Surveillance and molecular characterization of human adenovirus in patients with acute gastroenteritis in the era of rotavirus vaccine, Brazil, 2012-2017.

BACKGROUND: In Brazil, limited data are available regarding the incidence and molecular epidemiology of Human Adenovirus (HAdV) in diarrheic disease, especially in the post rotavirus (RVA) vaccine era.

OBJECTIVE: The aims of the study were to investigate the frequency of HAdV infections in patients with gastroenteritis during a 6-year period (2012-2017); conduct molecular typing of positive strains, and obtain further information on the HAdV seasonality.

STUDY DESIGN: A total of 3003 fecal samples negative for both, RVA and Norovirus, were selected and tested for HAdV by PCR. Positive HAdV samples were sequenced to obtain genotype identification.

RESULTS: HAdV was detected in 3.9% (117/3003); 76 belong to species F (70 HAdV-F41; 6 HAdVF40), 31 to species C (15 HAdV-C1; 13 HAdV-C2; 3 HAdV-C5), 5 belong to species D (3 HAdVD56 and 2 untyped), 4 belong to species A (2 HAdV-A12; 2 HAdV-A31), and 1 belong to HAdVB3. Detection rate significantly varied according to the year, suggesting that HAdV infections show a tendency to occur in natural oscillatory fluctuation. No consistent seasonal pattern was identified. Children ≤5 years exhibited higher positivity rate, reinforcing that HAdV is an important pathogen in childhood diarrhea. Genetic analysis indicated that HAdV strains circulating in Brazil were closely related to worldwide strains, and there is no evidence for the introduction of a particular HAdV variant in the country.

CONCLUSIONS: The present investigation does not suggest that HAdV has assumed an epidemiological importance in Brazil after the RVA vaccine introduction and contributed to the definition of the clinical and public health significance of HAdV infections.