Pandemic Influenza Virus 2009 H1N1 and Adenovirus in a High Risk Population of Young Adults: Epidemiology, Comparison of Clinical Presentations, and Coinfection

Abstract

BackgroundIn 2009, pandemic H1N1 influenza virus (2009 H1N1) emerged worldwide, causing morbidity and mortality that disproportionately affected young adults. Upper respiratory infection (URI), largely due to adenovirus, is an endemic cause of morbidity in military training. Whether clinical presentations differ or excess morbidity results from coinfection is unclear.MethodsThe Center for Advanced Molecular Detection evaluates epidemiology and rapid diagnostics of respiratory pathogens in trainees with URI. From May 1, 2009, to November 30, 2009, demographic, clinical, and PCR data from throat and nasal specimens for adenovirus and 2009 H1N1 were prospectively collected.Results375 trainees with URI enrolled and were tested for both adenovirus and 2009 H1N1 by PCR (median age 20; 89% male). Adenovirus PCR was positive in 72% (96% serotype E-4) and 2009 H1N1 in 20%. Males were more likely to have adenovirus and females more likely to have 2009 H1N1 (p = 0.047). Subjects with 2009 H1N1 presented an average of 1 week earlier in training, had shorter illness duration before enrollment, less sore throat, diarrhea, and fewer abnormal findings on throat exam. Coryza and cough were more common with 2009 H1N1 compared to adenovirus. Subjects with 2009 H1N1 were less likely to have adenovirus than those without, despite persistently high frequencies of adenovirus detections during peak 2009 H1N1 weeks (15% vs. 83%, p < 0.01). Coinfection with adenovirus and 2009 H1N1 was rare (4%). Rates of hospitalization and pneumonia did not differ between the adenovirus, 2009 H1N1, or coinfected groups.ConclusionMilitary trainees with 2009 H1N1 vs. adenovirus have differing clinical presentations, and males are more likely to have adenovirus. Despite high frequencies of adenovirus infection, coinfection with adenovirus and 2009 H1N1 is rare and apparently does not result in increased morbidity.

Type‐specific clinical characteristics of adenovirus‐associated influenza‐like illness at five US military medical centers, 2009–2014

“…Third, we utilized a multiplex PCR assay to assess the prevalence of other viral respiratory pathogens. The prevalence of viral codetection was rather high, even among adult patients, and several fold higher than those reported among military recruits . If these codetections do in fact represent coinfections, it is possible that previous clinical characterizations of adenovirus‐associated illness may have been confounded by the presence of other respiratory viral pathogens …”

Current knowledge, attitude and behaviour of hand and food hygiene in a developed residential community of Singapore: a cross-sectional survey

“…Moreover, we are proposing that having flu in the past six months is likely to be a social predictor of having diarrhoea around the same period as a result of poor hand hygiene behaviours, instead of a clinical predictor of flu severity. This is also supported by the fact that the association of diarrhoea as a clinical symptom of flu is less likely to be associated with young adults infected with influenza [49,50], compared with children hospitalised with influenza [51,52]. Furthermore, one study had shown the potential impact of good hand hygiene behaviour advocated during influenza pandemic can help to reduce acute diarrhoea during the same period [53].…”

Changes in Clinical Presentation and Epidemiology of Respiratory Pathogens Associated With Acute Respiratory Illness in Military Trainees After Reintroduction of Adenovirus Vaccine

“…Influenza causes annual epidemics which, in the context of an effective vaccine program, are typically limited in this population, but which can have considerable impact when new strains emerge. In summer and fall of 2009, influenza was responsible for 20% of FRI in those who were tested [ 20 , 21 ]. Large outbreaks of pharyngitis caused by S. pyogenes , complicated by acute rheumatic fever, pneumonia, necrotizing skin and soft tissue infections, and other suppurative and immunologic complications, have been reported throughout the past century, prompting widespread use of antimicrobial prophylaxis at training sites [ 22 – 24 ].…”