Occurrence and genotyping of Theileria equi in dogs and associated ticks in Egypt.

Theileriosis is a tick-borne protozoal disease caused by a piroplasm of the genus Theileria. Hard ticks are obligate hematophagous ectoparasites that serve as vectors of Theileria spp. Studies of the presence of theileriosis in Egyptian dogs and associated ticks are scarce. This study was conducted to detect and identify Theileria spp. in dogs and Rhipicephalus sanguineus ticks and to monitor the epidemiological data of this disease. The prevalence rates of Theileria equi infection were 12.02%, 0.73%, 2.93%, and 1.83% by microscopic examination of dog blood, tick hemolymph, tick midgut, and tick salivary smears, respectively. Conversely, the T. equi prevalence in dog blood and associated ticks assessed by PCR was 25.81% and 10.42%, respectively. Epidemiological data about Theileria infection revealed a significant difference in the infection between different seasons and different dog breeds (p value <0.05), whereas host, sex, and age of dogs had no significant effect on the infection. Sequencing of PCR products showed that all PCR positive samples were infected with T. equi. Transmission electron microscopy (TEM) described the different stages of Theileria in the midgut and salivary gland of infected ticks. The current study confirmed that T. equi is not specific to equine hosts, and confirmed that dogs are a susceptible host to T. equi.