s The Paralysis Tick of Australia, Ixodes holocyclus


The Paralysis Tick of Australia, Ixodes holocyclus

TREAT AS FOR CHF- Research at University of Qld suggests treating pulmonary oedema in the same way as for congestive heart failure. See below.

TICK NUMBERS ON THE RISE around Sydney- global warming, recent weather patterns, overgrown gardens, composting and mulching may be contributing to a steady increase in tick numbers by enhancing tick survival. Additionally, overgrown public recreational areas with abundant shade and overhanging branches are where pets and people are increasingly likely to pick up the ticks. (Bill Conroy, Aug 2000). Significant larval tick infestations reported in Sydneys northern suburbs - March 2003 (TAGS tick report, Jan 2003).

half-engorged Ixodes holocyclus female; image source: NF

ALERT- Rickettsia australis, the bacterium responsible for Australian Rickettsial Spotted Fever (="Queensland Tick Typhus") in humans, appears to be very prevalent amongst the tick population of the Pittwater area, just north of Sydney. See also Tick Alert Group Support (TAGS).

DON'T DELAY- even if you merely suspect signs of tick poisoning on your pet, please contact your local veterinarian early! Don't "wait and see".




The Australian Paralysis Tick, Ixodes holocyclus, is an important life-threatening parasite of man and animals. It is also the tick most commonly found on dogs, cats and humans on the East Coast. It's paralysing toxin has been estimated by Stone (1997) to affect as much as 100,000 domestic animals annually, with up to 10,000 companion animals being referred to veterinary surgeons for treatment. In human population health terms, tick envenomation is a far greater medical problem for children than snake or spider bite (Pitt, 1999). Humans also face a small but significant risk of acquiring tick-transmitted infectious diseases.

The aim of this site is to act as a source of information and links concerning recent developments in the prevention and treatment of tick poisoning as caused by Ixodes holocyclus. General information on the biology of the paralysis tick will hopefully also be of interest. The focus is on domestic animals, particularly dogs and cats which seem to be particularly sensitive, but I will also endeavour to collate information pertaining to native animals and humans. Most of the information comes from reputable published sources which have been referenced. I have inserted personal comments, based on direct observations, in square brackets where appropriate.

Please Note. The information presented here is not intended to substitute for professional veterinary, medical or acarological advice.

biology of Ixodes holocyclus

medicine of Ixodes holocyclus

images of ticks




There are a number of links within specific topics, but the following are some general ones:


research on Ixodes holocyclus

  • TREAT AS FOR CHF. Fiona Campbell (University of Queensland) has undertaken measurements of myocardial function before, during and after treatment for tick paralysis. Parameters included thoracic X-Rays, ultrasound, ECG, PCV, and assays of cortisol and adrenaline. This research has so far found evidence of myocardial depression, pulmonary oedema and rising PCV. Systemic hypertension was found not to be a major problem. Respiratory distress was found to be related more to pulmonary oedema and muscular fatigue than to central respiratory depression. Dr Rick Atwell believes that treatment for left-sided heart failure should be considered in all tick cases- eg using vasodilators and diuretics and supplemental oxygen (when it can be delivered in a stress free manner).
  • Stone (1997): "Ixodes holocyclus causes serious losses of livestock and losses and distress to pets and their owners; there may be at least 20,000 domestic animals in Australia affected by tick paralysis per year including at least 10,000 companion animals referred to veterinarians for treatment. Livestock animals are also vulnerable and the deaths of calves in northern New South Wales alone may be about 10,000 per year. There are many other livestock areas along the east coast of Australia where I. holocyclus occurs and adult cattle may also be affected by somewhat heavier infestations as are adult horses, sheep, goats and deer. However, juveniles such as piglets, foals, kids, lambs, and fawns, are at greatest risk. Annually, 100,000 animals or more may be affected to some degree. (BF Stone, unpublished data)."
    According to another source (UTS, 1998): "More than 80,000 cases of tick toxicosis are treated each year in eastern Australia. The worst affected area is Lismore on the NSW north coast, where the paralysis tick has spread through cattle and deer farms as well as many newly introduced livestock species such as alpacas."
  • Pitt (2000). Dr Rob Pitt MBBS FRACP FACEM, Director Paediatric Emergency Medicine, Mater Childrens Hospital in Brisbane (pers com, 1999). This comment naturally refers to areas where the paralysis tick is endemic and common. For full context of this subject see ticks on humans.
  • Tick Alert Group Support (TAGS) provides an information kit on Australian tick-transmitted diseases by writing to: TAGS at PO Box 95, Mona Vale, NSW 1660. The information is particularly relevant to the Northern Beaches area of Sydney.

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