Abstract
BackgroundTwo outbreaks of epidemic keratoconjunctivitis (EKC) occurred successively with an interval of 5 days in two primary boarding schools in Weixi Lisu Autonomous County, Diqing, and Tibetan Autonomous Prefecture, Yunnan. The aims of this study were to determine the intensity and characteristics of the outbreaks, as well as the clinical manifestations in the patients, the risk factors for infection and the pathogen responsible for the two outbreaks.MethodsAn outbreak investigation was conducted in two primary schools, and a case-control study including patients from the Weixi County Ethnic Primary School was performed. Relevant specimens were collected according to the case definition, and next-generation sequencing was employed to identify the pathogen. An epidemiological investigation method was used to analyse the related epidemiological characteristics, such as risk factors. The phylogenetic tree was constructed by MEGA 7.0.ResultsA total of 331 acute conjunctivitis cases, including probable cases of EKC, were reported in the two schools, and the attack rates were 30.59% (171/559, 95%CI: 26.76–34.42) and 20.41% (160/784, 95%CI: 17.58–23.24), respectively. Cases occurred in all grades and classes in both schools, and only one staff member in each school presented illness. The epidemics lasted for 54 days and 45 days, respectively. The patients had typical manifestations of EKC, such as acute onset, follicular hyperplasia, pseudomembrane formation, preauricular lymphadenopathy, corneal involvement and blurred vision, and a relatively long disease course (average 9.40 days, longest 23 days and shortest 7 days). The risk factor for infection was close contact with a patient or personal items contaminated by a patient. The pathogen responsible for the outbreaks was HAdV-8. The virus was highly similar to the 2016 HAdV-8 strain from Tibet, China.ConclusionsThis study strongly suggests that HAdV-8 could lead to serious consequences. This is the second report of a HAdV-8-associated EKC outbreak in mainland China. Tibetan HAdV-8 might be circulating in southwest China; therefore, it is necessary to monitor the pathogens causing acute conjunctivitis in this area.
Highlights
Two outbreaks of epidemic keratoconjunctivitis (EKC) occurred successively with an interval of 5 days in two primary boarding schools in Weixi Lisu Autonomous County, Diqing, and Tibetan Autonomous Prefecture, Yunnan
Hexon, as a major capsid component, is a target for host immune responses against Human adenoviruses (HAdV), Fibre and penton are important for viral cell entry, as they bind to cellular receptor(s) [12]
EKC [18,19,20] is caused by enterovirus type 70, human coxsackievirus A24 variant (CVA24v), and HAdV-11
Summary
Two outbreaks of epidemic keratoconjunctivitis (EKC) occurred successively with an interval of 5 days in two primary boarding schools in Weixi Lisu Autonomous County, Diqing, and Tibetan Autonomous Prefecture, Yunnan. Acute infectious conjunctivitis is a very common disease that is usually caused by viruses or bacteria; it has high incidence rates. Hexon, as a major capsid component, is a target for host immune responses against HAdV, Fibre and penton are important for viral cell entry, as they bind to cellular receptor(s) [12]. Based on their serological, biochemical and genetic properties, HAdVs have been classified into seven species (A-G) [11] and 88 types. EKC [18,19,20] is caused by enterovirus type 70, human coxsackievirus A24 variant (CVA24v), and HAdV-11. Outbreaks caused by adenovirus types 8, 56, 54 and enteroviruses CVA24v and EV70 have been reported in China and other countries or regions around the world [6, 15, 21,22,23,24,25,26,27]
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