Like other arachnids (e.g. spiders, scorpions and mites), ticks have eight legs. They pass through a number of life stages from egg, to larva, to nymph and then finally, the adult. Adult ticks (present in Australia between around August to February) cause problems to its human and animal hosts.
Ticks do not sting
Adult ticks attach themselves to the
tips of grass blades and vegetation, and transfer themselves to
passing animals or human. When humans are infested, the tick usually
crawls up inside clothing. Adult ticks attach themselves strongly
to their host by biting through the skin, and generally lodge
in the skin of the head or neck. The most common reaction is local
irritation and swelling. Tick saliva can also transmit infection,
and contains toxic proteins that can cause paralysis, and proteins
capable of triggering allergic reactions.
Tick Allergy
Minor local itching and swelling is
common at the site of a tick bite. Serious allergic reactions
(such as tick anaphylaxis) have also been described, in response
to a number of species of ticks, including the so-called Australian
paralysis tick, Ixodes holocyclus. Most reactions occur
when the tick is disturbed, such as scratching the bite site,
or after attempts to remove it. This has implications for what
should be done when a tick is discovered (see below).
Diagnosis and management of tick allergy
At this time, there is no reliable
skin or blood allergy test to confirm a diagnosis of tick allergy.
Limited research suggests that the allergen causing problems is
a salivary protein. Diagnosis is therefore based on the history
of the reaction. Management involves avoidance of ticks where
possible, and knowing what to do if bitten again. There is currently
no commercially available extract to use for immunotherapy/desensitization
to switch off the allergy.
Tick paralysis
This is beyond the scope of this article.
Further information can be obtained at:
o Medline
Plus
o Ulladulla
Veterinary Hospital
Ticks as a source of infectious disease
Ticks can transfer infection is from
animals to human hosts, such as Lyme disease or Spotted Fever.
This is beyond the scope of this article, but useful information
can be found by contacting:
o TAGS (Tick Alert
Group Support Inc., PO Box 95 Mona Vale, NSW 1660
o The Tick-Borne Diseases Research Unit, Royal
North Shore Hospital, Pacific Highway, St Leonards NSW 2065.
o American Centre
for Disease Control
o Medline
Plus
Reducing the risk of tick bites
The following measures may reduce the
risk of tick bite:
o Wear long-sleeved shirts and long trousers when walking in areas
where tick occur
o Tuck trouser legs into long socks
o Wear a hat
o Wear light clothes; this makes it easier to see ticks
o Brush clothing before coming inside to remove ticks
o Undress and check for ticks daily, checking carefully in the
neck and scalp
o An insect repellant may help, particularly ones containing DEET
(eg. Rid, Rid Tropical)
o In those allergic to ticks, carrying a spray can of "Aerostart"
(see below), emergency medication (EpiPen) and a means of summoning
assistance (such as mobile telephone), are essential components
of management.
What
to do when you are allergic to ticks and find one
Disturbing the tick can result in the
injection of allergen, and can trigger an allergic reaction. The
following steps are recommended:
o Do not forcibly remove the tick*
o Do not try to kill the tick using insecticide or chemicals
(eg. oil, turpentine, methylated spirits)
o Do kill the tick by spraying it with "Aerostart",
an ether-containing spray that freeze-dries the tick and kills
it instantly. This allows the tick to fall out without being able
to inject allergen-containing saliva. "Aerostart"
can be purchased from hardware stores and some service stations,
and is commonly used by mechanics to clear carburetors.
o Use EpiPen if potentially dangerous allergic symptoms occur.
o Seek medical attention in case additional treatment is required.
* Special Note
Whether to kill or remove ticks first, commonly causes confusion.
In part, this is because most of the literature is concerned with
reducing the risk from tick paralysis, rather than preventing
allergic reactions. In the past, it was often recommended that
ticks be killed first before removing them, to reduce the risk
that they would inject toxin and trigger paralysis. It was later
realized that ticks poisoned with insecticide or spirits did not
die immediately, and that such chemicals could actually disturb
them enough to inject more toxin. Currently, most writers concerned
with tick paralysis or tick-borne infection recommend that ticks
be removed using physical means only (e.g. using
special forceps . This is NOT appropriate for allergic patients!
The author of this article does not recommend any method other
than using "Aerostart" (or similar product) as described
above for patients with known tick bite allergy or tick anaphylaxis.
Additional Web links
NSW
Department of Health 2004 article
Australian Venom Research Unit, Department of Pharmacology, University of Melbourne
CSIRO Australia Entomology
University
of Sydney Department of Medical Entomology Additional information
References
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