Diagnosis of Acute Toxoplasmosis by IgG and IgM Antibodies and IgG Avidity in Pregnant Women from Mashhad, Eastern Iran

Abstract

Background: We aimed to evaluate the diagnosis of acute toxoplasmosis by IgG avidity test in pregnant women.
 Methods: In this cross-sectional study, 250 blood samples were collected from pregnant women with the first month of their pregnancy referring to health centers of University in Mashhad during 2016. Samples were centrifuged at 3000 rpm for 5 min for separation of serum and were kept in the -20 until use. To detection of acute and chronic toxoplasmosis, anti-Toxoplasma antibodies (IgG and IgM, and IgG avidity tests were performed using ELISA. Then, data analyzed using SPSS software by Frequency, Pearson Chi-Square, Likelihood Ratio, and Exact tests. And P-value<0.05 was statistically considered as significant.
 Results: Total prevalence of IgG and IgM was 23.2% and 7.2%, respectively. A significant correlation was observed between the mean age and IgG level (P<0.05). It was not found any correlation between the history of raw meat consumption, cats keeping, education, and residency site. Moreover, 16 people (6.4%) had IgM antibody, of which, 10 cases (62.5%) with low avidity for IgG and 1 people (6.2%) with moderate avidity and 5 cases (31.3%) with high avidity for IgG. Moreover, 76% of pregnant women were seronegative.
 Conclusion: More than half of the women (62.5%) with positive IgM antibody in their serum had a low avidity for IgG which revealed an acute infection among pregnant women. Toxoplasma infection should be considered as an important factor that affects the pregnancy and IgG avidity as an important test for screening the women who need the treatment.

Descriptive Comparison of ELISAs for the Detection of Toxoplasma gondii Antibodies in Animals: A Systematic Review

“…However, IgM antibodies can persist from a few months to a year, meaning that positive IgM results alone are not sufficient to discriminate between phases of infection [ 86 ]. However, testing IgM levels is useful when coupled with other diagnostic tests (e.g., IgG avidity testing, polymerase chain reaction) and widely used to determine the phase of infection in pregnancy-associated toxoplasmosis in humans [ 86 , 87 ]. IgG antibodies often persist for life in immunocompetent individuals, providing a reliable marker after primary infection, suggesting that a switch from isotype IgM to IgG has occurred, and they detect the chronic phase of T. gondii exposure in both animals and humans [ 29 , 30 , 85 ].…”

Estudo epidemiológico de gestantes atendidas pelo sistema único de saúde com ênfase na toxoplasmose

“…A presença da raça branca corrobora com estudo 18 sobre pré-natal de alto risco realizado em região próxima ao presente estudo, evidenciando ser uma característica étnica da população deste região. Com relação à faixa etária das gestantes, existe uma relação entre a soroprevalência e o acréscimo da idade 2,19 . Pessoas com mais de 18 anos, como encontrado neste estudo, possuem maior risco de serem soropositivas para IgG por terem maior tempo de exposição ao T. gondii no ambiente 20 .…”

“…A toxoplasmose é uma zoonose, portanto, transmitida ao homem pelos animais sendo que os cães podem atuar como vetores mecânicos de formas infectantes do T. gondii aderidos aos pêlos 24 . Em relação às associações entre os fatores de risco e a sororeatividade para T. gondii, destaca-se que não há evidências entre o patógeno e os diversos hábitos de comportamento, como consumir verduras e legumes crus, consumir carne crua ou mal passada, possuir gato, corroborando com achados em estudos anteriores 2,20,[24][25] .…”

“…toxoplasmose resulta da ingesta de oocistos em carne crua ou semicozida, contato com fezes de gatos infectadas com o oócito e transmissão vertical 1 . Na gestação, a principal forma de contaminação ocorre por meio do consumo de carne crua ou mal cozida, água contaminada, ou pela má higienização das mãos após contato com fezes de felinos em solo, areia ou lixo 2 .…”

Toxoplasmosis, a rare case report that led to a successful pregnancy.

“…High avidity can reject the possibility of acute infection. However, It seems that the combination of IgM and IgE anti-toxo antibody detection by ELISA is the most reliable method for acute infection diagnosis (13).…”