Respiratory viruses and influenza-like illness: a survey in the area of Rome, winter 2004-2005

Spotlight influenza: Laboratory-confirmed seasonal influenza in people with acute respiratory illness: a literature review and meta-analysis, WHO European Region, 2004 to 2017

Background

Across the World Health Organization European Region, there are few estimates of the proportion of people seeking medical care for influenza-like illness or acute respiratory infections and who have laboratory-confirmed seasonal influenza infection.

Methods

We conducted a meta-analysis of data extracted from studies published between 2004 and 2017 and from sentinel data from the European surveillance system (TESSy) between 2004 and 2018. We pooled within-season estimates by influenza type/subtype, setting (outpatient (OP)/inpatient (IP)) and age group to estimate the proportion of people tested who have laboratory-confirmed and medically-attended seasonal influenza in Europe.

Results

In the literature review, the pooled proportion for all influenza types was 33% (95% confidence interval (CI): 30–36), higher among OP 36% (95% CI: 33–40) than IP 24% (95% CI: 20–29). Pooled estimates for all influenza types by age group were: 0–17 years, 26% (22–31); 18–64 years, 41% (32–50); ≥ 65 years, 33% (27–40). From TESSy data, 33% (31–34) of OP and 24% (21–27) of IP were positive. The highest proportion of influenza A was in people aged 18–64 years (22%, 16–29). By subtype, A(H1N1)pdm09 was highest in 18–64 year-olds (16%, 11–21%) whereas A(H3N2) was highest in those ≥ 65 years (10%, 2–22). For influenza B, the highest proportion of infections was in those aged 18–64 years (15%, 9–24).

Conclusions

Laboratory-confirmed influenza accounted for approximately one third of all acute respiratory infections for which medical care was sought during the influenza season.

Viruses of Respiratory Tract: an Observational Retrospective Study on Hospitalized Patients in Rome, Italy

Respiratory tract infections account for high morbidity and mortality around the world. Fragile patients are at high risk of developing complications such as pneumonia and may die from it. Limited information is available on the extent of the circulation of respiratory viruses in the hospital setting. Most knowledge relates to influenza viruses (FLU) but several other viruses produce flu-like illness. The study was conducted at the University Hospital Policlinico Tor Vergata, Rome, Italy. Clinical and laboratory data from hospitalized patients with respiratory tract infections during the period October 2016-March 2019 were analysed. The retrospective analysis included 17 viral agents detected by FilmArray test and clinical data from medical records and hospital discharge sheets. Models were adjusted for relevant confounders such as clinical severity and risk of death, socio-demographic characteristics and surgical procedures. From a total of 539 specimens analysed, 180 (33.39%) were positive for one or more respiratory viruses. Among them, 83 (46.1 %) were positive for influenza viruses (FLU), 36 (20%) rhino/enteroviruses (RHV/EV), 17 (9.44%) human coronaviruses (HCOV-229E, -HKU1, -NL63, and -OC43), 17 (9.44%) respiratory syncytial virus, 15 (8.33%) human metapneumovirus (HMPV), 8 (4.44%) parainfluenza viruses (PIV) and 4 (2.22%) adenoviruses (ADV). The distribution of viral agents varied across age groups and month of detection. The positive specimens were from 168 patients [102 M, 66 F; median age (range): 64 years (19-93)]. Overall, 40% of them had a high-grade clinical severity and a 27% risk of death; 27 patients died and 22 of them (81.5%) had received a clinical diagnosis of pneumonia. Respiratory viral infections may have a severe course and a poor prognosis in hospitalized patients, due to underlying comorbidities. Monitoring the circulation of respiratory viruses in hospital settings is important to improve diagnosis, prevention and treatment.

Contribution of influenza viruses to medically attended acute respiratory illnesses in children in high-income countries: a meta-analysis

AIM

The burden of disease in children attributable to influenza viruses is difficult to quantify given the similarity of symptoms caused by infection due to influenza and other viruses. This uncertainty impacts clinical decision-making and estimates of burden. We aimed to systematically review the literature to determine the proportion of healthy children presenting for health care with an acute respiratory illness (ARI) who have laboratory-confirmed seasonal influenza (PROSPERO ID#CRD42014013896).

METHOD

We searched Ovid MEDLINE, EMBASE, Scopus, and references of included articles. We included studies that used polymerase chain reaction methods to test for influenza in healthy children aged ≤5 years who presented for health care in high-income countries with an influenza-like or ARI. A standardized form was used to collect data on positivity and other relevant study elements.

RESULTS

Seventeen studies covering 12 different influenza seasons were included. The proportion of influenza positivity ranged from 11% to 56%. Subgroup analyses were performed by influenza season, continent, healthcare setting, age group, and vaccination status. Higher influenza positivity was reported among children aged 3-5 years compared with children aged ≤2 years, and for unvaccinated children.

CONCLUSION

The minority of healthy patients aged ≤5 years with medically attended influenza-like or acute respiratory symptoms have laboratory-confirmed influenza virus infection, although this varied by influenza season. Prevention efforts should be targeted accordingly.

STATEMENT

Most influenza-like illnesses are not laboratory-confirmed and have similar clinical presentations. Consequently, the true contribution of influenza to acute respiratory infections in children remains uncertain. Our systematic review estimates that this proportion ranges from 11% to 56%. This finding can help both clinicians and public health professionals target prevention.

Respiratory viral pathogens among Singapore military servicemen 2009-2012: epidemiology and clinical characteristics

Background

Few studies have comprehensively described tropical respiratory disease surveillance in military populations. There is also a lack of studies comparing clinical characteristics of the non-influenza pathogens with influenza and amongst themselves.

Methods

From May 2009 through October 2012, 7733 consenting cases of febrile respiratory illness (FRI) (temperature [greater than or equal to]37.5degreesC with cough or sorethroat) and controls in the Singapore military had clinical data and nasal washes collected prospectively. Nasal washes underwent multiplex PCR, and the analysis was limited to viral mono-infections.

Results

49% of cases tested positive for at least one virus, of whom 10% had multiple infections. 53% of the FRI cases fulfilled the definition of influenza-like illness (ILI), of whom 52% were positive for at least one virus. The most frequent etiologies for mono-infections among FRI cases were Influenza A(H1N1)pdm09 (13%), Influenza B (13%) and coxsackevirus (9%). The sensitivity, specificity, positive predictive value and negative predictive value of ILI for influenza among FRI cases were 72%, 48%, 40% and 69% respectively. On logistic regression, there were marked differences in the prevalence of different symptoms and signs between viruses with fever more prevalent amongst influenza and adenovirus infections than other viruses.

Conclusion

There are multiple viral etiologies for FRI and ILI with differing clinical symptoms in the Singapore military. Influenza and coxsackevirus were the most common etiology for FRI, while influenza and adenoviruses displayed the most febrile symptoms. Further studies should explore these differences and possible interventions.

Viral etiology of influenza-like illnesses in Huizhou, China, from 2011 to 2013

Little information is available on the etiology and prevalence of viruses other than influenza viruses causing influenza-like illnesses (ILIs) in China. This study was conducted for simultaneous detection and identification of 14 respiratory viruses in Huizhou using real-time PCR. In total, viruses were detected in 48.66 % of ILI patient samples, in which influenza virus (19.98 %) was the most commonly detected, followed by rhinovirus (7.46 %), human coronaviruses (3.63 %), human metapneumovirus (3.06 %), parainfluenza virus (3.06 %), respiratory syncytial virus (2.39 %), adenovirus (2.29 %), and human bocavirus (1.43 %). Co-infections occurred in 5.35 % of all tested specimens and 11.00 % (56/509) of infected patients. Children under 5 years and adults older than 60 years were more likely to have one or more detectable viruses associated with their ILI (OR=1.75, 95 % CI: 1.37; 2.23). Influenza virus was detected during each month of each year, and increased viral activity was observed in 2013. Infections with adenovirus and human metapneumovirus had characteristic seasonal patterns. No significant differences were found in positive the rate between the gender groups, while significantly differences in positive rate were found among the different age groups (P-value<0.001). This study confirmed that multiple respiratory viruses may circulate concurrently in the population and play an important role in the etiology of ILI. The most frequent symptoms associated with respiratory viruses were sore throat, rhinorrhea and headache. This information needs to be considered by clinicians when treating patients presenting with ILI, and it could serve as a reference for government officers when designing and implementing effective intervention plans.

Surveillance of 16 respiratory viruses in patients with influenza-like illness in Nanjing, China

Much less is known about the etiology of influenza‐like illness in China. A continuous surveillance of 16 respiratory viruses was conducted from November 2010 to October 2011 of outpatients with influenza‐like illness in Nanjing, China. The two largest general hospitals and a provincial virus laboratory in Nanjing participated in this study. Throat swabs were collected from outpatients during medical visits for influenza‐like illness and were tested for 16 respiratory viruses using PCR. Three hundred seventeen viruses were detected in samples from 246 (50.6%) patients with influenza‐like illness. The viruses found mostly commonly were influenza, rhinovirus, hCoV HKU1, and adenovirus. The identification rates of respiratory viruses differed significantly among different sampling seasons (P = 0.0002). The rates of influenza A and hCoV HKU1 were much higher during the influenza‐like illness winter peak than during the influenza‐like illness summer peak and other months. Co‐infections were detected in 57 (11.7%) patients and were found most commonly in adults older than 60 years. RSV was detected in 5.9% and 2.6% of patients who were 0–5 and 6–15 years old, respectively, but was not detected in other age groups. This study confirmed that multiple respiratory viruses may circulate concurrently in the population and account for a large proportion of influenza‐like illness. In addition to influenza virus, hCoV HKU1 may be associated with the influenza‐like illness winter peak in Nanjing, China. J. Med. Virol. 84:1980–1984, 2012. © 2012 Wiley Periodicals, Inc.

The burden of influenza B: a structured literature review

We reviewed the epidemiology, clinical characteristics, disease severity, and economic burden of influenza B as reported in the peer-reviewed published literature. We used MEDLINE to perform a systematic literature review of peer-reviewed, English-language literature published between 1995 and 2010. Widely variable frequency data were reported. Clinical presentation of influenza B was similar to that of influenza A, although we observed conflicting reports. Influenza B-specific data on hospitalization rates, length of stay, and economic outcomes were limited but demonstrated that the burden of influenza B can be significant. The medical literature demonstrates that influenza B can pose a significant burden to the global population. The comprehensiveness and quality of reporting on influenza B, however, could be substantially improved. Few articles described complications. Additional data regarding the incidence, clinical burden, and economic impact of influenza B would augment our understanding of the disease and assist in vaccine development.

Outbreaks of pandemic (H1N1) 2009 and seasonal influenza A (H3N2) on cruise ship

To determine the extent and pattern of influenza transmission and effectiveness of containment measures, we investigated dual outbreaks of pandemic (H1N1) 2009 and influenza A (H3N2) that had occurred on a cruise ship in May 2009. Of 1,970 passengers and 734 crew members, 82 (3.0%) were infected with pandemic (H1N1) 2009 virus, 98 (3.6%) with influenza A (H3N2) virus, and 2 (0.1%) with both. Among 45 children who visited the ship's childcare center, infection rate for pandemic (H1N1) 2009 was higher than that for influenza A (H3N2) viruses. Disembarked passengers reported a high level of compliance with isolation and quarantine recommendations. We found 4 subsequent cases epidemiologically linked to passengers but no evidence of sustained transmission to the community or passengers on the next cruise. Among this population of generally healthy passengers, children seemed more susceptible to pandemic (H1N1) 2009 than to influenza (H3N2) viruses. Intensive disease control measures successfully contained these outbreaks.

Swabbing for respiratory viral infections in older patients: a comparison of rayon and nylon flocked swabs

The purpose of this study was to compare the sampling efficacy of rayon swabs and nylon flocked swabs, and of oropharyngeal and nasopharyngeal specimens for the detection of respiratory viruses in elderly patients. Samples were obtained from patients 60 years of age or above who were newly admitted to Sorlandet Hospital Arendal, Norway. The patients were interviewed for current symptoms of a respiratory tract infection. Using rayon swabs and nylon flocked swabs, comparable sets of mucosal samples were harvested from the nasopharynx and the oropharynx. The samples were analysed using real-time polymerase chain reaction (PCR) methods. A total of 223 patients (mean age 74.9 years, standard deviation [SD] 9.0 years) were swabbed and a virus was recovered from 11% of the symptomatic patients. Regardless of the sampling site, a calculated 4.8 times higher viral load (95% confidence interval [CI] 1.3-17, p = 0.017) was obtained using the nylon flocked swabs as compared to the rayon swabs. Also, regardless of the type of swab, a calculated 19 times higher viral load was found in the samples from the nasopharynx as compared to the oropharynx (95% CI 5.4-67.4, p < 0.001). When swabbing for respiratory viruses in elderly patients, nasopharyngeal rather than oropharyngeal samples should be obtained. Nylon flocked swabs appear to be more efficient than rayon swabs.

Excess drug prescriptions during influenza and RSV seasons in the Netherlands: potential implications for extended influenza vaccination

Influenza and respiratory syncytial virus (RSV) infections are responsible for considerable morbidity, mortality and health-care resource use. For the Netherlands, we estimated age and risk-group specific numbers of antibiotics, otologicals and cardiovascular prescriptions per 10,000 person-years during periods with elevated activity of influenza or RSV, and compared these with peri-season rates. Data were taken from the University of Groningen in-house prescription database (www.iadb.nl) and virological surveillance for the period 1998-2006. During influenza and RSV periods excess antibiotic prescriptions were estimated for all age groups. In the age groups 0-1 and 2-4 years, excess antibiotic prescriptions during periods with elevated RSV activity (65% and 59% of peri-seasonal rates) exceeded the surpluses estimated during the influenza-activity periods (24% and 34% of peri-seasonal rates) while for otologicals excess prescriptions were higher for influenza (22% and 27%) than for RSV (14% and 17%). Among persons of 50 years and older, notably those without medical high-risk conditions, excess prescriptions for cardiovascular medications were estimated during the influenza periods at approximately 10% (this was also already seen in persons aged 45-49). Our results may have implications for influenza vaccination policies. In particular, extension of influenza vaccination to groups of non-elderly adults and young children may lower excess prescriptions during these influenza periods for all three types of drug prescriptions investigated.

Identification of the novel KI polyomavirus in the respiratory tract of an Italian patient

Recently, a new human polyomavirus, KIV, was detected in respiratory specimens of patients with acute respiratory tract infection. Whether this reflects a causal role of the virus in the respiratory tract is still debated. To investigate the presence of KIV in respiratory samples of Italian patients and to determine the degree of similarity with other known polyomaviruses, 222 respiratory specimens collected by general practitioners between 2006 and 2007 were screened. The entire VP1 gene region was amplified and sequenced. Maximum Likelihood tree was generated by PAUP* software. One out of 222 samples tested was positive for KIV. Phylogenetic analysis indicated that this isolate clustered with other KIV isolates, while the WUV isolates seem to belong to a different lineage. The phylogenetic tree also showed that all other known polyomaviruses are quite distant from this isolate. This is the first report describing the presence of KIV in the respiratory tract of a 5-year-old Italian child with acute respiratory symptoms. Further investigations are needed to establish an etiological link of KIV with acute respiratory illness.