TICK SALIVA - RECENT ADVANCES AND IMPLICATIONS FOR VECTOR COMPETENCE

Secretions of the tick salivary glands are essential to the successful completion of the prolonged feeding of these ectoparasites as well as the conduit by which most tick-borne pathogens are transmitted to the host. In ixodid ticks the salivary glands are the organs of osmoregul ation, and excess water from the bloodmeal is returned via saliva into the host. Host blood must continue to flow into the feeding lesion as well as remain fluid in the tick mouthparts and gut. The host's haemo static mechanisms are thwarted by various anti-platelet aggregatory, a nticoagulatory and anti-vasoconstrictory factors in tick saliva. Saliv a components suppress the immune and inflammatory response of the host permitting the ticks to remain on the host for an extended period of time and, adventitiously, enhancing the transmission and establishment of tick-borne pathogens. Over the years much work has been done on th e numerous enzyme and pharmacological activities found in the tick sal iva. The present article reviews the most recent work on salivary glan d secretions with special emphasis on how they favour pathogen transmi ssion.