Modulation of host immunity by haematophagous arthropods

The medical and veterinary public-health importance of haematophagous arthr opods is immense and continuing to increase because of the emergence of new vector-borne infectious agents and the resurgence of well known ones. Cont rol of blood-feeding arthropods and the pathogens they transmit is compound ed by drug, insecticide and acaricide resistance. Novel control strategies are needed. Immunological control is one very promising approach to these p roblems. In order to develop anti-arthropod vaccines that block pathogen tr ansmission and establishment, the immunological interactions occurring at t he interface of the blood-feeding arthropod and host must be characterized. An important component of these interactions is arthropod modulation of th e host's innate and acquired, specific immune defences. This review discuss es current knowledge regarding the ability of haematophagous arthropods to alter their hosts' immune defences, the impact of those changes on pathogen transmission, the molecular bases for the immunomodulation, and strategies for identification of the molecules in arthropod saliva that are responsib le for the immunomodulation.