Ticks

Structure and Physiology:

Ticks suck the blood of a few vertebrates including humans. they are opportunistic rather than host specific and tend to suck blood from a number of large and small animals.

Ticks have four stage life cycle; egg, larva, nymph and adult. Although the larva, nymph and adult are all bloodsuckers, it is the adult tick that usually bites humans.

Ticks comprise two large families;Ixodidae (hard ticks) and Argasidae (soft ticks). Soft ticks have a leathery body that lacks a hard dorsal plate and the mouthparts are located ventrally and are not visiable, futhermore, they complete engorgement in a matter of minutes or a few hours. Hard ticks, on the other hand, have a hard dorsal plate and the mothparts are clearly visible, moreover, they take 7-9 days to digest the food.Similarilary, both hard and soft ticks serve as ectoparasites of humans.

taken from: https://www.lymediseaseaction.org.uk/image/soft_and_hard_ticks.htm

Clinical Syndromes:

Ticks may attach in any parts of the body but they favout the scalp hairline, ears, axillae and groin. The initial bite is usually painless, and the presence of the tick may not be detected for several hours of contact. After the tick has dropped off or has been removed manually, the area may become reddened, painful and pruitic. If the mouthparts remain attached after manual removal, the wound may become secondarily infected and necrotic.

There are 3 species of tick, D. andersoni, D.variabilis and A. americanum have been reported to cause tick paralysis. Tick paralysis is caused by an increase flaccid paralysis, fever, general intoxication which may lead to respiratory compromise and death. The paralysis is caused due to the toxic substances released in the saliva of the tick and may be reversed by tick removal.Tick paralysis is commonly found in young children when the tick attachment opposes to the central nervous system such as scalp, head and neck.

Ticks can also transmit infections, for example, Lyme disease, Rocky Mountain spotted fever, ehrlichiosis, Colorado tick fever and etc.

Treatment, Prevention and Control:

• It is important that attached ticks are removed earlier and may be accomplished by steady traction on the tick body. It is advisable to graspe the tick by forceps as close to the skin as possible. Avoid twisting or crushing the tick which would lead to the attachment of the mouthpart to the skin thus inject potentially infectious material into the wound. After removing the tick, the wound should be cleansed and observed for secondary infection as ticks may habour highly infectious agents. Moreover, the clinician should use appropriate infection control precautions such as usage of gloves, hand washing, proper disposal of ticks and contaminated material.
• Preventive measure used in tick-infested areas include wearing of protective clothing that fits perfectly about the ankles, wrists, waist and neck to reduce the changes of ticks gaining access to the skin.
• People and pets should be inspected for ticks after visits to tick-infested areas.