Viability of Trypanosoma cruzi in Triatoma pallidipennis Post-mortem

Given that contact with the feces of dead triatomine bugs poses a risk of Trypanosoma cruzi infection, this study evaluated parasite viability and infectious potential in dead triatomines across various post-mortem times and temperatures.

Three groups of nine of 5th-instar Triatoma pallidipennis nymphs (n = 27) were euthanized via insecticide 30 days post-infection (Ninoa strain). Nymphs were maintained at room temperature (10 -23 °C), refrigeration (4 °C), and incubation (27 °C). Fecal parasite concentration was assessed at 24 h and at 2, 5, 7, 10, 15, 20, 25, and 30 days post-mortem. To evaluate infectivity, two CD1 mice were inoculated with intestinal contents from other two bugs kept for 30 days under each condition (n = 6), and parasitemia curves were generated.

An increase in parasite counts in the feces of dead triatomines kept at room temperature was observed starting on day 15 post-mortem. This contrasted with the refrigeration and incubation groups, where parasite counts declined at days 5 and 7, respectively. Only mice inoculated with intestinal contents from the room temperature group showed positive parasitemia from day 20 onward.

Dead triatomines represent a potential infection source for T. cruzi, with storage temperature serving as a determining factor for parasite survival.