Rapidly fatal West Nile virus meningoencephalitis in an immunocompetent patient: a case report

Abstract Background West Nile virus (WNV) is a Flaviviridae most often transmitted by mosquitos. Clinical manifestations vary from no symptoms to neuroinvasive disease. Mortality is rare, but patients with neuroinvasive disease have a fatality rate of 4-14%. Diagnosis is made on epidemiological, clinical and serological criteria. Treatment is based on symptomatic and support therapy. WNV neuroinvasive disease seems associated to advancing age and diabetes, but poor prognosis risk factors are still not clearly recognized. During 2017-2018 10 patients affected by WNV infection were admitted to our Hospital (Policlinico of Modena): 3 patients had a rapid fatal outcome and 3 needed intensive care transfer. We report the most representative case. Case Report A 81-yr-old man from Emilia-Romagna was admitted to our unit with a 6 days history of fever (>38℃), fatigue, nausea, vomiting, hiccough and mild cognitive impairment treated with amoxicillin. Past medical history: type 2 diabetes mellitus, arterial hypertension, permanent pacemaker for type 3 atrioventricular block. Referred exposure to farm animals. No recent travels abroad. Chest x-ray showed a retrocardiac opacity, so empiric levofloxacin was started for suspected community acquired pneumonia. After two days the patient began lethargic with a Glasgow Come Score < 8. Neuroinvasive WNV disease was confirmed by electroencephalogram and rachicentesis. Before serologic results acyclovir and dexamethasone were initiated without benefit and patient diedon the fifth day after admission. Conclusions Risk factors for poor prognosis related to WNV Infection are still not clearly identified. Our patient underwent unexpected rapid clinical deterioration before invasive treatment could positively affect prognosis. This underlines the importance of clinical alert to WNV infections during transmission season in endemic areas and the necessity of more data on fatal WNV cases to define criteria to promptly recognize high-risk patients. Keywords encephalitis; meningoencephalitis; neuroinvasive disease; West Nile virus; fatal meningoencephalitis.