Common Bed Bugs: Non-Viable Hosts for <i>Trypanosoma rangeli</i> Parasites

The hemoflagellate parasite <i>Trypanosoma rangeli</i> is transmitted by triatomine kissing bugs and may co-infect humans together with its Chagas disease-causing congener <i>T. cruzi</i>. Using real-time quantitative polymerase chain reaction (RT-qPCR) and antimicrobial assays, we studied (<i>i</i>) the temporal and spatial distribution of <i>T. rangeli</i> in common bed bugs, <i>Cimex lectularius</i>, following oral ingestion and hemocoelic injection of <i>T. rangeli,</i> and (<i>ii</i>) the immune responses of bed bugs induced by <i>T. rangeli</i> infections. Irrespective of infection mode, no live <i>T. rangeli</i> were present in the bed bugs’ hemolymph, salivary glands, or feces. On day 1 following infection, the bed bugs strongly upregulated the antimicrobial peptide CL-defensin. Following hemocoelic injection of <i>T. rangeli</i>, live parasites were absent in any bed bug tissues examined throughout the 10-day study period. The ingestion of <i>T. rangeli</i>-infected blood had no significant effect on bed bug survival. Our findings indicate that bed bugs disable the development of <i>T. rangeli</i> within their body, in stark contrast to triatomine kissing bugs, which allow the development and transmission of <i>T. rangeli</i>. Our findings help unravel the intricate relationships between bed bugs and trypanosomes, and they contribute to our understanding of vector biology.