The left side of the image is showing the temperature increase caused by an<unk> <unk> after about 28 hours. Low-magnification micrograph showing wedge-shaped perivascular inflammation (superficial dermal perivascular lymphoeosinophilic infiltrate), the histomorphologic appearance of an<unk> <unk> (H&E stain). The reaction to a sting is of three types. The normal reaction involves the area around the<unk> with redness, itchiness, and pain. A large local reaction occurs when the area of swelling is greater than . Systemic reactions are when symptoms occur in areas besides that of the<unk> . With<unk>  stings a large local reaction may occur (an area of skin redness greater than in size). It can last one to two days. It occurs in about 10% of those bitten. Feeding<unk>  Feeding<unk>  have characteristic patterns and symptoms, a function of the feeding habits of the offending pest and the chemistry of its saliva. Pest Preferred body part Felt at time of<unk> Reaction mosquitoes exposed appendages usually not Low raised welt, itches for several hours. midges and no-see-ums exposed appendages usually Itches for several hours. fleas prefer ankles and bare feet usually May make red itchy welt; several days. Later<unk>  are less severe. biting flies (Tabanidae) any exposed skin painful and immediate Painful welt, several hours. bed bugs appendages, neck, exposed skin usually not Low red itchy welts, usually several together resembling rash, slow to develop and can last weeks. lice pubic area or scalp usually not Infested area intensely itchy, with red welts at<unk> sites. larval ticks Anywhere on body, but prefer covered skin, crevices. Usually not; may be scratched off before they are seen. Intensely itchy red welts lasting over a week. adult ticks covered skin, crevices, entire body usually not Itchy welt, several days. May transmit diseases.<unk>  mainly on the trunk and extremities usually not Intensely itchy welts and papules that may last for days. Microscopic appearance The histomorphologic appearance of<unk><unk>  is usually characterized by a wedge-shaped superficial dermal perivascular infiltrate consisting of abundant lymphocytes and scattered eosinophils. This appearance is non-specific, i.e. it may be seen in a number of conditions including: * Drug reactions, * Urticarial reactions, * Prevesicular early stage of bullous pemphigoid, and * HIV related dermatoses.
Insect bites and stings
Shingles
Arthropod bites and stings
Animal bite
Spider bite
Cat bite
Cigarette burns
Dog bite