Some factors affecting the sporogony of theileria parva in the salivary glands of its tick vector, rhipicephalus appendiculatus

Abstract

An investigation into several aspects of Theileria parva sporogony in unfed Rhipicephalus apoendiculatus ticks was carried out in the laboratory and in the field. In the first experiment an attempt was made to heat-stimmulate sporogony in unfed nymphal ticks infected with I.parva parva Kilae and I.,P.parva Muguga. Heat stirrulation of unfed adult ticks was also undertaken. The effectiveness of high ambient terTperatures and of feeding on rabbits as stirrulants to sporozoite maturation in I.parva-infected adult ticks were compared. Heat stimmulation of sporogony in adult ticks under natural conditions in the field at a high altitude area (2,100m) was attempted. Finally, the rate of transmission of I.parva sporozoites to cattle after heat stirrulation of sporogony in adult ticks was investigated. The study established the following three facts: 1. Unfed nyrrphal B,.apoendjculatus ticks infected with I.,Q.parva o Kilae can deyelop mature sporozoites if exposed to 37 C and high relative humd+ty for'-4-days. 2. Unfed adult B,.appendiculatus ticks, infected with I.Q.parva Kilae and I.Q. parva Muguga, exposed .to -'natural conditions in the field at Muguga, Kenya can develop mature sporozoites. 3. Heat stirrulated B,.appendiculatus adults infected with I.Q.parva Kilae can transmit the parasite to susceptible cattle - - within 24 hours of attachment. xii The study also confinmed previous findings that exposure of o R.appendicuJatus to 37 C is not as efficient in stinuJatingI.parva parva sporogony as is feeding the ticks on rabbits. Another observation made was that I.Q.parva Kilae seems to be more sensitive to heat stimulationthan I.Q.parva Muguga.