Outbreak of parainfluenza virus type 3 in an intermediate care neonatal nursery

Of the four serotypes of human parainfluenza virus, parainfluenza type 3 causes the majority of infections in young children and infants. Parainfluenza type 3 can occur in newborns, although most are born with neutralizing antibodies. There have been only infrequent reports of parainfluenza type 3 causing nosocomial respiratory infection in the newborn nursery setting. We report an outbreak occurring in the intermediate care nursery (IMCN) at St. Boniface Hospital, Winnipeg, Canada.

On August 6, 1996, nursing staff of IMCN notified Infection Control that six infants had developed respiratory tract symptoms including nasal discharge and cough. Three more cases were recognized by August 8, 1996. Infection control precautions including cohorting of infant cases and ill staff, gowning and reinforcement of hand washing practices and visitor regulations were instituted. When two further cases occurred on August 9, 1996, the unit was closed to all admissions and remained closed until August 30, 1996. The last infant case occurred on August 10, 1996.

The attack rate among infants was 63% (12 of 19). No mortality was associated with this outbreak and morbidity was minimal (no ventilator support was required), although one-half of the infants developed radiologic pulmonary infiltrates and one-half required supplemental oxygen therapy. Parainfluenza type 3 was isolated from nasopharyngeal secretions in 6 of 12 infant cases. There was a significant difference (P = 0.02) in age between the ill and non-ill infants; ill infants were a mean age of 42 days compared with a mean age of 11 days for non-ill infants at the midpoint of the outbreak. Sixteen of 65 (25%) IMCN nursing/medical staff reported an upper respiratory tract illness between July 10 and August 18, 1996. None of the staff was cultured.

High patient census, limited numbers of full time staff, inadequate cohorting attempts because of staffing constraints and crowding in the IMCN were thought to be contributors to this outbreak. Institution of basic barrier precautions and temporary closure of the unit were effective in preventing further spread of the outbreak.