937. Age-Specific Incidence of Parainfluenza Viruses Among Outpatients in the United States:  The Influenza Incidence Surveillance Project, 2010-2013
Session: Poster Abstract Session: Respiratory Infections
Friday, October 4, 2013
Room: The Moscone Center: Poster Hall C


Parainfluenza viruses (PIV) contribute substantially to pediatric hospitalizations in the United States.  However, to date, there has been no systematic domestic surveillance to ascertain the burden among pediatric outpatients, or for other age groups.  The Influenza Incidence Surveillance Project (IISP) conducts population-based surveillance to determine incidence of respiratory viruses in the outpatient setting, including PIV 1-4.


From August 2010 through April 2013, outpatient health care providers with enumerated patient populations representing all ages in 12 states and jurisdictions conducted surveillance of patients with influenza-like illness (ILI, defined as fever with cough or sore throat).  Respiratory (nasal or nasopharyngeal) specimens were collected from the first 10 ILI patients each week with demographic and clinical data.  Specimens were tested for multiple respiratory viruses, including PIV1-3 in all sites and PIV4 in three sites, using RT-PCR assays.  Cumulative incidence was calculated using provider patient population size as the denominator.


Parainfluenza viruses 1-3 accounted for 6.0% (651) of 10,882 ILI-related outpatient visits: 27% were PIV1, 31% PIV2, and 42% PIV3.  Of the 1803 ILI specimens tested for PIV4, 0.7% (13) were positive.  Virus circulation varied noticeably by year and type with PIV3 predominating in 2010-11 ( incidence 81 per 100,000 population), PIV1 in 2011-12 (40 per 100,000), and dual predominance of PIV2 and PIV3 (60 and 56 per 100,000 respectively) in 2012-13.  Parainfluenza viruses were detected in all age groups, with the highest incidence among patients age <18 years (Figure).  Among pediatric cases, the median age at detection for PIV3 was 2.0 years, which was significantly lower than the median ages at detection for PIV1 and PIV2: 4.0 years and 6.7 years, respectively (p<0.01).


The IISP provides a unique opportunity to conduct multi-year population-based surveillance for PIVs in outpatient practice.  Parainfluenza viruses were found in a substantial proportion of outpatients with ILI, and the incidence of PIVs was highest among pediatric outpatients.  The predominant PIV type varied by year; however co-dominance between PIV2 and PIV3 occurred in 2012-13.

Figure. Incidence of PIV 1-4 by age group and season

Andrea Giorgi, MPH1, Elizabeth Bancroft, MD SM2, Steve Di Lonardo, MS3, Jose Lojo, MPH4, Jonathan Temte, MD, PhD5, Ruth Lynfield, MD6, Oluwakemi Oni, MPH7, Brett L. Whitaker, MS8, Glen Abedi, MPH9, Dean Erdman, Dr PH8, Lyn Finelli, DrPH, MS10, Ashley Fowlkes, MPH11 and the IISP working group, (1)Council of State and Territorial Epidemiologists, Atlanta, GA, (2)Los Angeles County Department of Health Services, Los Angeles, CA, (3)New York City Department of Health and Mental Hygiene, Long Island City , NY, (4)Philadelphia Department of Public Health, Philadelphia , PA, (5)Family Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, (6)Acute Disease Investigation and Control, Minnesota Department of Health, St. Paul, MN, (7)Iowa Department of Public Health, Des Moines, IA, (8)Division of Viral Diseases, Ncird, CDC, Atlanta, GA, (9)Centers for Disease Control and Prevention, Atlanta, GA, (10)Centers for Disease Control and Prevention (CDC), Atlanta, GA, (11)Influenza Division, Ncird, CDC, Atlanta, GA


A. Giorgi, None

E. Bancroft, None

S. Di Lonardo, None

J. Lojo, None

J. Temte, None

R. Lynfield, None

O. Oni, None

B. L. Whitaker, None

G. Abedi, None

D. Erdman, None

L. Finelli, None

A. Fowlkes, None

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