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

Abstract

BackgroundFew 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.MethodsFrom 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.Results49% 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.ConclusionThere 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.

Evidence for Cross-Protection Against Subsequent Febrile Respiratory Illness Episodes From Prior Infections by Different Viruses Among Singapore Military Recruits 2009–2014

“…Given the relative ranking of virus families in conferring cross-protection, we suggest focusing the search for mechanisms on common factors induced by both adenovirus and influenza virus. Notably, our previous studies suggest that infections with these 2 infections may be more severe, because they are more likely to present with febrile illness [26] and higher temperatures (≥38°C) than infections due to other common circulating virus families [16]. This again supports a cytokine-mediated antiviral effect.…”

“…Samples were sent in viral transport medium (Copan Diagnostics, Murrieta, CA) for etiological testing within 24 hours of collection. During the 5-year study period, the ResPlex II multiplex polymerase chain reaction assay was used from December 2009 through 29 June 2012 to detect viral pathogens, after which it was replaced by in-house viral multiplex polymerase chain reaction assays (Supplementary Materials) [16].…”

Literature review of the epidemiology of influenza B disease in 15 countries in the Asia‐Pacific region

“…Three studies evaluated influenza in military personnel with febrile respiratory illness in 2006‐07, 2009‐10, and 2009‐12 . Influenza detection rate was 36.1% and 28.7% in the two earlier seasons, both with the proportion of influenza B at 33%.…”

Frequency of viral etiology in symptomatic adult upper respiratory tract infections

“…The frequency of respiratory viral infections (RVIs) in immunocompetent adults is often overlooked; however, available data suggest that RVIs are responsible for a significant number of respiratory infections affecting not only the elderly (persons aged ≥65 years) but also young adults. 12,13,[27][28][29][30][31][32] Although the majority of infections in young adults are not life-threatening they can impose a significant burden on communities since the affected population represents a large fraction of the work force in developing countries. Data presented in this report indicate that 65.1% (28/43) of virus-positive samples were detected in patients <60 years of age.…”