Case Presentation: A 54-year-old woman with no significant PMH presented with a macular rash, truncal pain, and progressive bilateral lower extremity weakness. She denied recent illness or travel, but did report frequent mosquito bites, as well as multiple recent sexual partners. She had no outdoor exposure except regular strolls on the Beltline, a popular urban walkway in Atlanta. A non-pruritic macular rash started a week prior to presentation, first on her abdomen, then on her legs, arms, and hands (including palms); the patient then developed severe pain in the back, hips, and neck, followed by bilateral lower extremity weakness over the proceeding 4-5 days, which progressed rapidly to the point where she could no longer stand. In the ED, she was febrile to 38.8° C, but otherwise hemodynamically stable. Physical exam revealed a diffuse, non-pruritic, macular rash. Neurologic exam showed 5/5 strength in her upper extremities, but 1/5 strength in her lower extremities with intact light and pinprick sensation but reduced vibratory sensation; reflexes were 2+ throughout. Initial labs showed normal WBC, mild thrombocytopenia, normal ESR, CRP, and negative HIV and RPR. MRI of the spine revealed extensive bilateral cord signal in the thoracic spine, concerning for transverse myelitis. LP demonstrated lymphocytic pleocytosis, moderately elevated protein, normal glucose levels, and negative gram stain; additional infectious and autoimmune markers were also sent. The patient was started on high dose steroids for treatment of transverse myelitis and was monitored closely with twice daily Negative Inspiratory Force (NIF) measurements. Shortly after initiating IV steroids she was transferred to the ICU due to concerns for ascending weakness affecting her diaphragm. She underwent several sessions of plasmapheresis. CSF PCR studies confirmed the diagnosis of West Nile virus. She was eventually discharged to acute rehabilitation.
Discussion: West Nile Virus (WNV) is the leading cause of mosquito-borne disease in the continental US. While more than 80% of the individuals infected with WNV are asymptomatic, most who are symptomatic develop mild illness including headache, myalgias, nausea, vomiting, rash, and chills. Risk factors for severe disease include increasing age and B cell depleting therapies. Approximately 1% of those affected develop neuroinvasive disease (1), which can manifest as meningoencephalitis, flaccid paralysis and respiratory failure, or other neurologic deficits (3). 10% of neuroinvasive cases prove to be fatal, with others suffering significant morbidity (4). Due to a variety of presenting symptoms, WNV is often a diagnosis of exclusion. The incidence of WNV in the United States varies, and it typically peaks in late August. There is higher incidence in regions with sub-tropical climates. From 2018-2022, the Georgia Department of Public Health reported 81 cases of WNV, and 537 total cases have been reported in Georgia since 1999 (6). Treatment of WNV is supportive. There is no vaccine currently available (2), though insect repellant is recommended.
Conclusions: Atlanta and surrounding areas in the state of Georgia experience seasonal outbreaks of West Nile Virus due to the high prevalence of mosquito activity, particularly during the warmer months. Clinicians should maintain a high index of suspicion for WNV, even in patients without significant travel history and outdoor activity, when evaluating new onset weakness or other unexplained neurologic symptoms.