Ticks
| Auteur: | Microbiology and Immunology on-line University of South Carolina |
| Tags: | Foto's/dia's Lessen/cursussen Leerboek Parasieten Hoger onderwijs Middelbaar onderwijs Engels Medisch/Veterinair |
| Bron: | http://pathmicro.med.sc.edu/parasitology/ticks.htm 
Melding defecte link. |
Ticks are found worldwide. They are blood-sucking, opportunistic parasites that can attach to the skin of a variety of vertebrate hosts. They have no segmentation and are dorso-ventrally flat with four pairs of legs (figure 1). Although all stages of the tick life cycle can suck blood, it is normally the adult tick that poses a problem for humans. Human tick-associated diseases are most common in the summer months when the likelihood of contact increases during outdoor activities, usually in wooded areas. Being bitten by a tick is often painless and the presence of the tick may not be detected for some time. Often the tick poses no problem for the human host other than an erythromatous papule and it drops off after engorging on blood. Sometimes, the site of attachment may itch and become painful. Secondary infections of the wound site may occur, often as a result of the mouthparts remaining attached after the tick is removed. Ticks can attach anywhere on the body but are frequently found at the hairline, around the ears, groin, armpits etc. Whilst the bites of most ticks are inconsequential, they can carry a number of human disease agents including viruses, bacteria and protozoa. There are two families of ticks: the hard ticks (Ixodidae) and the soft ticks (Argasidae) (figure 1). The Ixodidae attach to their host over a prolonged period of time (several days) while the Argasidae feed rapidly and then drop off. Consequently, they are frequently undetected. Although most tick-associated problems arise from disease-causing organisms carried by the ticks, in one case – tick paralysis – the problem arises directly from toxins in the tick’s saliva.
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