostic Methods of Toxoplasmosis in Pregnant Women and Immunodeficient Patients. Masters thesis, Tirunelveli Medical College, Tirunelveli.


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INTRODUCTION : Toxoplasmosis is caused by a coccidian protozoan parasite, Toxoplasma gondii. Humans and other warm-blooded animals are its intermediate hosts. The infection has a worldwide distribution. Approximately one-third of all humanity has been exposed to this parasite. Although usually asymptomatic in immunocompetent adults, it can cause severe disease manifestations and even death in immunocompromised patients. If acquired during pregnancy it can cause various congenital anomalies in the child. In India, the exact seroprevalence of this infection is not known. However, using various diagnostic tests, the prevalence has been reported to be as low as 1 per cent and as high as 80 per cent in adults. There is lack of awareness and knowledge about this zoonotic infection. AIMS AND OBJECTIVES : The study was designed with the following objectives 1. To find out the seroprevalence of toxoplasmosis in immunodeficient patients (HIV and malignant patients) and immunocompetent patients like pregnant women, ocular chorioretinitis cases and patients with lymphadenopathy in and around Tirunelveli district of Tamil Nadu. 2. To evaluate the IgG based tests like Modified direct Agglutination Test (MAT), Indirect Fluorescent Antibody Test (IFAT) and Enzyme Linked Immunosorbent Assay (ELISA) for serodiagnosis of toxoplasmosis. 3. To compare the utility of the IgG based tests like MAT, IFAT and ELISA for its suitability of the strategy for serodiagnosis and interpretation of toxoplasmosis. 4. To compare the CD4+/CD8+ count of T lymphocytes in HIV patients of seropositive and seronegative group of toxoplasmosis. MATERIALS AND METHODS : The present study was conducted at Tirunelveli Medical College Hospital, Palayamkottai, Tirunelveli District, Tamil Nadu from May 2006 to October 2007 to assess the seroprevalence of toxoplasmosis in and around Tirunelveli by using in-house IgG assays viz., IFAT, MAT and ELISA using laboratory own prepared antigen. Various risk factors associated with in the study group was statistically analysed and results were interpreted. A total of 350 peripheral blood samples for this study were collected from 175 immunodeficient patients (HIV and malignant patients) and 175 immunocompetent patients like pregnant women (135), ocular chorioretinitis cases (20) and patients with lymphadenopathy (20), in and around Tirunelveli district of Tamil Nadu those admitted at Tirunelveli Medical College Hospital. The odds ratio (OR) and 95 % confidence interval (CI) range was calculated for each risk factors of different category of case control study using David Hutchon’s odds ratio calculating software. The Chi-squared test was calculated for the analytic assessment by SPSS 11.5 version software and the p value was calculated using VassarStat software. The differences were considered to be statistically significant when the p value obtained was less than 0.05 (p<0.05). RESULTS : The T. gondii (RH strain) tachyzoite antigen was prepared by in vivo mice propagation and in vitro cell culture system in MDCK fibroblast cell line. The tachyzoites count was 1 x 107 and 1 x 109 per ml of antigen by in vivo and in vitro methods respectively. Formalin – killed T. gondii tachyzoite antigen was prepared for IFAT and MAT. The tachyzoite soluble antigen (TSA) with protein concentration of 0.63 mg/ml was prepared and used for ELISA. CONCLUSION : The study has highlighted an overall 13.14 per cent of seroprevalence of toxoplasmosis, which constitutes 15.43 per cent in immunocompromised and 10.86 per cent in immunocompetent patients in and around Tirunelveli. The study underlines the importance of screening of this parasite especially in the immunocompromised patients. The seroprevalence of toxoplasmosis in pregnant women was about 10 per cent, which necessitates initial screening for IgG antibodies and then a paired sera sample after 3 weeks should be tested for rise in titer. Thereafter, the IgM antibodies should be tested to exclude the recent infection. All seropositive women who seroconvert during pregnancy should be followed and their amniotic fluid / foetus should be screened by PCR and Ultrasound, respectively. Only 3 out of 19 (15. 79 Per cent) cases with bad obstetric history (BOH) were positive for toxoplasmosis, so BOH is not alone taken as criteria for routine screening of toxoplasmosis. The in-house IgG ELISA was found to be 90 per cent sensitivity and 100 per cent specificity. IFAT and MAT were equal in sensitivity and specificity. Since in-house assays were cost effective and can be used for routine serological screening. Fifteen per cent of HIV patients were found to have anti-Toxoplasma antibodies, so routine screening for serology for toxoplasmosis should be done especially when the CD4+ count was less than 200/μl, who may have a risk for development of toxoplasmosis as opportunistic infection.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Different Serodiagnostic Methods ; Evaluation ; Toxoplasmosis ; Pregnant Women ; Immunodeficient Patients.
Subjects: MEDICAL > Microbiology
Depositing User: Subramani R
Date Deposited: 14 Aug 2017 04:25
Last Modified: 14 Aug 2017 04:25
URI: http://repository-tnmgrmu.ac.in/id/eprint/1422

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