Ticks

Description

Ticks are small, round, parasitic arachnids that cling to one spot on their host, insert their head under the skin and engorge themselves on blood.   Every class of terrestrial vertebrate animal, including amphibians (and Fit Frogs), can get a tick parasite.  There are over 850 different species of ticks in two main groups.  Soft ticks, the argasids, are distinguished by their soft, leathery cuticle and by having mouthparts that are on the underside of the tick. Soft ticks are fast feeders and blow up like a balloon when engorged with blood. Hard ticks, the ixodids, have a hard plate on the dorsal surface and have terminal mouthparts.  This type of tick slices open the skin with its mouthparts and then attaches itself by secreting a cement that hardens and holds the tick to the host. Hard ticks are slow feeders, taking several days to finish their meal.  A tick may extract up to 8 ml (100x their body weight) of blood during a feeding. Interestingly, they concentrate the blood during feeding and will return much of the water to the host.

 Life Cycle

All ticks have four life cycle stages. The female tick must have a blood meal in order for eggs to develop. The eggs are laid in soil or leaf litter after the female drops off the host. These eggs hatch into larvae. The larva is the smallest stage and can be recognized by having only 3 pairs of legs. These ‘seed ticks’ are produced in great numbers. They must find a host and take a blood meal in order to moult to the next stage called the nymph. If the nymph can feed on a host, it will develop into the adult tick. Ticks vary greatly in how long this cycle takes and the number of hosts involved. Some ticks are one host ticks, others use multiple hosts.

Rocky Mountain Wood Tick (Dermacentor andersoni )

This tick is found from northern Arizona and northern New Mexico to British Columbia, Alberta, and Saskatchewan.  Immature ticks feed mainly on small mammals such as ground squirrels and chipmunks, whereas adult ticks feed on cattle, sheep, deer, humans, and other large mammals.  Their habitat is primarily fields and forested areas where there is brushy vegetation that encourages the small mammal hosts of immature ticks and sufficient forage to attract the large hosts of the adult ticks.

Females lay about 4,000 eggs in plant debris on the soil or in crevices, usually in masses of hundreds at a single location. Unfed larvae may live for 1-4 months, nymphs for 10 months, and adults for more than 12 months. Adults and nymphs can be found from March to mid- summer. Larvae are active throughout the summer and are associated with cool soil temperatures, shallow soil, abundant leaf litter, and high relative humidity.
Where you pick up ticks

Ticks prefer to hide in shady, moist ground litter, but can often be found above the ground clinging to tall grass, brush, shrubs, and low tree branches. They also inhabit lawns and gardens, especially at the edges of woodlands and around old stone walls.

Juvenile ticks usually live in the soil or at ground level. They will then climb up onto a blade of grass or the leaf of a plant to await a potential host. They will sense the presence of a host and begin standing up and waving their front legs. They are able to sense vibration, a shadow, changes in CO2 level, or temperature change. If they are unable to find a host they become dehydrated and climb back down the plant to the ground to become re-hydrated. Then back up the plant until they are successful or they die.

 Personal Protection

The best precaution against ticks is to avoid contact with soil, leaf litter, and vegetation as much as possible. Ticks cannot jump or fly, and will not drop from an above-ground perch onto a passing animal. People acquire ticks only by direct contact with them. Ticks don’t attach themselves right away. Once a tick gains access to human skin it generally climbs upward until it reaches a more protected area, often the back of the knee, groin, navel, armpit, ears, or nape of the neck. It then begins the slow process of embedding itself in the skin. It is much easier to remove ticks before they attach, and easier to remove newly attached ticks than ones that have been feeding for a while.

  • Wear light-coloured clothing with a tight weave to spot ticks more easily and prevent contact with the skin.
  • Wear long pants tucked into socks, long-sleeved shirts tucked into pants, and enclosed shoes or boots in conjunction with insect repellent.
  • Spray clothes with insect repellent containing either DEET or Permethrin (only DEET can be used on exposed skin, but never in high concentrations; make sure to follow the manufacturer’s directions carefully).
  • Wear a hat and keep long hair pulled back.
  • Stay on cleared, well-worn trails when ever possible.
  •  Spot-check yourself and others frequently for the presence of ticks on clothes; if you find one, there are likely to be others – check thoroughly.
  • Remove clothes after leaving tick-infested areas and, if possible, wash them to eliminate any unseen ticks.
  •  Check yourself, your children, and any pets from head to toe for the presence of ticks.
  • Shower and shampoo.

Removing a tick

To remove a tick, grasp it crosswise with narrow tweezers (do not rupture the tick) as close to the point of attachment as possible and pull s-l-o-w-l-y and gently, and the mouthparts will release. Some back-and-forth wiggling may be necessary but do not twist or rotate the tick. You should see a small crater in the skin. Disinfect the bite site and wash hands thoroughly with soap and water.

If you see what looks like black lines, you’ve left the head of the tick in. At this point you should visit a doctor as the head parts may lead to an infection. Ticks carry diseases, including Lyme’s disease and Rocky Mountain Spotted Fever, so you should wash your hands thoroughly with soap after handling a tick.

 Tips:

  • Don’t use any of the folklore remedies (matches, cigarettes, pins, gasoline) that will irritate the tick. They increase the likelihood that the tick will ‘spit up’ in you, which increases the risk of disease.
  • Oil is not effective because the breathing requirements of the tick are so small it could last hours.
  • The mouthpiece is barbed rather than spiralled, so trying to rotate the tick out doesn’t help.

Disposing of ticks

To dispose of a tick, drop it into alcohol to kill it, then dispose of it. Flushing them down the toilet will not kill them. Squishing them with a thumbnail is not recommended.  If you have been bitten, then save the tick in a jar of alcohol for identification, to help decide whether possible infection has occurred.

Role in diseases

Ticks are the usual vector for Rocky Mountain Spotted Fever and Lyme’s Disease. These diseases are usually successfully treated with antibiotics in their initial stages so early diagnosis is imperative. For this reason, it is recommended that the date of a tick bite be marked on a calendar.  A physician should be consulted if unexplained symptoms occur within two to three weeks.

The best means to prevent the transmission of tick-borne diseases is the prompt removal of ticks. This requires regular inspection of clothing and exposed skin for attached or unattached ticks.