Α molecular epidemiological analysis of adenoviruses from excess conjunctivitis cases

Abstract

Background: Τo perform a molecular epidemiological analysis of viral conjunctivitis among excess conjunctivitis cases recorded at the University Hospital of Patras, Greece, for the period March to June 2012.

Methods: A structured questionnaire containing demographic and clinical data was developed in order to collect retrospective data on the cases. Eye swab specimens were collected and molecular detection of adenoviruses was performed by nested PCR. Positive results were confirmed by sequencing. To determine the relatedness between the isolated sequences, a phylogenetic analysis was conducted.

Results: The epidemiological analysis (including retrospective data) included 231 conjunctivitis cases (47.1% male, and 52.8% female). Based on clinical features 205 of the cases were diagnosed of viral origin (46.3% male and 53.7% female), 4 of bacterial origin (50% male and 50% female) while 22 were undefined conjunctivitis. The outbreak excess cases (included 156 cases) affected all age groups regardless gender predilection. For the positive samples indicated that 29 samples (72.5%) were AdV17, and 5 (12.5%) as AdV54.

Conclusions: Molecular analysis could define the cause of viral conjunctivitis, while epidemiological data contributed to the assessment of the risk factors and underlined possible preventive measures. This study is one of the very few on viral conjunctivitis in Greece. This outbreak underscores the need for a national surveillance system for acute infectious conjunctivitis outbreaks. The epidemiological as well as molecular investigation on HAdV ocular infections is rather absent in Greece, which has no surveillance system for viral conjunctivitis.

Keywords: Adenovirus; Conjunctivitis; Eye; Infection; Molecular detection.

Fig. 1

Number of conjunctivitis cases referred to the General University Hospital of Patras (weeks 1–30, years 2011 and 2012). The incidence of infectious conjunctivitis cases increased between March and June 2012 compared to the corresponding period in 2011 (p < 0.005, t-test)

Fig. 2

a and b: Figures show the total and virological conjunctivitis cases by age. a Total conjunctivitis cases by age b) Virological conjunctivitis cases by age

Fig. 3

Number of infectious conjunctivitis cases per week in General University Hospital of Patras, during the period w1 to w30

Fig. 4

Dendrogram tree constructed to represent phylogenetic relationships among 34 HAdV strains, (abbreviated as Axxxx) isolated from Patras’ eye swab samples, along with 35 HAdV-D reference sequences. Two HAdV-F strains (HAdV40, Dukan, and HAdV41, Tak) [were used as out-groups for the analysis, and form a distinct clade to all human strains, as expected