Introduction

Chagas disease is endemic in South America, affecting humans and animals due to Trypanosoma cruzi, with high prevalence and mortality. The aim of this study was to determine the T. cruzi infection status of dogs and their ticks in a rural environment in Valparaiso district in Chile by PCR technique.

Methods

Thirty dogs and 93 ticks were studied. A blood sample for EDTA and guanidine tube, attached ticks, and ECG were obtained from each dog. All samples were individually identified. PCR technique using 121 and 122 primers was performed. Ticks were morphologically identified using taxonomic keys. Unpaired t-test (p<0,05) was calculated between haematological parameters and infection status to T. cruzi; and OR and RR between sinus arrhythmia presence and T. cruzi infection.

Results

Studied dogs were 80% mongrel; 18±1 kg weight; 1:0.07 male:female ratio; no regular deworming control presented. Eight out of 28 dogs and 7 out of 93 ticks were T. cruzi positive. Fourteen out of 27 dogs presented sinus arrhythmia on the ECG. Leucocytosis in T. cruzi-positive dogs was statistically different (p=0,032) compared to negative dogs and no more probability to present arrhythmia (OD=1 and RR=0.95). All positive ticks were Rhipicephalus sanguineus. Only 2 dogs showed positive serum and ticks to T. cruzi.

Conclusions

Dogs in this rural area are infected by T. cruzi being a reservoir of Chagas disease. Ticks were infected by T. cruzi, but their role as vector is not yet determined. More studies are needed to elucidate this role.