Bedbugs

The common bed bug, Cimex lectularius, is an exclusively hematophagous, 1-7 mm large, ectoparasite that belongs to the family Cimicidae. It occurs in subtropical and temperate zones. Cimex lectularis had practically disappeared in Central Europe by the 1950s, probably due to an improvement in general hygiene in homes and the effective use of DDT and other organochlorine compounds. Bed bugs have a life span of 4-6 months, during which the females lay 50-200 eggs. As developmental stages they need blood from humans or other mammals, including birds.

Since the early 1990s, bedbugs have been increasingly found in Central Europe again (Egg M et al. 2024). The worldwide reappearance concerned two species, C. lectularius and C. hemipterus. The latter is possibly regularly introduced by travelers from tropical to temperate regions, but the winter months in Central Europe are probably too cold for the species to become established there. The prevalence of C. hemipterus is much lower than that of C. lectularius. The reasons for the resurgence are controversial, but resistance to insecticides appears to be the main factor, along with the increase in international traffic due to tourism and trade.

Bedbugs nest mainly in dark cracks in furniture, walls and behind pictures in neglected rooms. They feed every 3-5 days at night. Survival times of several months without blood meals are possible (Egg M et al.2024). The saliva secretion injected with the bite causes an initially urticarial, later papular or bullous skin reaction. The bite marks typically occur on uncovered parts of the body.

See below Cimicosis

A patient with bullous bite reactions after sequential contact with C. lectularius over a period of one year was described. Immediate reactions to the salivary gland solution of C. lectularius were observed in skin tests, followed by a pronounced, partially blistering late phase. Immunoblot analysis of patient serum with salivary gland extracts and recombinant C. lectularius salivary proteins revealed specific IgE antibodies against the 32 kDa C. lectularius nitrophorin, but not against the 37 kDa C. lectularius apyrase. These data indicate that bullous cimicosis is the late phase of an allergic IgE-mediated hypersensitivity to C. lectularius nitrophorin (Leverkus M et al. 2006,Price JB et al. (2012).

All stages of the bedbug life cycle are sensitive to temperature and can be killed by dry heat or steam. Treatment of entire rooms requires heating to ^>600Cfor several hours. For clothes, hot washing ^>600Cis recommended, alternatively freezing to ^-200Cfor >2 hours. Fogging with chemical insecticides is considered unsafe (aerosols may not reach the bug's hiding place). They can also pose a health risk to humans. Furthermore, resistance has been reported worldwide (Egg M et al.2024).

Bed bugs have been credited with the transmission of more than 40 human diseases, but there is little evidence that such transmission has ever occurred. In older scientific literature, it has been postulated that bed bugs can be vectors of plague, yellow fever, tuberculosis, relapsing fever, leprosy, filariasis, kala azar (leishmaniasis), cancer, smallpox, yellow fever and Chagas disease (Trypanasoma cruzi). Recently, the possibility of transmission of human immunodeficiency virus and hepatitis B virus (HBV) by bed bugs was investigated and found to be unlikely.

One possible candidate for transmission of disease to humans by bed bugs is HBV. Bed bugs collected from huts in an HBV endemic area in northern Transvaal, South Africa, were hepatitis B surface antigen positive, as were samples from Senegal, Egypt, Côte d'Ivoire and China. Hepatitis B surface antigen has also been shown to persist in bed bugs for longer than 7 weeks after experimental feeding, but no replication of HBV has been detected in the insects.

To date, no study has demonstrated the "vector competence" of bed bugs (the ability to acquire, maintain and transmit an infectious agent) (Jourdain F et al. 2016).

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