Respiratory virus detection in the upper respiratory tract of asymptomatic, community-dwelling older people.

BACKGROUND: The prevalence of virus positivity in the upper respiratory tract of asymptomatic community-dwelling older people remains elusive. Our objective was to investigate the prevalence of respiratory virus PCR positivity in asymptomatic community-dwelling older people using saliva samples and nasopharyngeal and oropharyngeal swabs. METHODS: We analyzed 504 community-dwelling adults aged ≥ 65 years who were ambulatory and enrolled in a cross-sectional study conducted from February to December 2018 in Nagasaki city, Japan. Fourteen respiratory viruses were identified in saliva, nasopharyngeal and oropharyngeal samples using multiplex PCR assays. RESULTS: The prevalences of PCR positivity for rhinovirus, influenza A, enterovirus and any respiratory virus were 12.9% (95% CI: 10.1-16.1%), 7.1% (95% CI: 5.1-9.8%), 6.9% (95% CI: 4.9-9.5%) and 25.2% (95% CI: 21.5-29.2%), respectively. Rhinovirus was detected in 21.5% of subjects, influenza A in 38.9% of subjects, enterovirus in 51.4% of subjects and any virus in 32.3% of subjects using only saliva sampling. CONCLUSIONS: The prevalences of several respiratory viruses were higher than the percentages reported previously in pharyngeal samples from younger adults. Saliva sampling is a potentially useful method for respiratory virus detection in asymptomatic populations.

Risk of Transmission and Viral Shedding From the Time of Infection for Respiratory Syncytial Virus in Households.

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection worldwide, but reports of temporal changes in the risk of transmission among close contacts has been scarce. This study aimed to examine an association between the viral load trajectory and transmission risk to develop a better control strategy for the disease spread. We conducted a household-based prospective cohort study in Biliran Province, the Philippines, and enrolled 451 participants to observe the development of acute respiratory infection. Including the cases found at the health-care facility, we analyzed the data of viral loads with symptom records obtained from 172 followed participants who had household member positive for RSV with a rapid test during an RSV outbreak in 2018-2019. We developed a model estimating a temporal change in the viral shedding from the infection and evaluated transmission dynamics. We found that most transmission events occurred within approximately 7 days of the household exposure, including potential presymptomatic transmissions. The inferred risk of infection among those younger than 5 years was 3.5 times higher than that of those older than 5 years. This finding suggested that the initial week after the household exposure is particularly important for preventing RSV spread.

A decade of human metapneumovirus in hospitalized children with acute respiratory infection: molecular epidemiology in central Vietnam, 2007-2017.

Human metapneumovirus (hMPV) can cause severe acute respiratory infection (ARI). We aimed to clarify the clinical and molecular epidemiological features of hMPV. We conducted an ARI surveillance targeting hospitalized children aged 1 month to 14 years in Nha Trang, Vietnam. Nasopharyngeal swabs were tested for respiratory viruses with PCR. We described the clinical characteristics of hMPV patients in comparison with those with respiratory syncytial virus (RSV) and those with neither RSV nor hMPV, and among different hMPV genotypes. Among 8822 patients, 278 (3.2%) were hMPV positive, with a median age of 21.0 months (interquartile range: 12.7-32.5). Among single virus-positive patients, hMPV cases were older than patients with RSV (p < 0.001) and without RSV (p = 0.003). The proportions of clinical pneumonia and wheezing in hMPV patients resembled those in RSV patients but were higher than in non-RSV non-hMPV patients. Seventy percent (n = 195) were genotyped (A2b: n = 40, 20.5%; A2c: n = 99, 50.8%; B1: n = 37, 19%; and B2: n = 19, 9.7%). The wheezing frequency was higher in A2b patients (76.7%) than in those with other genotypes (p = 0.033). In conclusion, we found a moderate variation in clinical features among hMPV patients with various genotypes. No seasonality was observed, and the multiple genotype co-circulation was evident.

Scenarios to Manage the Demand for N95 Respirators for Healthcare Workers During the COVID-19 Pandemic.

BACKGROUND: By estimating N95 respirator demand based on simulated epidemics, we aim to assist planning efforts requiring estimations of respirator demand for the healthcare system to continue operating safely in the coming months. METHODS: We assess respiratory needs over the course of mild, moderate and severe epidemic scenarios within Singapore as a case study using a transmission dynamic model. The number of respirators required within the respiratory isolation wards and intensive care units was estimated over the course of the epidemic. We also considered single-use, extended-use and prolonged-use strategies for N95 respirators for use by healthcare workers treating suspected but negative (misclassified) or confirmed COVID-19 patients. RESULTS: Depending on the confirmed to misclassified case ratio, from 1:0 to 1:10, a range of 117.1 million to 1.1 billion masks are required for single-use. This decreases to 71.6-784.4 million for extended-use and 12.8-148.2 million for prolonged-use, representing a 31.8-38.9% and 86.5-89.1% reduction, respectively. CONCLUSION: An extended-use policy should be considered when short-term supply chains are strained but planning measures are in place to ensure long-term availability. With severe shortage expectations from a severe epidemic, as some European countries have experienced, prolonged use is necessary to prolong supply.

Transmission of Respiratory Syncytial Virus Among Children Under 5 Years in Households of Rural Communities, the Philippines.

BACKGROUND: To develop a more effective vaccination strategy for reducing the impact of respiratory syncytial virus (RSV) infection, especially in young infants (<6 months old), it is necessary to understand the transmission dynamics of RSV. METHODS: We conducted a community-based prospective cohort study from 2014 to 2016 in Biliran Province, the Philippines, on children <5 years old. We collected nasopharyngeal swabs from symptomatic children with acute respiratory infection (ARI) during household visits and at health facilities. In households (n = 181) with RSV-positive ARI cases (RSV-ARI), we also identified ARI episodes among other children <5 years old in the same household. In addition, we determined the serial interval to estimate the basic reproduction number (R 0), the average number of secondary cases generated by a single primary case. RESULTS: In the 181 households analyzed, we found 212 RSV-ARI in 152 households with a single case and 29 households with multiple cases, which included 29 1st RSV-ARI and 31 2nd RSV-ARI. We also found possible index cases among children <5 years old in the same household for 29.0% (18 of 62) of young infants with RSV-ARI. The estimated mean serial interval was 3.2 days, and R 0 was estimated to be 0.92-1.33 for RSV-A and 1.04-1.76 for RSV-B, which varied between different times (2014 and 2015) and places. CONCLUSIONS: Young infants are likely to acquire RSV infection from older children in the same household. Therefore, vaccination targeting older children might protect infants from RSV infection.

Local persistence and global dissemination play a significant role in the circulation of influenza B viruses in Leyte Island, Philippines.

The local and global transmission dynamics of influenza B virus is not completely understood mainly because of limited epidemiological and sequence data for influenza B virus. Here we report epidemiological and molecular characteristics of influenza B viruses from 2010 to 2013 in Leyte Island, Philippines. Phylogenetic analyses showed global dissemination of the virus among both neighboring and distant areas. The analyses also suggest that southeast Asia is not a distributor of influenza B virus and can introduce the virus from other areas. Furthermore, we found evidence on the local persistence of the virus over years in the Philippines. Taken together, both local persistence and global dissemination play a significant role in the circulation of influenza B virus.

Influenza and other respiratory viruses detected by influenza-like illness surveillance in Leyte Island, the Philippines, 2010-2013.

This study aimed to determine the role of influenza-like illness (ILI) surveillance conducted on Leyte Island, the Philippines, including involvement of other respiratory viruses, from 2010 to 2013. ILI surveillance was conducted from January 2010 to March 2013 with 3 sentinel sites located in Tacloban city, Palo and Tanauan of Leyte Island. ILI was defined as fever ≥38°C or feverish feeling and either cough or running nose in a patient of any age. Influenza virus and other 5 respiratory viruses were searched. A total of 5,550 ILI cases visited the 3 sites and specimens were collected from 2,031 (36.6%) cases. Among the cases sampled, 1,637 (75.6%) were children aged <5 years. 874 (43.0%) cases were positive for at least one of the respiratory viruses tested. Influenza virus and respiratory syncytial virus (RSV) were predominantly detected (both were 25.7%) followed by human rhinovirus (HRV) (17.5%). The age distributions were significantly different between those who were positive for influenza, HRV, and RSV. ILI cases were reported throughout the year and influenza virus was co-detected with those viruses on approximately half of the weeks of study period (RSV in 60.5% and HRV 47.4%). In terms of clinical manifestations, only the rates of headache and sore throat were significantly higher in influenza positive cases than cases positive to other viruses. In conclusion, syndromic ILI surveillance in this area is difficult to detect the start of influenza epidemic without laboratory confirmation which requires huge resources. Age was an important factor that affected positive rates of influenza and other respiratory viruses. Involvement of older age children may be useful to detect influenza more effectively.

Neutrophil-derived tumor necrosis factor-α contributes to acute wound healing promoted by N-(3-oxododecanoyl)-L-homoserine lactone from Pseudomonas aeruginosa.

BACKGROUND: Pseudomonas aeruginosa is frequently isolated from chronic wounds and causes serious infection in immunocompromised hosts. N-(3-Oxododecanoyl)-L-homoserine lactone (3-oxo-C12-HSL) is synthesized by an autoinducer synthase encoded by the bacterial lasI gene in P. aeruginosa, which regulates the production of virulence factors and biofilm formation in this bacterium. Recent studies have suggested that 3-oxo-C12-HSL contributes to the modulation of immune responses. However, the effect of this molecule on wound healing in P. aeruginosa infection remains to be elucidated. OBJECTIVE: We used an animal model to study the effect of 3-oxo-C12-HSL on wound healing in skin infected with P. aeruginosa. METHODS: Wounds were created on the backs of Sprague-Dawley (SD) rats and the P. aeruginosa strain PAO1 (PAO1) or its lasI deletion mutant (ΔlasI) was inoculated onto the wound surface. To examine the biological activity of 3-oxo-C12-HSL, rats were injected intraperitoneally with anti-3-oxo-C12-HSL antiserum or administered 3-oxo-C12-HSL at the wound surface. The wound tissues were harvested for analysis of the healing process and inflammatory response. RESULTS: PAO1 inoculation significantly accelerated the wound healing and inflammatory response on day 3 post-wounding. These responses were reversed by inoculation with ΔlasI instead of PAO1 or treatment with anti-3-oxo-C12-HSL antiserum. In contrast, administration of 3-oxo-C12-HSL in the absence of PAO1 significantly promoted these responses, which were suppressed by the anti-TNF-α mAb. CONCLUSION: These results strongly suggest that 3-oxo-C12-HSL may be involved in healing wounds infected with P. aeruginosa through induction of inflammatory responses.

Genetic characterization of human respiratory syncytial virus detected in hospitalized children in the Philippines from 2008 to 2012.

BACKGROUND: Human respiratory syncytial virus (HRSV) is the leading cause of acute lower respiratory tract infection in infants and young children. However, molecular characteristic of HRSV is still unknown in the Philippines. OBJECTIVE: To describe the molecular epidemiology of circulating HRSV detected in the Philippines. STUDY DESIGN: From May 2008 to April 2012, nasopharyngeal swabs were collected from infants and children aged between 7 days and 14 years who were hospitalized with severe pneumonia. HRSV was detected by nested PCR targeting M2 gene, and C-terminus of the G gene was sequenced for phylogenetic analysis. RESULT: Out of total 2150 samples, 19.3% (n = 415) were positive for HRSV, and 65.0% of them (n = 270) were identified as HRSV-A and 35.0% (n = 145) as HRSV-B. There were two major HRSV outbreaks: between June 2008 and February 2009, and between June and March 2012. Majority of HRSV strains detected during the former outbreak were HRSV-A (97.5%, 203/208) whereas during the later outbreak, both HRSV-A (54/158, 34.2%) and HRSV-B (104/158, 65.8%) were detected. All HRSV-A strains were classified as genotype NA1 and all HRSV-B as genotype BA, which had 60-nucleotide duplication in secondary hypervariable region of the G gene. Among HRSV-B positive samples, there were 2 distinct clusters with unique amino acid changes and low homology in compared to other strains in BA, suggesting emergence of new variant of HRSV-B. CONCLUSION: The study provides an overview of the genetic variation in circulating HRSV viruses in the Philippines along with identification of possibly a novel variant of HRSV-B.