An outbreak of Chagas disease through oral transmission: 115 years after discovery by Carlos Chagas, the disease is still hard to manage

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: 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.

Findings: 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.