Epidemiology of Human Adenoviruses: A 20-Year Retrospective Observational Study in Hospitalized Patients in Bern, Switzerland

Akello, Joyce Odeke; Kamgang, Richard; Barbani, Maria Teresa; Suter-Riniker, Franziska; Leib, Stephen L; Ramette, Alban

Four patients who died were aged ≤4 years (three males and one female) and one patient was a 6-year-old male. Our data showed that, of the three patients who died and whose samples were available for typing, one had been infected with HAdV1, one had been infected with HAdV2, and one had been infected with HAdV5. All three patients presented with sudden infant death syndrome. The case of another patient aged ≤4 years who died suffering from disseminated adenoviral infection with hepatitis, but whose sample was not available in this study for typing, was reported by Steiner and colleagues. 34 Although HAdV infections are usually self-limited and mild, several studies implicating HAdV causing fatal cases have been reported. 5, 6, 35 The association between HAdV genotypes and clinical presentations and comorbidities in infected patients have been examined in several studies: Wurzel and colleagues found that HAdV species C genotypes (HAdV1 and HAdV2) are predominant in the airways of young children and are therefore a likely etiological agent of the disease. 36 Wang and colleagues showed that only HAdV B, C and E were identified among children with significant respiratory symptoms. 37 Furthermore, Liu and colleagues reported that HAdV species B genotypes (HAdV3 and HAdV7) are predominant genotypes among paediatric population presenting with acute lower respiratory tract infections. 38 A strong association of HAdV40 and HAdV41 with gastroenteritis is known. In our study, we noticed that, besides these genotypes, other HAdV genotypes were identified in those presenting with gastrointestinal infection ( Figure 5B ), a finding that is similar to what was reported by Kumthip and colleagues. 39 In addition, it is known that specific HAdV species have distinct tissue tropism which may determine the clinical presentation. 40 The presence of HAdV in respiratory tract and stool samples from patients not presenting with any clinical symptoms might be detected incidentally, thus making interpretation of the clinical significance of a positive result difficult. Yet, in our study, samples of the patients who had any clinical presentation associated with HAdV infection were referred for laboratory diagnostics testing to our institute upon the request of the seeing physician when an adenovirus infection was suspected. Therefore, majority of the HAdV positive, hospitalized patients in this study had an adenovirus associated clinical presentation. Persistence of HAdV in a latent state among young children has been described. [41] [42] [43] Reports of asymptomatic individuals shedding virus into the stool was also described. 41, 44, 45 In our study, 86.1% of young children ≤4 years old whose stool sample tested positive for HAdV had a clinical presentation, with gastrointestinal infection, fever, and respiratory tract infection being the most predominant clinical presentations.