There are >90 species in the family Cimicidae. Most are associated with birds and/or bats and rarely bite humans. The common bed bug, Cimex lectularius, has been associated with humans at least for centuries and is cosmopolitan. The tropical bed bug, Cimex hemipterus, also feeds on humans and is similar in appearance to C. lectularius. It is common in tropical areas of Asia, Africa and Central and South America.
Bed bug infestations are typical of cluttered and unsanitary conditions, but greatly improving sanitation alone will not significantly reduce their numbers. They can be found in many developed countries and seem to be spreading and increasing in number wherever they occur.
Humans’ reactions to bed bugs’ bites is individual and usually increases in severity with greater numbers, or more frequent, or repeated bites. Bite reactions may be immediate or delayed (up to 18 days), or an individual may have both an immediate and delayed reaction to any given bed bug bite (or biting incident). Bites can be very irritating, prone to secondary infection after scratching, and may develop into hard swellings, welts, or even blisters (papules). Bed bugs feed at night while their hosts are sleeping but will feed during the day if conditions are favorable or if they become very hungry.
During the day they typically hide in cracks and crevices, under or in mattress seams, spaces under baseboards, or loose wallpaper. Chronic exposure to bed bugs may result in insomnia, nervousness and fatigue. Some studies have found that a high percentage of asthmatic patients had positive skin reactions to Cimex antigen.
There are 5 nymphal instars and each must take a bloodmeal to develop to the next stage. Adults have been reported to live 3-12 months in an untreated household situation. A given undisturbed bug may take 3-15 minutes to take a full bloodmeal depending on its life stage. They can survive long periods of time without feeding, reappearing from their hiding places when hosts again become available. They have special scent glands and often emit a characteristic odor that can usually be detected in heavily infested sites. Dark fecal spots on bedding or bedclothes, pearly-white eggs (1 mm long), and papery yellowish cast “skins” are other signs of infestation often found in cracks or crevices.
Bed bugs can be introduced into homes on infested baggage, bedding and belongings. They may pass from the clothing of one person to another on crowded public vehicles. In contingency situations, old dwellings should be surveyed for these and other pests before they are occupied.