The role of humans in the importation of ticks to New Zealand: a threat to public health and biosecurity.

Humans coming into New Zealand occasionally, and unwittingly, bring exotic ticks with them, either attached to their bodies or with luggage. Of the 172 available records for tick interception at New Zealand's border, half can be attributed to human agency. Here, together with an outline of tick biology and ecology, we present evidence of at least 17 species of ticks being brought in by humans, with Australia, North America and Asia the most frequent countries of origin. Risks posed by some of the nine species of ticks already in New Zealand are briefly examined. Sites of attachment of ticks and associated symptoms where these have been recorded are presented. Diseases transmitted by ticks and most likely to be encountered by travellers are briefly discussed together with the most practical method of tick removal. A plea is made for practitioners to increase their awareness of the risks to New Zealand's biosecurity and public health posed by ticks and to ensure that as many as possible of these unwelcome 'souvenirs' are collected and passed on for identification.