Occurrence of triatomine infestation without Trypanosoma cruzi transmission in Três Braços, Bahia-Brazil

Abstract

We have reported in part our epidemiological studies on human infection with Leishmania viannia braziliensis (Lvb) in the farms surrounding the hamlet of Tres Braços, Bahia, Brazil1. This community is still surrounded by one of the few surviving pieces of littoral forest Since the begining of our studies 15 years ago we have utilised serology to help in the diagnosis of Lvb infection in our patients and as an indicator of leishmanial activity after treatm ent The fact that no T. cruzi transmission occurred in the area helped in the interpretation of such serology (IFAT, Elisa) since T. cruzi and Leishmania cross react in these tests. Here we report the detection of domiciliated Panstrongylus megistus in the farm Piabanha which is under longitu dinal study. O f 24 houses visited in the farm 7 had evidence of triatomine infestation on the walls and in two live bugs were captured. All the ten adults and 4 juvenile stages captured were negative for T cruzi and measures to spray affected houses are being imple mented. It is possible that this domicilary invasion by P. megistus is from a sylvatic focus although to date no such focus has been detected. Years of work in São Felipe, Bahia where T. cruzi transmission by P. megistus was common failed to reveal P. megistus of sylvatic origin2. It is also possible that P. megistus was introduced into Piabanha by an infested visitor al though no evidence of this event was recorded.