A 17-year-old woman is evaluated in the emergency department in September for a 3-day history of headaches, low-grade fever, sore throat, cough, and stiff neck. She is otherwise well and takes no medications.
On physical examination, temperature is 37.9 °C (100.2 °F); the remainder of the vital signs are normal. The patient is alert, but photophobia is present on the ophthalmoscopic examination. The neck is stiff. A rash is noted over the face, thorax, and abdomen. The remainder of the physical examination is unremarkable.
Representative findings on the face are shown.
Cerebrospinal fluid studies reveal a leukocyte count of 354/µL (354 × 106/L), glucose level of 44 mg/dL (2.4 mmol/L), and protein level of 94 mg/dL (940 mg/L).
Which of the following is the most likely cause of this patient's findings?
B. Herpes simplex virus type 1
C. Herpes simplex virus type 2
D. West Nile virus
Answer and critique
The correct answer is A. Enterovirus. This content is available to MKSAP 19 subscribers as Question 106 in the Infectious Disease section.
Enteroviruses (Option A) are one of the most common causes of aseptic meningitis occurring in the summer and fall. Myalgia, sore throat, maculopapular rash, and cough are common symptoms in addition to typical meningitis symptoms. Lymphocytic pleocytosis of the cerebrospinal fluid (CSF) with a normal glucose level and mildly elevated protein level is typical. The diagnosis is confirmed by enterovirus polymerase chain reaction (PCR) CSF testing. Treatment is supportive, and the course is typically benign.
Herpes simplex virus (HSV) type 1 (Option B) is the most common cause of sporadic viral encephalitis. These patients may also present year round. The presence of abnormal brain function distinguishes encephalitis from meningitis. Patients with meningitis may be sick and uncomfortable, but brain function is normal. Patients with encephalitis may present with altered mental status, behavior and personality changes, hemiparesis, flaccid paralysis, paresthesias, or movement disorders. This patient does not have HSV-1 encephalitis.
HSV-2 infection (Option C) occurs year round. Patients with HSV-2 meningitis have CSF findings similar to enterovirus infection. HSV-2 meningitis is not associated with cough, pharyngitis, or rash. However, many adults with primary HSV-2 meningitis have a history of genital lesions that precede the meningitis by about 7 days. The course of HSV-2 meningitis in immunocompetent patients is benign, and supportive care is usually sufficient. Diagnosis is confirmed with CSF PCR testing.
West Nile virus (Option D) is a mosquito-borne illness that may present with a similar clinical and CSF profile to other causes of viral meningitis and occurs between June and October. West Nile may present with meningitis, encephalitis, or a combination of the two, or as an isolated myelitis. Isolated meningitis is more common in children. In its most severe form, infection of the anterior horn cells can cause a symmetric or asymmetric flaccid paralysis, analogous to that seen with polio. Patients with neuroinvasive disease may also have a maculopapular rash and a flu-like syndrome before neurologic disease onset, but it remains an uncommon cause of viral meningitis compared with enterovirus infection. The diagnosis of West Nile neuroinvasive disease can be confirmed through identification of the IgM antibody in CSF or the serum.
- Enterovirus meningitis commonly presents with myalgia, sore throat, cough, and maculopapular rash, in addition to typical meningitis symptoms.
- Many patients with primary herpes simplex virus type 2 meningitis have a history of genital lesions preceding the onset of meningitis by about 7 days.