Cimex lectularius, the bed bug, infests people, other mammals, especially bats, and birds around the world, including in Canada. Several other species of cimicid bugs occur on mammals and birds, but very rarely on people.  Infestation of domestic animals with any cimicid is very rare.  Anecdotal evidence suggests that people can readily acquire Cimex species (not C.lectularius) from bats.  Around the equator, a closely related species - Cimex hemipterus - also occurs.

The life cycle stages of Cimex species - adults, eggs, and nymphs - inhabit bedding, cracks in walls, and other sheltered refugia, where adults can survive for several weeks.  Adults and nymphs emerge from the refugia only to find a host, blood feed, and mate.  The feeding is essential for reproduction and development.  The bugs produce pheromones that attract other bugs to the host and others that signal alarm, causing the bugs to scurry back to their refugia, and bug-infested rooms have a characteristic musty smell. 

Other than the transmission of a few organisms mechanically, bed bugs are not considered important as pathogen vectors.  Their major pathogenic effects include discomfort and irritation associated with the bites (female bed bugs feed for up to 20 minutes approximately once a week), the risk of secondary infections in the bite wounds.  Bed bugs can also interfere with sleep and cause significant psychological stress in people.

In recent decades there has been a massive increase in bedbug populations, especially in the developed world, notably in hotels!  There are many probable reasons for this, including a lack of awareness of bed bugs and the problems they can cause, international travel involving exposure to the bugs (bed bugs can easily be translocated in suitcases, buses and taxis), as well as modern building techniques that facilitate local dispersion, and the frequent difficulties in achieving satisfactory bug control.  These population increases mean that bed bugs have become a major current public health problem.