Epidemiological role of humans, dogs and cats in the transmission of Trypanosoma cruzi in a central area of Argentina.

Trypanosoma cruzi prevalence rates of human, dog and cat populations from 47 households of 3 rural localities of the phytogeographical Chaquena area of Argentina were determined both by serological and xenodiagnostic procedures. Human prevalence rates were uniform and ranged from 49.6 to 58.7%. Overall pre­ valence rate in dogs (75.0%) was significantly higher than in humans (51 .0%) . The overall proportion of parasitemia individuals assessed by xenodiagnosis was significantly higher in either dog (64.2%) or cat (63.6%) populations than among humans (12 .5%) . Although both the average number of resident as well as in­ fected individuals per household was higher for people than for dogs (6.5 vs. 3.3, and 3.4 vs. 2.4, respectively), the reverse was recorded when parasitemic indi­ viduals were considered (1.0 vs. 2 .1) . Results are discussed in relation to dog between dogs and people, and dogs and bugs. In the light of present data, dogs must be considered as the major donors of parasites to vector bugs and thus, principal contributors to transmission in this region of Argentina.