Figure 1

The triad of canine vector-borne disease. The canine vector-borne diseases are characterized by the unique three-way interaction between the infectious agent, the vector and the host immune system. Vector salivary proteins injected into the dermal microenvironment during taking a blood meal modulate the host immune system creating a favourable environment for survival and replication of the infectious agent. This permits infection of co-feeding naïve vectors. The effects on host immunity are often to promote Th2-regulated humoral responses above the protective Th1-regulated cellular immune response. This allows persistence of the infection and encourages the development of inappropriate secondary immunopathology characterized by hypergammaglobulinaemia, autoantibody and immune complex formation.