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".

introduction

IXODES HOLOCYCLUS

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

PHOTOGRAPHS

photographs of adult female Ixodes holocyclus at various stages of engorgement- images total 80k

photographs of adult female Ixodes holocyclus (moderately engorged) - various angles
photographs of adult male Ixodes holocyclus
photographs of adult male compared with adult female Ixodes holocyclus
photographs of nymph stage of Ixodes holocylus
photographs of various forms of Ixodes holocyclus at Dept Of Medical Entomology, Westmead, Sydney
photograph of human tick lesion with associated Rickettsia australis infection
colour photographs of four ticks commonly found in eastern Australia- the "bush tick" Haemaphysalis longicornis, the "cattle tick" Boophilus microplus, the "brown dog tick" Rhipicephalus sanguineus, and of course the "paralysis tick" Ixodes holocyclus
comparison of the brown dog tick with the paralysis tick
picture of a tick (Ixodes scapularis) "questing" at UC Davis website or copied locally (source: Larisa Vredevoe, Deparment of Entomology, University of California, Davis)
photograph of Ixodes holocyclus mouthparts (source: Kelly, 1977)

SKETCHED PICTURES

colour sketches of adult male Ixodes holocyclus compared with adult female
colour sketches of adult female Ixodes holocyclus at various stages of engorgement
colour sketches of nymph stages of Ixodes holocyclus at various stages of engorgement
colour sketches of larval stages of Ixodes holocyclus at various stages of engorgement

DIAGRAMS

diagrams of the basic anatomy of Ixodid ticks in the section "Anatomy"
diagrams of Ixodid visceral anatomy
diagrams of relative sizes of larval, nymphal and adult ticks at various stages of engorgement

links

TICK RELATED LINKS

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

Ulladulla Veterinary Hospital Robert Wylie BVSc QDA - an excellent review from a practitioner with extensive experience with tick paralysis. A very good selection of frequently asked questions (FAQs).
For information about the cattle tick Boophilus microplus see NSW Department of Agriculture.
For information on ticks, mosquitoes and arthropod-transmitted diseases in Australia go to the Department of Medical Entomology, Westmead Hospital, Sydney- Tick Page,
Blue Mountains Veterinary Hospital, with Ross Bennett, also has some information about ticks in that locality.
and Iowa State University's page on images of american ticks at Entomology Image page-ticks,
and Rhode Island University's Tick Research Laboratory page,
The Tolga Bat Hospital, on the Atherton Tablelands near Cairns in Queensland is a centre for the rehabilition of local flying foxes, many of which suffer from tick paralysis.
Tick-transmitted Borreliosis in Europe- site based in Germany

VETERINARY LINKS

The most comprehensive listing of veterinary links I have seen is at the US site NetVet
for Australian veterinary academic links go to the University of Sydney - Faculty of Veterinary Science
for the UK-based links and classifieds go to VetWeb.

LOCAL ILLAWARRA LINKS

For anyone interested in links in the Illawarra, see The Illawarra Link Directory
Some local veterinary websites are at Balgownie Veterinary Hospital and Crown Street Veterinary Hospital
For a brief overview of Wollongong go to the Walkabout travel information page.

research on Ixodes holocyclus

Tick Paralysis Forum See Forum 1 Summary and Forum 2 Summary, July 2000
For specific research in various topics see Current Research.

footnotes

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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