High Prevalence of Congenital Trypanosoma cruzi Infection and Family Clustering in Salta, Argentina

Abstract

ABSTRACT. Objective. Trypanosoma cruzi, the causative agent of Chagas' disease, is transmitted mainly by insect vectors, but congenital and transfusion-borne infections occasionally occur. The factors that are involved in transmission from mother to offspring are not well understood. The objective of this study was to study the presence of T cruzi infection in children who were born to infected mothers and in the children's siblings to evaluate the epidemiologic risk factors associated with congenital transmission of Chagas' disease.Methods. Congenital T cruzi infection was studied in 340 children who were born to chronically infected mothers in Salta, Argentina. Infection was detected in 31 children, who were selected for additional study as infected index cases (IIC). Of the 309 noninfected children, 31 were taken as noninfected index cases (NIIC). We compared the prevalence of congenital T cruzi transmission in the remaining siblings of the IIC and NIIC. Data and blood samples were collected in house-to-house visits. Diagnosis of infection was established mainly by serologic methods, indirect hemmagglutination, and enzymelinked immunosorbent assay.Results. The prevalence was 31.4% (32 of 102 children) for IIC siblings, whereas no infected siblings were found in families with NIIC (0 of 112). Clustering of congenital infection was found in 14 families, in which >1 child was infected. Second-generation congenital transmission (from grandmother to mother to newborn) was established in 4 families. The association among low weight at birth, prematurity, and congenital transmission was highly significant. An important observation was the absence of pathologic findings in a high proportion of infected children. The detection of asymptomatic infections was a consequence of population screening, as opposed to hospital-based diagnosis, for which symptomatic cases predominate. Congenital transmission was associated with the geographic origin of mothers: women from areas where insect vectors proliferate were less likely to give birth to infected offspring than women from areas under active vector control.Conclusions. Siblings of an infant infected with T cruzi are at high risk for infection themselves and, even in the absence of symptoms, should also be screened for infection. The findings of family clustering of infection and of second-generation congenital infection in vectorfree areas suggest that new modalities of transmission, other than classic vector-borne spread, may occur both in endemic and in nonendemic areas. Pediatrics 2005; 115:e668-e672. URL: www.pediatrics.org/cgi

High levels of human infection with Trypanosoma cruzi associated with the domestic density of infected vectors and hosts in a rural area of northeastern Argentina

“…Given that infected bug abundance was highly correlated with overall bug abundance, taken together these results suggest the probability these two children were exposed to infected bugs was extremely low. In contrast, the average risk of vertical transmission from T. cruzi -seropositive mothers to newborns ranges from 1.9–9.1% [50–52]. Failure to diagnose congenital cases at birth or during routine controls over the first year of life translates into a lost opportunity for etiological treatment and cure.…”

The role of the ratio of vector and host densities in the evolution of transmission modes in vector-borne diseases. The example of sylvatic Trypanosoma cruzi

“…Vertical transmission has been reported among placental hosts such as rats and mice [22,23], and humans [24]. In addition, sylvatic hosts such as raccoons and opossums are opportunistic feeders whose diet includes insects, and experimental studies have shown that they can get infected by ingesting infected vectors [25,26].…”

Reversible Cysteine Protease Inhibitors Show Promise for a Chagas Disease Cure

“…Furthermore, mother-tochild transmission can maintain Chagas disease in populations long after vectorial transmission has ceased. Although congenital transmission is thought to occur in Ͻ5% of children born of positive mothers, family clustering and multigenerational transmission have been reported (4). Furthermore, due to international migrations, Chagas disease is now considered an emerging disease in several nonendemic areas in the world, including the United States, Europe, Japan, and Australia, where nonvectorial transmission of the parasite is becoming a serious public health threat (5).…”