A Molecular Study on Hepatozoon canis Infection in Dogs in Tehran (Iran)

Hepatozoonosis is a protozoal disease caused by various species of Hepatozoon. This parasite is transmitted from tick; the main vector of Hepatozoon canis is usually the brown dog tick (Rhipicephalus sanguineus). However, several species of ticks are disposed as the alternative vectors. Dogs are usually infected by eating the tick or a part of the tick organ infected by the mature oocysts containing infectious sporozoite. In the current study, a total of 145 blood samples were collected from the cephalic vein of pet, stray, and shelter dogs in Tehran. To conduct this study, first thin blood smears were prepared from all the samples and stained with the Giemsa method. Then, after extraction of DNA from the blood samples, in order to trace Hepatozoon canis, the 18S rRNA gene segment of the parasite was amplified using polymerase chain reaction (PCR). To confirm the PCR-positive results, five randomly selected PCR-positive samples were sequenced. According to the results, through direct observation of microscopic slides, no infection of H. canis parasite was observed, but according to the PCR results, 32 out of the 145 blood samples were found to be infected by H. canis.  In this study, infection to H. canis in older dogs was higher than in young dogs, and more male dogs were found to be infected by the parasite compared to female dogs; but no significant difference was observed in this regard (P > 0.05). Moreover, stray dogs showed a significantly higher rate of infection, compared to the pet and shelter ones (P < 0.05).