close encounters with the environment

What’s Eating You? Bedbugs LTC(P) Dirk M. Elston, MC USA, Fort Sam Houston, Texas MAJ Scott Stockwell, MSC USA, Fort Sam Houston, Texas

The order contains (Figure 1). The forewings have been re- whose wings are half membranous and duced to hemelytral (shoulder) pads. half sclerotic. Two families within the The hindwings are absent. The speci- order, (“bedbugs” and their mens pictured are from a laboratory relatives) and Reduviidae (reduviid colony fed by Scott Stockwell, PhD (aka bugs), include blood-sucking species of dinner, Figure 2). medical importance. All Cimicidae are The genus parasitizes both blood-sucking ectoparasites of mammals mammals and birds Cimex lectularius and or birds. They have flat, oval bodies and Cimex hemipterus (found in warmer cli- retroverted labium (mouthparts), with mates) affect most commonly. three segments, that reaches back as far C. lectularius also parasitizes bats, chick- as coxa (base) of the first pair of legs ens, and other domestic . C. lec- tularius ranges in size from 5 to 7 mm. From the Department of Dermatology (MCHE- Females are slightly longer than males. DD), Brooke Army Medical Center, and the C. hemipterus is roughly 25% longer than Medical Zoology Branch, Army Medical C. lecutularius. Interspecies mating oc- Department Center and School, Fort Sam curs in nature.1 The offspring differ from Houston, Texas. either species, often having the narrow REPRINT REQUESTS to Department of Dermatology (MCHE-DD), Brooke Army Medical pronotum and abdomen of C. Center, Army Medical Department Center and hemipterus, but the abdominal bristle School, Fort Sam Houston, TX 74148 (Dr. Elston). pattern of C. lectularius.2

FIGURE 1. Bedbug.

262 CUTIS® BEDBUGS

FIGURE 2. Bedbugs feeding.

All Cimex are red-brown in color. containing an anticoagulant. Bites are They have a small semicircular to tri- often noted in linear groups of three angular scutellum (dorsal sclerotic (sometimes referred to as “breakfast, plate) behind the pronotum. The an- lunch, and dinner”). Bites present as tennae have four segments, and the dis- erythematous papules. Exaggerated lo- tal three antennal segments are long and cal responses may be seen in individ- slender. They have widely separated uals with a high degree of immunity. compound eyes. On the distal extrem- Bedbugs have been implicated as a ities, the tarsus is composed of three seg- probable vector for hepatitis B.3-5 They ments with claws. The abdomen has have also been implicated as vectors of eleven segments. When engorged, the American trypanosomiasis (Chagas’ intersegmental membranes are exposed. disease).6 In contrast to body lice and The female has a ventral notch or par- fleas, bedbugs digest blood very slowly. agenital sinus on the posterior margin of The blood in the bug’s gut remains rel- the right side of the fifth segment. The atively unclotted and not membrane male has a paramere only on one side of bound. This may affect the ’s posterior abdomen. competence as a disease vector.7 For- The female deposits eggs on rough tunately, it appears unlikely that bed- surfaces of cracks and crevices. The bugs present a significant risk for trans- eggs are white in color, 1 mm in length, mission of HIV.8,9 Although the virus and half as wide. They are already fer- can survive for several hours in bed- tilized and partially developed when bugs, actual transmission of the virus is laid. They hatch in 4 to 5 days. unlikely. In countries where bedbug in- Bedbugs are nocturnal, demonstrat- festation is common, bedbug dung may ing peak activity just before dawn. play a role in asthma.10 They avoid light, hiding in cracks and Elimination of cracks and crevices as crevices or behind peeling paint. They well as the use of insecticides will de- respond to warmth and carbon dioxide crease the bedbug infestation of houses. (ie, they are attracted to warm, sleep- Various insecticides have activities ing, breathing bodies). When feeding, against bedbugs, dichlorvos being the grasps the skin with its among the best. Insecticides vary in forelegs, pierces skin, and injects saliva their residual activity on surfaces such

VOLUME 65, MAY 2000 263 BEDBUGS

as wood, cloth, and metal. The insecti- 7. Vaughan JA, Azad AF: Patterns of ery- cide used must take into account the sur- throcyte digestion by bloodsucking insects: face being treated. Permethrin, which constraints on vector competence. J Med can be used to impregnate clothing and Entomol 30: 214-216, 1993. mosquito netting, has intermediate ac- 8. Webb PA, Happ CM, Maupin GO, Johnson tivity against bedbugs.11 Permethrin-im- BJ, Ou Cy, Monath TP: Potential for insect pregnated bednets have proved effective transmission of HIV: experimental exposure in actual use.12 On mud daub walls, the of Cimex hemipterus and Toxorhynchites am- residual effect of some insecticides de- boinensis to immunodefeciency virus. pends on the organic content of the J Infect Dis 160: 970-977, 1989. mud.13 Microencapsulation of insecti- 9. Jupp PG, Lyons SF: Experimental assessment cides enhances persistence.14 of bedbugs (Cimex lectularius and Cimex Several insect repellents show effi- hemipterus) and mosquitoes (Aedes aegypti cacy against bedbugs, DEET (diethyl- formosus) as vectors for human immunode- toluamide) being among the best. feciency virus. AIS 1: 171-174, 1987. Those bedbugs that still bite take pro- 10. Abou Gamra EM, el Shayed FA, Morsy TA, gressively smaller meals in the face of Hussein HM, Shehata ES: The relation be- increasing concentrations of repel- tween Cimex lectularis antigen and bronchial lent.15 Paradoxically, the smaller meals asthma in Egypt. J Egypt Soc Parisitol 21: 735- may increase the chances of bedbugs’ 746, 1991. spreading disease, as they remain hun- 11. Fletcher MG, Axtell RC: Susceptibility of gry and transmission appears more the bedbug, Cimex lectualrius, to selected likely in the face of interrupted meals.16 insecticides and various treated surfaces. Med Veterin Entomol 7: 69-72, 1993. REFERENCES 12. Lindsay SW, Snow RW, Armstrong JR, 1. Walpole DE, Newberry K: A field study of Greenwood BM: Permethrin-impregnated mating between two species of bedbug in bednets reduce nuisance in northern Kwa Zulu South Africa. Med Vet- Gambian houses. Med Veterin Entomol 3: erin Entomol 2: 293-296, 1988. 377-383, 1989. 2. Newberry K: Production of hybrid between 13. LeSueur D, Sharp BL, Fraser C, Ngxongo bedbugs Cimex hemipterus and Cimex lectu- SM: Assessment of residual efficacy of larius. Med Veterin Entomol 2: 297-300, lambdacyhalothrin 1. A laboratory study 1988. using Anopheles arabiensis and Cimex lectu- 3. Jupp PG, McElligott SE, Lecatsas G: The larius (Hemiptera: Cimicidae) on treated mechanical transmission of hepatitis B daub wall substrates from Natal, South virus by the common bedbug (Cimex lectu- Africa. J Am Mosq Control Assoc 9: 408- larius L.) in South Africa. S African Med J 413, 1993. 63: 77-81, 1983. 14. Gao YT, Shen PY, Wang BH, Lu SD, Juang 4. Jupp PG, McElligott SE: Transmission ex- GC, Ho LS: Controlled release effect of in- periments with hepatitis B surface antigen secticide microcapsules and their results in and the common bedbug (Cimex lectualrius common household insect pest control. J L). S African Med J 56: 54-57, 1979. Microencapsulation 1: 307-315, 1984. 5. Ogsten CW, Wittenstein FS, London WT, 15. Kumar S, Prakash S, Rao KM: Compara- Millman I: Persistence of hepatitis B sur- tive activity of three repellents against bed- face antigen in the bedbug Cimex hemipterus bugs Cimex hemipterus (Fabr.) Ind J Med Res (Fabr.). J Infect Dis 140: 411-414, 1979. 102: 20-23, 1995. 6. Jorg ME: Cimex lectularius, L (la chinche 16. Jupp PG, Purcell RH, Philips JM, Shapiro commun de cama) tranmisor de Trypanox- M, Gerin JL: Attempts to transmit hepa- oma cruzi. Revista Da Sociedade Brasileira de titis B virus to chimpanzees by arthropods. Medicina Tropical 25: 277-278, 1992. S African Med J 79: 320-322, 1991.

264 CUTIS®