Monday, March 27, 2023
| Characteristic | Patient | ||||||
|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | |
| Age,y/sex | 28/F | 37/F | 55/F | 20/F | 57/M | 31/F | 27/F |
| Days from illness onset | 3 | 2 | 10 | 5 | 3 | 4 | 3 |
| Medical history | Uncontrolled hyperthyroidism | Unremarkable | Influenza A(H3N2) virus encephalitis in 2012 | Treated for Russell−Silver syndrome | Unremarkable | Recent breast implants | Unremarkable |
| Leukocyte count, cells/mm3 | 2 | 2 | 10 | 5 | 2 | 3 | 13 |
| CSF | |||||||
| Protein, g/L | 0.143 | 0.270 | 2.305 | 0.251 | 0.313 | 0.162 | 7.156 |
| Glucose, g/L | 0.61 | 0.50 | 0.74 | 1.07 | 0.55 | 0.71 | 1.22 |
| Chloride, g/L | ND | ND | 7.60 | 6.78 | 7.10 | 6.80 | 7.02 |
| Virus type | B seq EPI_ISL_179707 | B seq EPI_ISL_179711 | B | B | B seq EPI_ISL_182519 | B | B seq EPI_ISL_182518 |
| Cerebral imaging result | MRI, abnormal† | CT, normal | MRI, abnormal‡ | MRI, normal | MRI, normal | NA | MRI, abnormal§ |
| Diagnosis | Confirmed encephalitis | Possible encephalitis | Confirmed encephalitis | Confirmed encephalitis | Possible encephalitis | Cerebellar ataxia | Confirmed encephalitis |
| Length of hospitalization, d | 7 | 9 | 18 | 17 | 10 | 5 | 3 |
| Outcome | Died | Complete resolution | Complete resolution | Complete resolution | Complete resolution | Complete resolution | Died |
| Clinical findings | Fever, headache, sleepiness, left upper limb motor deficit, coma, GCS score 3–4 | Fever, headache, sleepiness, photophobia, vertigo, stiff neck, positive Romberg sign | Fever, confusion, photophobia, dizziness, right facial paralysis, aphasia, stiff neck, coma, GCS score 8 | Fever, agitation, nystagmus, stiff neck, coma, GCS score 9–10 | Fever, headache, dysarthria, right side motor deficit, vomiting | Fever, headache, vomiting, vertigo, photophobia, ataxia, positive Romberg sign, movement and balance disorder | Fever, headache, vomiting, lethargy, aphasia, upward deviation of eyes, seizures, coma, GCS score 3 |
Table. Characteristics of 7 patients with neurologic complications of influenza B virus infection, Romania*
*All patients showed negative RT-PCR results for influenza B virus in CSF. CSF, cerebrospinal fluid; CT, computed tomography; GCS, Glasgow coma scale; MRI, magnetic resonance imaging; NA, not available; ND, not determined.
†MRI on day 3. See Figure 1 for a detailed description.
‡MRI on day 8. See Figure 2 for a detailed description.
§MRI on day 2 showed multiple areas of hyperintensities.
This activity is intended for infectious disease clinicians, neurologists, internists, intensivists, and other clinicians caring for patients with influenza B-related neurologic manifestations.
The goal of this activity is to describe neurologic complications of influenza B virus infection in adults, based on a case series from a tertiary facility in Romania.
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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.
Influenza viruses are negative single-stranded RNA viruses belonging to the family Orthomyxoviridae and cause worldwide epidemics of influenza with high rates of illness and death. Human influenza A and B viruses cause a self-limited acute respiratory infection. This infection has an abrupt onset and causes fever, chills, headache, cough, and myalgia. Every year, different strains of influenza viruses emerge because of continuous antigenic drift and interspecies gene reassortment, which cause antigenic shifts. Severe complications of influenza can involve the lower respiratory tract (pneumonia), heart (myocarditis), and central nervous system (encephalitis, myelitis, meningitis, febrile and afebrile seizures, Guillain-Barré syndrome, cerebellar ataxia) and can lead to death.[1–3]
Although type A and B influenza viruses might induce neurologic complications, most published studies on virus neurotropism have focused on influenza A viruses, with an emphasis on the new A(H1N1)pdm09 virus strain after 2009.[4–7] Influenza B virus, which was isolated from a child in 1940, has steadily adapted to humans without a stable animal reservoir.[8–10] The earliest report of a case of influenza B viral encephalitis was in London, UK, in 1946,[11] but only sporadic cases with neurologic manifestations have been reported, especially in children and adolescents. Influenza B is generally considered a mild disease with less frequent neurologic complications than influenza A.[4–7]
There was major increased influenza activity in Romania during the 2014–15 influenza season: 3.5 times more cases of influenza-like illness (ILI) and acute respiratory infections than in the previous season. A total of 4,511 case-patients with ILI were reported, of which 1,709 (37.9%) were hospitalized; 3,297 (73.1%) were >14 years of age. Influenza B viruses prevailed (in 529 [56.4%] of the 938 laboratory-confirmed influenza cases), unlike the rest of Europe, where there was a predominance of type A influenza strains.[12] We characterized influenza B virus–related neurologic manifestations diagnosed at a tertiary care facility in Romania during the 2014–15 influenza season.
