A parasitic infection (also known as “American trypanosomiasis”) transmitted by the bite of the completely misnamed “kissing bug” (triatomine or reduviid bug). This nasty bug bites people and then defecates into or near the bite, depositing the parasite in the wound. The parasite in question is called Trypanosoma cruzi
(or just T. cruzi
for short), and it is very prevalent in Mexico, Central America, and South America. People infected with T. cruzi
have a relatively short period (up to a month or two) where the parasite is circulating in blood followed by a years to life-long chronic infection. The parasite tends to lodge in heart and gastrointestinal muscle, and the 25% or so who get symptoms have issues in one of those systems.
The incidence of Chagas Disease has risen significantly over the last several decades, especially in the Hispanic population, but there still seems to be only a low risk of transfusion transmission. A blood donor screening test to detect antibodies against T. cruzi is now required by the U.S. FDA, though there is a weird twist to this testing: Anti-T. cruzi testing is only required once in a donor’s entire lifetime. Current estimates suggest that 1 in 25,000 U.S. blood donors may be infected (but this rate may be MUCH greater in areas with a higher number of immigrants from endemic countries).