title: Human parainfluenza virus 4 outbreak and the role of diagnostic tests.
abstract: Owing to the difficulties in isolating the virus and the lack of routine surveillance, the clinical significance of human parainfluenza virus 4 (HPIV-4) is less well defined than that of the other human parainfluenza viruses. We describe the first outbreak of HPIV-4 infection in a developmental disabilities unit, involving 38 institutionalized children and three staff members, during a 3-week period in autumn 2004. Most subjects had upper respiratory tract infections (URTI), while lower respiratory tract infections (LRTI) occurred in three children (7%), one complicated by respiratory failure requiring ventilation support. All patients recovered. Nasopharyngeal aspirates tested for HPIV-4 were positive by reverse transcriptase PCR (RT-PCR) in all 41 cases (100%), by direct immunofluorescence in 29 of 39 tested cases (74%), and by cell cultures in 6 of 37 cases (16%), and serum was positive for antibodies against HPIV-4 in all 35 cases (100%) with serum samples available. In addition, RT-PCR detected HPIV-4 in four children (three LRTI and one URTI) out of 115 patients with community-acquired respiratory tract infection. Molecular analysis of the 1,198-bp phosphoprotein sequences showed that HPIV-4 isolates among the cases were genetically similar, whereas the community controls were more genetically distant, supporting nosocomial transmission of a single HPIV-4 genotype during the outbreak. Moreover, the HPIV-4 causing the outbreak is more closely related to HPIV-4A than HPIV-4B. HPIV-4 may be an important cause of more severe respiratory illness in children. The present RT-PCR assay is a sensitive, specific, and rapid method for the diagnosing HPIV-4 infection. To better define the epidemiology and clinical spectrum of disease of HPIV-4 infections, HPIV-4 should be included in the routine panels of respiratory virus detection on respiratory specimens.
authors.affiliation: Department of Microbiology, The University of Hong Kong, University Pathology Building, Queen Mary Hospital.
authors.forename: Susanna K P
authors.initials: SK
authors.lastname: Lau
authors.forename: Wing-Kin
authors.initials: WK
authors.lastname: To
authors.forename: Philomena W T
authors.initials: PW
authors.lastname: Tse
authors.forename: Alex K H
authors.initials: AK
authors.lastname: Chan
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
authors.forename: Hoi-Wah
authors.initials: HW
authors.lastname: Tsoi
authors.forename: Annie F Y
authors.initials: AF
authors.lastname: Leung
authors.forename: Kenneth S M
authors.initials: KS
authors.lastname: Li
authors.forename: Paul K S
authors.initials: PK
authors.lastname: Chan
authors.forename: Wilina W L
authors.initials: WW
authors.lastname: Lim
authors.forename: Raymond W H
authors.initials: RW
authors.lastname: Yung
authors.forename: Kwok-Hung
authors.initials: KH
authors.lastname: Chan
authors.forename: Kwok-Yung
authors.initials: KY
authors.lastname: Yuen
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D002675:Child, Preschool; D002522:Chlorocebus aethiops; D019411:Clinical Laboratory Techniques; D003428:Cross Infection / Q000175:diagnosis* / Q000453:epidemiology* / Q000821:virology; D004196:Disease Outbreaks; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D029482:Parainfluenza Virus 4, Human / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D012141:Respiratory Tract Infections / Q000175:diagnosis / Q000453:epidemiology / Q000821:virology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D019351:Rubulavirus Infections / Q000175:diagnosis* / Q000453:epidemiology* / Q000821:virology; D012680:Sensitivity and Specificity; D014709:Vero Cells; D014776:Virus Cultivation
chemical_list: D000914:Antibodies, Viral