Bed bug

Bed bugs are parasitic insects from the genus Cimex, which are micropredators that feed on blood, usually at night. Their bites can result in a number of health impacts, including skin rashes, psychological effects, and allergic symptoms. Bed bug bites may lead to skin changes ranging from small areas of redness to prominent blisters. Symptoms may take between minutes to days to appear and itchiness is generally present. Some individuals may feel tired or have a fever. Typically, uncovered areas of the body are affected. Their bites are not known to transmit any infectious disease. Complications may rarely include areas of dead skin or vasculitis.

Bed bug bites are caused primarily by two species of insects: Cimex lectularius (the common bed bug) and Cimex hemipterus, found primarily in the tropics. Their size ranges between 1 and 7 mm. They spread by crawling between nearby locations or by being carried within personal items. Infestation is rarely due to a lack of hygiene but is more common in high-density areas. Diagnosis involves both finding the bugs and the occurrence of compatible symptoms. Bed bugs spend much of their time in dark, hidden locations like mattress seams, or cracks in a wall.

Treatment is directed towards the symptoms. Eliminating bed bugs from the home is often difficult, partly because bed bugs can survive up to approximately 300 days without feeding. Repeated treatments of a home may be required. These treatments may include heating the room to 50 °C (122 °F) for more than 90 minutes, frequent vacuuming, washing clothing at high temperatures, and the use of various pesticides.

Fossils found in Egypt show bed bugs have been known as human parasites for at least 3,500 years. Despite being nearly eradicated in developed countries after World War II, infestations have increased since the 1990s and bed bugs are now relatively common in all regions of the globe. Experts point to several factors that have contributed to the explosion in infestations over the last three decades: increased immigration and international travel; expanded markets for second-hand goods; a greater focus on control of other pests; the banning of certain pesticides and increased resistance to pesticides still in use.

Bed bugs infest dwellings and bite people, causing irritation and sometimes other issues. There is no evidence that bed bugs transmit infectious diseases even though they appear physically capable of carrying pathogens and this possibility has been investigated.

The most common skin findings associated with bed bug bites are itching, flat and bumpy, reddish lesions. Each lesion is about 2–5 mm (0.08–0.2 in) but may be as large as 2 cm (0.8 in) in diameter and there may or may not be a central spot (punctum). Bites are usually present on areas of exposed skin, especially exposed areas not covered by sheets or blankets, such as arms, legs, feet, face or neck. Individual responses to bites vary, ranging from no visible effect (in about 20–70%), to small flat (macular) spots, to the formation of prominent blisters (wheals and bullae) along with intense itching that may last several days. Vesicles and nodules may also form. The lesions due to bites may become secondarily infected due to scratching but systemic effects from bed bug bites are very rare. A central spot of bleeding may also occur due to the release of blood thinning substances in the bug's saliva.

Symptoms may not appear until some days after the bites have occurred. Reactions often become brisker after multiple bites due to possible sensitization to the salivary proteins of the bed bug. Numerous bites may lead to a red rash or hives.

Bedbug bites may cause other symptoms and health issues. Serious allergic reactions including anaphylaxis from the injection of serum and other non-specific proteins have been documented, though rarely. As each bite takes a tiny amount of blood, chronic or severe infestation may lead to anemia. Scratching bites may lead to bacterial skin infection. Systemic poisoning may occur if the bites are numerous. The bite itself may be painful thus resulting in poor sleep and worse work performance.