Higher congenital transmission rate of Trypanosoma cruzi associated with family history of congenital transmission

Abstract INTRODUCTION: Congenital transmission (CT) of Trypanosoma cruzi has led to globalization of Chagas disease and its growing relevance as a public health problem. Although the occurrence of CT has been associated with several factors, its mechanisms are still unknown. This study aimed to analyze the geographical and familiar variables of mothers and their association with CT of Chagas disease in a population living in non-endemic areas of Argentina for the last decades. METHODS: We developed a retrospective cohort study in a sample of 2120 mother-child pairs who attended three reference centers in the cities of Buenos Aires, Santa Fe, and Salta between 2002 and 2015. RESULTS: The highest CT rates were observed in children born to Argentinean mothers (10.7%) and in children born to mothers from Buenos Aires (11.7%). Considering the areas of origin of the mothers, those from areas of null-low risk for vector-borne infection had higher CT rates than those from areas of medium-high risk (11.1% vs 8.2%). We also observed a significant intra-familiar "cluster effect," with CT rates of 35.9% in children with an infected sibling, compared to 8.2% in children without infected siblings (RR=4.4 95% CI 2.3-8.4). CONCLUSIONS: The associations observed suggest a higher CT rate in children born to mothers who acquired the infection congenitally, with familiar antecedents, and from areas without the presence of vectors. These observations are considered new epidemiological evidence about Chagas disease in a contemporary urban population, which may contribute to the study of CT and may also be an interesting finding for healthcare professionals.

Maternal risk factors for the transmission of congenital chagas disease

The present article looks at the association between the epidemiological history of women infected with Trypanosoma cruzi and the risk of vertical transmission. Eighty-three chronically infected mothers and their 237 children were studied, using a cohort design. All patients reside in Santa Fe city, Argentina. Twenty-five women transmitted the infection to 38 children. The potential risk factors evaluated in the mothers were exposure to vector transmission, blood transfusion history, maternal seropositivity, parasitemia and age at birth of the child. 72% (18/25) of the mothers who transmitted the infection to their children, had little or no contact with the vector, while only 28% (7/25) of the mothers presented a history of medium or high risk of vector infection. The differences were significant (p < 0.05). Forty-one percent of the women who presented maternal history as the probable route of infection, transmitted the parasite to more than one child (1.86 ± 0.33; CI95% = 1.03-2.68). In addition, the most frequent history, among the women who transmitted the disease to their children, was the absence of exposure to vector transmission and transfusion with unknown maternal serology. The route of infection was probably transplacental. These observations suggest that there are family genetic characteristics involved in vertical transmission. The parasite was found in 71% of the mothers who transmitted the infection to their children and were able to perform xenodiagnoses. After controlling for the other variables, the logistic regression analysis showed that xenodiagnosis (+) is a risk factor for congenital transmission; the relative risk was 12.2 (95% confidence interval: 2.9 - 50.1). No differences were found when analyzing the mother's age and transfusion history. The highest risk of congenital transmission was associated with detectable parasitemia and less maternal exposure to the vector.

Utilidad de la técnica de aglutinación directa en el diagnóstico de la infección chagásica / Usefulness of the direct agglutination test for the diagnosis of chagasic infection

La técnica de aglutinación directa para diagnóstico de infección chagásica es sencilla y económica. Tiene buena sensibilidad y especificidad cuando es utilizada junto con otras técnicas serológicas y/o parasitológicas. Ha sido reemplazada por otras reacciones de mayor rapidez en los resultadosy más fácil lectura (ELISA, hemaglutinación indirecta). Actualmente es difícil conseguir equipos comerciales. Se presentan en el siguiente trabajo una serie de casos que muestran la utilidad de la aglutinación directa para determinar precozmente infección aguda y/o congénita y para diferenciarinfecciones agudas de crónicas.

The direct agglutination technique for chagasic infection diagnosis is easy to perform and inexpensive. It has good sensitivity and specificity when used in conjunction with other serological and/or parasitological techniques. It has been replaced with other reactions with faster results and easiness to read (i.e. immunoenzymatic assay (ELISA) and indirect hemagglutination). Currently it is difficult to obtaincommercial kits. In the present paper we present a series of cases that show the usefulness of the direct agglutination test to early determine acute and/or congenital infection and to differentiate acute from chronic infections.