Serial foodborne norovirus outbreaks associated with multiple genotypes

Interaction between norovirus and Histo-Blood Group Antigens: A key to understanding virus transmission and inactivation through treatments?

Human noroviruses (HuNoVs) are a main cause of acute gastroenteritis worldwide. They are frequently involved in foodborne and waterborne outbreaks. Environmental transmission of the virus depends on two main factors: the ability of viral particles to remain infectious and their adhesion capacity onto different surfaces. Until recently, adhesion of viral particles to food matrices was mainly investigated by considering non-specific interactions (e.g. electrostatic, hydrophobic) and there was only limited information about infectious HuNoVs because of the absence of a reliable in vitro HuNoV cultivation system. Many HuNoV strains have now been described as having specific binding interactions with human Histo-Blood Group Antigens (HBGAs) and non-HBGA ligands found in food and the environment. Relevant approaches to the in vitro replication of HuNoVs were also proposed recently. On the basis of the available literature data, this review discusses the opportunities to use this new knowledge to obtain a better understanding of HuNoV transmission to human populations and better evaluate the hazard posed by HuNoVs in foodstuffs and the environment.

Norovirus infections and knowledge, attitudes and practices in food safety among food handlers in an informal urban settlement, Kenya 2017

Introduction

A leading cause of acute gastroenteritis, norovirus can be transmitted by infected food handlers but norovirus outbreaks are not routinely investigated in Kenya. We estimated norovirus prevalence and associated factors among food handlers in an informal urban settlement in Nairobi, Kenya.

Methods

We conducted a cross-sectional survey among food handlers using pretested questionnaires and collected stool specimens from food handlers which were analyzed for norovirus by conventional PCR. We observed practices that allow norovirus transmission and surveyed respondents on knowledge, attitudes, and practices in food safety. We calculated odd ratios (OR) with 95% confidence intervals (CI) to identify factors associated with norovirus infection. Variables with p < 0.05 were included in multivariate logistic regression analysis to calculate adjusted OR and 95% CI.

Results

Of samples from 283 respondents, 43 (15.2%) tested positive for norovirus. Factors associated with norovirus detection were: reporting diarrhea and vomiting within the previous month (AOR = 5.7, 95% CI = 1.2–27.4), not knowing aerosols from infected persons can contaminate food (AOR = 6.5, 95% CI = 1.1–37.5), not knowing that a dirty chopping board can contaminate food (AOR = 26.1, 95% CI = 1.6–416.7), observing respondents touching food bare-handed (AOR = 3.7, 95% CI = 1.5–11.1), and working in premises without hand washing services (AOR = 20, 95% CI = 3.4–100.0).

Conclusion

The norovirus infection was prevalent amongst food handlers and factors associated with infection were based on knowledge and practices of food hygiene. We recommend increased hygiene training and introduce more routine inclusion of norovirus testing in outbreaks in Kenya.

A foodborne norovirus outbreak in a nursing home and spread to staff and their household contacts

On 16 March 2018, a nursing home notified a possible acute gastroenteritis outbreak that affected 11 people. Descriptive and case-control studies and analysis of clinical and environmental samples were carried out to determine the characteristics of the outbreak, its aetiology, the transmission mechanism and the causal food. The extent of the outbreak in and outside the nursing home was determined and the staff factors influencing propagation were studied by multivariate analysis. A turkey dinner on March 14 was associated with the outbreak (OR 4.22, 95% CI 1.11-16.01). Norovirus genogroups I and II were identified in stool samples. The attack rates in residents, staff and household contacts of staff were 23.49%, 46.22% and 22.87%, respectively. Care assistants and cleaning staff were the staff most frequently affected. Cohabitation with an affected care assistant was the most important factor in the occurrence of cases in the home (adjusted OR 6.37, 95% CI 1.13-36.02). Our results show that staff in close contact with residents and their household contacts had a higher risk of infection during the norovirus outbreak.

High prevalence of norovirus in children with sporadic acute gastroenteritis in Manaus, Amazon Region, northern Brazil

BACKGROUND

Norovirus (NoV) is a major cause of acute gastroenteritis (AGE) worldwide, especially in children under five years. Studies involving the detection and molecular characterisation of NoV have been performed in Brazil, demonstrating its importance as an etiological agent of AGE.

OBJECTIVES

The objectives of this study were to investigate the frequency of human NoV and to genotype the strains isolated from 0-14-year-old patients of AGE in Manaus, Brazil, over a period of two years.

METHODS

A total of 426 faecal samples were collected between January 2010 and December 2011. All samples were tested for the presence of NoV antigens using a commercial enzyme immunoassay kit. RNA was extracted from all faecal suspensions and reverse transcription-polymerase chain reaction (RT-PCR) for the NoV-polymerase partial region was performed as a trial test. Positive samples were then subjected to PCR with specific primers for partial capsid genes, which were then sequenced.

FINDINGS

NoV was detected in 150 (35.2%) faecal samples, for at least one of the two techniques used. NoV was detected in children from all age groups, with the highest positivity observed among the group of 1-2 years old. Clinically, fever was verified in 43% of the positive cases and 46.3% of the negative cases, and vomiting was observed in 75.8% and 70.8% cases in these groups, respectively. Monthly distribution showed that the highest positivity was observed in January 2010 (81.2%), followed by February and April 2010 and March 2011, when the positivity rate reached almost 50%. Phylogenetic analyses performed with 65 positive strains demonstrated that 58 (89.2%) cases of NoV belonged to genotype GII.4, five (7.7%) to GII.6, and one (1.5%) each to GII.7 and GII.3.

MAIN CONCLUSIONS

This research revealed a high circulation of NoV GII.4 in Manaus and contributed to the understanding of the importance of this virus in the aetiology of AGE cases, especially in a region with such few studies available.

Dissemination of gastroenteric viruses in the production of lettuce in developing countries: a public health concern

Investigation of major viruses responsible for acute viral gastroenteritis, such as norovirus (NoV), rotavirus species A (RVA) and human adenovirus (HAdV), was conducted in the mountainous region of the state of Rio de Janeiro in a lettuce-producing area. Irrigation water and lettuce samples were collected at different production stages. Viruses were concentrated using an adsorption-elution method and detected by quantitative polymerase chain reaction (qPCR). We detected HAdV in all collection points, although no virus infectivity was shown. The RVA was the most prevalent virus from both water (16.7% [10/60]) and lettuce samples (11.1% [4/36]), with loads ranging from 2.97 × 102 to 6.88 × 103 genomic copies per litre (gc L-1) and 6.24 × 102 to 1.30 × 104 gc per 25 g, respectively. NoV was detected in 8.33% [8/96] in water and lettuce samples, with concentrations ranging from 7.29 × 101 to 1.92 × 103 gc L-1 and from 4.29 × 101 to 2.98 × 103 gc 25 g-1, respectively. Escherichia coli values also demonstrated poor quality of the irrigation and washing water. The presence of at least two different virus strains in all sites reveals the need to improve basic sanitation measures in order to increase food safety.

Case-control study of diarrheal disease etiology in individuals over 5 years in southwest China

Background

Acute diarrhea is one of the major public health problems worldwide. Most of studies on acute diarrhea have been made on infants aged below 5 years and few efforts have been made to identify the etiological agents of acute diarrhea in people over five, especially in China.

Methods

271 diarrhea cases and 149 healthy controls over 5 years were recruited from four participating hospitals between June 2014 and July 2015. Each stool specimen was collected to detect a series of enteric pathogens, involving five viruses (Rotavirus group A, RVA; Norovirus, NoV; Sapovirus, SaV; Astrovirus, As; and Adenovirus, Ad), seven bacteria (diarrheagenic Escherichia coli, DEC; non-typhoidal Salmonella, NTS; Shigella spp.; Vibrio cholera; Vibrio parahaemolyticus; Aeromonas spp.; and Plesiomonas spp.) and three protozoa (Cryptosporidium spp., Giardia lamblia, G. lamblia, and Blastocystis hominis, B. hominis). Standard microbiological and molecular methods were applied to detect these pathogens. Data was analyzed using Chi square, Fisher-exact tests and logistic regressions.

Results

The prevalence of at least one enteric pathogen was detected in 29.2% (79/271) acute diarrhea cases and in 12.1% (18/149) in healthy controls (p < 0.0001). Enteric viral infections (14.4%) were the most common in patients suffering from acute diarrhea, followed by bacteria (13.7%) and intestinal protozoa (4.8%). DEC (12.5%) was the most common causative agent in diarrhea cases, followed by NoV GII (10.0%), RVA (7.4%) and B. hominis (4.8%). The prevalence of co-infection was statistically higher (p = 0.0059) in the case group (7.7%) than in the healthy control (1.3%). RVA–NoV GII (3.0%) was the most common co-infection in symptomatic cases.

Conclusions

DEC was the most predominant pathogen in diarrhea cases, but it was largely overlooked because the lack of laboratory capacities. Because of the high prevalence of co-infections, it is recommended the urgent development of alternative laboratory methods to assess polymicrobial infections. Such methodological improvements will result in a better prevention and treatment strategies to control diarrhea illness in China.

Electronic supplementary material

The online version of this article (doi:10.1186/s13099-016-0141-1) contains supplementary material, which is available to authorized users.

Use of sequence analysis of the P2 domain for characterization of norovirus strains causing a large multistate outbreak of norovirus gastroenteritis in Germany 2012

Human norovirus is the main cause of non-bacterial gastroenteritis worldwide. It is transmitted from person to person, by fecally contaminated food or water or through virus containing aerosols originating during vomiting of infected persons. In September and October 2012, the largest foodborne norovirus outbreak in Germany so far spread over 5 Federal States (Berlin, Brandenburg, Saxony, Saxony-Anhalt, and Thuringia) affecting nearly 11,000 people mainly in schools and child care facilities. Epidemiological and trace-back investigations supported the assumption that a batch of frozen strawberries imported from China was the likely source of the outbreak. Sequence analysis of the capsid region encoding the P2 domain was used successfully for identification of transmission routes and epidemiologic relationship but was hampered by a lack of universal primers for all known genotypes so far. In the present study, a molecular approach was designed to track outbreak-related samples from the affected states of the large foodborne outbreak in Germany. Therefore, sequence analysis within the highly variable P2 domain of the capsid gene using newly developed universal P2 primers for genogroup I and genogroup II strains in combination with sequencing of the polymerase gene (region A) and the orf1/orf2 junction (region c) was used. The sequence analysis of 138 norovirus positive stool samples suspected to be outbreak-related revealed a considerable genomic diversity. At least 3 strains of genogroup I (I.3, I.4, and I.9) and 5 strains of genogroup II (II.6, II.7, II. 8, and recombinants II.P7_II.6, and II.P16_II.13) as well as 19 samples containing mixtures of these strains were detected. Six samples were considered as not linked to the outbreak. The most prevalent genotype was GI.4 (48/132; 36%). Genotype I.9 and the recombinant strain II.P16_II.13 were detected for the first time in Germany. Notably, the genotype II.P16_II.13 could also be determined in one of the samples of the frozen strawberry lot suspected as infection source. Especially, due to the good concordance of the P2 sequences from infected patients of 5 Federal States the outbreak-relation of the strains could be demonstrated. The high diversity of virus strains and the occurrence of sub-clusters within genotypes I.3, II.8, II.P16_II.13, and II.7 revealed the complex mixture of the outbreak source suggesting a possible waterborne fecal contamination of the strawberries. The typing system described here is in general useful for analysis of outbreaks caused by mixed infection sources. Extensive sequence analysis of different gene regions including the highly variable P2 domain in a sufficient number of cases is required to confirm the epidemiological relation of samples from outbreaks with high diversity of strains spreading over several geographic locations.

Full-genomic analysis of a human norovirus recombinant GII.12/13 novel strain isolated from South Korea

Norovirus (NoV) genogroups I and II are frequently recognized as the main causes of acute gastroenteritis and outbreaks of non-bacterial foodborne diseases. Furthermore, variants and recombinant strains of this virus are continuously emerging worldwide. The aim of this study was to identify NoV strains and to investigate and characterize rare genotypes. Stool samples (n = 500) were collected from patients with symptoms of acute gastroenteritis in Korea between December 2004 and November 2007. For analysis of the samples, rapid genotype screening was performed using reverse transcriptase-polymerase chain reaction. Full sequencing, using a newly designed set of 12 primers, revealed GII-12/13 strain. The partial sequence of GII-12/13 strain was compared with published NoV (GII-1 - 14) sequences targeting RdRp and capsid regions using phylogenetic analysis with the SimPlot program, which could evaluate recombination breakpoints. SimPlot analysis was also performed with the strain GII-12/Gifu-96/JPN (AB045603) for the RdRp region and with GII-13/G5175B-83/AUS(DQ379714) for the capsid region. NoV was detected in 19 of the 500 stool samples (3.8%). Genogroup GII-4 was found most frequently (n = 9, 1.8%), followed by GII-3 (n = 4, 0.8%), GII-6 (n = 3, 0.6%), GI-6 (n = 2, 0.4%), and GII-12/13 (n = 1, 0.2%). Importantly, we identified a novel NoV recombinant strain, C9-439 (KF289337), indicating potential risks, which suggested that, recombination occurred in the region between open reading frames 1 and 2 of the GII-12/13 strain and that breakpoints occurred in the polymerase region.