Longitudinal study of influenza B symptomatology and interferon production in children and college students

Implementation of a Prospective Index-Cluster Sampling Strategy for the Detection of Presymptomatic Viral Respiratory Infection in Undergraduate Students

Background

Index-cluster studies may help characterize the spread of communicable infections in the presymptomatic state. We describe a prospective index-cluster sampling strategy (ICSS) to detect presymptomatic respiratory viral illness and its implementation in a college population.

Methods

We enrolled an annual cohort of first-year undergraduates who completed daily electronic symptom diaries to identify index cases (ICs) with respiratory illness. Investigators then selected 5-10 potentially exposed, asymptomatic close contacts (CCs) who were geographically co-located to follow for infections. Symptoms and nasopharyngeal samples were collected for 5 days. Logistic regression model-based predictions for proportions of self-reported illness were compared graphically for the whole cohort sampling group and the CC group.

Results

We enrolled 1379 participants between 2009 and 2015, including 288 ICs and 882 CCs. The median number of CCs per IC was 6 (interquartile range, 3-8). Among the 882 CCs, 111 (13%) developed acute respiratory illnesses. Viral etiology testing in 246 ICs (85%) and 719 CCs (82%) identified a pathogen in 57% of ICs and 15% of CCs. Among those with detectable virus, rhinovirus was the most common (IC: 18%; CC: 6%) followed by coxsackievirus/echovirus (IC: 11%; CC: 4%). Among 106 CCs with a detected virus, only 18% had the same virus as their associated IC. Graphically, CCs did not have a higher frequency of self-reported illness relative to the whole cohort sampling group.

Conclusions

Establishing clusters by geographic proximity did not enrich for cases of viral transmission, suggesting that ICSS may be a less effective strategy to detect spread of respiratory infection.

Influenza B infections in children: A review

Influenza B (IFB) virus belongs to the Orthomyxoviridae family and has two antigenically and genetically distinct lineages; B/Victoria/2/87-like (Victoria lineage) and B/Yamagata/16/88-like (Yamagata lineage). The illness caused by IFB differs from that caused by influenza A. Outbreaks of IFB occur worldwide and young children exposed to IFB are likely to have a higher disease severity compared with adults. IFB mostly causes mild to moderate respiratory illness in healthy children. However, the involvement of other systems, a severe disease especially in children with chronic medical conditions and immunosuppression, and rarely mortality, has been reported. Treatment with oseltamivir or zanamivir decreases the severity of illness and hospitalization. Due to the enormous health and economic impact of IFB, these strains are included in vaccines. IFB illness is less studied in children although its impact is substantial. In this review, the epidemiology, clinical manifestations, treatment, prognosis, and prevention of IFB illness in children are discussed.

Clinical differences of influenza subspecies among hospitalized children

AIM

Clinical findings, mortality, and morbidity rates differ among influenza subspecies. Awareness of these differences will lead physicians to choose the proper diagnostic and therapeutic strategies and to foresee possible complications. The aim of this study was to evaluate the clinical differences of influenza subspecies among hospitalized children.

MATERIAL AND METHODS

Hospitalized children with proven influenza infection by polymerase chain reaction on nasopharyngeal swab specimens in our clinic, between December 2013 and March 2016, were enrolled. These children were divided into 3 groups as Influenza A/H1N1 (n=42), Influenza A/H3N2 (n=23), and Influenza B (n=35).

RESULTS

The median age of the children was 51.5 months (range, 3-204 months). The most common presenting symptoms were fever (n=83), cough (n=58), and difficulty in breathing (n=25). The most common non-respiratory findings were lymphadenopathy (n=18) and gastrointestinal system involvement (n=17). Sixty-two percent of the patients (n=62) had chronic diseases. H1N1 and H3N2 were significantly more common among patients with chronic neurologic disorders and renal failure, respectively. Leukopenia (n=32) and thrombocytopenia (n=22) were the most common pathologic laboratory findings. Neutropenia, elevated CRP levels, and antibiotic use were significantly more common among patients with H1N1 infection. Seven patients were transferred to the intensive care unit with diagnoses of acute respiratory distress syndrome (n=4), encephalitis (n=2), and bronchiolitis (n=1). Two patients with chronic diseases and H1N1 infection died secondary to acute respiratory distress syndrome.

CONCLUSIONS

Influenza A/H1N1 infection represented more severe clinical disease.

Hospitalization for Influenza A Versus B

BACKGROUND

The extent to which influenza A and B infection differs remains uncertain.

METHODS

Using active surveillance data from the Canadian Immunization Monitoring Program Active at 12 pediatric hospitals, we compared clinical characteristics and outcomes of children ≤16 years admitted with laboratory-confirmed influenza B or seasonal influenza A. We also examined factors associated with ICU admission in children hospitalized with influenza B.

RESULTS

Over 8 nonpandemic influenza seasons (2004-2013), we identified 1510 influenza B and 2645 influenza A cases; median ages were 3.9 and 2.0 years, respectively (P < .0001). Compared with influenza A patients, influenza B patients were more likely to have a vaccine-indicated condition (odds ratio [OR] = 1.30; 95% confidence interval [CI] = 1.14-1.47). Symptoms more often associated with influenza B were headache, abdominal pain, and myalgia (P < .0001 for all symptoms after adjustment for age and health status). The proportion of deaths attributable to influenza was significantly greater for influenza B (1.1%) than influenza A (0.4%); adjusted for age and health status, OR was 2.65 (95% CI = 1.18-5.94). A similar adjusted OR was obtained for all-cause mortality (OR = 2.95; 95% CI = 1.34-6.49). Among healthy children with influenza B, age ≥10 years (relative to <6 months) was associated with the greatest odds of ICU admission (OR = 5.79; 95% CI = 1.91-17.57).

CONCLUSIONS

Mortality associated with pediatric influenza B infection was greater than that of influenza A. Among healthy children hosptialized with influenza B, those 10 years and older had a significant risk of ICU admission.

Clinical features of children hospitalized with influenza A and B infections during the 2012-2013 influenza season in Italy

Background

Influenza is a major public health issue worldwide. It is characterized by episodes of infection that involve hundreds of millions of people each year. Since that in the seasons 2010–2011 and 2011–2012 the circulation of FLUB was decreasing we evaluated the clinical presentation, demographic characteristics, admitting department, and length of stay in children who contracted influenza admitted to Bambino Gesù Children’s Hospital, during the 2012–2013 influenza season, with the aim to establish if the recover of FLUB was associated to a clinical worsening, in comparison with those due to FLUA.

Methods

A total of 133 respiratory specimens, collected from patients with symptoms of respiratory tract infections, positive for the Influenza A and B viruses (FLUA and B) were subtyped. Comparisons between the FLUA and FLUB groups were performed with the one-way ANOVA for continuous parametric variables, the Mann-Whitney test for non-parametric variables, or the Chi-Square test or Fisher’s exact test (if cells <5) for categorical variables.

Results

87.09 % of the FLUA isolates were the H1N1 subtype and 12.90 % were H3N2. Among the FLUB isolates, 91.54 % were the B/Yamagata/16/88 lineage and 8.45 % were the B/Victoria/02/87 lineage. The largest number of FLUA/H1N1 cases was observed in children less than 1 years old, while the B/Yamagata/16/88 lineage was most prevalent in children 3–6 years old. Fever was a common symptom for both FLUA and B affected patients. However, respiratory symptoms were more prevalent in patients affected by FLUA. The median length of stay in the hospital was 5 days for FLUA and 3 days for FLUB.

Conclusions

The clinical features correlated to different Influenza viruses, and relevant subtypes, were evaluated concluding that the increasing of FLUB in the season 2012–2013 was without any dramatic change in clinical manifestation. Our findings suggest, finally, that a stronger commitment to managing patients affected by FLUA is required, as the disease is more severe than FLUB.

Analysis of Vis-NIR spectra changes to measure the inflammatory response in the nasal mucosal region of influenza A and B virus-infected patients

BACKGROUND

Human influenza A and B viruses cause severe seasonal respiratory tract infections, especially in infants and young children. Influenza A and B viruses have been reported to produce different symptoms and/or severity in infected patients, although these remain inconclusive.

OBJECTIVES AND STUDY DESIGN

In this study, non-invasive visible and near-infrared (Vis-NIR) spectroscopy was used for comparative analysis of the inflammatory response to influenza A and B virus infections, by measuring changes in water peak (970 nm) spectra collected from patient nasal mucosal regions.

RESULTS

The results suggested that infection with influenza B virus induced more severe inflammatory responses in the nasal mucosal region than influenza A virus.

CONCLUSIONS

These are the first data showing different inflammatory responses to influenza A and B viruses at the sites of virus infection.

The clinical diagnosis of influenza

Effective management of influenza depends on early recognition of influenza in the community and on rapid diagnosis. Early recognition is achieved by integrated clinical and laboratory based surveillance programmes in representative populations. The recent introduction of 'near patient tests' for influenza provide increased opportunities for surveillance but diagnosis remains largely clinically based. The combination of cough and fever in conditons of known local influenza virus circulation provide a useful indicator of diagnosis to guide management.

Comparison of influenza A and influenza B virus infection in hospitalized children

BACKGROUND

Influenza A and B viruses were cocirculating in Australia in the winter of 1997.

OBJECTIVE

To compare the clinical and demographic features of children with influenza A or influenza B virus infection admitted to a paediatric tertiary referral centre.

METHODOLOGY

Retrospective chart review of 91 hospitalized children with culture-proven influenza A or B virus infection during 1997.

RESULTS

Thirty-six (56%) of 64 children with influenza A were under 12 months of age compared with seven (26%) of 27 children with influenza B virus infection (P = 0.02). Influenza B virus infection was more common in children with underlying medical problems (P = 0. 01). Neurological manifestations were present in eight (12.5%) of 64 children with influenza A and none with influenza B virus infection (P = 0.09). There were no significant differences in signs and symptoms of children with influenza A and B virus infection, in severity of illness or in duration of hospital stay.

CONCLUSIONS

A greater proportion of children admitted with influenza A virus infection were under 12 months of age. Influenza B virus infection is associated more commonly with underlying medical disorders. It is not possible to differentiate between influenza A or B virus infection from presenting clinical signs and symptoms.