Encephalitis associated with influenza B virus infection in 2 children and a review of the literature

Neurologic complications associated with influenza A in children during the 2003-2004 influenza season in Houston, Texas

OBJECTIVES

Our objectives were to (1) describe the clinical characteristics of and viruses isolated from patients who presented with neurologic symptoms associated with influenza A infection and were hospitalized at Texas Children's Hospital during October and November 2003 and (2) to raise awareness of the neurologic complications of influenza among US children.

METHODS

We reviewed the medical and laboratory records of all children who were hospitalized with neurologic symptoms and who also had evidence of influenza virus infection by rapid antigen testing or viral isolation.

RESULTS

Eight children aged 5 months to 9 years with neurologic complications associated with influenza A were identified. None of the children had received the influenza vaccine. Four presented with seizures, 3 with mental status changes, and 1 with mutism. All but 1 of the patients had influenza A viral antigen detected in nasal wash samples. Influenza A virus was isolated in culture from nasal wash specimens obtained from 6 of the patients; influenza A virus was also isolated from the cerebrospinal fluid of 1 of these patients. None of the patients had serum metabolic abnormalities or other cerebrospinal fluid abnormalities. Three of the patients had brain imaging abnormalities. Five of the patients were treated with antivirals. All 8 of the patients survived, 6 with complete recovery and 2 with sequelae (1 mild and 1 severe).

CONCLUSIONS

Neurologic symptoms and sequelae were associated with influenza A virus infection in children during the 2003-2004 influenza season in Houston, Texas. Influenza should be considered in the differential diagnosis in patients with seizures and mental status changes, especially if they present with respiratory symptoms or during an influenza outbreak.

Psychotropic viruses

Viruses are increasingly being recognized as important factors in the pathogenesis of acute and chronic mental illness. Here we review clinical and epidemiologic data concerning viral infection and mental illness, as well as animal models that provide insight into the myriad of mechanisms by which infection can cause brain dysfunction.

Nosocomial influenza in children

Influenza is the most important cause of acute respiratory illness leading to hospitalization among children during community epidemics. This illness can cause extensive nosocomial outbreaks with serious morbidity and mortality among specific groups of children. Paediatric patients with community-acquired influenza and healthcare workers are the main reservoir for the nosocomial spread of the virus. During epidemics in the community, testing for influenza should be requested in all children with compatible symptoms admitted in the hospital, and measures should be introduced for the prevention or early control of an outbreak. Recent advances in the management of influenza include rapid diagnoses based on antigen detection and the identification of the new neuraminidase inhibitors zanamivir and oseltamivir. Annual vaccination against influenza of children with high-risk conditions, their family members and healthcare workers is the principle measure for the prevention of nosocomial outbreaks. Although vaccination against influenza appears to be cost-effective at all ages in terms of prevention of illness, related hospitalizations, deaths, reduction of healthcare costs and productivity loss, vaccination coverage among target groups is limited.

Viral meningitis and encephalitis: traditional and emerging viral agents

In the United States, the annual number of central nervous system (CNS) infections that occur as a result of viral agents far exceeds that of infections caused by bacteria, yeast, molds, and protozoa combined. The recent incursion of West Nile virus (WNV) into North America has led to a dramatic change in the incidence and epidemiology of summer-associated viral CNS disease. As a result of increased testing for WNV, lesser known viral causes of CNS infection have been identified. Even the epidemiology of such traditional viral neuropathogens as rabies has changed in recent years. This review provides an overview of viruses traditionally associated with meningitis and encephalitis (enteroviruses, La Crosse virus, St. Louis encephalitis virus, eastern and western equine viruses, varicella-zoster virus), as well as several of the less common (Powassan virus, lymphocytic choriomeningitis virus, Colorado tick fever virus, rabies virus, influenza viruses, etc.) and emerging (West Nile virus) viral pathogens.