Snapshot A 14-year-old boy presents to the emergency department with a severe headache. His headache is diffuse and is associated with fever, nausea, and 2 episodes of emesis. He denies any sick contacts but his mother stated they traveled to Ohio and returned to New York City approximately 5 days ago. His temperature is 102°F (38.9°C), blood pressure is 118/78 mmHg, pulse is 105/min, and respirations are 19/min. During the physical examination, the patient undergoes generalized tonic-clonic epileptic movements, requiring sedation. A non-contrast CT scan of the head is unremarkable. A lumbar puncture is performed and cerebral spinal fluid analysis is notable for a lymphocytic pleocytosis. IgM specific antibodies for arboviruses eventually returns positive for California encephalitis virus. Introduction Classification arthropod-borne viruses (hence arboviruses), which are RNA viruses note that hantavirus is not an arbovirus Microbiology segmented, negative, single-stranded RNA viruses Associated condition bunyaviruses cause California encephalitis Rift Valley fever Crimean-Congo hemorrhagic fever hantavirus pulmonary syndrome Bunyaviruses Disease Presentation Diagnostic Studies Treatment California encephalitis Symptoms headache nausea vomiting Physical exam fever seizures focal neurologic deficit (e.g., aphasia) Lumbar puncture testing the cerebral spinal fluid with an enzyme-linked immunosorbent assay (ELISA) Supportive treatment (e.g., monitoring and treating seizures) Rift valley fever Symptoms headache myalgias malaise arthralgias Physical exam fever seizures Cell culture Polymerase chain reaction (PCR) ELISA Supportive treatment Crimean-Congo hemorrhagic fever Symptoms headache arthralgia abdominal pain vomiting Physical exam fever erythematous oropharynx palatal petechiae ELISA Real-time PCR (RT-PCR) Supportive treatment Hantavirus cardiopulmonary syndrome Symptoms headache chillsmyalgiasdry cough myalgias dry cough Physical exam fever respiratory compromise (e.g., increased oxygen demand) Radiography of the chest bilateral diffuse interstitial edema Laboratory rapid decline in platelets left-shifted granulocytic series increased immunoblast ELISA can be used Supportive treatment (e.g., aggressive cardiopulmonary support) Lumbar puncture testing the cerebral spinal fluid with an enzyme-linked immunosorbent assay (ELISA) Supportive treatment