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Dermatology · Infections: bacterial, viral, fungal, parasitic: bed bug bites
Sample itemA woman wakes with three itchy erythematous papules in a straight line on her exposed forearm, and her partner has similar lesions. There are no burrows, and nothing is found on her body. Which is the most likely source?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
A. Cimex lectularius hiding in the mattress seams
Bed bugs feed at night on exposed skin and then retreat to mattress seams, bed frames and furniture cracks. They typically cause grouped or linear itchy papules, sometimes called breakfast, lunch and dinner. Treatment is symptomatic, with eradication from the bedroom.
Option by option
A. Cimex lectularius hiding in the mattress seams (correct)
Correct. Linear groups of bites on exposed skin on waking, with the bed partner affected, suggest bed bugs.
B. Ctenocephalides felis in a pet's bedding
Cat fleas bite mainly the ankles and lower legs, usually with a pet involved.
C. Pediculus humanus capitis in the hair
Head lice cause scalp itch and nits on the hair shafts, not forearm bites.
D. Sarcoptes scabiei mites in the stratum corneum
Scabies produces burrows with web-space and genital involvement, not linear exposed-area bites.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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