Ticks are important to human and veterinary medicine
for a variety of reasons:
- as vectors of bacterial, protozoal, rickaettsial, spirochaetal
and viral diseases of humans, domestic stock and companion animals.
- as ectoparasites with irritating bites causing extensive harm
to their hosts due to blood loss, damage to the skin and anorexia
leading to reduction in growth.
- as agents of 'tick paralysis' in man and animals, probably due
to the secretion of toxic substances in their saliva.
- in exacerbating the lesions caused by Dermatophilosus
congolensis (dermatophilosis) in cattle, goats and sheep; this is
caused by immunosuppressive effects of the tick feeding.
- in predisposing their hosts to other arthropod infestations
such as the screwworm fly, Cochliomyia hominovorax.
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Rhipicephalus
appendiculatus, the brown ear tick, feeding on the ear of a calf.
This African tick transmits Theileria parva infections, Anaplasma
centrale and Babesia bigemina which cause East Coast fever,
anaplasmosis and babesiosis respectively in cattle.
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Engorged female of Hyalomma sp. feeding on the skin between
the spines of a hedgehog.
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