Multicluster nosocomial outbreak of parainfluenza virus type 3 infection in a pediatric oncohematology unit: a phylogenetic study.
BACKGROUND
Human parainfluenza virus type 3 (hPIV-3) has been reported to cause nosocomial outbreaks of respiratory infection, in particular among hematopoietic stem cell transplantation recipients.


METHODS
From September 2007 through January 2008 several episodes of hPIV-3 infection were observed among young patients followed at the Oncohematology Unit (OHU) or other units of the Pediatrics Department. In 32 young patients (median age 3.5 years, range 21 days-27 years), hPIV-3 infection was diagnosed by direct fluorescent antibody staining of cells from respiratory secretions, and virus quantified by real-time RT-PCR in nasopharyngeal aspirates or bronchoalveolar lavage samples. In addition, the epidemiologic relatedness of hPIV-3 strains was investigated by sequencing two variable regions of the hemagglutinin-neuraminidase gene (nt 1-569 and nt 762-1239).


RESULTS
Of the 32 hPIV-3-positive patients, 19 were hematopoietic stem cell transplantation recipients, 8 had hematologic malignancies, and 5 were immunocompetent children. Sixteen patients had upper, and 16 lower respiratory tract infection. All patients but one had high viral load in nasopharyngeal aspirates (>1.0x10(6) RNA copies/mL). One patient died from respiratory failure with a high viral load in bronchoalveolar lavage. Phylogenetic analysis showed that 16/32 strains were identical. Besides this major cluster, three other clusters were identified, each one defining a smaller outbreak.


CONCLUSIONS
Phylogenetic analysis allows identification of the role of a single or multiple hPIV-3 strains in the person-to-person transmission within an outbreak occurring in clinical units.
Servizio di Virologia, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
Antonio
A
Piralla
Elena
E
Percivalle
Alessandra
A
Di Cesare-Merlone
Franco
F
Locatelli
Giuseppe
G
Gerna
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D003428:Cross Infection / Q000150:complications / Q000453:epidemiology / Q000821:virology*; D004196:Disease Outbreaks; D015707:HN Protein / Q000235:genetics; D019337:Hematologic Neoplasms / Q000150:complications / Q000628:therapy; D006776:Hospitals, Pediatric; D006801:Humans; D007121:Immunocompetence; D016867:Immunocompromised Host; D007223:Infant; D007231:Infant, Newborn; D007558:Italy / Q000453:epidemiology; D010224:Parainfluenza Virus 3, Human / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D010253:Respirovirus Infections / Q000150:complications / Q000453:epidemiology / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D055815:Young Adult
D015707:HN Protein; D012367:RNA, Viral