Journal of the New Zealand Medical Association, 16-December-2011, Vol 124 No 1347
Jeremy Hornibrook, Simon Pollard
Clinical presentation—A 41-year-old Irish veterinary surgeon (who worked with horses) presented saying “I ‘tink I have a tick in my ear”. Three times a day he experienced an irritation and scratching sound in his left ear, which he had tried to relieve with a cottonbud.
Microscopy of the left ear showed a tick wedged in the anterior recess with its legs contacting the tympanic membrane, which had extensive bruising (Figure 1). It was tightly attached and could not be ‘drowned’ with framycetin drops, so the ear canal was anaesthetised by injection and the tick removed with a small hook.
Figure 1. Tick wedged in left ear canal and bruising of the drum (image captured by fibreoptic endoscope video and converted to a still image)
Discussion—Haemaphysalis longicornis (Ixodidae, Acari) commonly known as the cattle or horse tick, is a parasitic, eight-legged haemophagic arachnid. It uses its mouthparts to penetrate the host's skin, injects an anticoagulant, and then feeds on its blood. H. longicornis is found in many temperature countries around the world and was probably introduced to New Zealand in the late 19th Century.
It is common throughout the North Island and the northern part of the South Island of New Zealand. Its principal host is domestic cattle, but in New Zealand it has been found on most of the introduced mammals, including humans and a number of introduced and native bird species including the North Island brown kiwi. Although, the cattle tick has been known to be a vector for diseases (e.g. Lyme disease, encephalitis) in the Northern Hemisphere, it is not known to carry any diseases in New Zealand.
Females reproduce asexually (parthenogenetically) and lay up to 2000 eggs over a 1–2 week period and these hatch into larvae after 60–90 days. The larvae climb vegetation and wait for a suitable host to pass by. If this happens, they attach themselves to the host and feed on its blood for about 5 days, before detaching and dropping onto the ground to enter a premoult phase for about 30 days.
After moulting into a nymph, they again climb vegetation and wait for a host, on which they will feed for about 7 days, before detaching and developing into an adult after 40 days. The adult female repeats the behaviour of the larvae and nymph, but may feed for 7 days or longer, before dropping off the host to lay eggs.
Ears are prime real estate for this tick, although the groin and armpits are the most common sites for infestation in most hosts.
Author information: Jeremy Hornibrook, Otolaryngologist-Head and Neck Surgeon, Christchurch Hospital—and Adjunct Professor in the Department of Communication Disorders, University of Canterbury, Christchurch; Simon Pollard, Curator of Invertebrate Zoology, Canterbury Museum—and Adjunct Professor of Science Communication, College of Science, University of Canterbury, Christchurch
Correspondence: Jeremy Hornibrook, Department of Otolaryngology-Head and Neck Surgery, Christchurch Hospital, 2 Riccarton Avenue, Christchurch 8011, New Zealand. Fax: +64 (0)3 3640273; email: email@example.com
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