Elucidating the mechanism ofTrypanosoma cruziacquisition by triatomine insects: evidence from a large field survey ofTriatoma infestans

Abstract

Blood-sucking triatomine bugs transmit the protozoan parasite Trypanosoma 14 cruzi, the etiologic agent of Chagas disease. We measured the prevalence of T. cruzi 15 infection in 58,519 Triatoma infestans captured in residences in and near Arequipa, Peru. 16 Among bugs from infected colonies, T. cruzi prevalence increased with stage from 12% in 17 second instars to 36% in adults. Regression models demonstrated a linear relationship 18 between infection prevalence and developmental stage. Prevalence increased by 5.4 19percentage points with each additional stage. We postulate that the probability of acquiring 20 the parasite may be related to the number of feeding events. Transmission of the parasite 21does not appear to be correlated with the amount of blood ingested during feeding. Similarly, 22other hypothesized transmission routes such as coprophagy fail to explain the observed 23 pattern of prevalence. Our results could have implications for the feasibility of late-acting 24 control strategies that preferentially kill older insects. 25