Neurologic Complications of Influenza B Virus Infection in Adults, Romania

Abstract

We characterized influenza B virus-related neurologic manifestations in an unusually high number of hospitalized adults at a tertiary care facility in Romania during the 2014-15 influenza epidemic season. Of 32 patients with a confirmed laboratory diagnosis of influenza B virus infection, neurologic complications developed in 7 adults (median age 31 years). These complications were clinically diagnosed as confirmed encephalitis (4 patients), possible encephalitis (2 patients), and cerebellar ataxia (1 patient). Two of the patients died. Virus sequencing identified influenza virus B (Yam)-lineage clade 3, which is representative of the B/Phuket/3073/2013 strain, in 4 patients. None of the patients had been vaccinated against influenza. These results suggest that influenza B virus can cause a severe clinical course and should be considered as an etiologic factor for encephalitis.

Keywords: B (Yam)-lineage clade 3; B/Phuket/3073/2013; Romania; adults; influenza; influenza B virus; influenza vaccine; meningitis/encephalitis; neurologic complications; respiratory infections; tertiary care facility; viruses.

Figure 1

Magnetic resonance imaging of the brain of a 28-year-old woman (patient 1) who had neurologic complications of influenza B virus infection, Romania. A) Axial T2 image showing multiple areas of T2-associated hyperintense lesions with involvement of the genu corpus callosum, bilateral internal capsule, and several areas of white matter in the right frontal lobe, and more discreetly at the limit between the right parietal and occipital lobe. B) Axial diffusion-weighted image showing restricted diffusion associated with lesions. C) Coronal fluid–attenuated inversion recovery image showing multiple hyperintense lesions in the right caudate head and the cortical and deep white matter of the frontal lobes. D) Coronal diffusion-weighted image showing restricted diffusion associated with lesions.

Figure 2

Magnetic resonance imaging of the brain of a 55-year-old woman (patient 3) who had neurologic complications of influenza B virus infection, Romania. Axial diffusion-weighted image showing restricted diffusion in the bilateral frontal cortex.