The 2016-2017 influenza season, dominated by the H3N2 strain, saw an uptick in the number of children experiencing neurological manifestations of influenza.
Throughout the 2016-2017 influenza season, many patients admitted into treatment demonstrated neurological manifestations of influenza.
Typically, neurological symptoms, such as seizures, encephalopathy and encephalitis, are associated with Influenza A H1N1 and B. Despite influenza H3N2 having been the predominant strain during the 2016-2017 season, juvenile patients still exhibited neurological manifestations of the flu.
According to the Centers for Disease Control and Prevention (CDC), H3N2-predominant seasons have been associated with more severe illness and mortality, particularly among the elderly and young children, relative to seasons during which H1N1 or B viruses predominated.
“Influenza viruses cause a variety of neurologic manifestations in children, including simple and complex febrile seizures, exacerbations of underlying seizure disorders, encephalopathy and encephalitis,” study authors wrote. “The type and frequency of influenza-associated neurologic diseases in children are influenced by circulating strains, predisposing host factors and uptake and efficiency of influenza vaccinations.”
In the study, investigators sought to identify clinical characteristics of children with neurological manifestations of influenza, as well as to compare demographics and clinical characteristics with influenza-positive controls.
The retrospective cohort study analyzed 182 children admitted to the Children’s Hospital Colorado with an influenza infection between Dec. 27, 2016, and April 12, 2017. According to the study, children with neurological manifestations of influenza accounted for 43% of all influenza-related hospital admissions during this time span, and over half, or 54%, of these patients needed ICU care.
Investigators found that 18% had neurological manifestations of influenza, including seizures and encephalopathy. Furthermore, 85% of these children were infected with the prevalent H3N2 influenza strain. The majority of patients experienced seizures only, according to the study. The remaining patients experienced encephalopathy only, or both seizures and encephalopathy.
Patients with neurological manifestations of influenza had were 3.5 times more likely to have neurological comorbidity than those without neurological manifestations, as well as a to-fold increase in chances of hospitalization.
Investigators acknowledged that 30% of children with neurologic manifestations of influenza had an underlying neurologic condition. However, these patients did not have more severe symptoms or greater morbidity compared with children without neurologic conditions, according to the study.
"Our findings suggest that influenza testing among febrile children with altered mental status or seizures should be considered and highlight the importance of influenza vaccination among children with an underlying neurologic disorder,” authors wrote.
The CDC recommends annual influenza vaccinations for children ages 6 months and older and has concluded that vaccinations are an important initial step in combating the flu. During the 2016-2017 influenza season, private manufacturers distributed approximately 145.9 million doses of the influenza vaccination in the US.
The study, “Neurological Manifestations of Hospitalized Children with Influenza During the 2016—2017 Season,” was published online in the Journal of Pediatric Infectious Diseases Society.