Dataset Information

Norovirus infections in symptomatic and asymptomatic food handlers in Japan.

ABSTRACT: Noroviruses are the leading cause of outbreaks of gastroenteritis in the world. At present, norovirus genogroup II, genotype 4 (GII/4), strains are the most prevalent in many countries. In this study we investigated 55 outbreaks and 35 sporadic cases of norovirus-associated gastroenteritis in food handlers in food-catering settings between 10 November 2005 and 9 December 2006 in Japan. Stool specimens were collected from both symptomatic and asymptomatic individuals and were examined for norovirus by real-time reverse transcription-PCR; the results were then confirmed by sequence analysis. Norovirus was detected in 449 of 2,376 (19%) specimens. Four genogroup I (GI) genotypes and 12 GII genotypes, including one new GII genotype, were detected. The GII/4 sequences were predominant, accounting for 19 of 55 (35%) outbreaks and 16 of 35 (46%) sporadic cases. Our results also showed that a large number of asymptomatic food handlers were infected with norovirus GII/4 strains. Norovirus GII had a slightly higher mean viral load (1 log unit higher) than norovirus GI, i.e., 3.81 x 10(8) versus 2.79 x 10(7) copies/g of stool. Among norovirus GI strains, GI/4 had the highest mean viral load, whereas among GII strains, GII/4 had the highest mean viral load (2.02 x 10(8) and 7.96 x 10(9) copies/g of stool, respectively). Importantly, we found that asymptomatic individuals had mean viral loads similar to those of symptomatic individuals, which may account for the increased number of infections and the predominance of an asymptomatic transmission route.

SUBMITTER: Ozawa K

PROVIDER: S-EPMC2168587 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature

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Norovirus infections in symptomatic and asymptomatic food handlers in Japan.

Ozawa Kazuhiro K Oka Tomoichiro T Takeda Naokazu N Hansman Grant S GS

Journal of clinical microbiology 20071010 12

Noroviruses are the leading cause of outbreaks of gastroenteritis in the world. At present, norovirus genogroup II, genotype 4 (GII/4), strains are the most prevalent in many countries. In this study we investigated 55 outbreaks and 35 sporadic cases of norovirus-associated gastroenteritis in food handlers in food-catering settings between 10 November 2005 and 9 December 2006 in Japan. Stool specimens were collected from both symptomatic and asymptomatic individuals and were examined for norovir ...[more]

PMID: 17928420

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Project description:BackgroundIn February 2015 an outbreak of gastroenteritis occurred in a distillery in Kinmen, Taiwan. At least 450 affected employees developed the symptoms of diarrhea and vomiting after attending a lunch banquet on 6 February. Epidemiological, laboratory and environmental investigations were conducted to identify the agent and source of this outbreak.MethodsA case-control study was carried out among lunch attendees from the distillery. Using a semi-structured questionnaire, food and beverage consumption in the lunch banquet was assessed, as well as demographic and clinical data of the exposed people. An outbreak case was defined as a diner who developed at least three following symptoms: diarrhea, vomiting, abdominal pain, nausea, chills and/or weakness in the 72 h following the lunch. Controls were defined as lunch attendees who did not have any of the above symptoms. Rectal swabs or stool samples of the symptomatic exposed diners and food handlers as well as food and environmental samples were collected to test potential bacteria and viruses. Norovirus was detected by reverse transcription-polymerase chain reaction and sequence analysis. An environmental assessment, including environmental inspection of the restaurant and a review of work practices of food workers, was undertaken.ResultsOf 363 respondents with complete data, 169 met the case definition and 111 met the control definition. Consumption of pork liver in cold appetizers (adjusted odd ratio (aOR) 3.23; 95 % confidence interval (CI): 1.26-8.30) and lamb chops (aOR: 3.98, 95 % CI: 1.74-9.11) were each associated with increased risk of illness. No cases but two asymptomatic food handlers who prepared or cooked the implicated foods tested positive for norovirus genotype I.6. Food and environmental samples were negative for any bacteria. Environmental assessment indicated that hand washing facilities were not properly accessible to food handlers. Inappropriate hygiene practices in food handlers may have contributed to food contamination.ConclusionOur investigation suggests that etiological agent of this outbreak was norovirus. The food vehicles were pork liver and lamb chops, which may have been contaminated by asymptomatic infected food handlers. Strict adherence to hand hygiene practices and access to hand washing facilities should be reinforced to prevent such foodborne outbreaks.

Project description:Shiga toxin-producing Escherichia coli (STEC) can cause severe gastrointestinal disease and colonization among food handlers. In Japan, STEC infection is a notifiable disease, and food handlers are required to undergo routine stool examination for STEC. However, the molecular epidemiology of STEC is not entirely known. We investigated the genomic characteristics of STEC from patients and asymptomatic food handlers in Miyagi Prefecture, Japan. Whole-genome sequencing (WGS) was performed on 65 STEC isolates obtained from 38 patients and 27 food handlers by public health surveillance in Miyagi Prefecture between April 2016 and March 2017. Isolates of O157:H7 ST11 and O26:H11 ST21 were predominant (n = 19, 29%, respectively). Non-O157 isolates accounted for 69% (n = 45) of all isolates. Among 48 isolates with serotypes found in the patients (serotype O157:H7 and 5 non-O157 serotypes, O26:H11, O103:H2, O103:H8, O121:H19 and O145:H28), adhesion genes eae, tir, and espB, and type III secretion system genes espA, espJ, nleA, nleB, and nleC were detected in 41 to 47 isolates (85-98%), whereas isolates with other serotypes found only in food handlers were negative for all of these genes. Non-O157 isolates were especially prevalent among patients younger than 5 years old. Shiga-toxin gene stx1a, adhesion gene efa1, secretion system genes espF and cif, and fimbrial gene lpfA were significantly more frequent among non-O157 isolates from patients than among O157 isolates from patients. The most prevalent resistance genes among our STEC isolates were aminoglycoside resistance genes, followed by sulfamethoxazole/trimethoprim resistance genes. WGS revealed that 20 isolates were divided into 9 indistinguishable core genomes (<5 SNPs), demonstrating clonal expansion of these STEC strains in our region, including an O26:H11 strain with stx1a+stx2a. Non-O157 STEC with multiple virulence genes were prevalent among both patients and food handlers in our region of Japan, highlighting the importance of monitoring the genomic characteristics of STEC.

Dataset Information

Norovirus infections in symptomatic and asymptomatic food handlers in Japan.

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Norovirus infections in symptomatic and asymptomatic food handlers in Japan.

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