Molecular, epidemiological, and hematological evaluation in Ehrlichia canis infected dogs from an endemic region in Egypt.

Background: Canine monocytic ehrlichiosis (CME) is considered a multisystemic, life-threatening, rickettsial, and tick-borne disease that affects canine species and is caused by Ehrlichia canis (E. canis). Clinical signs of CME vary from asymptomatic to severe illness with three clinical phases. E. canis has the potential to infect humans.

Aim: This study aimed to provide recent information as there is limited data about the disease in Egypt. Therefore, this work was conducted to study the molecular prevalence of E. canis and evaluate the corresponding risk factors, hematology, biochemistry, and molecular characterization of the genus Ehrlichia and E. canis species among Egyptian dogs.

Methods: One hundred eighty dogs of both sexes from 3 months to 8 years from different breeds: stray and foreign breeds were examined for clinical signs in all seasons in two delta governorates: El-Dakahlia and El-Gharbia. Blood samples were collected from dogs for microscopic and haemato-biochemical analysis, and then molecular characterization of the genus Ehrlichia and species-specific E. canis was performed, followed by sequencing and phylogenetic analysis.

Results: Out of 180 samples examined by polymerase chain reaction (PCR) assay, 42 (23.33%) were positive for the genus of Ehrlichia and the species-specific E. canis. Only twenty-four dogs (13.33%) were positive for PCR, infested with ticks, and showed fever, anemia, loss of body weight, pale mucous membrane of gum and conjunctiva, blindness, paralysis, hemoglobinuria, and Melena. The univariate logistic regression revealed that all variables, including age, season, tick infestation, hemorrhage from natural orifices, and ectoparasitic treatments per year, showed statistical significance (p ≤ 0.05), except breed and sex, which also did not exhibit any relation between CME infection in multivariate logistic regression. The presence of morulae inside leukocytes in 66 dogs out of the total examined 180 (36.67%), only 39 (59.1%) were positive for morulae and PCR-positive for E. canis. Dogs positive for E. canis suffered from anemia, severe thrombocytopenia, the absolute value of WBCs and their fractions, alanine aminotransferas (ALT), AST, ALKP, γ-GT, total. P, T.BIL, urea, globulin, and creatinine were significantly increased in dogs infected with E. canis when compared to those with negative PCR results, while the levels of albumin and A: G ratios were significantly decreased.

Conclusion: The current study proves the existence of E. canis in El-Dakahlia and El-Gharbia governorates, and this is the first large-scale study concerning the epidemiological, clinicopathological examination, molecular characterization, sequencing, and phylogenetic analysis of reported from the center of the Delta of the Nile in Egypt.