An ecological analysis on a populational basis, using data obtained from the Reportable Diseases Information System (Sinan, in the Portuguese acronym), of the Ministry of Health, was carried out with the goal of identifying an epidemiological profile of the transmission of acute Chagas disease in Brazil. Chagas disease is caused by the parasite Trypanosoma cruzi, transmitted by an insect called kissing bug, and is present in 21 countries in Latin America. The disease affects the heart and organs of the digestive system, in two stages: the acute phase takes place right after infection and may last up to four months; the chronic stage follows the acute stage and has a long duration. In Brazil, only acute cases are reportable to the Sinan.
The study analyzed the epidemiological characteristics and the space-time trends of reports, including all cases of acute Chagas disease reported between 2001 and 2018 (5,184 cases). The work was coordinated by Fred Luciano Neves Santos, researcher of Fiocruz Bahia, and was described in a paper published on PLOS Neglected Tropical Diseases. The findings may help with surveillance actions aiming to prevent new cases of the disease.
The authors of the research stated that the space-time distribution of the disease in this period was heterogeneous in the country. They also reported that the annual incidence rate was 0.16 per 100,000 inhabitantes, and identified a rapid increase of notifications before 2005, a stable drop between 2005 and 2009, followed by an increase after 2009. The higher infection frequencies were observed in children, adolescents and adults in the Northern region, throughout the period under study, and in women and in people from 20 to 64 years old in the North-Eastern region, between 2001 and 2009.
Vector transmission was the main form of transmission reported up to 2005, while oral transmission saw a significant increase in the North during the other time frames. The study also showed that the northern state of Pará is responsible for 81% of cases caused by oral transmission in the Northern region, with higher rates of cases occurring after the harvest of açaí (acai berry) and bacaba berries, following the ingestion of products derived from these fruits, contaminated with kissing bug feces.
With these results, the authors concluded that although the occurrance of Chagas disease has fallen all over Brazil, it is still a public health threat, as highlighted by the occurrance of acute cases in more than 50% of Brazil’s micro regions. They also highlighted the need for entomological actions and for the adoption of sanitation measures to reduce oral transmission. Reporting chronic cases in Brazil, including in blood banks, should be strongly considered as a measure, according to the scientists involved in the research.