Abstract
Organisms highly similar to Blastocrithidia triatomae, a pathogenic parasite of Chagas disease triatomine bug vectors, were detected using polymerase chain reaction amplification and DNA sequence analysis of a segment of the small subunit rRNA gene in 3 of 203 triatomine specimens collected in Texas from June 2005 to October 2006. The parasite was identified in three species of triatomine bugs (Triatoma gerstaeckeri, T. indictiva, and T. neotomae) collected from three distinct geographic locations. Flagellated organisms indistinguishable from Trypanosoma cruzi were observed by direct microscopy in hindgut material of two of the three specimens. Coinfection with T. cruzi and Blastocrithidia was detected by molecular methods in one of the specimens. Parsimony analysis provided strong support for clustering of the new sequences within a Blastocrithidia group, clearly separated from other flagellated protozoans. Confirmation of Blastocrithidia in U.S. triatomine species complicates microscopic diagnosis of T. cruzi due to the morphologic similarity of the parasites.