A 7-year-old boy is brought to the office for evaluation of anal pruritus. A month ago, the patient went on a weekend camping trip with a group of friends. During the weekend, they learned to swim in the lake and stayed together in a log cabin. After returning home, the patient began to have increasing anal pruritus that is most severe at night. He has continued to have a healthy appetite and has had no vomiting or diarrhea. The patient has no chronic medical conditions, takes no daily medications, and has no known allergies. Vital signs are normal. Physical examination shows a well-appearing patient in no apparent distress. Skin examination is normal. The lungs are clear to auscultation, and the abdomen is soft and nondistended. Inspection of the anus shows mild perianal erythema with multiple excoriations, but no induration, fluctuance, or fissures. Which of the following is the most appropriate treatment for this patient?

Question

A 7-year-old boy is brought to the office for evaluation of anal pruritus.  A month ago, the patient went on a weekend camping trip with a group of friends.  During the weekend, they learned to swim in the lake and stayed together in a log cabin.  After returning home, the patient began to have increasing anal pruritus that is most severe at night.  He has continued to have a healthy appetite and has had no vomiting or diarrhea.  The patient has no chronic medical conditions, takes no daily medications, and has no known allergies.  Vital signs are normal.  Physical examination shows a well-appearing patient in no apparent distress.  Skin examination is normal.  The lungs are clear to auscultation, and the abdomen is soft and nondistended.  Inspection of the anus shows mild perianal erythema with multiple excoriations, but no induration, fluctuance, or fissures.  Which of the following is the most appropriate treatment for this patient?

Quizplus · Accepted Answer

11ec25c8_d6bc_d913_bc81_4ba41127b3bd_MD0003_00 This patient most likely has a pinworm infection (enterobiasis), a common helminthic infection that frequently affects school-age children. The life cycle of Enterobius vermicularis, a nematode, occurs within the gastrointestinal tract. Transmission occurs via ingestion of eggs, typically due to autoinoculation from contaminated hands. The larvae develop to adult worms within the small intestine. At night, female worms migrate through the rectum and deposit eggs in the perianal region, resulting in nocturnal perianal pruritus with associated perianal erythema and excoriations. Other symptoms may include nausea, vomiting, abdominal pain, and vulvovaginitis. Enterobius vermicularis Diagnosis is based on visualization of adult worms or eggs. Common diagnostic tests include the "scotch tape test" or "pinworm paddle test", in which the Enterobius eggs adhere to the adhesive surface and are visualized under microscopy. Stool cultures are of limited value as eggs are rarely passed in the stool. Treatment is with either pyrantel pamoate or albendazole; the patient and all household contacts should be treated because the infection is highly contagious. (Choice A) Clotrimazole is used to treat Candida albicans infections, which can involve the perianal area and cause pruritus ani. Candida infections typically present with a beefy-red rash within skin folds (eg, intertrigo) and associated satellite lesions, not seen in this patient. (Choice B) Ivermectin is the first-line treatment for strongyloidiasis, which presents with urticaria, abdominal pain, and respiratory problems (eg, dry cough, dyspnea, wheezing). Onchocerciasis ("river blindness") causes ocular lesions and dermatitis and is also treated with ivermectin. strongyloidiasis (Choice C) Metronidazole is used for protozoan infections such as amebiasis (eg, acute dysentery, liver abscess) and trichomoniasis (eg, green-yellow, frothy, malodorous discharge) as well as for anaerobic intraabdominal infections (eg, diverticulitis, peritonitis, cholangitis, abscess). It is not used for enterobiasis. (Choice D) Permethrin is the first-line treatment for scabies, which causes intense pruritis that is often worse at night; however, scabies more commonly affects the extremities and has associated papules and burrows, making this diagnosis unlikely. (Choice E) Praziquantel is used to treat schistosomiasis, which can present as pruritus after swimming in fresh water; however, patients initially have an urticarial rash on the lower legs or feet, followed several weeks later with diarrhea, weight loss, and right upper quadrant pain. Educational objective: Enterobius vermicularis (pinworm) infection is highly contagious and manifests as nocturnal perianal pruritus. First-line treatment is with pyrantel pamoate or albendazole. References: Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. (http://www.ncbi.nlm.nih.gov/pubmed/16679166)

A 7-Year-Old Boy Is Brought to the Office for Evaluation