Chagas disease in the Bolivian Chaco: Persistent transmission indicated by childhood seroscreening study

Abstract

Background: Screening for Trypanosoma cruzi infection was performed amongst children in a rural community in the Bolivian Chaco, an area known for high prevalence. The force of infection (FOI) was estimated. Methods: A total of 423 children attending the local school were screened using the Chagas Detect Plus (CDP) rapid test (InBios International, Inc.). CDP-positive specimens were further tested by indirect haemagglutination assay (IHA) and Wiener Recombinante v3.0 ELISA. A catalytic model was used to estimate FOI. Results: Confirmed seroprevalence was 0.22, rising steeply with age. The mean age of seropositive individuals was 13 years. The calculated specificity of the rapid test was 91.9%. The annual incidence estimated from the FOI was 0.021. Conclusions: This study demonstrates persistent transmission and continuing high levels of T. cruzi infection in the Bolivian Chaco, and highlights the practicality of school-based screening.

Indoor residual spraying practises against Triatoma infestans in the Bolivian Chaco: contributing factors to suboptimal insecticide delivery to treated households

“…During the current study, the prevalence of T. cruzi infection in children (2-15 year old) in Itanambikua was 20% [18]. Similar childhood infection seroprevalences are reported for nearby Guarani communities, showing an increase in prevalence with age with the vast majority of residents >30 years old infected [17].…”

“…In contrast, IRS activities against Tri. infestans vectors in the Gran Chaco region have not been noticeably successful evidenced by the high incidence of vector-borne transmission [16, 17, 18, 28, 29]. This study evaluated IRS practises and procedures in Itanambikua, identified as one such focus of chronic vector-borne transmission [18].…”

“…perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for this this version posted December 22, 2020. ; https://doi.org/10.1101/2020.12.21.20248629 doi: medRxiv preprint incidence of T. cruzi infection and vectorial transmission amongst these communities are the highest worldwide [5,16,17,18], and where26%-72% of houses are infested with Tri.…”

“…The consequences of poor vector control are far reaching. Bolivian Chaco communities register childhood infection prevalences of 20%-25%, with annual force of infection rates of 0.021 and 0.046 [16,17,18]. [56], but which is criticised for its low sensitivity [57], particularly to detect infestations in wall crevices [58].…”

“…The inhabitants in this region are some of the most marginalised, living in extreme poverty with little access to health care [15]. The incidence of T. cruzi infection and vectorial transmission amongst these communities are the highest worldwide [5, 16, 17, 18], and where26%-72% of houses are infested with Tri. infestans [11, 19], and 40%-56% of Tri.…”