WBR0088

Author	[[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Neurology, SubCategory::Infectious Disease
Prompt	[[Prompt::A 38-year old male was brought to the emergency department by his mother with complaints of hydrophobia and disorientation. History revealed that he has had three episodes of seizures in the past 2 weeks. Some days later, he was said to have had hallucinations, lapsed into a coma and died. The causative organism involved acts through which of the following?]]
Answer A	AnswerA::FGF3 receptors
Answer A Explanation	AnswerAExp::Cell-signaling defect of FGF (Fibroblast growth factor) receptor 3 is seen in achondroplasia, which results in dwarfism.
Answer B	AnswerB::CD4 receptors
Answer B Explanation	AnswerBExp::CD4 is the receptor for HIV, which is used as a marker of disease progression and when to commence therapy for HIV infection.
Answer C	AnswerC::LDL receptors
Answer C Explanation	AnswerCExp::LDL receptor is associated with familial hypercholesterolemia, an autosomal dominant disorder with absent or decreased LDL receptors. It causes an accelerated atherosclerosis, tendon (Achilles) xanthomas and corneal arcus.
Answer D	AnswerD::CCR5 receptors
Answer D Explanation	AnswerDExp::CCR5 receptor is a co-receptor for HIV virus found on macrophages and TH cells.
Answer E	AnswerE::Ach receptors
Answer E Explanation	AnswerEExp::The rabies virus binds to nicotinic Ach receptors to cause the disease.
Right Answer	RightAnswer::E
Explanation	[[Explanation::The patient in this vignette has Rabies Encephalitis, transmitted from dog, bat, raccoon and skunk bites. The disease progresses from fever, malaise to agitation, photophobia, hydrophobia, seizures, hallucination and then to paralysis, coma and death. After the bite from an infected animal, the virus binds to peripheral nerves by binding to nicotinic acetylcholine receptors or indirectly into the muscle at the site of inoculation. The virus moves by retrograde axoplasmic transport to dorsal root ganglia and the spinal cord. The brain becomes rapidly infected when the virus gets to the spinal cord. Educational Objective: References: ]]
Approved	Approved::Yes
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