QUEENSLAND |
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74 Kallista
Rd |
email qldbwc@yahoo.com |
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Ticks
(On a few of our recent walks some of our members have fallen victim to
"Scrub Itch". Many thanks to Lynn Cavanagh who has given the Club the
following information.)
"Scrub Itch" is caused by the larvae and nymph stage of the Paralysis Tick (Ixodes holocyclus). It produces an itchy red rash soon after bushwalking and can be very irritating. But first a little about the tick itself.
The tick has minimal effect on native animals but causes paralysis in others. It is a serious pest and can kill cattle and small domestic animals. Some human deaths have been recorded from the Paralysis Tick, mainly in young children.
It is a three-host tick with the larva and nymph requiring a blood meal to moult to the next stage.
Typically larvae occur late February to April-May, followed by nymphs up to September-October. The adult tick population increases to a peak around December. Under favourable conditions a second cycle may result in a second peak in May. However infestations by adults can occur at any time of the year when conditions are suitable, even mid winter.
The adult female can lay 2,000 to 6,000 eggs. It lays them into moist vegetation over a period of 2-5 weeks, and then dies.
The hatched larva climbs vegetation and attaches to a passing host (the 1st). It feeds for 4-6 days and then falls to the ground. It then moults to a nymph. Larvae are just visible to the naked eye, 0.5 x 0.4 mm (unfed) to 1.15 x 1.0 mm (engorged).
Nymphs are very active and readily attach to another host (the 2nd). After feeding they fall to the ground. Nymphs are 1.2 x 0.85 mm (unfed) to 3.5 x 2.5 mm (engorged), less than the size of a match head.
Newly moulted adult females seek and attach to another host (the 3rd). They engorge for a period of 6-30 days. Male ticks after crawling onto a host do not attach or feed on blood. Rather they wander over the host in search of unfertilized females. Adult ticks are match head up to large pea size.
The tick bite is usually surrounded by an area of redness which progresses over days to a firm swelling. The lump may remain for several weeks or months even after the removal of the tick.
Ticks may also carry other diseases such as Tick Typhus caused by a Rickettsial organism and Lyme Disease which fortunately is rare in Australia.
o Remove the tick as soon as possible
o Use fine-point tweezers or a tick remover
o Grasp the tick as close to the skin as possible
o Gently pull the tick straight out with steady pressure
o If you have any difficulty seek medical attention
o Wash your hands, disinfect the bite and tweezers
o CHILDREN: tell them to seek adult help for proper tick removal
Do not grasp the body of the tick and pull as this can cause the tick to inject more toxin.
Note: TAGS does not recommend killing the tick before removal in humans. The fear is that applying chemicals may only irritate the tick and increase the risk of injecting more toxin.
Other sources recommend killing the tick before removal with alcohol, methylated spirits, turpentine, pyrethrin, kerosene etc. If a tick has been killed with some chemical, then it will desiccate and shrivel and fall off or be readily scrapped off after some time.
The Department of Medical Entomology states that a small amount of repellent containing DEET can be applied over the body of the attached tick before removal. This will kill the tick within 20-30 minutes.
Ticks occur in moist sheltered bushy areas. They may drop on clothing as you brush against shrubbery, or drop from overhanging branches. Ticks like weedy areas, especially lantana.
Dress appropriately for bushwalks. Wear a wide-brimmed or floppy hat, long-sleeved shirt, and long trousers tucked into socks. Ticks are more easily seen on light coloured clothing.
Spray clothes and hat with insect repellant brands containing pyrethrum/pyrethroids, preferably the night before wearing. Pay attention to openings (eg collar, cuffs, fly) and hang on a coat hanger to dry or treat clothing with permethrin which will endure up to 7 washings.
Use insect repellant with DEET on exposed skin. Most common insect repellants contain DEET (eg Aerogard, Rid). DEET is apparently the most effective topical insect repellent for humans.
Check clothing before entering the house. Remove clothing to check for ticks. Pay attention to head, behind ears, groin, armpits and back of knees. It is a good idea to use a set of "outdoor" clothes which can be promptly removed (and ideally washed in hot water) once inside the house.
Be careful where you put the clothing e.g. it may introduce ticks into your bedroom, carpeted areas, sofas etc.
The best means of tick prevention is to avoid the areas where they are. If you can, walk on the wider tracks and avoid brushing the vegetation along the edges. Because animals often traverse the edges of clearings, these tend to be hot tick spots.
Larvae and nymphs as well as adults are capable of causing allergic reactions. Redness, swelling and a maddening itch may develop within 2-3 hours of attachment of even one larva. When large numbers of larvae are involved severe allergic dermatitis can occur. The rash that results is commonly referred to as "Scrub Itch". Outbreaks are seasonal in southeast Queensland and occur most commonly during January, February and March when larval populations are at their peak.
Multiple tick bites of the larval stage are best removed if you soak for 30 minutes in a bath with 1 cup of bicarb soda (recommended by TAGS).
"Scrub Itch" is caused by the larvae and nymph stage of the Paralysis Tick (Ixodes holocyclus). It produces an itchy red rash soon after bushwalking and can be very irritating. But first a little about the tick itself.
Adult Paralysis Tick
The tick has minimal effect on native animals but causes paralysis in others. It is a serious pest and can kill cattle and small domestic animals. Some human deaths have been recorded from the Paralysis Tick, mainly in young children.
Life cycle
The life cycle consists of four stages - egg, larva, nymph and adult. Larvae have three pairs of legs and the nymphs and adults four pairs of legs.It is a three-host tick with the larva and nymph requiring a blood meal to moult to the next stage.
Typically larvae occur late February to April-May, followed by nymphs up to September-October. The adult tick population increases to a peak around December. Under favourable conditions a second cycle may result in a second peak in May. However infestations by adults can occur at any time of the year when conditions are suitable, even mid winter.
The adult female can lay 2,000 to 6,000 eggs. It lays them into moist vegetation over a period of 2-5 weeks, and then dies.
The hatched larva climbs vegetation and attaches to a passing host (the 1st). It feeds for 4-6 days and then falls to the ground. It then moults to a nymph. Larvae are just visible to the naked eye, 0.5 x 0.4 mm (unfed) to 1.15 x 1.0 mm (engorged).
Nymphs are very active and readily attach to another host (the 2nd). After feeding they fall to the ground. Nymphs are 1.2 x 0.85 mm (unfed) to 3.5 x 2.5 mm (engorged), less than the size of a match head.
Newly moulted adult females seek and attach to another host (the 3rd). They engorge for a period of 6-30 days. Male ticks after crawling onto a host do not attach or feed on blood. Rather they wander over the host in search of unfertilized females. Adult ticks are match head up to large pea size.
Tick bites
The bites of ticks can go unnoticed at first. They do not seem to deliberately attach to bodily recesses but tend to be found in such areas as they are less likely to be brushed off eg behind the ears and the scalp.The tick bite is usually surrounded by an area of redness which progresses over days to a firm swelling. The lump may remain for several weeks or months even after the removal of the tick.
Ticks may also carry other diseases such as Tick Typhus caused by a Rickettsial organism and Lyme Disease which fortunately is rare in Australia.
Removal of ticks.
TAGS (Tick Alert Group Support, Australia) gives the following recommendations (2000):o Remove the tick as soon as possible
o Use fine-point tweezers or a tick remover
o Grasp the tick as close to the skin as possible
o Gently pull the tick straight out with steady pressure
o If you have any difficulty seek medical attention
o Wash your hands, disinfect the bite and tweezers
o CHILDREN: tell them to seek adult help for proper tick removal
Do not grasp the body of the tick and pull as this can cause the tick to inject more toxin.
Note: TAGS does not recommend killing the tick before removal in humans. The fear is that applying chemicals may only irritate the tick and increase the risk of injecting more toxin.
Other sources recommend killing the tick before removal with alcohol, methylated spirits, turpentine, pyrethrin, kerosene etc. If a tick has been killed with some chemical, then it will desiccate and shrivel and fall off or be readily scrapped off after some time.
The Department of Medical Entomology states that a small amount of repellent containing DEET can be applied over the body of the attached tick before removal. This will kill the tick within 20-30 minutes.
Prevention
(TAGS recommendations, 2000)Ticks occur in moist sheltered bushy areas. They may drop on clothing as you brush against shrubbery, or drop from overhanging branches. Ticks like weedy areas, especially lantana.
Dress appropriately for bushwalks. Wear a wide-brimmed or floppy hat, long-sleeved shirt, and long trousers tucked into socks. Ticks are more easily seen on light coloured clothing.
Spray clothes and hat with insect repellant brands containing pyrethrum/pyrethroids, preferably the night before wearing. Pay attention to openings (eg collar, cuffs, fly) and hang on a coat hanger to dry or treat clothing with permethrin which will endure up to 7 washings.
Use insect repellant with DEET on exposed skin. Most common insect repellants contain DEET (eg Aerogard, Rid). DEET is apparently the most effective topical insect repellent for humans.
Check clothing before entering the house. Remove clothing to check for ticks. Pay attention to head, behind ears, groin, armpits and back of knees. It is a good idea to use a set of "outdoor" clothes which can be promptly removed (and ideally washed in hot water) once inside the house.
Be careful where you put the clothing e.g. it may introduce ticks into your bedroom, carpeted areas, sofas etc.
The best means of tick prevention is to avoid the areas where they are. If you can, walk on the wider tracks and avoid brushing the vegetation along the edges. Because animals often traverse the edges of clearings, these tend to be hot tick spots.
Scrub Itch
While bushwalking, any disturbance of taller plants (especially during damp summers) can produce a shower of tick larvae.Larvae and nymphs as well as adults are capable of causing allergic reactions. Redness, swelling and a maddening itch may develop within 2-3 hours of attachment of even one larva. When large numbers of larvae are involved severe allergic dermatitis can occur. The rash that results is commonly referred to as "Scrub Itch". Outbreaks are seasonal in southeast Queensland and occur most commonly during January, February and March when larval populations are at their peak.
Multiple tick bites of the larval stage are best removed if you soak for 30 minutes in a bath with 1 cup of bicarb soda (recommended by TAGS).
Notify any errors to qldbwc@yahoo.com
Last Updated 2009-04-10
