Clinical and epidemiological aspects of an enterovirus outbreak in a neonatal unit

An outbreak of enterovirus infection occurred among neonates in a maternity hospital between July 7 and 22, 1999. Twenty neonates became ill (18 confirmed and two probable), an attack rate of 33%. The incubation period ranged from three to six days (mean, 4.2). The male:female ratio was 11:9 and the mean age at the onset of illness was 5.5 days. All the babies had fever, eight, a maculopapular rash, and six had symptoms of gastroenteritis, 11 developed meningitis. Nineteen neonates required hospitalization for three to seven days, but all were discharged home without sequelae. Enteroviral RNA was detected in all of 18 urines, and 14 cerebrospinal fluid specimens tested. A case-control study was conducted to determine risk factors associated with the outbreak. Rooming in the nursery ward was a significant risk factor (odds ratio=33.35; 95% confidence interval, 3.79-800; P=0.00002). No association was found between illness and other possible risk factors. Appropriate control measures resulted in resolution of the outbreak. Our findings demonstrate the potential for enteroviruses to cause widespread illness among newborns, and emphasize the usefulness of polymerase chain reaction in the early diagnosis of infection, and underline the role of effective control measures in interrupting viral transmission.