Differential access to hosts sleeping in hammock or bed by Chagas disease vector Triatoma dimidiata

In the Yucatan peninsula, Mexico, the causative agent of Chagas disease Trypanosma cruzi is transmitted by the bug Triatoma dimidiata. While T. dimidiata invades and colonizes houses in other regions, this species has an intrusive behavior in Yucatan, likely attracted by artificial light and potential vertebrate hosts, but has limited ability to establish colonies. Bugs collected inside the homes also have a low nutritional status, suggesting that they cannot efficiently feed inside these houses. We hypothesized here that this low feeding status of T. dimidiata may be associated with the local practice in Mayan communities to sleep in hammocks instead of beds, as this sleeping habit could be an obstacle for triatomines to easily reach their host, particularly for nymphal instars which are unable to fly. To test this hypothesis, we used an experimental chamber of 100 cm x 50 cm x 50 cm in which we placed a miniature bed in one side and a miniature hammock on the other side. After placing a mouse enclosed in a small cage in the bed and another one in the hammock as baits, T. dimidiata specimens were released in the chamber and their activity was video recorded during the night (7 pm-7 am). Our results show that bugs were similarly attracted to both mice in the bed and in the hammock. However, they were able to reach the mouse located in the bed significantly more frequently than that located in the hammock. Adults reached the bed most frequently by walking, while they reached the hammock most frequently by flying. Interestingly, nymphs were also able, in few occasions, to reach the mouse in hammock by walking. We conclude that sleeping in hammocks as in rural Yucatan makes the host less accessible to triatomines and may explain, at least in part, the low nutritional status and limited colonization of houses by T. dimidiata in the region.