Dogs with the presumptive diagnosis of Chagas disease are
commonly sent to our School of Veterinary Medicine by independent veterinarians.
This prompted us to evaluate the prevalence of canine trypanosomiasis in
some villages of the Central Valley of Costa Rica.
A total of 54 dogs (21 males and 33 females) from five rural villages,
with ages between 3 months and 10 years old, were bled and submitted to
three serological tests: indirect immunofluorescence, indirect hemagglutination
and ELISA. Among all animals, 15 (27.7%) revealed antibodies (6 pure bred
and 9 mongrels) and in 3 of them the parasite was also demonstrated by xenodiagnosis.
All positive animals except 1, and 9 negative animals (control group) were
examined by X-rays and electrocardiography, revealing different degrees
of cardiomegaly and ECG alteration, consistent with Chagas disease pathology
in one dog (SA-11) of the infected ones.
Examination of 50 inhabitants living in the houses where dogs and Triatoma
dimidiata were found, yielded negative serological reactions. This was assumed
to support the hypothesis that dogs are commonly infected by the oral route,
a more effective means of infection compared with the vector transmission
mechanism that occurs in humans.