Influenza and other respiratory virus infections in outpatients with medically attended acute respiratory infection during the 2011-12 influenza season.
BACKGROUND
Respiratory tract infections are a major cause of outpatient visits, yet only a portion is tested to determine the etiologic organism. Multiplex reverse transcriptase polymerase chain reaction (MRT-PCR) assays for detection of multiple viruses are being used increasingly in clinical settings.


METHODS
During January-April 2012, outpatients with acute respiratory illness (≤ 7 days) were tested for influenza using singleplex RT-PCR (SRT-PCR). A subset was assayed for 18 viruses using MRT-PCR to compare detection of influenza and examine the distribution of viruses and characteristics of patients using multinomial logistic regression.


RESULTS
Among 662 participants (6 months-82 years), detection of influenza was similar between the MRT-PCR and SRT-PCR (κ = 0.83). No virus was identified in 267 (40.3%) samples. Commonly detected viruses were human rhinovirus (HRV, 15.4%), coronavirus (CoV, 10.4%), respiratory syncytial virus (RSV, 8.4%), human metapneumovirus (hMPV, 8.3%), and influenza (6%). Co-detections were infrequent (6.9%) and most commonly occurred among those <18 years old. In regression analyses, compared with non-viral illnesses, RSV and hMPV were significantly more frequent in children and less frequent in 18- to 49-year-olds than in those ≥ 50 years (P = 0.01), fever was more common in hMPV and influenza infections (P = 0.008), nasal congestion was more frequent in CoV, HRV, hMPV, influenza and RSV infections (P = 0.001), and body mass index was higher among those with influenza (P = 0.036).


CONCLUSIONS
Using MRT-PCR, a viral etiology was found in three-fifths of patients with medically attended outpatient visits for acute respiratory illness during the influenza season; co-detected viruses were infrequent. Symptoms varied by viral etiology.
Department of Family Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Richard K
RK
Zimmerman
Charles R
CR
Rinaldo
Mary Patricia
MP
Nowalk
Balasubramani
B
Gk
Mark G
MG
Thompson
Krissy K
KK
Moehling
Arlene
A
Bullotta
Stephen
S
Wisniewski
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction; D010045:Outpatients; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014777:Virus Diseases / Q000453:epidemiology* / Q000821:virology*; D014780:Viruses / Q000145:classification* / Q000302:isolation & purification*; D055815:Young Adult
Co-detection; RT-PCR; influenza; viral infections