Epidemiological investigation of an acute case of Chagas disease in an area of active transmission in Peruvian Amazon region

Abstract

SUMMARYThe study objective was to investigate an acute case of Chagas disease in the San Pedro de Shishita community, Pebas District, in the Peruvian Amazon basin, a non-endemic area. Both parents of the index case (acute case) were thoroughly interviewed, a seroepidemiological survey was carried out in the community, parasitological exams were carried out only in relatives of the index case, and triatomine bugs were searched for inside houses, peridomiciliary, and in wild environments. Seroprevalence for IgG anti-T. cruzi antibodies was 1/104 (0.96%), using an ELISA test and an indirect immunofluorescence assay. Panstrongylus geniculatus and Rhodnius pictipes adults were found. The index case is autochthonous from San Pedro de Shishita, but the source of transmission is unknown.

New focus of active transmission of Chagas disease in indigenous populations in the Peruvian Amazon basin

“…Samples positive for Trypanosomes were further analyzed, and an entomologic evaluation was performed in patients' houses and surrounding areas. To identify collateral cases, blood samples were obtained according to the methods described elsewhere 5,8 , and serum samples were evaluated to detect anti-T. cruzi IgG antibodies with Chagatest ELISA recombinant v. 30, Wiener Lab ® , and by indirect immunofl uorescence (IIF) with a diagnostic titer value of 1:32. Only when both tests were reactive was a patient considered seropositive for T. cruzi infection.…”

“…The entomologic investigation was performed by manual collection according to the methods described elsewhere 5 . Live triatomines were transported to the laboratory for investigation of natural infection by Trypanosoma and taxonomic identifi cation according to the key of Lent and Wygodzinsky 9 .…”

“…One case has been reported in the selva central in Pozuzo, Pasco department 8 , and another in Loreto department in the selva baja 5 . Nevertheless, no cases had been reported within indigenous Amazon populations.…”

“…In Peru, departments located in the Amazon basin or the Southwestern region are endemic for Chagas disease, as are those along the Northern Coast region 5 . The fi rst case of acute Chagas disease (ACD) in the country was reported in 1919 from Madre de Dios department 6 in the selva baja (below 400 m above sea level) in the Amazon basin, and it took another 34 years to detect 2 new ACD cases in 2 children from San Martín department, located in the selva alta (1,000-4000m above sea level) 7 .…”

“…A case of ACD reported in the community by the surveillance system was considered the index case and was defi ned accordingly, as described elsewhere 5 .…”