A 5-year study of adenoviruses causing conjunctivitis in Izmir, Turkey

Adenoviruses are a common cause of conjunctivitis. Genotypes are diverse and differ according to population and geographical distribution of the virus. There is limited data regarding ocular adenoviral infections and genotype distribution in Turkey. This study aimed to determine the adenovirus genotypes and their epidemiological features among patients with conjunctivitis between 2006 and 2010, in Izmir, Turkey. Adenoviral DNA was detected by PCR in 213 of 488 (44%) of the ocular samples collected from patients with viral conjunctivitis during the 5-year study period. Of these, 101 (47%) were randomly chosen and genotyped by sequence analysis. Seven genotypes were identified, including 3, 4, 8, 11, 19, 37, and 53. Genotype 8 and 4 were the dominant types detected in 67 (66.3%) and 25 (24.7%) of the samples, respectively. Other five genotypes (3, 11, 19, 37, 53) were detected in 9 (8.9%) samples. Genotype and seasonal differences observed throughout the study. Human adenoviruse (HAdV)-8 was the most frequent type, except 2008. The prevalence of genotype 4 increased starting from 2006, became dominant in 2008 and decreased in the following years. The peak season was mostly spring months, although it was possible to detect positive samples throughout the year. In conclusion, genotype 8 followed by genotype 4 was the most frequent adenoviral types causing conjunctivitis during the 5-year study period. Findings suggest that there is a slow shift between genotypes throughout the years.