Over a period of seven months the weekly coaint per animal averaged 

 only 27.3 adiilt brovm ear- ticks, varying from sixteen to Ul on 

 each. Higher counts had been anticipated in view of the apparently 

 favorable conditions for these ticks in the area and because of the 

 presence of East Coast fever. The same report gives average counts 

 from other areas, correlated with rainfall, vegetation, and incidence 

 of disease. 



The distribution of the brown ear-tick in South Africa, brief- 

 ly summarized from Theiler's (1949) detailed study, is as follows: 

 It is present in areas with annual rainfall above fifteen inches, 

 provided that bush and shrub coverage is adequate. With proper 

 dipping practices and restriction of wild game movement this tick 

 can be eradicated*. Theiler's report should be consulted by any- 

 one seriously concerned with this parasite. 



In Kenya, where temperatures are higher than in South Africa, 

 an average rainfall of twenty inches or more appears necessary for 

 R. appendicirLatus to maintain itself (Wiley 1953). Because various 

 workers have so intimately associated their studies on the life 

 cycle and their observations on the seasonal incidence of the brown 

 ear-tick, this subject has been discussed under Life Cycle above. 

 Other climatic factors are presented below. 



Lewis' (1939A) findings in Kenya corroborate Theiler's state- 

 ments for South Africa. There, the tick is absent from the plains, 

 desert, and high plateau areas, but common, especially between 

 4,800 feet and 7,000 feet elevation, where vegetation provides 

 enough shade to meet its requirements. /~It is of interest to 

 interpolate here that Kajo Kaji, Yei, ana Katire, from where these 

 specimens were taken in the Sudan, are at about 3000 feet elevation; 

 these areas are more forested than most of Torit District "J. Lewis 

 concluded that R. appendiculatus is active at all times of the year 

 but more so during tne rainy season, and that it thrives best when 

 the mean maximum temperatiH-e is between 60°F. and 80°F., and the 

 mean minimum between 50°F. and 60°F. Lewis' 1931 and 1932 papers 

 give other details of the presence or absence of R. appendiculatus 

 in Kenya. " 



*A niunber of veterinarians believe that under most African condi- 

 tions complete eradication is impossible and while control to 

 prevent otitis and lymphangitis should be practiced, restricted 

 populations shoiild be allowed to remain to induce East Coast fever 

 immunity in calves. 



- 611 - 



