IgG Avidity in Samples Collected on Filter Paper: Importance of The Early Diagnosis of Congenital Toxoplasmosis

Abstract Objective 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. Methods 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. Results 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. Conclusion The results of the present study indicate that the avidity test may be another valuable method for the diagnosis of congenital toxoplasmosis in newborns.

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Toxoplasma gondii seroprevalence among pregnant women in Rabat, Morocco

Tropical Medicine and Health ◽

10.1186/s41182-021-00311-5 ◽

2021 ◽

Vol 49 (1) ◽

Author(s):

Majda Laboudi ◽

Zoubida Taghy ◽

Oussama Duieb ◽

François Peyron ◽

Abderrahim Sadak

Keyword(s):

Toxoplasma Gondii ◽

Pregnant Women ◽

Congenital Toxoplasmosis ◽

Immunoglobulin M ◽

Bivariate Analysis ◽

Enzyme Linked Immunosorbent Assay ◽

Seroprevalence Rate ◽

Recent Infection ◽

Igg Avidity ◽

Avidity Test

Abstract Background Toxoplasmosis is an infectious disease caused by a protozoan parasite named Toxoplasma gondii (T.gondii). Pregnant women are considered one of the risk groups. The objective of this retrospective study is to provide an updated estimate of the seroprevalence of anti-T. gondii antibodies among a group of Moroccan pregnant women monitored at the Parasitology Laboratory of the National Institute of Hygiene in Rabat in Morocco. Methods Serum samples were tested for the presence of specific anti-T. gondii immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies using indirect enzyme-linked immunosorbent assay (ELISA). Anti-Toxoplasma IgM- and IgG-positive cases were also evaluated with the anti-Toxoplasma IgG avidity test. All cases were evaluated according to the age, parity, and historical of abortion. Results Among 677 pregnant women, 94.1% (637/677) were serologically screened for the first time and therefore had no knowledge of their serological status, and only 5.9% (40/677) were screened for the second or third time. The overall anti-T. gondii IgG and IgM seropositivity among the 637 pregnant women included in the study analysis was 43% (274/637) and 3.9% (25/637), respectively. The use of the IgG avidity test allowed excluding recent infection among 83% of cases with IgG and IgM positive sera. The mean age was 29.4 ± 6.3 years. The result of the bivariate analysis revealed that the age influenced significantly the seroprevalence rate, while the parity and the existence of previous spontaneous abortion did not have any significant statistical correlation with seropositivity to T. gondii. Conclusion This study shows that 43% of pregnant women were positive and 57% of them had no antibody against the T. gondii infection. However, the pregnancy follow-up and the counseling of pregnant women remain essential for the prevention of congenital toxoplasmosis.

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EVALUATION OF Toxoplasma gondii SEROPREVALENCE AND IGG AVIDITY TEST RESULTS AMONG CHILDBEARING-AGE WOMEN IN KARABUK PROVINCE

Gevher Nesibe Journal, IESDR ◽

10.46648/gnj.204 ◽

2021 ◽

Vol 6 (12) ◽

pp. 98-103

Author(s):

Meryem COLAK ◽

Nergis ASGIN

Keyword(s):

Toxoplasma Gondii ◽

Congenital Toxoplasmosis ◽

Epidemiological Data ◽

Test Results ◽

Childbearing Age ◽

Igg Antibody ◽

Seropositivity Rate ◽

Igg Avidity ◽

Avidity Test ◽

Childbearing Age Women

Toxoplasmosis is a zoonotic infectious disease that is common worldwide and caused by the Toxoplasma gondii. Congenital toxoplasmosis is one of the major complications of this infection. The present study aimed to investigate T.gondii seroprevalence and evaluate the IgG avidity test results among childbearing- age women retrospectively. A total of 9401 samples obtained from childbearing -age (15-49 years of age) women who attended Karabuk University Training and Research Hospital between February 2016- January 2020, over the four-year, were included in the study.The Toxoplasma-IgM, Toxoplasma-IgG antibody, and Toxoplasma IgG avidity tests were analyzed chemiluminescent method by using ARCHITECT I 2000 SR immunoassay device (Abbott Laboratories, USA). Toxoplasma-IgM and Toxoplasma-IgG seropositivity were detected as 0.7% (67/9401) and 15.7% (1415/9005) respectively. A high percentage of Toxoplasma-IgM and Toxoplasma-IgG seropositivity were detected among 31-35 years of age group. The Toxoplasma seropositivity increased by age, but no statistically difference was found (P >0.05).The Toxoplasma IgG avidity was high in 45 patients (69.4%), low avidity was detected in 16 patients (22.6%) and from the remaining 6 patients were borderline (8%). The Toxoplasma IgM and IgG seropositivity rate decreased 2016 to 2020. The highest Toxoplasma IgM and IgG seropositivity were in 2016 with 1.2% and 16.8%, respectively. The T. gondi seropositivity rate was decreased from 2016 to 2020; it is probably a result of increasing awareness of the disease among patients. We think our results will contribute to the epidemiological data in our province and country and raise awareness.

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Detection of Acute and Chronic Toxoplasma gondii Infection among Women with History of Abortion in the Southwest of Iran

Journal of Parasitology Research ◽

10.1155/2021/6693070 ◽

2021 ◽

Vol 2021 ◽

pp. 1-6

Author(s):

Jasem Saki ◽

Maryam Zamanpour ◽

Mahin Najafian ◽

Niloofar Mohammadpour ◽

Masoud Foroutan

Keyword(s):

Toxoplasma Gondii ◽

Pregnant Women ◽

Umbilical Cord ◽

Enzyme Linked Immunosorbent Assay ◽

High Avidity ◽

Normal Delivery ◽

Blood Samples ◽

Igg Avidity ◽

Avidity Test ◽

History Of

Background. Toxoplasma gondii (T. gondii) is one of the most common intracellular protozoan parasites, which can infect humans and a wide range of mammals and birds. The current study is aimed at investigating the occurrence of T. gondii infection in women with a history of abortion in Khuzestan, Iran. Materials and Methods. A total of 480 women with an abortion history, as well as 200 pregnant women with a normal delivery, were examined in this study. The blood, placenta, and umbilical cord blood samples were assessed by the enzyme-linked immunosorbent assay (ELISA) and nested-polymerase chain reaction (PCR) assay. Results. Based on the results of ELISA assay, the prevalence of toxoplasmosis was 30.83% in women with a history of abortion (25.62% with T. gondii IgG and 5.20% with T. gondii IgM). According to the IgG avidity test, 60.16% of IgG-positive samples showed high avidity, while 27.64% showed low avidity. On the other hand, the prevalence of toxoplasmosis in women with a normal delivery was 23% (21.5% with T. gondii IgG and 1.5% with T. gondii IgM). According to the IgG avidity test, 81.39% of these women showed high avidity, while only 4.65% showed low avidity. Based on the nested-PCR method, T. gondii DNA was detected in 14.18% of blood samples, 4.69% of placental samples, and 1.34% of umbilical cord samples, collected from 148 seropositive women with a history of abortion. Besides, using this method, the parasite DNA was identified in 4.34% of blood samples, collected from 46 seropositive women with a normal delivery, but not in any of the umbilical cord or placenta samples. Conclusion. The present results showed that T. gondii infection contributes to abortion in Khuzestan Province, Iran. Therefore, it is essential to investigate toxoplasmosis in pregnant women, especially in those who are seronegative, using molecular and serological methods and inform them about their disease and the associated risks.

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Evaluation of the TGS TA system for the detection of anti-Toxoplasma antibodies

Microbiologia Medica ◽

10.4081/mm.2017.6583 ◽

2017 ◽

Vol 32 (1) ◽

Author(s):

Olivia Arpino ◽

Annalisa Cianflone ◽

Maria Teresa Manco ◽

Alessia Paganini ◽

Massimo De Paschale ◽

...

Keyword(s):

High Avidity ◽

Past Infection ◽

Recent Infection ◽

Igm Antibodies ◽

Igg Avidity ◽

Avidity Test ◽

Group 3 ◽

Group 2 ◽

Group 1

Background and aims. The aim of the present study was to evaluate the new chemiluminescence TGS TA system of Technogenetics (Milan, Italy) for detecting anti-Toxoplasma IgG and IgM antibodies and IgG avidity. The TGS TA system was compared with our chemiluminescence routinely used system, LIAISON XL, supplied by Diasorin (Saluggia, Italy), for the detection of IgG and IgM antibodies. Only in positive IgM samples (retrospective study) and for the IgG avidity (if existent), TGS TA system was compared to an Enzyme Linked Fluorescent Assay (ELFA) test (VIDAS, BioMérieux, Marcy-l’Étoile, France). Materials and methods. Three hundred and one sera samples, from women who came to our centre for the routine follow up pregnancy, were examined with the TGS TA system and divided in 3 groups according to IgG and IgM screening LIAISON XL tests: 106 were non-immune women (Group 1), 100 were pregnant with past infection (Group 2) and 95 were pregnant with positive or equivocal IgM (82 with positive IgG and 13 with negative IgG) (Group 3). Results. The overall concordance of the IgG results between LIAISON XL and TGS TA was 99.3%: 100% in Group 1, 98% in Group 2 and 100% in Group 3. The overall concordance of the IgM results between LIAISON XL and TGS TA was 93.9%: 100% in Group 1, 94% in Group 2 and 82.8% in Group 3. In Group 3, the concordance between the results of the IgG avidity with the ELFA and TGS TA tests was 81.7%. Comparing the clinical diagnosis obtained with our protocol and that of the TGS TA system, the overall concordance was 92.7%: 100% in Group 1, 92.0% in Group 2 and 78.9% in Group 3. Conclusions. The overall concordance of IgG antibodies is excellent for both protocols while for IgM antibodies is very high in the first group and lower in the third group, due to the presence of non-specific IgM subjects in this group. The TGS TA avidity test seems to predict ealier the maturation of the IgG compared to the ELFA test since many samples with low avidity with the ELFA were seen with moderate avidity with TGS TA and all those with borderline avidity with the ELFA were seen with high avidity with TGS TA. This system shows to be a valuable tool with overall good clinical correlation and able to clearly identify nonspecific subjects, those with a non-recent infection.

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Immunoglobulin G Avidity in Diagnosis of Toxoplasmic Lymphadenopathy and Ocular Toxoplasmosis

Clinical and Diagnostic Laboratory Immunology ◽

10.1128/cdli.6.4.514-518.1999 ◽

1999 ◽

Vol 6 (4) ◽

pp. 514-518 ◽

Cited By ~ 27

Author(s):

Malgorzata Paul

Keyword(s):

Pregnant Women ◽

Immunoglobulin G ◽

Large Range ◽

Congenital Toxoplasmosis ◽

Chronic Phase ◽

Ocular Toxoplasmosis ◽

Enzyme Linked Immunosorbent Assay ◽

Ocular Infection ◽

High Avidity ◽

Igg Avidity

ABSTRACT Traditional serological techniques have some limitations in evaluating the duration of Toxoplasma gondii infection in pregnant women, patients with lymphadenopathy, and older children suspected of having congenital toxoplasmosis. In these three groups of patients, two variants of T. gondii immunoglobulin G (IgG) avidity tests were used: an EIA Kit (Labsystems) and a noncommercial enzyme-linked immunosorbent assay specially elaborated in the laboratory. The avidity of specific IgG in sera from 23 patients with a known recently acquired infection (mainly pregnant women) was low (less than 30%), whereas that in sera from 19 patients with toxoplasmic lymphadenopathy of 3 weeks to 6 months in duration (mean, 8.3 weeks) covered a large range (between 0.2 and 57.8%; mean, 25.7%); high avidity results were observed for 10 of 19 patients (52.6%). The large range of IgG avidity in patients with toxoplasmic lymphadenopathy suggests various durations of infection in these patients, with a tendency for a chronic phase of toxoplasmosis. According to the avidity marker, five patients with lymphadenopathy for less than 3 months did not have a recent Toxoplasma infection. In 6 of 19 patients with lymphadenopathy (31.6%), low IgG avidity values persisted until 5 months after the first serological examination. In all four patients with a documented chronic course of Toxoplasma infection (6 months to 8 years after the first positive serology), high IgG avidity values were observed. Among sera from 10 children and young immunocompetent adults suspected of having ocular reactivation of congenital toxoplasmosis, all had high IgG avidity values (over 40%), suggesting congenitally acquired ocular infection rather than noncongenital infection. In conclusion, the avidity of IgG is a valuable marker of recent toxoplasmosis in pregnant women, suggests the duration of invasion in patients with lymphadenopathy, and may be helpful for differentiation between reactivation of congenital infection and recently acquired ocular toxoplasmosis in immunocompetent patients. A low IgG avidity does not always identify a recent case of toxoplasmosis, but a high IgG avidity can exclude primary infections of less than 5 months’ duration.

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Toxoplasma-IgM and IgG-avidity in single samples from areas with a high infection rate can determine the risk of mother-to-child transmission

Revista do Instituto de Medicina Tropical de São Paulo ◽

10.1590/s0036-46652006000200007 ◽

2006 ◽

Vol 48 (2) ◽

pp. 93-98 ◽

Cited By ~ 21

Author(s):

Myrian Morussi Reis ◽

Maria Madalena Tessaro ◽

Pedro Alves D'Azevedo

Keyword(s):

Pregnant Women ◽

Congenital Toxoplasmosis ◽

High Avidity ◽

Mother To Child Transmission ◽

Child Transmission ◽

Serum Samples ◽

Serologic Marker ◽

Igg Avidity ◽

Mother To Child ◽

Infected Newborn

Anti-Toxoplasma IgG-avidity was determined in 168 serum samples from IgG- and IgM-positive pregnant women at various times during pregnancy, in order to evaluate the predictive value for risk of mother-to-child transmission in a single sample, taking the limitations of conventional serology into account. The neonatal IgM was considered the serologic marker of transmission. Fluorometric tests for IgG, IgM (immunocapture) and IgG-avidity were performed. Fifty-one of the 128 pregnant women tested gave birth in the hospital and neonatal IgM was obtained. The results showed 32 (62.75%) pregnant women having high avidity, IgM indexes between 0.6 and 2.4, and no infected newborn. Nineteen (37.25%) had low or inconclusive avidity, IgM indexes between 0.6 and 11.9, and five infected newborns and one stillbirth. In two infected newborns and the stillbirth maternal IgM indexes were low and in one infected newborn the only maternal parameter that suggested fetal risk was IgG-avidity. In the present study, IgG-avidity performed in single samples from positive IgM pregnant women helped to determine the risk of transmission at any time during pregnancy, especially when the indexes of the two tests were analysed with respect to gestational age. This model may be less expensive in developing countries where there is a high prevalence of infection than the follow-up of susceptible mothers until childbirth with monthly serology, and it creates a new perspective for the diagnosis of congenital toxoplasmosis.

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Toxoplasmosis and pregnancy: Perinatal results and association of the IgG avidity test with congenital infection in pregnant women with positive anti-Toxoplasma gondii IgM [Abstract in English]

Scientia Medica ◽

10.15448/1980-6108.2010.1.6266 ◽

2010 ◽

Vol 20 (1) ◽

pp. 45

Author(s):

Virgílio Gonçalves de Souza-Júnior ◽

Ernesto Antonio Figueiró-Filho ◽

Danilo De Cerqueira Borges ◽

Vanessa Marcon Oliveira ◽

Lílian Rezende Coelho

Keyword(s):

Toxoplasma Gondii ◽

Pregnant Women ◽

Predictive Value ◽

Congenital Infection ◽

Neonatal Infection ◽

High Avidity ◽

Igg Avidity ◽

Risk Pregnancy ◽

Avidity Test ◽

Acute Toxoplasmosis

AIMS: To verify the perinatal outcomes in pregnant women with acute toxoplasmosis, and to determine if there was association between the results of Toxoplasma gondii-specific IgG avidity test and the presence or absence of fetal/neonatal infection. METHODS: A cross-sectional study included pregnant women with serological diagnosis of acute toxoplasmosis (presenting a positive Toxoplasma gondii-specific IgM test) attended at the outpatient unit for high-risk pregnancy of the Faculty of Medicine, Federal University of Mato Grosso do Sul, Brazil, in the period from November 2002 to November 2007. Test results demonstrating IgG avidity index above 30% were considered high avidity, while values below 30% were considered low avidity. Fetal and/or neonatal infection was defined by positive result for the polymerase chain reaction in amniotic fluid, or by a positive Toxoplasma gondii-specific IgM test in the newborn's serum. RESULTS: Considering all pregnant women referred to the outpatient unit for high-risk pregnancy in the period of study, frequency of pregnant women with positive Toxoplasma gondii-specific IgM was 10.8% (176/1.634). The rate of congenital infection in these patients was 4% (7/176). The IgG avidity test was performed in 162 patients (92% of the 176 pregnant women with positive IgM), and the avidity was high in 144 (88.9%). There was an association (p=0.003) between high avidity and no fetal/neonatal toxoplasmosis in our sample, with a prevalence ratio of 13.4 (confidence interval [CI] 95% 2.2-86.6). The positive predictive value of the avidity test (probability of congenital infection with a low avidity) was 22% (95% 6%-47%), while the negative predictive value (probability of absence of congenital infection with a high avidity) was 98% (95% CI 94% -99%). CONCLUSIONS: In this study the rate of congenital infection in pregnant women diagnosed with acute toxoplasmosis was 4%. In pregnant women with positive Toxoplasma gondii-specific IgM, results of Toxoplasma gondii-specific IgG avidity test were associated with the presence or absence of congenital infection, with a high negative predictive value (no fetal/neonatal infection when avidity was high).

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IgG Avidity Test in Congenital Toxoplasmosis Diagnoses in Newborns

Pathogens ◽

10.3390/pathogens6020026 ◽

2017 ◽

Vol 6 (2) ◽

pp. 26 ◽

Cited By ~ 3

Author(s):

Zulmirene Cardoso Fonseca ◽

Isolina Maria Xavier Rodrigues ◽

Natália Cruz e Melo ◽

Juliana Boaventura Avelar ◽

Ana Maria Castro ◽

...

Keyword(s):

Congenital Toxoplasmosis ◽

Igg Avidity ◽

Avidity Test

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Seroprevalence of Toxoplasma gondii infection among pregnant women in Windhoek, Namibia, in 2016

Southern African Journal of Infectious Diseases ◽

10.4102/sajid.v35i1.25 ◽

2020 ◽

Vol 35 (1) ◽

Author(s):

Berta E. Van der Colf ◽

Gert U. Van Zyl ◽

Bruce H. Noden ◽

Dismas Ntirampeba

Keyword(s):

Developing Countries ◽

Toxoplasma Gondii ◽

Antenatal Care ◽

Pregnant Women ◽

Demographic Data ◽

Congenital Toxoplasmosis ◽

Immunoglobulin M ◽

Enzyme Linked Immunosorbent Assay ◽

Igg Avidity ◽

Specific Igg

Background: When a pregnant woman contracts Toxoplasma gondii (T. gondii) infection during pregnancy, it may be vertically transmitted to the foetus. Information on the incidence of congenital toxoplasmosis (CT) in developing countries is scarce. Most studies focus on the seroprevalence of T. gondii infection among pregnant women. This study aimed to determine the seroprevalence of T. gondii infection among pregnant women attending public antenatal care in Windhoek, Namibia, in 2016.Methods: In this descriptive study, 344 urban pregnant women attending public antenatal care were voluntarily enrolled in the study. Seroprevalence of anti-T. gondii Immunoglobulin G (IgG) was determined by automated immunoassay. Samples with a positive T. gondii IgG result were tested for T. gondii Immunoglobulin M (IgM) and specific IgG avidity by using an enzyme-linked immunosorbent assay (ELISA) test. A questionnaire captured demographic data and exposure to risk factors. Data were analysed using Statistical Package for the Social Sciences (SPSS) and R.Results: Anti-T. gondii IgG was found in nine (2.61%) pregnant women. There was no association of anti-T. gondii IgG with demographic characteristics or exposure to risk factors.Anti-T. gondii IgM was positive in one (0.3%) woman, while three (0.9%) women had borderline anti-T. gondii IgM results. Specific IgG avidity was low, equivocal and high in 0%, 33% and 67% of seropositive pregnant women, respectively.Conclusion: Seroprevalence of anti-T. gondii IgG is much lower in Namibia than is reported in other developing countries. Investigation into specific IgM seropositivity and IgG avidity showed that pregnant women in the central region of Namibia are at low risk of vertical transmission and development of CT.

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Evaluation of the Abbott AxSYM Cytomegalovirus (CMV) Immunoglobulin M (IgM) Assay in Conjunction with Other CMV IgM Tests and a CMV IgG Avidity Assay

Clinical and Diagnostic Laboratory Immunology ◽

10.1128/cdli.8.1.196-198.2001 ◽

2001 ◽

Vol 8 (1) ◽

pp. 196-198 ◽

Cited By ~ 23

Author(s):

T. Lazzarotto ◽

C. Galli ◽

R. Pulvirenti ◽

R. Rescaldani ◽

R. Vezzo ◽

...

Keyword(s):

Pregnant Women ◽

Accurate Diagnosis ◽

Immunoglobulin M ◽

Igg Antibodies ◽

Cmv Infection ◽

Avidity Assay ◽

Igg Avidity ◽

Avidity Test ◽

Reflex Testing ◽

Initial Reactivity

ABSTRACT The measurement of the avidity of cytomegalovirus (CMV) immunoglobulin G (IgG) antibodies has been shown by several investigators to be useful in identifying and excluding primary CMV infections in pregnant women. In this work, we examined the diagnostic utility of reflex testing of CMV IgM-positive specimens from pregnant women by using a CMV IgG avidity assay. The utility of this approach was directly dependent on the sensitivity of the CMV IgM assay employed during the initial screen. The higher initial reactivity rate of the AxSYM CMV IgM assay was necessary in order to detect CMV IgM in specimens containing low-avidity CMV IgG antibodies, indicative of a primary CMV infection, which other CMV IgM assays (Behring, Vidas, Captia, and Eurogenetics) fail to detect in some cases. The use of the AxSYM CMV IgM assay, followed by an avidity test, should result in more accurate diagnosis of CMV infection in pregnant women.

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