Virology USMLE Step 1 Practice Question
A 19-year-old male college student presents to the emergency department with a 2-day history of fever (39.2°C), severe frontal headache, and neck stiffness. Physical examination reveals a petechial rash on the trunk and lower extremities. Cerebrospinal fluid analysis shows: protein 85 mg/dL (elevated), glucose 28 mg/dL (low), WBC 450/μL (predominantly lymphocytes), and PCR positive for enterovirus. The patient reports receiving meningococcal conjugate vaccine (MCV4) 2 years ago and is otherwise healthy with no immunocompromise. Which of the following best explains the relationship between the patient's vaccination status and his current presentation?
Answer choices
- AThe meningococcal vaccine does not provide protection against enteroviral meningitis, which accounts for significant morbidity despite high meningococcal vaccination rates in college populationsCorrect answer
- BThe meningococcal vaccine provides only serogroup-specific immunity and would have prevented infection by meningococcal serogroup B exclusively
- CThe patient required a booster dose within 18 months of initial vaccination, and the interval since vaccination explains vaccine failure
- DThe vaccine is contraindicated in patients with enteroviral exposure, leading to reduced immunogenicity and this breakthrough infection
- EThe meningococcal vaccine should have prevented this infection, indicating a failure of the patient's adaptive immune response
- FEnteroviral meningitis is a known adverse effect of meningococcal vaccination that occurs in a small percentage of vaccinees
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