View source for WBR0083

 {{WBRQuestion
|QuestionAuthor=Kalsang Dolma
|ExamType=USMLE Step 2 CK
|MainCategory=Internal medicine
|SubCategory=Infectious Disease, Infectious Disease
|MainCategory=Internal medicine
|SubCategory=Infectious Disease, Infectious Disease
|MainCategory=Internal medicine
|SubCategory=Infectious Disease, Infectious Disease
|MainCategory=Internal medicine
|MainCategory=Internal medicine
|SubCategory=Infectious Disease, Infectious Disease
|MainCategory=Internal medicine
|SubCategory=Infectious Disease, Infectious Disease
|MainCategory=Internal medicine
|SubCategory=Infectious Disease, Infectious Disease
|MainCategory=Internal medicine
|SubCategory=Infectious Disease, Infectious Disease
|MainCategory=Internal medicine
|MainCategory=Internal medicine
|SubCategory=Infectious Disease, Infectious Disease
|Prompt=A 30 year old immigrant from Africa presents to the clinic with complaints of skin swelling. On physical examination, subcutaneous nodules are noted. A skin biopsy of a nodule is taken and incubated in normal saline at room temperature for 24 hours. The sample shows microfilariae of oncocerca volvulus. Treatment of choice for this patient is:
|Explanation=The treatment of choice for onchocerciasis is ivermectin which  is given in the dose of 150 mcg/kg orally in one dose every 6 months, for both adults and children. Ivermectin kills by interfering with nervous system and muscle function of the microfilariae. Ivermectin has been shown to reduce the occurrence of blindness, and to reduce the occurrence and severity of skin symptoms. 
 
An evolving treatment for oncocerciasis is doxycycline, which has been shown in studies to kill Wolbachia, an endosymbiotic rickettsia-like bacteria that appears to be required for the survival of the O.volvulus macrofilariae and for embryogenesis. Doxycycline does not kill the microfilariae, so treatment with ivermectin would be needed to result in a more rapid decrease of symptoms.
|AnswerA=Ivermectin 150 mcg/kg orally in one dose every 6 months
|AnswerAExp=This is the correct dosing regimen for treating adults and children with onchocerciasis.
|AnswerB=Ivermectin 150 mg/kg orally in one dose every 6 months
|AnswerBExp=This is not the correct dosing regimen for treating adults and children with onchocerciasis. The correct dose is 150 micrograms per kilogram in one dose every six months.
|AnswerC=Ivermectin 150 mcg/kg orally in one dose every 3 months
|AnswerCExp=This is not the correct dosing regimen for treating adults and children with onchocerciasis. The correct dose is 150 micrograms per kilogram in one dose every six months.
|AnswerD=Ivermectin 150 mg/kg orally in one dose every 3 months
|AnswerDExp=This is not the correct dosing regimen for treating adults and children with onchocerciasis. The correct dose is 150 micrograms per kilogram in one dose every six months.
|RightAnswer=A
|Approved=Yes
}}