Trypanosoma cruzi Parasite Load Modulates the Circadian Activity Pattern of Triatoma infestans

Abstract

American trypanosomiasis is a disease caused by the flagellate protozoan Trypanosoma cruzi, which is transmitted mainly in endemic areas by blood-sucking triatomine vectors. Triatoma infestans is the most important vector in the southern cone of South America, exhibiting a nocturnal host-seeking behavior. It has been previously documented that the parasite produces changes in some triatomine species, but this is the first time that the behavior of a vector has been evaluated in relation to its parasite load. After comparing the movement events and distance traveled of infected and non-infected T. infestans, we evaluated the change produced by different T. cruzi parasite loads on its circadian locomotor activity. We observed differences between infected and non-infected triatomines, and a significant relation between the parasite load and the increase in locomotor activity of T. infestans, which was accentuated during the photophase. This could have direct implications on the transmission of T. cruzi, as the increased movement and distance traveled could enhance the contact of the vector with the host, while increasing the predation risk for the vector, which could both constitute a risk for vectorial and oral transmission to mammals.

The Parasite Load of Trypanosoma cruzi Modulates Feeding and Defecation Patterns of the Chagas Disease Vector Triatoma infestans

“…We fed two groups of T. infestans on infected rodents: One group was composed of 39 third instar and 17 fourth instar nymphs that were fed on naturally infected O. degus , and the second group was composed of 26 fifth instar nymphs that were fed on experimentally infected M. musculus . The hosts were anesthetized during the feeding of triatomines as described [ 24 ].…”

“…All triatomine insects used in this study were subjected to a behavioral analysis of their locomotor activity for 24 h, as reported [ 24 ]. After that, each insect was returned to its individual plastic jar in the climatic chamber and was maintained there for 5 ± 2 days before starting the feeding and defecation activity experiments.…”

“…The triatomines were euthanized by freezing immediately after finishing the feeding and defecation experiment. DNA extraction, detection, and quantification were performed as previously described [ 24 ]: T. cruzi was quantified using its nuclear satellite DNA as a target, with primers Cruzi 1 (5′-ASTCGGCTGATCGTTTTCGA-3′) and Cruzi 2 (5′-AATTCCTCCAAGCAGCGGATA-3′) [ 28 ]; the endogenous control targeting the conserved region of rDNA of T. infestans was quantified using primers 18S For (5′-TCCTTCGTGCTAGGAATTGG-3′) and 18S Rev (5′-GTACAAAGGGCAGGGACGTA-3′ [ 46 ].…”

“…For all tests, a 95% confidence interval (α = 0.05) was used in IBM SPSS Statistics v26 software. For figures, outliers were calculated as previously reported in Chacón et al (2022) [ 24 ].…”

“…In contrast, T. cruzi -infected Rhodnius prolixus (Stal, 1859) nymphs feed less frequently than non-infected nymphs [ 19 ]. In R. prolixus , Triatoma pallidipennis (Stal, 1872), Triatoma longipennis (Usinger, 1939), M. spinolai, and T. infestans, there are also reports on modification of their locomotor behavior [ 20 , 21 , 22 , 23 , 24 ].…”