The effect of repeated Rhipicephalus appendiculatus Neumann 1901, (Ixodidae) infestations on the health of cattle

CIinical-pathological responses were investigated in Bos taurus and guinea pigs infested with ticks from a 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, musculo-skeletal , 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 X . 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.