An outbreak of Chagas disease through oral transmission: 115 years after discovery by Carlos Chagas, the disease is still hard to manage
Authors: Alves Simões-Neto Eudes , Santos Daniel Wagner de Castro Lima , Bomfim Maria Rosa Quaresma , Costa Jackson Maurício Lopes , Simões Amanda Ferreira , Vasconcelos Lucas Dias , Sodré Domingos Carvalho , Costa Ana Cleide Mineu , Dumont Samuel Vieira Rodrigues , Melo Bruna de Oliveira de , de Azevedo Conceição de Maria Pedrozo e Silva 
Published: May 2024

Background

Orally transmitted acute Chagas disease (ACD) mostly affects low-visibility and low-income individuals, mainly in tropical and subtropical zones. However, even more than 100 years after Carlos Chagas’ discovery, several difficulties in managing ACD are still faced. Ita expansion to other, non-endemic areas through globalization processes has transformed it into a global health problem.

Methodology and findings

This report addresses an outbreak of 39 cases of ACD due to oral transmission. A clinical-epidemiological investigation with an entomological search was performed. Laboratory criteria (positive peripheral blood smear (PBS), seroconversion of IgG and 2x increase in IgG titer) and clinical-epidemiological criteria (clinical findings, epidemiological exposure and at least one positive IgG) were used for diagnoses. In-house conventional polymerase chain reaction (PCR) was performed on 33 samples. All patients were treated with benznidazole. After 4.5 years, IgG was investigated in 26 individuals. Their mean age was 33.6 years, with no difference in gender distribution; the mean incubation period was 13.8 days and mean time between symptom onset and treatment was 16.6 days. The most frequent symptoms were fever and lymphadenopathy (90%). For 66.6%, laboratory criteria yielded the diagnosis and for 23%, clinical-epidemiological criteria, while 10.2% showed negative tests but were treated due to high clinical suspicion. Test positivity rates: PBS 69.7%; serology 91.4%; PCR 100%. There were no deaths. Serological cure was achieved for 34.6% and decreased IgG titers for 15.3%.

Conclusions and significance

We present all the barriers encountered in managing real-life situations: vulnerability of the population; dependence on old diagnostic techniques; lack of standardization of molecular biology techniques; and few therapeutic options. We demonstrated the importance of rapid surveillance action with early treatment, such that this outbreak did not give rise to deaths. We also propose that conventional PCR should become standardized within the diagnostic routine.

AUTHOR SUMMARY

In this study we present an outbreak of orally transmitted acute Chagas disease (ACD), a neglected tropical disease. The source of transmission was bacaba juice served at a celebration held in a quilombola community and 39 individuals were affected. The focus of this study was clinical-epidemiological investigation and diagnostic tools. There were no deaths due to this event, probably because of the quick action of the surveillance team and the early start of treatment. We show all the difficulties facing a real-life situation (vulnerability of population affected, weaknesses regarding good food safety practices and obstacles to following what guidelines recommend), discuss the performance and executability of the diagnostic method used and address the global threat that Chagas disease may pose. Furthermore, we propose that the polymerase chain reaction should become standardized in diagnosing acute disease, given that this was the only method with 100% positivity, even among patients whose other tests were all negative.