Case Presentation: A 81 year-old Caucasian male presented to the emergency department with fever and altered mental status for two days. Further chart review revealed history of nausea, vomiting, myalgias, abdominal pain, and unintentional 35 pound weight loss over the six months prior. At the time of admission the patient was lethargic, febrile and tachycardic. Initial investigation showed elevated WBC count. Since previous CT head in 2017, CT head showed progressive brain matter loss with possible normal pressure hydrocephalus. Due to electrolyte imbalances, altered mental status, and no source of infection causing meningitis or encephalitis, toxic metabolic encephalopathy was considered. Infectious disease and neurology were consulted for ongoing fever and mental status changes. The patient was started on broad spectrum antibiotics for possible meningitis. Throughout his hospitalization course, he also developed a maculopapular rash on his right hip that migrated towards his inner thigh. Extensive work up included lumbar puncture, MRI brain, EEG, Lyme, West Nile Virus antibody, and ANA panel. The rest of the workup was negative except for significant elevation of West Nile virus antibody in the blood and CSF. On further questioning the family endorsed recent travel to their cottage in northern Michigan 3 weeks before hospital admission. With supportive care his fever resolved on day 7 but mental status did not improve.
Discussion: West Nile Virus is a RNA arbovirus that is the most common and widespread mosquito-borne virus in North America. Birds are the main reservoir and it is transmitted via mosquitos. The incubation period of WNV is ~2-15 days, where the majority of cases (80%) of those infected humans with WNV are asymptomatic, and 20% develop West Nile fever. Symptomatic infections are typically mild and include myalgia, malaise and a self-limiting fever. Up to 50% of patients present with a maculopapular rash on the trunk. Neuroinvasive WNV is a rare and sometimes deadly complication of WNV infection that occurs in less than 1% of infected people. These patients initially present with features of encephalitis or meningitis that progresses rapidly. In these cases, neurological symptoms such as changes in mental status, severe muscle weakness, seizures or flaccid paralysis can be seen. When spread to the central nervous system, the virus replicates primarily inducing injury, inflammation and cytotoxic response. This results in a loss of neurons within the spinal cord and brainstem grey matter. Treatment involves primarily supportive care, although several agents have been tried such as interferon, ribavirin, and IVIG with no efficacy. There is no vaccine currently available for prevention.
Conclusions: Here we present a case of West Nile virus encephalitis to increase awareness among practicing community to consider this as a diagnosis in patients who present with altered mental status and fever with unknown source.