An experimental study of East Coast fever in Uganda I. A study of the type of East Coast fever reactions produced when the number of infected ticks is controlled

Abstract

Doubt exists as to why, in endemic areas, a varying proportion of calves die of East Coast fever while others survive. A series of experiments was therefore conducted to ascertain if the number of infected Rhipicephalus appendiculatus engorging simultaneously on susceptible calves influenced the course of East Coast fever reactions. The ages of the calves used in the various experiments varied, but other conditions were kept as uniform as possible.When ten calves were grazed in a 1-acre paddock where the number of infected R. appendiculatus was high, eight died of acute East Coast fever.In the second experiment, seventeen calves in all were grazed in the same paddock. These calves were given some protection from infected R. appendiculatus infestation, as two of the calves were immune to East Coast fever and the ears of ten of the susceptible calves were sprayed with tickicidal solutions. Four died from acute East Coast fever and one of subacute East Coast fever complicated with a helminth infection.