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LB 5 An Outbreak of Human Parainfluenza Virus 3 Infection in an Outpatient Hematopoietic Stem Cell Transplant Clinic: Implications for Surveillance and Infection Control

Sunday, April 3, 2011
Trinity Ballroom (Hilton Anatole)
Emily RM Sydnor, MD , Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD
Amy Greer, PhD , Division of Medical Microbiology, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
Alicia P. Budd, MPH , Department of Hospital Epidemiolgy and Infection Control, The Johns Hopkins Hospital, Baltimore, MD
Miriana Pehar, BSN , Department of Hospital Epidemiolgy and Infection Control, The Johns Hopkins Hospital, Baltimore, MD
Supriya Munshaw, PhD , Division of Medical Microbiology, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
Dionissios Neofytos, MD , Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD
Trish M. Perl, MD, MSc , Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD
Alexandra Valsamakis, MD, PhD , Division of Medical Microbiology, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
Background: Parainfluenza viruses commonly cause respiratory tract infections in adults and children, with peak activity occurring during spring and summer. Human parainfluenza virus type 3 (hPIV-3) can cause lower respiratory tract infections and lead to increased morbidity and mortality among hematopoietic stem cell transplant (HSCT) patients. Immunocompromised patients may experience prolonged or asymptomatic viral shedding, enhancing transmission.

Objective: To investigate the epidemiology of and describe the infection prevention measures implemented during an hPIV-3 outbreak among HSCT patients attending the Johns Hopkins Cancer Center Inpatient/Outpatient (IPOP) Care Continuum Clinic.

Methods: A case-patient was defined as any patient positive for hPIV-3 on respiratory viral testing who attended the IPOP clinic between June 1st and October 1st, 2010. Cases were identified using automated surveillance software. Diagnostic viral testing was performed by direct immunofluorescence (DFA) or multiplex polymerase chain reaction (PCR) on nasopharyngeal swabs, washes, or bronchoalveolar lavage specimens. Active surveillance for respiratory illness and infection control interventions were instituted. Retrospective molecular investigation of outbreak viral strains was performed by direct sequencing of a non-coding region of the viral F gene of hPIV-3.

Results: Twelve hPIV-3 infections were identified among 216 HSCT patients attending the IPOP clinic during the time of interest. Respiratory virus season infection control precautions were instituted including droplet isolation of laboratory confirmed cases and masking of all staff and caregivers within 6 feet of patients. Additional infection control measures were implemented on July 20th due to continued identification of hPIV-3 positive patients. These measures included universal screening for respiratory symptoms and universal masking within the IPOP clinic. 11/12 case-patients had overlapping clinic days. 5/12 patients were admitted secondary to hPIV-3 infection. One patient died. Retrospective molecular analysis of 10 available case-patient viral sequences identified a single strain of hPIV-3 in 9 of 10 patients, lending strong support for healthcare-associated transmission in the outpatient setting.

Conclusions: We identified an outbreak of hPIV-3 infection among HSCT patients attending an outpatient clinic. This outbreak resulted in significant morbidity and one fatality. Molecular sequencing of hPIV-3 isolates from case-patients suggested healthcare-associated transmission in the clinic setting. This outbreak highlights the need for expanded respiratory virus surveillance methods in this patient population outside of peak respiratory virus season, and vigilance with infection control measures that prevent viral transmission.