Adenovirus infections within a family cohort in Iran

Abstract

Background: Adenovirus is one of the most frequent viruses associated with acute respiratory infections (ARI). There is limited information of its transmission within the community. Methods: Cohorts of 50 families with ≥two children were visited weekly for 2 months to ascertain the presence ARI in Rasht, Iran. Nasopharyngeal swabs were obtained from symptomatic participants and at 3-4-day intervals to assess the duration of adenovirus shedding. Adenoviruses were identified by PCR and adenovirus positive amplicons were subjected to DNA sequencing. Results: Thirty-three (35%) of 94 ARI episodes in children and 8 (27%) of 30 episodes in adults were due to adenovirus (not significant, NS). 25/50 (50%) families had adenovirus infections. Children had more infections than adults, were more likely to develop symptoms if there was a symptomatic case within the household and episodes had a longer duration (P<0.05). Adenoviruses were recovered for a median of 11 (interquartile range 5-26) days of follow up in children and 7 (2-20) days in adults (NS). Adenovirus-7 was the most frequent serotype (12 families), followed by adenovirus-6 (5 families), adenovirus-1 and 2 (4 families each), and adenovirus-5 (3 families). Both adenovirus-5 and 7 amplicons fell into two clusters. No mutations were observed during transmission within a family. Conclusion A substantial proportion of ARI in the community are due to adenovirus with further transmission within the family. Children ≥2 years experienced a higher proportion of infections than younger children and adults. Viral shedding was more prolonged in children and adenovirus-7 and 5 predominated with several clusters co-circulating in the same season. © 2009 Wiley-Liss, Inc.