Twelve years' detection of respiratory viruses by immunofluorescence in hospitalised children: impact of the introduction of a new respiratory picornavirus assay

Abstract

BackgroundDirect immunofluorescence assays (DFA) are a rapid and inexpensive method for the detection of respiratory viruses and may therefore be used for surveillance. Few epidemiological studies have been published based solely on DFA and none included respiratory picornaviruses and human metapneumovirus (hMPV). We wished to evaluate the use of DFA for epidemiological studies with a long-term observation of respiratory viruses that includes both respiratory picornaviruses and hMPV.MethodsSince 1998 all children hospitalized with respiratory illness at the University Hospital Bern have been screened with DFA for common respiratory viruses including adenovirus, respiratory syncytial virus (RSV), influenza A and B, and parainfluenza virus 1-3. In 2006 assays for respiratory picornaviruses and hMPV were added. Here we describe the epidemiological pattern for these respiratory viruses detected by DFA in 10'629 nasopharyngeal aspirates collected from 8'285 patients during a 12-year period (1998-2010).ResultsAddition of assays for respiratory picornaviruses and hMPV raised the proportion of positive DFA results from 35% to 58% (p < 0.0001). Respiratory picornaviruses were the most common viruses detected among patients ≥1 year old. The seasonal patterns and age distribution for the studied viruses agreed well with those reported in the literature. In 2010, an hMPV epidemic of unexpected size was observed.ConclusionsDFA is a valid, rapid, flexible and inexpensive method. The addition of assays for respiratory picornaviruses and hMPV broadens its range of viral detection. DFA is, even in the "PCR era", a particularly adapted method for the long term surveillance of respiratory viruses in a pediatric population.

Practical Guidance for Clinical Microbiology Laboratories: Viruses Causing Acute Respiratory Tract Infections

“…Compared to molecular detection methods, DFA and IFA assays have significantly reduced sensitivity and specificity (197). Some argue that the lower sensitivity can identify "clinically relevant infections" in some patient populations (e.g., hospitalized pediatric patients) (198) in contrast to detection of free nucleic acid as in molecular detection. Additionally, microscopic examination of samples for DFA testing can directly determine specimen quality (199) by allowing for observation of the number of epithelial cells present in the sample.…”

Respiratory syncytial virus. Clinical and epidemiological pattern in pediatric patients admitted to a children’s hospital between 2000 and 2013

“…IIF allows to identify viral agents generally related to ALRTIs, such as respiratory syncytial virus (RSV), i n f l u e n z a , p a r a i n f l u e n z a , a n d adenovirus. [6][7][8][9][10] The rapid identification of viral etiologic agents is essential for the epidemiological monitoring of this condition, it helps to reduce the unnecessary use of antibiotics and, as a result, decreases bacterial resistance, therefore improving the care provided to hospitalized patients and optimizing available resources. In addition, it enables to adopt measures aimed at reducing nosocomial transmission by implementing contact or respiratory isolation measures as appropriate.…”

“…10 Even in the "PCR era", IIF is a method especially adapted for the ongoing surveillance for local epidemiology of respiratory viruses in the pediatric population. 9 Particularly, RSV is the major pathogen causing bronchiolitis and pneumonia in young infants, and different epidemiological studies have shown that the primary RSV infection takes place between 6 weeks of age and 2 years old. 2,[11][12][13][14][15][16][17] Given the magnitude of the problem caused by ALRTIs, it is important to describe their clinical and epidemiological pattern and the burden of RSV in our setting and identify risk factors for RSV infection.…”

Virus respiratorio sincicial. Patrón clínico epidemiológico en niños internados en un hospital pediátrico durante los años 2000-2013

“…Permite identificar los agentes virales que usualmente están relacionados con IRAB, como son virus respiratorio sincicial (VRS), influenza, parainfluenza y adenovirus. [6][7][8][9][10] La identificación rápida de los agentes etiológicos virales resulta indispensable para el monitoreo epidemiológico de esta patología, brinda la posibilidad de disminuir el uso innecesario de antibióticos y, por ende, la disminución de la resistencia bacteriana, lo que mejora la atención de los pacientes hospitalizados y optimiza los recursos disponibles. Posibilita, además, la adopción de medidas tendientes a disminuir el contagio intrainstitucional mediante el uso de medidas de aislamiento de contacto o respiratorio según corresponda.…”

“…10 La IFI es, incluso en la "era de la PCR", un método particularmente adaptado para la vigilancia continua de la epidemiología local de los virus respiratorios en la población pediátrica. 9 Particularmente el VRS es el principal patógeno causante de bronquiolitis y neumonía en el lactante pequeño y diferentes estudios epidemiológicos demuestran que la infección primaria por VRS ocurre entre las 6 semanas y los 2 años de vida. 2,[11][12][13][14][15][16][17] Dada la magnitud del problema de las IRAB, es importante describir su patrón clínico-epidemiológico y la carga de enfermedad debida a VRS en nuestro medio e identificar los factores de riesgo de la infección por este virus.…”