Abstract and Introduction
Abstract
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.
Introduction
Each year hundreds of millions of people are afflicted with respiratory tract infections caused by a wide range of viruses. Most cases of respiratory viral infections are asymptomatic or relatively mild, causing minor illness before the patient fully recovers. Serious illness can develop, especially among certain high-risk groups, leading to hospitalization, worsening of chronic conditions, and even death. In between are cases of moderate to severe respiratory tract infections in which patients seek outpatient medical attention, referred to as medically attended acute respiratory infection (ARI). These infections frequently result in lost productivity in the form of work or school absenteeism or reduced productivity due to attendance at work or school while sick (presenteeism).
The most common viruses associated with respiratory tract infections are human adenovirus (ADNO), human coronavirus (CoV), human metapneumovirus (hMPV), human rhinovirus (HRV), influenza virus (influenza), parainfluenza virus (PIV), and respiratory syncytial virus (RSV). These viral pathogens vary in their pathogenesis, epidemiology, and temporal appearance throughout the year, but typically share a common set of symptoms including cough, fever, and rhinorrhea. Among the many viral ARIs seen in primary care each year, only a portion has been routinely tested to determine the offending organism because (i) rapid testing to differentiate among viruses is not readily available, and (ii) available treatments for most respiratory viruses are chiefly palliative, with the exception being antivirals for treatment of influenza.
New assay methods using multiplex reverse transcriptase polymerase chain reaction (MRT-PCR) are becoming available that allow for relatively rapid detection of multiple virus types. During the 2011–2012 influenza season, the multicenter U.S. Influenza Vaccine Effectiveness (Flu VE) Network conducted a study designed to determine the effectiveness of the season's influenza vaccine. That study used singleplex RT-PCR (SRT-PCR) to detect influenza virus. The University of Pittsburgh site of the Flu VE Network also used MRT-PCR. The purposes of this study were to (i) compare the agreement between SRT-PCR and MRT-PCR for influenza virus detection; (ii) examine the distribution of viruses associated with ARI visits during January through April 2012 in Allegheny County, Pennsylvania, using MRT-PCR; and (iii) compare personal characteristics and symptoms among those infected with various viruses. This study is among the first to examine a wide range of respiratory viral infections, including four CoVs and four PIVs, resulting in outpatient primary care visits among individuals across a broad age spectrum.
Influenza Resp Viruses. 2014;8(4):397-405. © 2014 Blackwell Publishing
