Tiny puncture wounds in the skin inflicted by blood. sucking insects, such as osquitoes, lice, midges, gnats, horseflies, sand flies, fleas, and bedbugs. Some small arachnids (eight-legged animals similar to insects), such as ticks and mites, can?cause similar injuries.
Most bites cause only temporary pain (or itching for a day or two) although some people have severe skin reactions. In the tropics and subtropics, insect bites are potentially more serious because certain biting species can transmit disease (see Insects and disease).
Causes
Insects that bite do so to obtain a blood meal. The mouthparts of biting insects are specially adapted for piercing skin and sucking blood. Insect bites are most common on exposed parts of the head, hands, arms, or legs. Although mosquitoes (which attack mainly after dark) may be the most troublesome biting insects, many bites blamed on mosquitoes are in fact caused by cat or dog fleas. These fleas inhabit various domestic locations where the pet habitually rests (e.g., carpets, sleeping baskets, or sofas); when their normal host is absent, they may jump onto humans to feed.
Of the more easily visible insects, horseflies can produce a particularly painful bite, while gnats can be a menace if encountered in a swarm.
Symptoms
All insect bites provoke a reaction in the skin that is primarily an allergic response to substances in the insect?s saliva or its feces, which are often deposited at or near the site of the bite and rubbed in by scratching. Reactions vary from innocuous red pimples to painful swellings (which may weep) or an intensely itching rash. People vary in their reactions to the same biting insect; in some people the reaction is extremely severe.
Avoidance
Avoiding insect bites can be particularly important for campers and hikers, anyone living in a mosquito infested area, and travelers or residents in tropical countries.?Bites outdoors can be reduced by wearing trousers, socks, and long sleeved?shirts (especially after dark, when mosquitoes are most active), and by using insect repellents. Indoors, bites can be reduced by using insect screens over open windows and by spraying bedrooms with aerosols containing pyrethroid insecticides?before going to bed. If this fails, it may be necessary to use mosquito nets and slow burning antimosquito coils that give off pyrethroids.
Treatment
Bites or bitten areas should be thoroughly washed with soap and water, and a soothing ointment, such as calamine lotion, should be applied. Scratching should be avoided. If there is a severe reaction, a physician should be called; a cream containing an antihistamine may be required.?Severe itching on the scalp or in the pubic hair suggests the possibility of a louse infestation, which is treated with insecticidal lotions (see Lice). In the case of flea bites, the entire residence (not just the pet) may require treatment with insecticide to Kill the flea population. (See also Spider bites; Mites and disease; Ticks and disease.)
Source: http://www.medicalwebbook.com/?p=197
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