engleski

Demographic, clinical and laboratory characteristics of patients with West Nile virus neuroinvasive disease in Croatia, 2012-2013

Objective: In the last few years, West Nile virus (WNV) has re-emerged in many European countries. In Croatia, cases of WNV infection were detected during the two consecutive transmission seasons (2012-2013). We analyzed demographic, clinical and laboratory characteristics of Croatian patients with WNV neuroinvasive disease. Methods: WNV IgM/IgG and IgG avidity testing on serum samples were performed using a commercial ELISA (Euroimmun, Lübeck, Germany) and confirmed by virus neutralization test. For 19 patients, cerebrospinal fluid (CSF) samples were tested for WNV RNA by real- time RT-PCR. All patients met clinical and laboratory criteria for confirmed cases according to the EU case definition for WNV infection. Results: WNV neuroinvasive infection was confirmed in 27 patients. There were 20 (74.1%) males and 7 (25.9%) females (male to female ratio 2.9:1). The median age was 63 (range 28-79) years. The majority of patients (20/74.1%) were older than 50 years. Twenty-one (77.8%) patients presented with meningoencephalitis, 4 (14.8%) with meningitis, while in two (7.4%) patients disease started with meningitis followed by acute flaccid paralysis. Most of them (18/66.7%) reported underlying diseases, the most common being hypertension (14/51.8%) and diabetes (7/25.9%). Two patients (7.4%) underwent organ transplantation. The main clinical symptoms and signs include fever (27/100%), headache (13/48.1%), nuchal rigidity (10/37.0%), tremor (9/33.3%), vomiting (9/33.3%), nausea (8/29.6%) and fatigue (8/29.6%). Altered level of consciousness and disorientation were detected in 7/25.9% and 6/22.2% patients, respectively. Two (7.4%) patients were mechanically ventilated due to respiratory failure. Total leukocyte count in peripheral blood was elevated in 8/29.6% patients. CSF examination showed pleocytosis with leukocyte counts ranging from 10- 3580 cells/mm3 (mononuclear cell predominance in 19/70.4% patients), elevated protein levels (0.49-2.5 g/L) and normal glucose levels. Abnormal EEG findings (irregular and/or diffuse slowing) were obtained in 22/24 (91.6%) patients. Of 22 patients with either CT or MRI scans, 14 (63.6%) had normal findings, while in 8 (36.4%) nonacute abnormalities were found (brain atrophy, chronic vascular lesions). Serology results showed WNV IgM antibodies in all patients (ratio 1.51-4.14) and WNV IgG antibodies in 26 patients (28-170 RU/ml). WNV IgG avidity was low in 24/92.3% (11%-37%) and borderline in 2/7.7% patients (40% and 60%, respectively). In 14 paired serum samples, a negative-to-positive seroconversion of IgG antibodies was documented. Titer of neutralizing antibodies was 5-80. All tested CSF samples were negative for WNV RNA. The median hospitalization time was 17 (range 11-74) days. A complete recovery was seen in 22/81.5% patients, while 5/18.5% patients presented neurologic sequelae (muscle weakness). Conclusion: The majority of the Croatian patients with confirmed WNV neuroinvasive disease were older than 50 years (74.1%) and reported several comorbidities (66.7%). The main clinical presentation was meningoencephalitis (77.8%). Persistent neurologic sequelae were detected in 18.5% patients.

West Nile virus; neuroinvasive disease; Croatia

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