Adenovirus infections within a family cohort in Iran

Adenovirus is one of the most frequent viruses associated with acute respiratory infections (ARI). There is limited information of its transmission within the community.

Cohorts of 50 families with > or =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.

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.

A substantial proportion of ARI in the community are due to adenovirus with further transmission within the family. Children > or =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.