Parasite Load Modulates the Circadian Activity Pattern of .

American trypanosomiasis is a disease caused by the flagellate protozoan , which is transmitted mainly in endemic areas by blood-sucking triatomine vectors. 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 , we evaluated the change produced by different 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 , which was accentuated during the photophase. This could have direct implications on the transmission of , 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.