Professor of Veterinary Medicine The Heberew University of Jerusalem Rehovot, Yerushalayim, Israel
Presentation Description / Summary: Dogs and cats infected with a vector-borne pathogen are frequently co-infected by more than one infectious agent. Some pathogens can be transmitted by the same vector, such as the Brown dog tick transmitting Ehrlichia canis and Babesia vogeli, while other pathogens, such as Leishmania infantum and Hepatozoon canis, are transmitted by sand flies and ticks, respectively. The interaction between infectious agents and the immune responses mounted against them is intriguing. Several studies have shown an association between different co-infections, with higher infection rates, more severe pathological consequences, and higher mortality rates, compared to mono-infections. Studies from Europe, Asia and South America have found that cats with feline immunodeficiency virus (FIV) infection are more likely to be infected with L. infantum than cats negative for this retrovirus. Association between canine tick-borne coinfections, such as E. canis and babesiosis, with L. infantum detection and clinical severity, has also been demonstrated. A study published in 2019 found that dogs with 3 or more tick-borne infections were 11 times more likely to progress from sub-clinical infection to clinical leishmaniasis than dogs with no tick-borne disease. The mechanisms responsible for these associations include shifting of cytokine responses, modification of antibody production, suppression of lymphocyte proliferation in response to pathogen stimuli, and changes in leukocyte populations, resulting in increased parasite loads and more severe clinical disease. In conclusion, it is essential to test cats and dogs infected with vector-borne agents for co-infection with other pathogens. Furthermore, specific treatment is needed to combat different vector-borne infections.
Learning Objectives:
Discern that vector-borne co-infections are common in dogs in endemic regions, and are rather the rule, not the exception.
Learn why co-infection can drive sub-clinical infection into clinical disease.
Understand how interaction between co-infecting agents and the immune responses mounted against them may promote clinical deterioration.
Appreciate that the diagnosis and clinical management of complicated co-infections is challenging and requires understanding the pathophysiology and specific drug susceptibilities of pathogens involved.
