IgG avidity Archives - Revista Brasileira de Ginecologia e Obstetrícia
, , , , , Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2021;43(12):887-893
, , , , , The purpose of the present study is to standardize and evaluate the use of the immunoglobulin G (IgG) antibody avidity test on blood samples from newborns collected on filter paper to perform the heel test aiming at its implementation in ongoing programs.
Blood samples from newborns were collected on filter paper simultaneously with the heel prick test. All samples were subjected to immunoglobulin M IgM and IgG enzyme-linked immunosorbent assays (ELISA). Peripheral blood was collected again in the traditional way and on filter paper from newborns with high IgG levels (33). Three types of techniques were performed, the standard for measuring IgG in serum, adapted for filter paper and the technique of IgG avidity in serum and on filter paper. The results of the avidity test were classified according to the Rahbari protocol.
Among the 177 samples, 17 were collected in duplicate from the same child, 1 of peripheral blood and 1 on filter paper. In this analysis, 1 (5.88%) of the 17 samples collected in duplicate also exhibited low IgG avidity, suggesting congenital infection. In addition, the results obtained from serum and filter paper were in agreement, that is, 16 (94.12%) samples presented high avidity, with 100% agreement between the results obtained from serum and from filter paper.
The results of the present study indicate that the avidity test may be another valuable method for the diagnosis of congenital toxoplasmosis in newborns.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2021;43(12):887-893
, , , , , The purpose of the present study is to standardize and evaluate the use of the immunoglobulin G (IgG) antibody avidity test on blood samples from newborns collected on filter paper to perform the heel test aiming at its implementation in ongoing programs.
Blood samples from newborns were collected on filter paper simultaneously with the heel prick test. All samples were subjected to immunoglobulin M IgM and IgG enzyme-linked immunosorbent assays (ELISA). Peripheral blood was collected again in the traditional way and on filter paper from newborns with high IgG levels (33). Three types of techniques were performed, the standard for measuring IgG in serum, adapted for filter paper and the technique of IgG avidity in serum and on filter paper. The results of the avidity test were classified according to the Rahbari protocol.
Among the 177 samples, 17 were collected in duplicate from the same child, 1 of peripheral blood and 1 on filter paper. In this analysis, 1 (5.88%) of the 17 samples collected in duplicate also exhibited low IgG avidity, suggesting congenital infection. In addition, the results obtained from serum and filter paper were in agreement, that is, 16 (94.12%) samples presented high avidity, with 100% agreement between the results obtained from serum and from filter paper.
The results of the present study indicate that the avidity test may be another valuable method for the diagnosis of congenital toxoplasmosis in newborns.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2006;28(3):158-164
DOI 10.1590/S0100-72032006000300004
PURPOSE: to describe and analyze the results of conventional serology for toxoplasmosis in pregnant women during prenatal care at the Hospital Materno-Infantil Presidente Vargas in Porto Alegre. METHODS: specific IgG and IgM determinations were performed using fluorometric tests, with IgM capture. A second sample within two to three weeks was requested from all IgM-positive pregnant women and IgG avidity was performed in IgM-positive pregnant women at the beginning of pregnancy. Neonatal IgM was obtained when the delivery occurred at the institution. The analysis was based on the binomial distribution, through simple ratio estimate, to assess soropositivity prevalence and susceptibility to T. gondi infection. RESULTS: the prevalence of infection in 10,468 pregnant women was 61.1% and 38.7% pregnant women were susceptible. Among the 272 IgG and IgM-positive pregnant women, 87 returned for a second test and in 84 of them the antibody levels remained unchanged. Of nine pregnant women with avidity, there was only one low avidity and her newborn was IgM positive. In 44 newborns delivered at the institution, the neonatal IgM was positive in four. CONCLUSIONS: a high prevalence of infection and congenital toxoplasmosis was found in pregnant women, even without data on seroconversion. Most of the IgM-positive serologies were related to past infection. The cost-benefit ratio of prenatal care in isolated samples may be optimized analyzing the risk of mother-to-child transmission in IgM-positive pregnant women. When there is a risk, a neonatal IgM test must be requested and the newborn should be followed during the first year of life.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2006;28(3):158-164
DOI 10.1590/S0100-72032006000300004
PURPOSE: to describe and analyze the results of conventional serology for toxoplasmosis in pregnant women during prenatal care at the Hospital Materno-Infantil Presidente Vargas in Porto Alegre. METHODS: specific IgG and IgM determinations were performed using fluorometric tests, with IgM capture. A second sample within two to three weeks was requested from all IgM-positive pregnant women and IgG avidity was performed in IgM-positive pregnant women at the beginning of pregnancy. Neonatal IgM was obtained when the delivery occurred at the institution. The analysis was based on the binomial distribution, through simple ratio estimate, to assess soropositivity prevalence and susceptibility to T. gondi infection. RESULTS: the prevalence of infection in 10,468 pregnant women was 61.1% and 38.7% pregnant women were susceptible. Among the 272 IgG and IgM-positive pregnant women, 87 returned for a second test and in 84 of them the antibody levels remained unchanged. Of nine pregnant women with avidity, there was only one low avidity and her newborn was IgM positive. In 44 newborns delivered at the institution, the neonatal IgM was positive in four. CONCLUSIONS: a high prevalence of infection and congenital toxoplasmosis was found in pregnant women, even without data on seroconversion. Most of the IgM-positive serologies were related to past infection. The cost-benefit ratio of prenatal care in isolated samples may be optimized analyzing the risk of mother-to-child transmission in IgM-positive pregnant women. When there is a risk, a neonatal IgM test must be requested and the newborn should be followed during the first year of life.
