Cimex lectularius – an unwelcome train attendant

ARTICLE

Auteur(s) : Diana Anders, Eva-B Bröcker, Henning Hamm

Department of Dermatology, University Clinics Würzburg, Josef-Schneider-Str. 2, D-97080 Würzburg

When travelling by train one frequently has to accept crowded carriages and delays but pruritus is an unusual after-effect. As a consequence of globalization, with growing international tourism and trade as well as modified strategies in pest control, the incidence of cimicosis is nowadays rising again. We would like to add a particular incident to the expanding list of pertinent observations in Europe.

A 17-year-old male presented with itchy red urticarial papules and plaques on his arms, back of feet, ankles and knees that had suddenly arisen after a one-week study visit to Rome. The lesions were arranged in groups and long lines (figure 1). Some of them showed a central haemorrhage, more visible by diascopic examination. The patient belonged to a tour group of 11 people who slept in two cabins of a sleeping-car when returning to Germany. Soon after their arrival five other members of the group from both cabins developed similar, but less pronounced symptoms. Under treatment with a topical corticosteroid and an oral antihistamine, symptoms largely subsided within one week. Although the culprits were not identified, the history and clinical appearance of the skin lesions suggest that bed bugs caused the complaints.

Bed bugs have been known since antiquity. Besides improved hygiene standards, the use of chlorinated hydrocarbons and other insecticides since the 1940s controlled the spread of the insects, although they never completely disappeared. Increased travel, second hand exchanges, a shift from using broad-spectrum insecticides to more selective control tactics and increasing insecticide resistance are all thought to have contributed to their sudden resurgence [1]. The common bed bug (Cimex lectularius) is a nocturnal, sanguivorous ectoparasite of humans, avians and small mammals. It has a size of 4-6 millimeters and six legs. By day the flat, brownish insects hide in the crevices and cracks of walls, bed frames, mattresses and old furniture [2]. Even without blood meals they can survive up to twelve months. Attracted by human body heat and carbon dioxide production, they bite the innocent sleeper, simultaneously injecting an anticoagulant, a vasodilator (nitrogen oxide which is bound to nitrophorin as a transporter in saliva), anaesthetising substances and proteolytic enzymes [3, 4]. After the blood meal the insect’s appearance changes impressively, resembling a large drop of blood. Skin lesions can either be caused by irritation or, as shown by our group in a case of bullous cimicosis, by IgE-mediated hypersensitivity to nitrophorin [5]. While bites are not felt immediately, intensive pruritus develops after several hours and within 1-3 days infiltrated papules, plaques, papulovesicles or even bullae may occur. Symptomatic relief is achieved by use of topical corticosteroids and oral antihistamines. For the eradication of bed bugs, cracks in walls and floors have to be removed, old furniture should be discarded. Additional measures include powerful vacuuming and heating rooms and clothes. Mattresses should either be discarded or put into a special cover. Nevertheless an exterminator is frequently required with professional insecticides [1, 6].

Differential diagnosis includes urticaria, pityriasis lichenoides et varioliformis acuta, erythema multiforme, bullous dermatoses and primarily papular urticaria induced by hypersensitivity to the bites, stings, and contact with mites, spiders, fleas, midges, flies, and even caterpillars. Skin reactions due to pulex irritans more often involve the legs and the waist, and tend to be less aggregated than in cimicosis.

Predominantly, bugs colonise hotels and youth hostels with a rapidly changing clientele as well as public transport. A sweet, musty scent as well as spots of blood or faeces on seats and bed linen might indicate the invisible danger. Repellents or a night light may be used to protect the traveller from bites. In Europe recent reports indicate the problematical spread of bed bugs and of other vermin in trains of the Italian railway company Trenitalia. As a consequence hundreds of trains were removed and another 2000 carriages were treated by vermin destruction. In the USA bed bugs are currently spreading as quickly as before the Second World War.

We conclude that in the near future itchy souvenirs typically arranged in line may be seen more often among travellers. Hitchhiking in seams of clothing and luggage, bed bugs may even be imported to private households.

Acknowledgments

References

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5 Leverkus M, Jochim RC, Schäd S, et al. Bullous allergic hypersensitivity to bed bug bites mediated by IgE against salivary nitrophorin. J Invest Dermatol 2006; 126: 91-6.

6 Ter Poorten MC, Prose NS. The return of the common bedbug. Pediatr Dermatol 2005; 22: 183-7.