First norovirus outbreaks associated with consumption of green seaweed (Enteromorpha spp.) in South Korea.

In February 2012, an outbreak of gastroenteritis was reported in school A; a successive outbreak was reported at school B. A retrospective cohort study conducted in school A showed that seasoned green seaweed with radishes (relative risk 7·9, 95% confidence interval 1·1-56·2) was significantly associated with illness. Similarly, a case-control study of students at school B showed that cases were 5·1 (95% confidence interval 1·1-24·8) times more likely to have eaten seasoned green seaweed with pears. Multiple norovirus genotypes were detected in samples from students in schools A and B. Norovirus GII.6 isolated from schools A and B were phylogenetically indistinguishable. Green seaweed was supplied by company X, and norovirus GII.4 was isolated from samples of green seaweed. Green seaweed was assumed to be linked to these outbreaks. To our knowledge, this is the first reported norovirus outbreak associated with green seaweed.

Comparative virulence of reproductive diseases caused by type 1 (European-like) and type 2 (North American-like) porcine reproductive and respiratory syndrome virus in experimentally infected pregnant gilts.

The aim of this study was to compare the virulence of type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) as assessed by the level of viral replication, viral distribution and apoptosis in stillborn fetuses and live-born piglets from infected pregnant gilts. Type 1 or type 2 PRRSV was given intranasally to pregnant gilts at 3 weeks before the expected date of parturition. Regardless of virus genotype, PRRSV-infected gilts farrowed between 102 and 109 days of gestation, while control uninfected gilts carried the pregnancy to term and farrowed at 114-115 days of gestation. There were no significant differences in the mean number of virus-infected cells per unit area of tissue when type 1 and type 2 virus infections were compared between stillborn fetuses and live-born piglets. Stillborn fetuses from the type 1 PRRSV-infected pregnant gilts had a significantly higher mean number of apoptotic cells per unit area of thymus (P = 0.013) than those from type 2 PRRSV-infected pregnant gilts. Significant differences in virulence were not observed between types 1 and 2 PRRSV in terms of female reproductive failure, although thymic apoptosis differed in stillborn fetuses from type 1 and type 2 PRRSV-infected pregnant gilts.

Outbreak of enterotoxigenic Escherichia coli O169 enteritis in schoolchildren associated with consumption of kimchi, Republic of Korea, 2012.

Enterotoxigenic Escherichia coli (ETEC) is now recognized as a common cause of foodborne outbreaks. This study aimed to describe the first ETEC O169 outbreak identified in Korea. In this outbreak, we identified 1642 cases from seven schools. Retrospective cohort studies were performed in two schools; and case-control studies were conducted in five schools. In two schools, radish kimchi was associated with illness; and in five other schools, radish or cabbage kimchi was found to have a higher risk among food items. Adjusted relative risk of kimchi was 5·87-7·21 in schools that underwent cohort studies; and adjusted odds ratio was 4·52-12·37 in schools that underwent case-control studies. ETEC O169 was isolated from 230 affected students, and was indistinguishable from the isolates detected from the kimchi product distributed by company X, a food company that produced and distributed kimchi to all seven schools. In this outbreak, we found that the risk of a kimchi-borne outbreak of ETEC O169 infection is present in Korea. We recommend continued monitoring regarding food safety in Korea, and strengthening surveillance regarding ETEC O169 infection through implementation of active laboratory surveillance to confirm its infection.