Paralysis tick

(Ixodes holocyclus)

Importance and impact of paralysis tick on cattle

  • A single engorged adult female paralysis tick can produce sufficient toxin to paralyse a young calf. See tick paralysis.

Nearly 70 species of ticks worldwide are capable of causing paralysis. In Australia, the most common paralysis tick is Ixodes holocyclus, or the eastern Australian paralysis tick, and it is the cause of tick paralysis in thousands of domestic animals each year, including cattle.

Another close relative, Ixodes cornuatus, commonly known as the southern or Tasmanian paralysis tick also has documented cases of paralysis in some companion animals. It is likely that other Ixodes-type ticks may also be involved in causing paralysis but data and research in this area are lacking.

Life cycle type

3 host tick. Larvae, nymphs and adults attach and feed on different hosts.

Host

Bandicoots are the preferred host of paralysis tick. They also infest numerous other native hosts including bettongs, koalas, flying foxes, echidnas and birds as well as domestic animals including cattle, and humans.

Average time spent on host

Only adult female ticks produce sufficient toxin to affect cattle. After mating the adult female starts feeding and may engorge for a period of 6 to 21 days (average around 10 days). Signs of paralysis take a minimum of 4 days to appear and may take as long as 3 weeks.

Male paralysis ticks have short mouth parts and don’t feed from the host although they may feed from the female tick. They are usually found in close proximity to the female.

Life stages

  • Engorged females drop off the host and lay 2000 to 5,000 eggs (many won’t survive) in leaf litter under trees and shrubs then they die.
  • Eggs take 60 to 100 days to hatch into larvae depending on temperature and humidity.
  • The larvae mature in 1 to 4 weeks then quest for a host from the tips of leaves. Once attached to a host they feed for up to 6 days then drop to the ground.
  • The engorged larva takes 3 to 6 weeks to moult into a nymph.
  • 5 to 6 days after moulting, the nymphs attach to another host, feed for about a week then drop to the ground.
  • The engorged nymph takes 3 to 10 weeks to moult into an adult.
  • Adults usually attach to a new host about a week later and feed for 6 to 21 days.
  • The full life cycle can be completed in as short as 4 months or as long as 18 months depending on temperature and humidity (usually takes about a year).

Location on animal

  • Paralysis ticks can attach anywhere but they are generally found around the head and neck area.
     

Figure 1. Paralysis ticks feeding on a cow. Image courtesy of Lex Turner.
Figure 1. Paralysis ticks feeding on a cow. Image courtesy of Lex Turner.
Figure 2. Geographic distribution of paralysis ticks in Australia. Image courtesy of Virbac.
Figure 2. Geographic distribution of paralysis ticks in Australia. Image courtesy of Virbac.

Seasonality

  • Larvae rise in autumn.
  • Nymphs peak autumn to spring.
  • Adult numbers peak August to December and up to February (late spring and summer).

Warm humid conditions are required for tick survival. Temperatures around 27°C with high humidity are ideal. High temperatures (high thirties and over) and low temperatures (single digit figures) for several days can be fatal to all stages of the tick.

Figure 3. Engorged adult female paralysis tick. Image courtesy Greta Busch.
Figure 3. Engorged adult female paralysis tick. Image courtesy Greta Busch.

Diagnosis

Adult female paralysis ticks are relatively easy to distinguish from non-paralysis inducing species of ticks based on the following features. See also the tick identification guide.

  • They have different coloured legs with the front and back pairs being darker than the middle 2 pairs.
  • Their legs are close to their mouth parts and form a V shape line from the snout.
  • Their large, prominent mouth parts leave a crater at the site of attachment.
  • They have a pear shaped body that is yellow-grey to light grey in colour with black bands on the side (Figure 3).

 

Follow these links to read more about paralysis tick treatment and management.