Molecular epidemiology of norovirus in asymptomatic food handlers in Busan, Korea, and emergence of genotype GII.17

Abstract

The molecular epidemiology of norovirus infections was studied in food handlers without any symptoms from January to December 2015 in Busan city, Korea. A total of 2,174 fecal specimens from asymptomatic food handlers were analyzed, and 2.3% (49/2,174) were norovirus-positive. Fourteen of 335 samples (4.2%) were positive in January; fifteen of 299 samples (5.0%) in February, and seven of 189 samples (3.7%) in December. However, norovirus was rarely detected in other months. From sequencing analysis, 11 genotypes (five GI and six GII genotypes) were detected. Among the 42 capid gene sequences identified, 14 were from the GI genogroup, while 28 were from the GII genogroup. The most commonly detected genotype was GII.17, comprising 15 (35.7%) of positive samples. From January 2012 to December 2015, 5,138 samples were collected from gastroenteritis patients and outbreaks in Busan. The most detected genotype in 2012, 2013, and 2014 was GII.4 (121, 24, and 12 cases, respectively), but in 2015, GII.17 (25 cases) was the most common. The GII.4 genotype was the major cause of acute gastroenteritis from 2012 to 2014, but the GII.17 genotype became the most prevalent cause in 2015. Continued epidemiological surveillance of GII.17 is needed, together with assessment of the risk of norovirus infection.

Occurrence of norovirus infection in an asymptomatic population in Indonesia

“…In the only previous study of NoV infections in Indonesia, NoV was not found in the control subjects (Subekti et al, 2002b). The prevalence of asymptomatic NoV infection in our present investigation was higher than those reported in non-outbreak settings: 11.9% of a series of food handlers in Japan (Okabayashi et al, 2008), and 1.02%−2.3% in food handlers in Korea (Jeong et al, 2013;Koo et al, 2016) had asymptomatic NoV infection. However, a study performed in a small community in southwestern Cameroon found high asymptomatic NoV prevalences of 27% in adults and 30.8% in children (Ayukekbong et al, 2014a).…”

“…Kawasaki, which is prevalent in East Asian countries such as Japan, China and Korea (Koo et al, 2016;Wang et al, 2016), GII.4 Sydney 2012, which has been the most prevalent in worldwide outbreaks (Eden et al, 2014), and GII.1, which was found to be prevalent in Hawaii and the United Kingdom (Bon et al, 2005).…”

Epidemiological characteristics of asymptomatic Norovirus infection in a population from oyster (Ostrea rivularis Gould) farms in southern China

“…During the period from January to December 2014, a total of 184 out of 4549 stool samples were identified and positively screened for norovirus; the total asymptomatic infection rate was 4.04% among all age groups. The highest infection rate was detected in January (7.72%), July (8.52%) and December (9.82%); these results very similar with data from Netherlands (5.2%) [6], somewhat higher compared with data from Korea (2.3%) [13] and significantly lower compared with data from Japan (12%) [14] and England (12%) [4]. The study carried out in Netherlands was based on community population; studies in Korea and Japan were based on food handlers, while the study in England investigated all age groups between 1993 and 1996.…”

Foodborne Infectious Diseases Mediated by Inappropriate Infection Control in Food Service Businesses and Relevant Countermeasures in Korea

“…The current Food Safety Act does not provide the necessary criteria for patients during shedding. Under these hazardous circumstances, several recent cross-sectional studies on norovirus in Korea [43,66] have revealed the state of the asymptomatic carriers by analyzing stool samples of the food handlers. The samples were collected for legal monitoring of S. typhi at the local health centers.…”

“…The most adopted type of study is the retrospective cohort study that establishes exposure and non-exposure groups, while backtracking the time (Tables 1 and 2). Owing to the cost and time effectiveness of cross-sectional studies, surveillance aimed at asymptomatic patients has been conducted [22,43,66]. In contrast, only a few cohort studies have been conducted in Korea compared with foreign nations, most probably because of their shortcomings, such as increased cost and/or duration [44].…”