CIinical-pathological responses were investigated
in Bos taurus and guinea pigs infested with ticks from
laboratory colony. Infestation regimes involved
three instars individually or concurrently in five sep¬
arate groups with five calves each except one. Repeated
infestations were made over calf ears and guinea pig
trunks. Systematic clinical examinations, haematological
and biochemical estimations, and autopsies were
undertaken. Tick feeding and oviposition performance
was monitored. Demonstration and corroboration of
the findings was effected by further experiments invol¬
ving cutaneous anaphylaxis tests and use of antihistami¬
nes against induced responses.
Prominent responses occurred in the integumentary,
, cardiovascular, lymphatic and nervous
systems. Significant findings were: inflammation,
exudations and encrustations, hypersensitivity reactions;
extreme emaciation, prostration and death; mono and
diphasic pyrexia, congestion, anaemia, excessive mucosal
secretions, significant haematological and biochemical
differences between calf groups; lymph node enlargement
and abscessation; grooming associated with pruritis.
Autopsies confirmed clinical manifestations. Ticks
were adversely affected^especially larvae. Cutaneous
anaphylaxis, antihistaminic effects, vivid guinea pig
circulatory disturbance were demonstrated.
Rhipicephalus appendiculatus infestations caused
serious effects culminating in death; and exsanguination
and intoxication are strongly incriminated. There¬
fore field studies should consider the role of ticks.
But the precise mechanism causing debility is not clear,
thus a critical study of the factors causing loss in
productivity is indicated.