An 18-month-old boy is brought to the emergency department due to fever lasting 2 days. Yesterday, he developed a fever, achiness, and fatigue. Today, the patient vomited 3 times but has had no cough, rhinorrhea, or diarrhea. He has no chronic medical conditions and takes no daily medications. However, the patient has not yet received the routine 12- to 15-month vaccines because of a cross-country move. Temperature is 39.4 C (102.9 F). Physical examination reveals an alert but irritable child who cries and closes his eyes during funduscopic examination. The anterior fontanel is closed. When the examiner flexes the neck, the child flexes the knees. Mucous membranes are dry. The oropharynx has no erythema or exudate. Patellar and Achilles deep tendon reflexes are 2+. Cerebrospinal fluid analysis results are as follows: Which of the following is the most likely cause of this patient's illness?

Question

An 18-month-old boy is brought to the emergency department due to fever lasting 2 days.  Yesterday, he developed a fever, achiness, and fatigue.  Today, the patient vomited 3 times but has had no cough, rhinorrhea, or diarrhea.  He has no chronic medical conditions and takes no daily medications.  However, the patient has not yet received the routine 12- to 15-month vaccines because of a cross-country move.  Temperature is 39.4 C (102.9 F).  Physical examination reveals an alert but irritable child who cries and closes his eyes during funduscopic examination.  The anterior fontanel is closed.  When the examiner flexes the neck, the child flexes the knees.  Mucous membranes are dry.  The oropharynx has no erythema or exudate.  Patellar and Achilles deep tendon reflexes are 2+.  Cerebrospinal fluid analysis results are as follows:  Which of the following is the most likely cause of this patient's illness?

Quizplus · Accepted Answer

11ec25c8_d6f7_2251_bc81_413817bf8141_MD0003_00 This child has fever, irritability, vomiting, photophobia, and a positive Brudzinski sign. Cerebrospinal fluid analysis shows an elevated white blood cell count (pleocytosis), an elevated protein concentration, and a normal glucose concentration. These findings are highly suggestive of viral (aseptic) meningitis. Of the viruses listed, only mumps virus is capable of causing viral meningitis in a previously healthy child. Other classic complications of mumps include parotitis and orchitis. Some children may have >1 complication simultaneously. mumps This patient is at increased risk for mumps because he has not yet received his first dose of measles, mumps, and rubella (MMR) vaccine, which is recommended at age 1 and again at age 4. Mumps was virtually eliminated in the United States following the introduction of the MMR vaccine, but the incidence of these diseases is rising because vaccine coverage rates have declined in the past decade. This patient is also notably at risk for rubella, but rubella does not cause viral meningitis. (Choice A) Cryptococcus neoformans is a cause of fungal meningitis among immunocompromised patients, including those with organ transplantation or primary immunodeficiency. C neoformans meningitis is an AIDS-defining illness for HIV-positive patients. It is extremely rare in immunocompetent hosts. (Choice B) Cytomegalovirus causes a mononucleosis-like illness during primary infection. It does not cause viral meningitis in healthy patients. (Choices C, D, and F) Haemophilus influenzae, Listeria monocytogenes, and Streptococcus pneumoniae are bacterial causes of meningitis, particularly in unvaccinated (H influenzae, S pneumoniae) or immunocompromised (L monocytogenes) patients. Bacterial meningitis presents with marked pleocytosis, low glucose, and high protein on cerebrospinal fluid analysis, making it unlikely. Listeria meningitis can cause normal CSF glucose but generally presents in neonates or older adults; it would be an unlikely pathogen in this 18-month-old patient. Educational objective: Among patients with meningitis, a viral etiology is suggested when cerebrospinal fluid analysis reveals a mildly elevated white blood cell count and protein level and normal glucose concentration. Mumps virus is capable of causing viral meningitis in unvaccinated individuals. References: Mumps: an emergency medicine-focused update. (http://www.ncbi.nlm.nih.gov/pubmed/29110978) Hospital admissions for viral meningitis in children in England over five decades: a population-based observational study. (http://www.ncbi.nlm.nih.gov/pubmed/27527749)

An 18-Month-Old Boy Is Brought to the Emergency Department Due