ASSOCIATE PROFESSOR SHERYL VAN NUNEN
Tick-induced Allergies Research and Awareness Centre
It’s the time of year again when the weather starts to warm up, we spend more time outdoors – and suddenly ticks are on people’s minds and bodies again. While for some people a tick bite poses no problem, for others they can be highly toxic or even life-threatening events.
The most common medical problems caused by ticks are allergic reactions – large swellings at the site of the bite. Anaphylaxis to ticks (life-threatening allergic reactions triggered immediately an adult tick is disturbed) and mammalian meat allergy (beginning some weeks to months after bites from nymphs or adults and occurring two to 10 hours after eating mammalian meat or mammalian products), range in severity from gut ache to severe life-threatening anaphylaxis, with four known deaths in Australia due to tick anaphylaxis.
In our region, 95% of tick bites in humans are due to Ixodes holocyclus, or Australian paralysis tick.
ANGEL PUT THIS graphic credit IN SMALL POINT BELOW GRAPHIC
Illustration courtesy of Stephen L. Doggett, Department of Medical Entomology, Westmead Hospital
Mammalian meat allergy was first described by Professor Sheryl van Nunen and colleagues in 2007. The Sydney Basin has the highest estimated prevalence of mammalian meat allergy in the world – 113/100,000 compared to Southeastern USA with 11/100,000 and Germany 4/100,000. Blame a potent mix of humid micro-climate conditions (which ticks thrive on) particularly on the Peninsula as well as an increase in tick host numbers and increasingly more people living in tick host regions like ours.
For those with this meat allergy, vent the mere act of turning on the family barbecue is enough to trigger a meat allergy reaction.
“It’s what we call an emergent allergy,” she said, “because only very few cases had been seen until about 2003 onwards when a remarkable increase in cases occurred.” Cases of this allergy have now been reported in North America, Europe, Korea and Japan, Panama and Africa‘s Ivory Coast. Mammalian meat allergy is the only allergy where we know what has caused the allergy – a tick bite!
So prevention is key, because a single tick bite can be sufficient to generate these allergies in those susceptible.
TICK BITE PREVENTION
If you live in a tick infested area, precautions are crucial if tick-induced allergies are to be prevented, so:
- Dress for the occasion
*Buy light coloured clothing so you can see ticks.
* Use permethrin-treated clothes – it is a pesticide. Tuck your permethrin-treated long-sleeved T shirt, fitted at the wrist, into your permethrin-treated long trousers and tuck your trousers into your permethrin treated socks! But them in shops or online at Safari, Craghoppers, Anaconda or Kathmandu.
*Apply a longer acting insect repellent (DEET or Picaridin) to areas which remain unprotected by the above.
- Treat your back yard
And consider making it less friendly to ticks e.g. remove leaf litter, decrease the humidity by removing overhanging branches and keep the lawns mown to reduce tick havens.
*Don’t scratch anything you can’t see (because it could be a tick)
*Don’t disturb a tick (because the tick will squirt allergen into you if you do)
*Kill the tick where it is so it can’t squirt allergen into you i.e. “Freeze it, don’t squeeze it!”
Ask your pharmacist for advice about freezing agents available.
Spray the tick with freezing agent (don’t use the applicators) five times from about 0.5cm above the tick to kill it (so you don’t disturb it) and then wait for it to drop off and that’s the safest way to deal with an adult tick.
For small ticks, larval ticks and nymphs, “Dab it, don’t grab it!” by using permethrin cream and again leave it drop off if possible, so it cannot be squeezed. Don’t squeeze a tick, because you’ll squeeze allergen into yourself – household tweezers are tick squeezers!
- It’s not just about the meat for those severely affected
As the allergen in the meat (alphagal) occurs in lots of medicines, vaccines, snake anti-venene and some heart valve prostheses, treatments which could otherwise save your life or keep you more healthy could give you a nasty allergic reaction if you develop a severe allergy to mammalian meat.