Children hospitalized with influenza B infection.

An outbreak of influenza virus type B infection occurred in Philadelphia from December, 1985, to April, 1986. During this epidemic 24 patients were admitted to Children's Hospital from whom influenza B was isolated from routine respiratory viral cultures. All were younger than 3 years of age. Clinical findings included fever (greater than or equal to 38 degrees C) (88%), rhinorrhea (62.6%), cough (50%), otitis (50%), rhonchi (42%), vomiting (38%), diarrhea (33%), rales (21%), pharyngitis (13%) and croup (4%). Remarkably 75% of the patients had underlying diseases which may have contributed to the severity of the infection. Nine (41%) patients had pneumonia. Two patients died of respiratory failure caused by overwhelming influenza B virus infection. Patients admitted to the hospital with respiratory and underlying diseases should have viral respiratory cultures which include influenza B.