Almost everyone will tell you bed bugs (Cimex lectularius) aren't known to transmit diseases to humans. This is widely-accepted, but it turns out it may not be true. According to a recent study published in The American Journal of Tropical Medicine and Hygiene*, the common bed bug, Cimex lectularius, was found to be able to carry and transmit the parasite Trypanosoma cruzi. This parasite causes Chagas disease, but there have been no reports of C. lectularius transmitting T. cruzi to humans outside of a laboratory.
In this study, the researchers tried to show that T. cruzi makes C. lectularius less likely to survive and reproduce. The study indicated this may not be true which means it should be possible for bed bugs to transmit parasites that cause human disease outside of a laboratory.
It will be interesting to see how much our knowledge of bed bugs and the risks posed by them will change as bed bug populations continue to increase. With more people being exposed to bed bugs, if it is possible for bed bugs to transmit diseases, these pests may quickly become deemed a public nuisance for health reasons.
* Peterson, J.K., Salazar R., Castillo-Neyra, R., Borrini-Mayori, K., Condori, C., Bartow-McKenney, C., ... Levy, M.Z. “Trypanosoma cruzi Infection Does Not Decrease Survival or Reproduction of the Common Bed Bug, Cimex lectularius.” The American Journal of Tropical Medicine and Hygiene (2018) The American Journal of Tropical Medicine and Hygiene. http://www.ajtmh.org/. 5 February 2018.