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Bed Bugs

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[Cimex hemipterus] [Cimex lectularius]

Causal Agents

The two species of bed bugs (Insecta: Hemiptera: Cimicidae) usually implicated in human infestations are Cimex lectularius and C. hemipterus. Although rare, humans may become incidental hosts of Cimex species of bats and birds.

Life Cycle

lifecycle

Adults and all nymphal stages of Cimex spp. need to take blood meals from warm-blooded hosts, which are typically humans for C. lectularius and C. hemipterus, although other mammals and birds can be utilized in the absence of a human host. Female bed bugs lay about five eggs The Number 1 daily throughout their adult lives in a sheltered location (mattress seams, crevices in box springs, spaces under baseboards, etc). Eggs hatch in about 4-12 days into first instar nymphs The Number 2 which must take a blood meal before molting to the next stage. The bugs will undergo five nymphal stages (The Number 2, The Number 3, The Number 4, The Number 5, The Number 6 ), each one requiring a blood meal before molting to the next stage, with the fifth stage molting into an adult The Number 7. Nymphs, although lacking wing buds, resemble smaller versions of the adults. Nymphs and adults take about 5-10 minutes to obtain a full blood meal. The adults may take several blood meals over several weeks, assuming a warm-blooded host is available. Mating occurs off the host and involves a unique form of copulation called ‘traumatic insemination’ whereby the male penetrates the female’s abdominal wall with his external genitalia and inseminates into her body cavity. Adults live 6-12 months and may survive for long periods of time without feeding.

Geographic Distribution

Cimex lectularius is cosmopolitan in distribution; C. hemipterus is distributed in the tropics and sub-tropics

Clinical Presentation

Although bed bugs have been found naturally-infected with blood-borne pathogens, they are not effective vectors of disease. The primary medical importance is inflammation associated with their bites (due to allergic reactions to components in their saliva)

Cimex lectularius.

 

The two most common species of bed bugs implicated in human infestations are Cimex lectularius and C. hemipterus; the former of which is cosmopolitan, and the latter being found mostly in the tropics and sub-tropics. Adults are on average 5 mm long, oval-shaped and dorso-ventrally flattened. Like other members of the order, Hemiptera, they possess piercing-sucking mouthparts. Adults are brachypterous; the hindwings are nearly absent and the forewings are reduced to small, leathery pads. Nymphs look like smaller, paler versions of the adults. While Cimex spp. have been found to be naturally-infected with several blood-borne pathogens, they are not effective vectors of disease. The primary medical importance is inflammation associated with their bites.
Figure A: Two adults and one nymph (arrow) of C. lectularius, collected in a hotel in urban Georgia.
Figure E: Higher magnification of the specimen in Figure D, showing a close-up of the typical hemipteran piercing-sucking mouthparts (arrow).
Figure B: Close-up of one of the adults in Figure A.
Figure E: Nymph of C. lectularius. The blue marks represent 1 mm.
Figure C: Higher magnification of the specimen in Figure B. Note the reduced forewings (arrow).
Figure D: Ventral view of the specimen in Figure B.

Laboratory Diagnosis

The inflammatory reaction to the bites is not diagnostic specifically for bed bugs, and confirmation of a bed bug bite or infestation is best achieved by identification of adults or nymphs collected in sheltered areas near where the patient was bitten. Bed bugs possess stink glands and emit a distinctive odor; homes or motel/hotel rooms with heavy infestations may have this odor.

Treatment Information

Treatment information for bedbugs can be found at: https://www.cdc.gov/bed-bugs/hcp/clinical-care/index.html

DPDx is an educational resource designed for health professionals and laboratory scientists. For an overview including prevention, control, and treatment visit www.cdc.gov/parasites/.