Seroprevalence of Trypanosoma cruzi Infection in Schoolchildren and in Pregnant Women from an Amazonian Region in Orellana Province, Ecuador

Abstract

Abstract. Chagas disease is a parasitic disease caused by the protozoan parasite Trypanosoma cruzi and about 230,000 persons are estimated to be infected in Ecuador. However, limited studies have been performed in the Amazon region, on the eastern side of the country. We evaluated here the seroprevalence of Trypanosoma cruzi infection in 12 rural villages of the Loreto canton, Orellana Province in schoolchildren aged 5-15 years and in pregnant women. A total of 1,649 blood samples were tested for Trypanosoma cruzi antibodies by enzyme-linked immunosorbent assay and indirect hemaglutination, and discordant samples were tested by indirect immunofluorescence assay. We detected a seroprevalence of anti-Trypanosoma cruzi antibodies of 1.3% in schoolchildren aged 5-15 years, indicating the persistence of a constant and active vectorial transmission in the Loreto County and confirming the need of the implementation of nonconventional vector control. We also observed a seroprevalence of 3.8% in pregnant women, indicating a clear risk of congenital transmission. Further studies should help define this risk more precisely and implement current international guidelines for the diagnosis, treatment, and care of these cases.

Ten years (2004–2014) of Chagas disease surveillance and vector control in Ecuador: successes and challenges

“…Conversely, the southern highland valleys west of the Andes, previously classified as a high‐risk area , only account for 18% of the cases, in spite of reports of frequent house infestation and a seroprevalence of 3.6% . Further studies should confirm the possible epidemiological changes in the Amazon region, which may be associated with increasing deforestation .…”

“…About 36% of all cases originate from this region. The Amazon region, which was initially classified as of medium risk , appears as the main source of cases in the country (45% of cases) and should thus be considered a very high priority for surveillance and control . Conversely, the southern highland valleys west of the Andes, previously classified as a high‐risk area , only account for 18% of the cases, in spite of reports of frequent house infestation and a seroprevalence of 3.6% .…”

“…Human case records span the years 1990–2014 and are based on both passive and active surveillance of cases. Only confirmed cases were included, based on the definitions of the Ministry of Public Health , that is cases with a positive direct parasitological test or at least two positive serological tests of different principles (ELISA, indirect hemagglutination assay and/or indirect immunofluorescence) . Data were available at the parish level for all years.…”

“…In Ecuador, there are an estimated 100–200 000 cases and both the cardiac and the digestive forms of the chronic phase have been observed . The seroprevalence of T. cruzi infection is highly variable among the provinces, ranging from <1 to 5–6%, with a national average of 0.7% . In 1978, Chagas disease notification became mandatory in Ecuador, which also joined the intergovernmental Initiative of Andean Countries for Chagas Disease Control in 1997.…”

Chagas Disease Has Not Been Controlled in Ecuador

“…Moreover, no formal vector control intervention has been implemented in the Amazon region, where nearly half of the cases of the country seem to originate [ 7 ], and active transmission still occurs through triatomine species including Rhodnius robustus and R . pictipes [ 8 , 9 ]. Especially in the Amazon, human activities (deforestation, urbanization) disturb the natural balance between the vectors, their wild hosts and the parasite, favoring the emergence of new transmission cycles in which humans may be included [ 8 , 9 , 11 , 20 ].…”