Vector-borne pathogens in dogs in Egypt: Molecular and immunological insights

Abstract

Canine vector-borne diseases (CVBD) constitute a significant global health challenge, impacting dogs and posing zoonotic risks to humans. These diseases are transmitted through blood-feeding vectors such as ticks, fleas, and mosquitoes. This study, conducted in Cairo and Giza, Egypt, aimed to assess the prevalence, diversity, and clinical impact of CVBD in both domestic and stray dogs. Using microscopic and molecular diagnostic techniques, several pathogens were identified, including two primary zoonotic blood pathogens, Anaplasma platys and Leishmania spp., as well as other blood pathogens with varying degrees of zoonotic potential, such as Ehrlichia canis (E. canis), Anaplasma phagocytophilum, Anaplasma marginale, Babesia canis vogeli (B. canis vogeli), Hepatozoon canis, and Trypanosoma evansi. Stray dogs exhibited a higher prevalence of infection than domestic dogs, frequently presenting with co-infections. Clinically, infected dogs displayed clinical signs including weight loss, pale mucous membranes, lethargy, and anorexia, with more severe manifestations observed in cases with co-infections, particularly involving B. canis vogeli and E. canis. The immune response in these dogs was marked by elevated levels of inflammatory cytokines, such as tumor necrosis factor-α, interferon-γ, and interleukin-1β, which were significantly higher in symptomatic dogs, indicating a robust immune defense against the pathogens. Furthermore, markers of oxidative stress, including glutathione, malondialdehyde, and nitric oxide, were elevated in infected dogs, suggesting increased cellular damage due to prolonged infection and inflammation. The findings underline the key significance of stray dogs in the transmission and maintenance of CVBD and emphasize the necessity for comprehensive diagnostic, preventive, and control strategies to mitigate the prevalence of these diseases in dog populations and their potential zoonotic impact on human health.