MOLECULAR EPIDEMIOLOGY OF 2 CONSECUTIVE OUTBREAKS OF PARAINFLUENZA-3 IN A BONE-MARROW TRANSPLANT UNIT

Two consecutive nosocomial outbreaks of parainfluenza 3, in which 5 of 15 infected patients died, occurred in an adult bone marrow transplan t unit. Parainfluenza 3 strain variation was assessed by reverse trans cription-PCR sequencing of part of the parainfluenza 3 F gene, includi ng the noncoding region, directly from clinical samples. Sequence data from the outbreaks were compared with those from 15 other parainfluen za 3 isolates circulating concurrently in the community; altogether, 1 3 strains which fell into three lineages were identified. Four immunos uppressed patients shed virus persistently for between 1 and 4 months without change in sequence. The first outbreak lasted 4 months and inv olved three parainfluenza 3 strains, and one persistently infected pat ient was implicated as the source of infection for three others. The s econd outbreak lasted for 1 month but involved only one strain. These data indicate that introduction of community parainfluenza 3 strains t o the bone marrow transplant unit was followed by person-to-person tra nsmission within the unit rather than reintroduction of virus from the community.