Alien Invasion

Unwanted aliens arrived in Balclutha this week and it is only through the vigilance of an owner that we are not facing these aliens establishing themselves in South Otago.


When it comes to exotic disease surveillance most people think of Foot and Mouth and the disaster that it would bring to New Zealand, or the Painted Apple Moth and the attempts at eradicating it from the North Island. However, unwanted organisms can creep in via many routes and this week saw one arrive in Balclutha.


On Monday a client of Clutha Vets presented us with a tick that she had found on her dog. The only tick known to live in New Zealand is a cattle tick that is not routinely found in South Otago, so alarm bells immediately rang. Our local pathologist at Invermay quickly identified it as the Brown Dog Tick and a notifiable organism – this meant that MAF became involved. At the time of writing we are still uncertain if the tick is a ‘one off’ or the tip of an infestation.


The tick is common in northern Australia and the Pacific Islands, and MAF are used to dealing with it in Auckland, where it is most commonly found in furniture being brought into New Zealand from these places. It is unusual among the tick family in being able to complete its entire lifecycle indoors – so if this tick has made it indoors, our cold South Otago winters won’t necessarily get rid of it!


Dogs are the favoured hosts of this tick (hence its name) and it is brown in colour! It will make do with other animals or humans if no dog is present. It can survive well in the environment depending on where in its lifecycle it is – unfed, adult ticks have been shown to survive up to 568 days! Ticks are blood sucking parasites, so the size also varies depending on the stage and whether the tick has fed recently – an engorged female will be the size of a small grape, but the larvae and nymphs may be only a few millimetres in length before they have fed.


The tick that was found was a partially engorged adult female – which could have travelled here on clothing or in baggage from Australia or the Pacific Islands. The other possibility is she came from an infestation in the Balclutha area – which we would rather not have!


This tick is a vector for several infectious diseases which can affect dogs – the main reason that it is not wanted in New Zealand. The effort to keep it out of New Zealand relies on vigilance from the public.


Please check your dogs for any unwelcome guests. If you do find a tick on your dog or any other animal it is important that you seek veterinary input; they are all significant in South Otago!