Uraiwan Krainara. Comparison of indirect fluorescence antibody and the sabin-feldman dye test for detection of Toxoplasma gondii antibody in pregnant Thai women . Master's Degree(Tropical Medicine). Mahidol University. : Mahidol University, 2004.
Comparison of indirect fluorescence antibody and the sabin-feldman dye test for detection of Toxoplasma gondii antibody in pregnant Thai women
Abstract:
Toxoplasmosis is a world-wide infection in humans. It is usually asymptomatic
in individuals, but it causes serious problems in the fetus and immunocompromised
hosts such as HIV-infected persons and organ transplant the recipients.
The Sabin-Feldman dye test (SFT) is used to detect Toxoplasma antibodies.
Although it is the gold standard test for toxoplasmosis, it needs live parasites and
accessory factors that are hard to perform. It is not common or easy to offer in a small
laboratory. Alternative tests are needed; the indirect fluorescence antibody test (IFAT)
was selected for the present study. It is the most widely used serological method for
diagnosis of toxoplasmosis at present.
The aims of this study were to determine the specific IgG antibody for
Toxoplasma gondii in pregnant Thai women by IFAT using formalin-fixed whole
tachyzoites, comparing the sensitivity, specificity, positive predictive value and negative
predictive value with those of the SFT. Blood samples were collected from 300
pregnant Thai women, who came on the first visit at antenatal clinic of Rajavithi
Hospital, Bangkok during the months, May to October 2003.
The result of antibody measurement showed 32 (10.6%) of 300 subjects
positive for Toxoplasma IgG by IFAT technique and 29 (9.6%) positive by SFT. The
sensitivity, specificity, positive and negative predictive values of IFAT were 75.9, 96.3,
68.8 and 97.4 percent, respectively.
The IFAT technique is easy to perform and formalin-fixed whole antigens can
be kept for a long time. Nevertheless, IFAT is still time-consuming and requires an
expensive fluorescence microscopy. This technique should be recommended as a
selective test for screening pregnant women that can be used in laboratories, that can not
perform the SFT test. However, IFAT should be used with caution due to its lower
sensitivity and positive predictive value