Several individuals in a Florida neighborhood develop a febrile illness during the summer. Most of them experience abrupt-onset fever, headache, confusion, and lethargy. Some patients also develop tremors, seizures, and focal motor or sensory deficits. Physical examination shows signs of meningeal irritation and altered mental status. Cerebrospinal fluid evaluation reveals lymphocytic pleocytosis with no organisms seen on Gram stain. Brain imaging shows no abnormalities. Which of the following would be most helpful in controlling this disease outbreak?

Question

Several individuals in a Florida neighborhood develop a febrile illness during the summer.  Most of them experience abrupt-onset fever, headache, confusion, and lethargy.  Some patients also develop tremors, seizures, and focal motor or sensory deficits.  Physical examination shows signs of meningeal irritation and altered mental status.  Cerebrospinal fluid evaluation reveals lymphocytic pleocytosis with no organisms seen on Gram stain.  Brain imaging shows no abnormalities.  Which of the following would be most helpful in controlling this disease outbreak?

Quizplus · Accepted Answer

11ec160b_380e_d447_9249_df2809a073d6_MD0001_00 These patients have a febrile illness with signs of meningitis (eg, neck stiffness, headache) and encephalitis (eg, confusion, seizure, tremor, focal deficits), raising strong suspicion for an outbreak of arbovirus meningoencephalitis (eg, West Nile virus, La Crosse virus). Arboviruses are small RNA viruses that are harbored by birds and small mammals and are transmitted to humans via biting arthropods (eg, mosquitos, ticks, fleas), primarily during the summer months when arthropod populations are at their peak. Infections in otherwise healthy individuals usually result in an asymptomatic low-level viremia that is cleared within a week by the humoral antibody response. In contrast, patients who cannot mount a rapid, effective antibody response (eg, elderly, immunocompromised) may have persistent and more severe viremia; these individuals often develop a severe flu-like illness (eg, fever, headache, fatigue, arthralgias) that may progress to meningitis and/or encephalitis. Most arbovirus infections are self-limited and resolve with supportive care, but some cases of meningoencephalitis are fatal. Because no vaccines are currently available for North American arboviruses (Choice E), prevention primarily relies on the elimination of vector arthropod breeding grounds (eg, stagnant water) and the early identification of infected arthropods (and birds) so that aerosolized insecticide can be sprayed. (Choice B) Histoplasmosis is an endemic mycosis of the Ohio and Mississippi River Valleys that can be transmitted by bird or bat droppings. Most patients are asymptomatic, but a minority develop pneumonia. Dissemination to the CNS can occur occasionally but is associated with focal brain lesions on imaging. (Choice C) Meningococcal meningitis requires isolation of infected individuals (droplet precautions) to prevent transmission. Patients often initially develop flu-like symptoms that can progress within hours to petechial/hemorrhagic rash, sepsis, and death. Cerebrospinal fluid will show neutrophilic pleocytosis. (Choice D) Aseptic meningitis is often caused by enteroviruses (eg, Coxsackievirus, echovirus) that are transmitted via the fecal-oral route through contaminated food or water. However, enteroviruses are less likely to cause signs of encephalitis (eg, confusion, focal neurologic deficits, tremors, seizures) than arboviruses. Educational objective: Arboviruses, small RNA viruses transmitted by biting arthropods, are the most common cause of encephalitis outbreaks in the United States. Because no vaccines are currently available, prevention primarily involves eliminating the vector arthropods (eg, infected mosquitos).

Several Individuals in a Florida Neighborhood Develop a Febrile Illness