Suspected vertical transmission of Chagas disease caused by DTU TcIV in an infection probably transmitted orally, during anoutbreak in the Brazilian Amazon

[Estimation of prevalence of chronic Chagas disease in Brazilian municipalitiesEstimación de la prevalencia de la enfermedad de Chagas crónica en los municipios brasileños]

Objective

The objective of this study is to estimate the prevalence of chronic Chagas disease (CCD) in Brazil: in the general population, in women, and in women of childbearing age.

Methods

A meta-analysis of the literature was conducted to extract data on the prevalence of CCD in municipalities in Brazil in the 2010-2022 period: in the general population, in women, and in women of childbearing age. Municipal-level CCD indicators available in health information systems were selected. Statistical modeling of the data extracted from the meta-analysis (based on data obtained from information systems) was applied to linear, generalized linear, and additive models.

Results

The five most appropriate models were selected from a total of 549 models tested to obtain a consensus model (adjusted R2 = 54%). The most important predictor was self-reported CCD in the primary health care information system. Zero prevalence was estimated in 1 792 (32%) of Brazil's 5 570 municipalities; in the remaining 3 778 municipalities, average prevalence of the disease was estimated at 3.25% (± 2.9%). The number of carriers of CCD was estimated for the Brazilian population (~3.7 million), for women (~2.1 million) and for women of childbearing age (~590 000). The disease reproduction rate was calculated at 1.0336. All estimates refer to the 2015-2016 period.

Conclusions

The estimated prevalence of CCD, especially among women of childbearing age, highlights the challenge of vertical transmission in Brazilian municipalities. Mathematical projections suggest that these estimates should be included in the national program for the elimination of vertical transmission of Chagas disease.

Exclusion of Horizontal and Vertical Transmission as Major Sources of Trypanosoma Cruzi Infections in a Breeding Colony of Rhesus Macaques (Macaca Mulatta)

The vector-borne protozoal parasite Trypanosoma cruzi causes Chagas disease in humans and animals. This parasite is endemic to the southern United States where outdoor-housed NHP at biomedical facilities are at risk of infection. In addi- tion to the direct morbidity caused by T. cruzi, infected animals are of limited biomedical research use because infections can produce confounding pathophysiologic changes even in animals with no clinical disease. In part due to concerns for direct T. cruzi transmission between animals, infected NHP at some institutions have been culled, removed, or otherwise isolated from uninfected animal populations. However, data that document horizontal or vertical transmission in captive NHP in the United States are not available. To evaluate the potential for inter-animal transmission and to identify environmental factors that affect the distribution of new infections in NHPs, we conducted a retrospective epidemiologic study of a rhesus macaque ( Macaca mulatta ) breeding colony in south Texas. We used archived biologic samples and husbandry records to identify the time and location of macaque seroconversion. These data were used to perform a spatial analysis of how geographic location and animal associations affected the spread of disease and to infer the importance of horizontal or vertical routes of transmission. The majority of T. cruzi infections were spatially clustered, suggesting that environmental factors promoted vector exposure in various areas of the facility. Although we cannot not rule out horizontal transmission, our data suggest that horizontal transmission was not a critical route for spread for the disease. Vertical transmission was not a contributing factor in this colony. In conclusion, our findings suggest that local triatome vectors were the major source of T. cruzi infections in captive macaques in our colony. Therefore, limiting contact with vectors, rather than segregation of infected macaques, is a key strategy for disease prevention at institutions that house macaques outdoors in the southern United States.

Detection of Trypanosoma cruzi DTUs TcI and TcIV in two outbreaks of orally-transmitted Chagas disease in the Northern region of Brazil

This study describes the laboratory investigation of two acute Chagas disease outbreaks that occurred in the riverside communities of Marimarituba and Cachoeira do Arua, in the Santarem municipality, Para State, located in the Northern region of Brazil, and occurred in March 2016 and August 2017, respectively. The generation of data regarding the diversity of Trypanosoma cruzi parasites circulating in the Amazon region is key for understanding the emergence and expansion of Chagas disease. This study aimed to identify T. cruzi Discrete Typing Units (DTUs) involved in two outbreaks of acute Chagas disease (ACD) directly from the patient's biological sample. Nested and multiplex PCR targeting the 24Sα (rRNA) and mini-exon genes, respectively, were used to identify T. cruzi DTU in blood samples from patients diagnosed with ACD. The samples with positive cPCR were submitted for analysis for T. cruzi DTUs, which included 13 samples from the patients with ACD by oral transmission and two samples collected from two newborns of two women with ACD, from Marimarituba and Cachoeira do Arua. The samples were classified as T. cruzi TcIV, from Marimarituba's outbreak, and T. cruzi TcI, from Cachoeira do Arua's outbreak. The molecular identification of T. cruzi may increase understanding of the role of this parasite in Chagas disease's emergence within the Amazon region, contributing to the improvement of the management of this important, but also neglected, disease.