Bed bugs are a type of insect that feed on human blood, usually at night. Their bites can result in a number of health effects including skin rashes, psychological effects and allergic symptoms. Bed bug bites may lead to skin changes ranging from invisible to prominent blisters. Symptoms may take between minutes to days to appear. Itchiness is common, while some may feel tired or have a fever. Typically, uncovered areas of the body are affected and three bites occur in a row. Bed bugs bites are not known to transmit any infectious disease.
Bed bug bites are caused primarily by two species of the insect Cimex: Cimex lectularius (the common bed bug) and Cimex hemipterus. 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 the wall.
Treatment is symptomatic. Eliminating bed bugs from the home is often difficult, partly because bed bugs can survive up to a year 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.
Bed bugs occur in all regions of the globe. Rates of infestations are relatively common, following an increase since the 1990s. The exact causes of this increase is unclear; with proposals including greater travel, more frequent exchange of second-hand furnishings, a greater focus on control of other pests, and increasing resistance to pesticides. Bed bugs have been known human parasites for thousands of years.