Case 1- 83 year old male with past medical history of knee surgeries and lumbar laminectomy presented with acute onset of fever, confusion and left lower extremity weakness for the past three days. Physical examination confirmed the same. He was started on empiric antibiotics for epidural abscess. MRI brain and spine, ECHO and EEG were unrevealing. His blood cultures were negative but CSF studies showed normal glucose(46 mg/dl) , elevated proteins (87mg/dl) consistent with aseptic meningitis and positive WNV IgG and IgM antibodies. Antibiotics were discontinued and supportive care was initiated. His clinical course was complicated by a new onset atrial fibrillation for which anticoagulation and beta blockers were initiated. He developed dysphagia and gastrostomy tube was inserted. His mental status gradually improved and was discharged to inpatient rehabilitation center.
Case 2 – 81 year old male with past medical history of transient ischemic attack in 2000, hypertension, hyperlipidemia, colon cancer in remission and arthritis presented with acute onset of altered mental status, generalized weakness, dysarthria one week prior to admission. CT brain, MRI brain and EEG were normal. With a working diagnosis of encephalopathy and meningitis, empiric treatment was initiated. The labs revealed normal ammonia, lactic acid, procalcitonin, negative blood cultures but CSF studies showed normal glucose (71mg/dl), elevated proteins (82 mg/dl) consistent with aseptic meningitis and positive for WNV IgG and IgM antibodies. His mental status gradually improved with supportive care and patient was discharged to inpatient rehabilitation.
Discussion: West Nile Virus (WNV) Encephalitis, a mosquito borne disease, has increased incidence and high morbidity risk in the elderly population. 293 cases of WNV infections were reported in Texas in 2016. WNV infection causes flu – like illness that may progress to encephalitis, meningitis and polyradiculitis in some patients. We report two cases of elderly males who presented this past summer with acute altered mental status diagnosed to have WNV encephalitis.
Conclusions: 1 in 150 WNV infections manifest as neuroinvasive disease/encephalitis. WNV should be considered in patients who have encephalitis and otherwise unexplained extremity weakness in endemic areas especially during summer season. It is prudent to look for other etiology of meningoencephalitis when a patient has inadequate response to empiric treatment of bacterial meningitis. These cases illustrate that awareness of the varying presentation of WNV can help us in prompt diagnosis, initiation of supportive care and encourage the community to use protective measures to decrease exposure to infected mosquitoes.