Detection of respiratory viruses by real-time polymerase chain reaction in outpatients with acute respiratory infection

Smartphone-based mobile digital pressure sensor for quantitative point-of-care testing of respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is a major cause of acute respiratory tract infections in infants and elderly individuals, leading to hospitalisation and potentially fatal outcomes, posing a serious threat to global health and economy. This study proposes a smartphone-based mobile digital pressure sensor (smartphone-MDPS) for the quantitative detection of the RSV fusion protein (RSV-F) in clinical nasopharyngeal samples. The smartphone-MDPS utilized two monoclonal antibodies (mAbs) specific to the F protein, of which mAb1 was conjugated with Au@PtNPs (Au@PtNPs-mAb1) as the detection antibody and mAb2 was coupled with magnetic beads (MB-mAb2) as a coating antibody to establish a novel sandwich immunoassay. During the immune reaction, the substrate H2O2 was catalyzed to release O2 gas by the Au@PtNPs nanozyme within the Au@PtNPs-mAb1-RSV-F-mAb2-MB immunocomplexes. The pressure intensity of O2 was measured using a mobile digital pressure sensor and transmitted wirelessly to a smartphone application for analysis. The programming codes for the sensor module and Android app were developed considering the performance requirements of the smartphone-MDPS. With a quantitation range of 0.09-1.953 ng/mL, the system had a limit of quantitation (LOQ) of 0.09 ng/mL and a limit of detection (LOD) of 0.03 ng/mL. When nasopharyngeal samples from 27 patients with RSV infection and 46 healthy individuals were tested, the smartphone-MDPS and enzyme-linked immunosorbent assays (ELISA) exhibited 100 % positivity and specificity as well as a strong correlation coefficient (R2 = 0.991) for quantitative measurements between these two assays. In conclusion, the smartphone-MDPS has high portability, affordability, efficiency, sensitivity, and specificity, making it a promising immunoassay for quantitative point-of-care testing of RSV infection.

Viral co-detection of influenza virus and other respiratory viruses in hospitalized Brazilian patients during the first three years of the coronavirus disease (COVID)-19 pandemic: an epidemiological profile

Introduction

In Brazil, few studies were performed regarding the co-detection of respiratory viruses in hospitalized patients. In this way, the study aimed to describe the epidemiological profile of hospitalized patients due to influenza virus infection that presented co-detection with another respiratory virus.

Methods

The epidemiological analysis was made by collecting data from Open-Data-SUS. The study comprised patients infected by the influenza A or B virus with positive co-detection of another respiratory virus, such as adenovirus, bocavirus, metapneumovirus, parainfluenza virus (types 1, 2, 3, and 4), rhinovirus, and respiratory syncytial virus (RSV). The markers [gender, age, clinical signs and symptoms, comorbidities, need for intensive care unit (ICU) treatment, and need for ventilatory support] were associated with the chance of death. The data was collected during the first three years of the coronavirus disease (COVID)-19 pandemic-from December 19, 2019, to April 06, 2023.

Results

A total of 477 patients were included, among them, the influenza A virus was detected in 400 (83.9%) cases. The co-detection occurred, respectively, for RSV (53.0%), rhinovirus (14.0%), adenovirus (13.4%), parainfluenza virus type 1 (10.7%), parainfluenza virus type 3 (5.2%), metapneumovirus (3.8%), parainfluenza virus type 2 (3.6%), bocavirus (3.4%), and parainfluenza virus type 4 (1.5%). The co-detection rate was higher in the male sex (50.7%), age between 0-12 years of age (65.8%), and white individuals (61.8%). The most common clinical symptoms were cough (90.6%), dyspnea (78.8%), and fever (78.6%). A total of 167 (35.0%) people had at least one comorbidity, mainly cardiopathy (14.3%), asthma (8.4%), and diabetes mellitus (7.3%). The need for ICU treatment occurred in 147 (30.8%) cases, with most of them needing ventilatory support (66.8%), mainly non-invasive ones (57.2%). A total of 33 (6.9%) patients died and the main predictors of death were bocavirus infection (OR = 14.78 [95%CI = 2.84-76.98]), metapneumovirus infection (OR = 8.50 [95%CI = 1.86-38.78]), race (other races vs. white people) (OR = 3.67 [95%CI = 1.39-9.74]), cardiopathy (OR = 3.48 [95%CI = 1.13-10.71]), and need for ICU treatment (OR = 7.64 [95%CI = 2.44-23.92]).

Conclusion

Co-detection between the influenza virus and other respiratory viruses occurred, mainly with RSV, rhinovirus, and adenovirus being more common in men, white people, and in the juvenile phase. Co-detection of influenza virus with bocavirus and metapneumovirus was associated with an increased chance of death. Other factors such as race, cardiopathy, and the need for an ICU were also associated with a higher chance of death.

Utility of multiplex real-time PCR for diagnosing paediatric acute respiratory tract infection in a tertiary care hospital

Background

Acute respiratory infections (ARIs) are responsible for considerable morbidity and mortality among children all over the world. Many of the etiologic agents of the infections especially viral go undiagnosed for lack of requisite facility and the cost factors. We have used a commercially available platform for diagnosis of ARIs in children receiving inpatient and outpatient services in a tertiary care centre.

Methods

The framework of the study was prospective and observational. In this study, clinical samples of children suffering from ARIs were subjected to real-time multiplex PCR targeting both viral and bacterial pathogens.

Results

Of 94 samples received at our centre (49 male and 45 female), the positivity for respiratory pathogens was detected in 50 (53.19%) samples. Clinical symptoms of patients and age distribution have been elaborated in text. A single pathogen (n = 29/50), two pathogens (15/50) and three pathogens (n = 6/50) were detected by multiplex RT-PCR. Of 77 isolates detected, maximum numbers were of human rhinovirus (HRV) (n = 14) (18.18%) Streptococcus pneumoniae (n = 14) (18.18%) followed by Staphylococcus aureus (n = 10) (12.98%).

Conclusion

The epidemiology of ARIs considering viral etiologies is poorly understood due to less number of studies especially in Indian subcontinent. The advent of latest advanced molecular methods has made it possible to identify common respiratory pathogens and has contributed to cover the gap in existing knowledge.

Application of MRT-qPCR for pathogen detection of lower respiratory tract infection

OBJECTIVE

To analyze and clarify the application value of multiplex quantitative real-time PCR (MRT-PCR) assay in detecting pathogens involved in lower respiratory tract infection (LRTI), so as to realize accurate and rapid detection of respiratory pathogens.

METHODS

Bronchial alveolar lavage fluid (BALF) specimens from 186 patients with LRTI collected in the Cangzhou Central Hospital from June 2020 to September 2021 were analyzed retrospectively. Pathogen detection was performed by both MRT-PCR and direct immunofluorescence assay (DFA), and the results of different inspection methods were compared.

RESULTS

Among the seven pathogens detected by MRT-PCR, 140 positive specimens were identified out of the 186 patients, with the top three pathogens with the highest positive rates being influenza A virus (Flu A; 36 [19.35%]), respiratory syncytial virus (RSV; 30 [16.13%]) and human adenovirus (HAdV; 23 [12.37%]), and the pathogen with the lowest positive rate being parainfluenza virus type 3 (PIV3; 9 [4.84%]). DFA showed 110 pathogen-positive specimens, and the top three pathogens with the highest positive rates were Flu A (30 [16.13%]), HAdV (21 [11.29%]) and RSV (19 [10.22%]). The total sensitivity and accuracy of MRT-PCR assay were 93.01% and 98.69% respectively, which were statistically higher than those of 48.45% and 91.24% of DFA (P<0.05). The two inspection methods showed no significant difference in specificity (99.4% for MRT-PCR assay and 97.28% for DFA) (P>0.05).

CONCLUSIONS

MRT-PCR is rapid, accurate and specific in detecting pathogens of LRTI, which significantly improves the detection rate, with reliable performance and it has high clinical application value.

Charlson comorbidity index scores and in-hospital prognosis of patients with severe acute respiratory infections

BACKGROUND

Respiratory infections are one of the leading causes of mortality, and comorbid conditions play a significant role in the severity and fatality of these infections.

AIMS

We evaluated the Charlson Comorbidity Index (CCI) score and possible predictors of mortality in hospitalised patients with severe acute respiratory infection (SARI), aiming to test if the CCI is a valid in-hospital prognostic indicator.

METHODS

Patients older than 14 years, hospitalised from 2010 to 2016 due to SARI by viral infection and who were submitted to respiratory virus testing were included. We assessed comorbidity retrospectively through chart review and calculated four variants of the CCI.

RESULTS

Of the 291 patients assessed, 72.8% (n = 212) presented comorbidities, and 24% died (n = 70). The most recurrent comorbidities were chronic pulmonary disease (n = 76/212, 36%) and HIV (n = 50/212, 23.6%). The 1994 age-adjusted CCI predicted in-hospital mortality in SARI patients (P = 0.04), and HIV was associated with in-hospital mortality (P = 0.032).

CONCLUSIONS

The comorbidity scores used to assess mortality risk in hospitalised patients with SARI displayed poor results, but HIV infection was considered a marker of severity. However, other factors should be considered in order to compose a score system that allows us to specifically assess the risk of mortality in patients with SARI.

Biosensors for the detection of respiratory viruses: A review

The recent events of outbreaks related to different respiratory viruses in the past few years, exponentiated by the pandemic caused by the coronavirus disease 2019 (COVID-19), reported worldwide caused by SARS-CoV-2, raised a concern and increased the search for more information on viruses-based diseases. The detection of the virus with high specificity and sensitivity plays an important role for an accurate diagnosis. Despite the many efforts to identify the SARS-CoV-2, the diagnosis still relays on expensive and time-consuming analysis. A fast and reliable alternative is the use of low-cost biosensor for in loco detection. This review gathers important contributions in the biosensor area regarding the most current respiratory viruses, presents the advances in the assembly of the devices and figures of merit. All information is useful for further biosensor development for the detection of respiratory viruses, such as for the new coronavirus.

Evaluation of TaqMan Array card (TAC) for the detection of 28 respiratory pathogens

Background

Respiratory infections are a serious threat to human health. So, rapid detection of all respiratory pathogens can facilitate prompt treatment and prevent the deterioration of respiratory disease. Previously published primers and probes of the TaqMan array card (TAC) for respiratory pathogens are not sensitive to Chinese clinical specimens. This study aimed to develop and improve the TAC assay to detect 28 respiratory viral and bacterial pathogens in a Chinese population.

Methods

To improve the sensitivity, we redesigned the primers and probes, and labeled the probes with minor groove binders. The amplification efficiency, sensitivity, and specificity of the primers and probes were determined using target-gene containing standard plasmids. The detection performance of the TAC was evaluated on 754 clinical specimens and the results were compared with those from conventional methods.

Results

The performance of the TAC assay was evaluated using 754 clinical throat swab samples and the results were compared with those from gold-standard methods. The sensitivity and specificity were 95.4 and 96.6%, respectively. The lowest detection limit of the TAC was 10 to 100 copies/μL.

Conclusions

TAC is an efficient, accurate, and high-throughput approach to detecting multiple respiratory pathogens simultaneously and is a promising tool for the identification of pathogen outbreaks.

Molecular and Immunological Diagnostic Techniques of Medical Viruses

Viral infections are causing serious problems in human population worldwide. The recent outbreak of coronavirus disease 2019 caused by SARS-CoV-2 is a perfect example how viral infection could pose a great threat to global public health and economic sectors. Therefore, the first step in combating viral pathogens is to get a timely and accurate diagnosis. Early and accurate detection of the viral presence in patient sample is crucial for appropriate treatment, control, and prevention of epidemics. Here, we summarize some of the molecular and immunological diagnostic approaches available for the detection of viral infections of humans. Molecular diagnostic techniques provide rapid viral detection in patient sample. They are also relatively inexpensive and highly sensitive and specific diagnostic methods. Immunological-based techniques have been extensively utilized for the detection and epidemiological studies of human viral infections. They can detect antiviral antibodies or viral antigens in clinical samples. There are several commercially available molecular and immunological diagnostic kits that facilitate the use of these methods in the majority of clinical laboratories worldwide. In developing countries including Ethiopia where most of viral infections are endemic, exposure to improved or new methods is highly limited as these methods are very costly to use and also require technical skills. Since researchers and clinicians in all corners of the globe are working hard, it is hoped that in the near future, they will develop good quality tests that can be accessible in low-income countries.

Molecular Diagnosis of Pneumonia Using Multiplex Real-Time PCR Assay RespiFinder® SMART 22 FAST in a Group of Moroccan Infants

Background

In Morocco, pediatric pneumonia remains a serious public health problem, as it constitutes the first cause of mortality due to infectious diseases. The etiological diagnosis of acute respiratory tract infections is difficult. Therefore, it is necessary to use Multiplex real-time polymerase chain reaction assay tests in a routine setting for exact and fast identification.

Objectives

In this paper, we present the clinical results of pediatric pneumonia and describe their etiology by using molecular diagnosis. Study design: Tracheal secretion was collected from infants presenting respiratory distress isolated or associated with systemic signs, attending the unit of Neonatology between December 1, 2016, and Mai 31, 2018. Samples were tested with the multiplex RespiFinder® SMART 22 FAST which potentially detects 18 viruses and 4 bacteria.

Results

Of the 86 infants considered in this study (mean age 31 ± 19 days) suspected of acute respiratory tract infections, 71 (83%) were positive for one or multiple viruses or/and bacteria. The majority of acute respiratory tract infections had a viral origin (95%): respiratory syncytial viruses (A and B) (49%), rhinovirus (21%), coronaviruses 229E (11%), humain metapneumovirus (5%), influenza A (3%), influenza H1N1 (1%), adenovirus (2%), and parainfluenza virus type 4 (2%). Among our patients, 6% had Mycoplasma pneumoniae. Coinfections were not associated with severe respiratory symptoms.

Conclusion

The clinical spectrum of respiratory infections is complex and often nonspecific. Thus, the early and fast detection of related causative agents is crucial. The use of multiplex real time polymerase chain reaction may help choose an accurate treatment, reduce the overall use of unnecessary antibiotics, preserve intestinal flora, and decrease nosocomial infection by reducing the length of hospitalization.

Molecular detection of respiratory pathogens among children aged younger than 5 years hospitalized with febrile acute respiratory infections: A prospective hospital-based observational study in Niamey, Niger

BACKGROUND AND AIMS

In Niger, acute respiratory infections (ARIs) are the second most common cause of death in children aged younger than 5 years. However, the etiology of ARI is poorly understood in the country. This study aims to describe viral and bacterial infections among children aged younger than 5 years hospitalized with febrile ARI at two hospitals in Niamey, Niger's capital city, and the reported clinical procedures.

METHODS

We conducted a prospective study among children aged younger than 5 years hospitalized with febrile ARI at two national hospitals in Niamey between January and December 2015. Clinical presentation and procedures during admission were documented using a standardized case investigation form. Nasopharyngeal specimens collected from each patient were tested for a panel of respiratory viruses and bacteria using the Fast Track Diagnostic 21 Plus kit.

RESULTS

We enrolled and tested 638 children aged younger than 5 years, of whom 411 (64.4%) were aged younger than 1 year, and 15 (2.4%) died during the study period. Overall, 496/638 (77.7%) specimens tested positive for at least one respiratory virus or bacterium; of these, 195 (39.3%) tested positive for respiratory viruses, 126 (25.4%) tested positive for respiratory bacteria, and 175 (35.3%) tested positive for both respiratory viruses and bacteria. The predominant viruses detected were respiratory syncytial virus (RSV) (149/638; 23.3%), human parainfluenza virus (HPIV) types 1 to 4 (78/638; 12.2%), human rhinovirus (HRV) (62/638; 9.4%), human adenovirus (HAV) (60/638; 9.4%), and influenza virus (INF) (52/638; 8.1%). Streptococcus pneumoniae (249/638; 39.0%) was the most frequently detected bacterium, followed by Staphylococcus aureus (112/638; 12.2%) and Haemophilus influenzae type B (16/638; 2.5%). Chest X-rays were performed at the discretion of the attending physician on 301 (47.2%) case patients. Of these patients, 231 (76.7%) had abnormal radiological findings. A total of 135/638 (21.2%) and 572/638 (89.7%) children received antibiotic treatment prior to admission and during admission, respectively.

CONCLUSION

A high proportion of respiratory viruses was detected among children aged younger than 5 years with febrile ARI, raising concerns about excessive use of antibiotics in Niger.

Respiratory Pathogens in Infants Diagnosed with Acute Lower Respiratory Tract Infection in a Tertiary Care Hospital of Western India Using Multiplex Real Time PCR

OBJECTIVE

To determine the frequency of respiratory pathogens in infants diagnosed with acute lower respiratory tract infections.

METHODS

A prospective cross-sectional observational study was conducted in infants hospitalized with a diagnosis of acute lower respiratory tract infection (ALRTI), in a tertiary care hospital in a metropolitan city of Western India. Nasopharyngeal swabs were analyzed by multiplex real time polymerase chain reaction, for 18 viruses and 3 bacteria (H. influenzae type b, C. pneumoniae and M. pneumoniae). The entire data was entered in Microsoft excel sheet and frequencies were determined.

RESULTS

One hundred eligible infants were enrolled. Pathogens were detected in 82 samples, which included Respiratory syncytial viruses (RSV) A / B (35.4%), Human rhinovirus (25.6%), Adenovirus (22%), Human Parainfluenza viruses (11%), Human bocavirus (9.8), Human metapneumovirus A / B (8.5%), Influenza A (H1N1) pdm 09 (6.1%), Parechovirus (3.7%), Human coronaviruses (3.66%), Haemophilus influenzae type b (6.1%), Chlamydia pneumoniae (2.4%) and Mycoplasma pneumoniae (2.4%). Influenza A (other than H1N1), Influenza B, Human Coronavirus 229E and Enterovirus were not detected. The rate of coinfection was 34% and rhinovirus was the most common of the multiple pathogens.

CONCLUSIONS

Spectrum of viral etiologies of ALRTI is highlighted. Etiological diagnosis of ALRTI would enable specific antiviral therapy, restrict antibiotic use and help in knowing burden of disease.

Clinical characteristics and viral etiologies of outpatients with acute respiratory infections in Huzhou of China: a retrospective study

BACKGROUND

Viruses are commonly found in patients with acute respiratory infections (ARIs). However, the viral etiologies and clinical characteristics of outpatients with ARIs are poorly understood in China. Here, we identified the viral etiologies in outpatients with ARIs in Huzhou, China.

RESULTS

Our results indicated that of 426 outpatients, 246 were positive for viruses. Of them, 221 were positive for a single virus, including influenza A, which comprised H3N2 (28.5%) and pandemic H1N1 (2009) (19.0%), enterovirus (10.4%), and influenza B (8.6%). Other single viruses were detected at less than 8.0%. Twenty-five patients were positively coinfected with two viruses. The prevalent viruses in coinfections were rhinovirus and H3N2 virus (28.0%). Viruses were major pathogens in young children (< 5 years) (75.0%). Coinfections were prevalent in older adults (11.9%) and young children (9.5%). Virus-positive outpatients presented higher temperatures and more sore throat, fatigue and shortness of breath than virus-negative outpatients. ARIs and most virus detections peaked during the winter, but enteroviruses emerged between April and September.

CONCLUSION

Viruses are major agents of ARIs among outpatients in Huzhou, China. There was a variation in the distribution of viruses across different age groups and seasons. These findings are beneficial for planning prevention and treatment services for outpatients with ARIs.

Risk factors of respiratory syncytial virus infection among pediatric influenza-like illness and severe acute respiratory infections in Suzhou, China

The characteristics and risk factors of respiratory syncytial virus (RSV) infection among children has not yet been fully understood. To address the characteristics of RSV-associated illness and risk factors of RSV infection among children under 5 years of age in Suzhou, China. From April 2011 to March 2014, we conducted a prospective surveillance among children in Suzhou, China. Nasal or throat swabs were collected from outpatients with influenza-like illness (ILI) and inpatients with severe acute respiratory infections (SARI). RSV was detected by reverse-transcriptase polymerase chain reaction and direct fluorescent antibody assay for children with ILI and SARI, respectively. Multivariable logistic-regression models were constructed to explore risk factors and symptoms of RSV infection. Of 3267 ILI and 1838 SARI children enrolled in the study, 192 (5.9%) and 287 (15.6%) tested positive for RSV, respectively. Among ILI patients, children with RSV infections visited clinics more often (P = 0.005) and had longer duration of fever (P = 0.032) than those without RSV infection. All RSV-positive children had an increased risk of having cough (OR = 2.9), rhinorrhea (OR = 1.6), breathing difficulty (OR = 3.4), wheezing (OR = 3.3), and irritability (OR = 2.7). Children aged <2 years, had history of prematurity (OR = 2.0) and recent respiratory infections (OR = 1.3) were more likely to get infected by RSV. Children with SARI had higher positive rate of RSV than those with ILI. Cough, rhinorrhea, and wheezing were the most common symptoms in RSV infection. Children aged <2 years, had history of prematurity and recent respiratory infections were the potential risk factors for RSV infection.

Bacterial and viral pathogen spectra of acute respiratory infections in under-5 children in hospital settings in Dhaka city

The study aimed to examine for the first time the spectra of viral and bacterial pathogens along with the antibiotic susceptibility of the isolated bacteria in under-5 children with acute respiratory infections (ARIs) in hospital settings of Dhaka, Bangladesh. Nasal swabs were collected from 200 under-five children hospitalized with clinical signs of ARIs. Nasal swabs from 30 asymptomatic children were also collected. Screening of viral pathogens targeted ten respiratory viruses using RT-qPCR. Bacterial pathogens were identified by bacteriological culture methods and antimicrobial susceptibility of the isolates was determined following CLSI guidelines. About 82.5% (n = 165) of specimens were positive for pathogens. Of 165 infected cases, 3% (n = 6) had only single bacterial pathogens, whereas 43.5% (n = 87) cases had only single viral pathogens. The remaining 36% (n = 72) cases had coinfections. In symptomatic cases, human rhinovirus was detected as the predominant virus (31.5%), followed by RSV (31%), HMPV (13%), HBoV (11%), HPIV-3 (10.5%), and adenovirus (7%). Streptococcus pneumoniae was the most frequently isolated bacterial pathogen (9%), whereas Klebsiella pneumaniae, Streptococcus spp., Enterobacter agglomerans, and Haemophilus influenzae were 5.5%, 5%, 2%, and 1.5%, respectively. Of 15 multidrug-resistant bacteria, a Klebsiella pneumoniae isolate and an Enterobacter agglomerans isolate exhibited resistance against more than 10 different antibiotics. Both ARI incidence and predominant pathogen detection rates were higher during post-monsoon and winter, peaking in September. Pathogen detection rates and coinfection incidence in less than 1-year group were significantly higher (P = 0.0034 and 0.049, respectively) than in 1–5 years age group. Pathogen detection rate (43%) in asymptomatic cases was significantly lower compared to symptomatic group (P<0.0001). Human rhinovirus, HPIV-3, adenovirus, Streptococcus pneumonia, and Klebsiella pneumaniae had significant involvement in coinfections with P values of 0.0001, 0.009 and 0.0001, 0.0001 and 0.001 respectively. Further investigations are required to better understand the clinical roles of the isolated pathogens and their seasonality.

Respiratory Virus Detection and Clinical Diagnosis in Children Attending Day Care

BACKGROUND

Respiratory viruses often have been studied in children with respiratory tract infection (RTI), but less knowledge exists about viruses in asymptomatic children. We have studied the occurrence of a broad panel of respiratory viruses in apparently healthy children attending day care, taking into account the influence of possible confounding factors, such as age, clinical signs of respiratory tract infection (RTI), location (day-care section) and season.

METHODS

We have studied 161 children in two day-care centers, each with separate sections for younger and older children, during four autumn and winter visits over a two-year period. A total of 355 clinical examinations were performed, and 343 nasopharyngeal samples (NPS) were analyzed by semi-quantitative, real-time, polymerase chain reaction (PCR) tests for 19 respiratory pathogens.

RESULT

Forty-three percent of all NPS were PCR-positive for ≥ 1 of 13 virus species, with high species variation during visits. Rhinovirus 26% (88/343 NPS), enterovirus 12% (40/343) and parechovirus 9% (30/343) were detected in every visit, and the rates varied in relation to age, day-care section and season. Ten other viruses were detected in ≤ 3% of the NPS. Generally, viruses occurred together in the NPS. In 24% (79/331) of the clinical examinations with available NPS, the children had clear signs of RTI, while in 41% (135/331) they had mild signs, and in 35% (117/331) the children had no signs of RTI. Moreover, viruses were found in 70% (55/79) of children with clear signs of RTI, in 41% (55/135) with mild signs and in 30% (35/117) without any signs of RTI (p < 0.001).

CONCLUSIONS

Positive PCR tests for respiratory viruses, particularly picornaviruses, were frequently detected in apparently healthy children attending day care. Virus detection rates were related to age, presence of clinical signs of RTI, location in day care and season.