Epidemiological and genetic analysis of a sustained community-wide outbreak of hepatitis A in the Republic of Korea, 2008: A hospital-based case–control study

Hepatitis A Virus and Hepatitis E Virus as Food- and Waterborne Pathogens-Transmission Routes and Methods for Detection in Food

Foodborne viruses are an important threat to food safety and public health. Globally, there are approximately 5 million cases of acute viral hepatitis due to hepatitis A virus (HAV) and hepatitis E virus (HEV) every year. HAV is responsible for numerous food-related viral outbreaks worldwide, while HEV is an emerging pathogen with a global health burden. The reported HEV cases in Europe have increased tenfold in the last 20 years due to its zoonotic transmission through the consumption of infected meat or meat products. HEV is considered the most common cause of acute viral hepatitis worldwide currently. This review focuses on the latest findings on the foodborne transmission routes of HAV and HEV and the methods for their detection in different food matrices.

Real-time, selective, and low-cost detection of trace level SARS-CoV-2 spike-protein for cold-chain food quarantine

Due to the friendly temperature for virus survival, SARS-CoV-2 is frequently found in cold-chain foods, posing a serious threat to public health. Utilizing an interdigitated microelectrode chip modified with an antibody probe and integrating dielectrophoresis enrichment with interfacial capacitance sensing, a strategy is presented for the detection of trace level spike-protein from SARS-CoV-2. It achieves a limit of detection as low as 2.29 × 10^-6 ng/mL in 20 s, with a wide linear range of 10^-5-10^-1 ng/mL and a selectivity of 234:1. The cost for a single test can be controlled to ~1 dollar. This strategy provides a competitive solution for real-time, sensitive, selective, and large-scale application in cold-chain food quarantine.

Foodborne transmission of hepatitis A and hepatitis E viruses: A literature review

Foodborne viruses have been recognized as a growing concern to the food industry and a serious public health problem. Hepatitis A virus (HAV) is responsible for the majority of viral outbreaks of food origin worldwide, while hepatitis E virus (HEV) has also been gaining prominence as a foodborne viral agent in the last years, due to its zoonotic transmission through the consumption of uncooked or undercooked infected meat or derivatives. However, there is a lack of scientific reports that gather all the updated information about HAV and HEV as foodborne viruses. A search of all scientific articles about HAV and HEV in food until March 2020 was carried out, using the keywords "HAV", "HEV", "foodborne", "outbreak" and "detection in food". Foodborne outbreaks due to HAV have been reported since 1956, mainly in the USA, and in Europe in recent years, where the number of outbreaks has been increasing throughout time, and nowadays it has become the continent with the highest foodborne HAV outbreak report. Investigation and detection of HAV in food is more recent, and the first detections were performed in the 1990s decade, most of them carried out on seafood, first, and frozen food, later. On the other hand, HEV has been mainly looked for and detected in food derived from reservoir animals, such as meat, sausages and pate of pigs and wild boars. For this virus, only isolated cases and small outbreaks of foodborne transmission have been recorded, most of them in industrialized countries, due to HEV genotype 3 or 4. Virus detection in food matrices requires special processing of the food matrix, followed by RNA detection by molecular techniques. For HAV, a real-time PCR has been agreed as the standard method for virus detection in food; in the case of HEV, a consensus assay for its detection in food has not been reached yet. Our investigation shows that there is still little data about HAV and HEV prevalence and frequency of contamination in food, prevalent viral strains, and sources of contamination, mainly in developing countries, where there is no research and legislation in this regard. Studies on these issues are needed to get a better understanding of foodborne viruses, their maintenance and their potential to cause diseases.

Risk factors for viral hepatitis A infection in Gampaha District, Sri Lanka: an unmatched case control study

Background

Hepatitis A virus (HAV) is one of the commonest food and water borne infectious diseases. The objective of the study was to determine the risk factors of HAV infection in the Gampha District in Sri Lanka.

Methods

This was an unmatched case control study conducted between January 2015 and November 2016 comprising of 504 participants with a case control ratio of 1:1. The study population included individuals of age 1 year and above who were permanent residents of the district. Cases included participants admitted to four secondary care state hospitals with an acute HAV diagnosed by detecting serum anti-HAV IgM antibodies. Controls were randomly selected individuals from the community with serum negative for Anti-HAV IgM and IgG. An interviewer administered questionnaire was used for the data collection and multiple logistic regression was applied to determine the independent risk factors. The results are expressed as adjusted odds ratios (AOR) and 95% confidence intervals (CI).

Results

Risk factors for HAV infection were poor knowledge regarding hepatitis (AOR;3.98, 95% CI = 1.97–8.05), unhygienic sanitary practices (OR = 2.73; 95% CI = 1.42–5.23), unhygienic practices related to drinking water (OR = 2.67; 95% CI = 1.37–5.21), residing in urban areas (OR = 5.94; 95% CI = 2.98–11.86) and lower family income (OR = 2.83; 95% CI = 1.30–6.13).

Conclusions

The independent modifiable risk factors for HAV infection were poor knowledge regarding hepatitis, unhygienic sanitary practices, and unhygienic practices related to drinking water. Community awareness must be raised on hygienic practices and safe water drinking practices. Inequities of social determinates of health must be addressed.

Assessment of Salmonella spp. and Escherichia coli O157:H7 growth on lettuce exposed to isothermal and non-isothermal conditions

This study aimed to assess the growth of Salmonella and Escherichia coli O157:H7 on lettuce exposed to isothermal and non-isothermal conditions. Pathogens were inoculated on lettuce separately and stored under isothermal condition at 5 °C, 10 °C, 25 °C, 37 °C for both bacteria, at 40 °C for Salmonella and 42 °C for E. coli O157:H7. Growth curves were built by fitting the data to the Baranyi's DMFit, generating R2 values greater than 0.92 for primary models. Secondary models were fitted with Ratkowsky equations, generating R2 values higher than 0.91 and RMSE lower than 0.1. Experimental data showed that both bacteria could grow at all temperatures. Also, the growth of both pathogens under non-isothermal conditions was studied simulating temperatures found from harvest to supermarkets in Brazil. Models were analysed by R2, RMSE, bias factor (Bf) and accuracy factor (Af). Salmonella and E. coli O157:H7 were able to grow in this temperature profile and the models could predict the behavior of these microorganisms on lettuce under isothermal and non-isothermal conditions. Based on the results, a negligible growth time (ς) was proposed to provide the time which lettuce could be exposed to a specific temperature and do not present an expressive growth of bacteria. The ς was developed based on Baranyi's primary model equation and on growth potential concept. ς is the value of lag phase added of the time necessary to population grow 0.5 log CFU/g. The ς of lettuce exposed to 37 °C was 1.3 h, while at 5 °C was 3.3 days.

Selected Viruses Detected on and in our Food

PURPOSE OF REVIEW

The purpose of this review is to provide an update on recent literature and findings concerning selected foodborne viruses. Two groups of viruses were selected: (a) the most important viruses contaminating food, based on numbers of publications in the last 5 years and (b) viruses infecting sources of food that might have an impact on human health.

RECENT FINDINGS

Important foodborne viruses such as norovirus, hepatitis A and rotavirus are usually "only" contaminating food and are detected on the surface of foodstuffs. However, they are threats to human public health and make up for the majority of cases. In contrast, the meaning of viruses born from within the food such as natural animal and plant viruses is still in many cases unknown. An exception is Hepatitis E virus that is endemic in pigs, transmitted via pork meat and is recognised as an emerging zoonosis in industrialised countries.

SUMMARY

Even though the clinical meaning of "new" foodborne viruses, often detected by next generation sequencing, still needs clarification, the method has great potential to enhance surveillance and detection particularly in view of an increasingly globalised food trade.

Prevalence and evaluation strategies for viral contamination in food products: Risk to human health-a review

Nowadays, viruses of foodborne origin such as norovirus and hepatitis A are considered major causes of foodborne gastrointestinal illness with widespread distribution worldwide. A number of foodborne outbreaks associated with food products of animal and non-animal origins, which often involve multiple cases of variety of food streams, have been reported. Although several viruses, including rotavirus, adenovirus, astrovirus, parvovirus, and other enteroviruses, significantly contribute to incidence of gastrointestinal diseases, systematic information on the role of food in transmitting such viruses is limited. Most of the outbreak cases caused by infected food handlers were the source of 53% of total outbreaks. Therefore, prevention and hygiene measures to reduce the frequency of foodborne virus outbreaks should focus on food workers and production site of food products. Pivotal strategies, such as proper investigation, surveillance, and reports on foodborne viral illnesses, are needed in order to develop more accurate measures to detect the presence and pathogenesis of viral infection with detailed descriptions. Moreover, molecular epidemiology and surveillance of food samples may help analysis of public health hazards associated with exposure to foodborne viruses. In this present review, we discuss different aspects of foodborne viral contamination and its impact on human health. This review also aims to improve understanding of foodborne viral infections as major causes of human illness as well as provide descriptions of their control and prevention strategies and rapid detection by advanced molecular techniques. Further, a brief description of methods available for the detection of viruses in food and related matrices is provided.

Epidemiological and genetic analysis of a 2014 outbreak of hepatitis A in Japan

Hepatitis A virus (HAV) is one of the most common causes of feces-transmitted acute hepatitis worldwide. In Japan, most of HAV infections have been sporadic cases and a relatively low number of cases (approximately 100-150) of acute hepatitis A were reported in 2012 and 2013. However, in 2014, 342 cases were reported as of week 22. In order to characterize the viral agents causing this outbreak, we collected stool or sera (and both for three case) from patients with hepatitis A from many regions throughout Japan and performed genotyping of the VP1/P2A regions of HAV. We then used a multiple-alignment algorithm to compare the nucleotide sequences with those of reference strains. Phylogenetic tree analyses revealed that the 159 HAV isolates were divided into three subgenotypes: IA (137 cases), IB (4 cases), and IIIA (18 cases). The most unique feature of this outbreak was that for most subgenotype IA cases (103 out of 137 IA cases) the sequences analyzed shared 100% homology. Interestingly, the peak week for these IA infections was almost the same nationwide, suggesting that the epidemic of hepatitis A caused by this subgenotype IA strain may have expanded from a single source possibly because of one food-borne or waterborne source that was distributed nationwide at once.

Full-length genomic sequence of subgenotype IIIA hepatitis A virus isolate in Republic of Korea

Hepatitis A virus is known to cause acute hepatitis and has significant implications for public health throughout the world. In the Republic of Korea, the number of patients with hepatitis A virus infection has been increasing rapidly since 2006. In this study, the Kor-HAV-F strain was identified as subgenotype IIIA by RT-PCR, and its identity was confirmed by nucleotide sequencing and alignment analysis. Moreover, detailed phylogenetic analysis indicated that the Kor-HAV-F strain clustered into subgenotype IIIA, including strains isolated in Japan, Norway, and India. The entire amino acid sequence of the VP1 and 2A regions was compared with that of the reference strains isolated in various countries. We found 2 amino acid changes (T168A and L96P, resp.) in the VP1 and 2A regions, which had not been found in any other hepatitis A virus strain. To our knowledge, this study is the first to report the full-length sequence of a hepatitis A virus isolated in the Republic of Korea.

Genotypic shift of the hepatitis A virus and its clinical impact on acute hepatitis A in Korea: a nationwide multicenter study

BACKGROUND

The genotypic shift of hepatitis A virus (HAV) and its correlation with clinical course has not been evaluated in acute hepatitis A (AHA).

METHODS

From June 2007 to May 2009, we prospectively enrolled 546 AHA patients. We performed a nested reverse transcriptase polymerase chain reaction (RT-PCR) using the serum samples in addition to phylogenetic analysis, then we compared patient clinical features.

RESULTS

Among 351 successfully genotyped patients, we found genotype IIIA in 178 patients (51%) and IA in 173 patients (49%). The sequences of genotype IA are identical to previously reported Korean genotype IA, and the new IIIA genotype is closely related to NOR24/Norway. We retrospectively analyzed 41 AHA samples collected from 2000 to 2006 and found that all of them were genotype IA. Patients with genotype IIIA showed significantly higher levels of aspartate aminotransferase, higher levels of alanine aminotransferase, and lower platelet counts than patients with genotype IA when comparing baseline laboratory data or peak/lowest laboratory data during the disease course. However, there were no differences in duration of hospital stay, incidence of cholestatic hepatitis, acute kidney injury, and acute liver failure, or mortality between them.

CONCLUSIONS

A genotypic shift of the HAV was identified in Korean AHA subjects, and genotype IIIA HAV has become endemic. Although there were significant differences in the biochemical responses of AHA between genotype IA and genotype IIIA patients, we did not detect any differences in clinical outcomes such as complications or mortality.

Risk factors for acute hepatitis A infection in Korea in 2007 and 2009: a case-control study

This study aimed to identify the risk factors associated with acute hepatitis A virus (HAV) infection in the Korean population. Participants were recruited from five referral hospitals across the country in 2007 and from 11 hospitals in 2009. Patients with positive anti-HAV IgM antibody tests became the case group, while patients treated for non-contagious diseases at the same hospitals were recruited as controls. A total of 222 and 548 case-control pairs were studied in the 2007 and 2009 surveys, respectively. Data from the surveys were analyzed jointly. In a multivariate analysis, sharing the household with HAV-infected family members (OR, 6.32; 95% CI, 1.4-29.6), contact with other HAV-infected individuals (OR, 4.73; 95% CI, 2.4-9.4), overseas travel in 2007 (OR, 19.93; 95% CI, 2.3-174.4), consumption of raw shellfish (OR, 2.51; 95% CI, 1.8-3.5), drinking bottled water (OR, 1.64; 95% CI, 1.3-8.4), and occupation that involve handling food (OR, 3.30; 95% CI, 1.3-8.4) increased the risk of HAV infection. Avoiding contact with HAV-infected individuals and avoiding raw foods eating could help minimize the risk of hepatitis A infection. Immunization must be beneficial to individuals who handle food ingredients occupationally or travel overseas to HAV-endemic areas.

Increased circulation of hepatitis A virus genotype IIIA over the last decade in St Petersburg, Russia

The current study, covering the period 2004-2009, is a part of long-term monitoring for hepatitis A virus (HAV) strains circulating in St Petersburg, Russia. The HAV RNA was isolated directly from the sera of hepatitis A patients and RT-PCR was carried out using primer pairs for VP1/2A and VP1 genomic regions. PCR products were sequenced and 324 nucleotides from VP1/2A and 332 from the VP1 region were used for phylogenetic analysis. The results show that the IA subtype was the most common circulating subtype during the follow-up period, as found in the previous study: almost 90% of the isolated HAV strains belonged to the IA subtype. The large hepatitis A food-borne outbreak in St Petersburg in 2005 was caused by HAV IA. However, the proportion of HAV isolates belonging to subtype IIIA significantly increased in the period 2001-2009 (7.9%) compared to the period 1997-2000 (none found). The subtype IIIA was first found in St Petersburg in 2001 among a group of intravenous drug users. The increase in its circulation during the decade suggests that this previously unusual genotype has been permanently introduced into the general population of St Petersburg. These results indicate the usefulness of molecular epidemiological methods for studying changes in the circulation of HAV strains.

Laboratory diagnosis of hepatitis A

The diagnostic gold standard for hepatitis A is the detection of anti-hepatitis A virus (HAV) IgM antibodies and the determination of total anti-HAV by enzyme immunoassay. However, detection of HAV RNA can be useful in the diagnosis of patients without specific antibodies for hepatitis A and for the monitoring of infection. Studies using real-time PCR have demonstrated that HAV RNA can be detected not only in feces, but also in serum and saliva samples earlier than detection of antibodies, and that viremia may be present for a much longer period than the convalescent phase of hepatitis A. Alternative samples have been proposed for diagnosis, epidemiological studies, investigation of outbreaks and selection of persons receptive to vaccination. Understanding the events of clinical course that take place during the hepatitis A infection may lead to more effective diagnosis.

Optimal time for repeating the IgM anti-hepatitis A virus antibody test in acute hepatitis A patients with a negative initial test

BACKGROUND/AIMS

The nonspecific clinical presentation of acute hepatitis A (AHA) mandates the detection of anti-hepatitis A virus IgM antibodies (IgM anti-HAV) in the serum for obtaining a definitive diagnosis. However, IgM anti-HAV might not be present during the early phase of the disease. The aim of this study was to determine the optimal time for repeating the IgM anti-HAV test (HAV test) in AHA patients with a negative initial test.

METHODS

In total, 261 patients hospitalized with AHA were enrolled for this retrospective study. AHA was diagnosed when the test for IgM anti-HAV was positive and the serum alanine aminotransferase (ALT) level was ≥400 IU/L. Repeat HAV test was conducted after 1-2 weeks if the initial HAV test was negative but AHA was still clinically suspected.

RESULTS

The results of the initial HAV test were negative in 28 (10.7%) patients. The intervals from symptom onset to the initial-HAV-test day and from the peak-ALT day to the initial-HAV-test day were significantly shorter in the negative-initial-HAV-test group, but on multivariate analysis only the latter was significantly associated with negative results for the initial HAV test (β=-0.978; odds ratio [95% confidence interval]=0.376 [0.189-0.747]; P=0.005). The HAV test was positive in all patients when it was performed at least 2 days after the peak-ALT day.

CONCLUSIONS

The results of HAV tests were significantly associated with the interval from the peak-ALT day to the HAV-test day. The optimal time for repeating the HAV test in clinically suspicious AHA patients with a negative initial HAV test appears to be at least 2 days after the peak-ALT day.

Epidemiological changes in hepatitis A in Korea: increasing age and its effect on clinical outcomes

Korea has recently experienced an increasing number of acute hepatitis A cases. We investigated the dynamics of hepatitis A and changes in the mean age of patients in a hospital in Seoul, Korea. Mean age increased consistently from 19 years in 1996 to 30 years in 2009 (P < 0·0001). Between two acute hepatitis A outbreaks in 1998–1999 and in 2008–2009, mean age increased from 23 to 30 years (P < 0·001). However, the hepatitis A clinical outcomes were similar between the outbreaks. Duration of hospital stay, creatinine level and prothrombin time did not differ. Throughout the study period, individuals born in the 1970s and 1980s comprised the largest proportion (84%) of patients. As this susceptible generation ages, the mean age of hepatitis A patients in Korea will increase consistently. However, at present, the impact of increasing age on clinical outcomes is not apparent.

Epidemiological and genetic analyses of a diffuse outbreak of hepatitis A in Japan, 2010

BACKGROUND

Hepatitis A virus (HAV) is still one of the most common causative agents of acute hepatitis in Japan. Although a relatively small number of annual acute hepatitis A cases (approximately 100-150, 0.78-1.17 per million) were recently reported, a larger number of cases (346, 2.71 per million) were reported in 2010.

OBJECTIVES

To investigate the causes of the 2010 HAV resurgence in Japan by using molecular epidemiological and genetic analyses.

STUDY DESIGN

HAV specimens were obtained from 61 cases from 22 different prefectures. These viral specimens were genotyped by PCR amplification and sequencing of the VP1/2A region of HAV genome.

RESULTS

Phylogenetic analysis revealed that 61 HAV strains could be divided into three genotypes: IA (44 cases), IB (1 case) and IIIA (16 cases). The IA genotype consisted of two genomic sub-lineages. The sequences of one of the two IA sub-lineages (corresponding to 31 cases) were very similar, 26 of these 31 isolates had 100% identity. The other IA sub-lineage corresponded to strains endemic to Japan. The sequences of Japanese IIIA strains were similar to those of strains that caused a large epidemic in the Republic of Korea from 2007 to 2009.

CONCLUSIONS

The resurgence of HAV in 2010 can be attributed to importation of two newly emerged HAV genotypes.

Clinical significance of the detection of antinuclear antibodies in patients with acute hepatitis a

Background/Aims

The findings of several recent studies suggest that antinuclear antibodies (ANAs) are frequently detected in patients with acute hepatitis A (AHA). However, the clinical significance of a positive ANA test remains uncertain. This study was performed to evaluate the clinical significance of ANAs in AHA patients.

Methods

All patients admitted with AHA were consecutively enrolled in this study. An ANA assay was performed by indirect immunofluorescence during hospitalization. ANA positivity was defined as an ANA titer ≥1:80. The peak international normalized ratio (INR), peak alanine aminotransferase (ALT) and peak bilirubin levels were assessed over the duration of the hospitalization, and the incidence of AHA complications was evaluated.

Results

A total of 422 patients were enrolled in this study (age, 31±7 years), of which 260 (61.6%) were men. ANAs were detected in 179 AHA patients (42.4%). The proportion of ANA-positive patients varied significantly with AHA status on the day of the ANA assay (4.7% during the prodromal period vs 52.1% during the icteric or recovery period, p<0.001) and sex (56.2% in women vs 33.8% in men, p<0.001). The ANAs became undetectable in all ANA-positive patients within 3 months. The incidence of complications, including mortality, fulminant hepatic failure, renal dysfunction, relapse, and cholestatic hepatitis, did not differ significantly between ANA-positive and ANA-negative patients.

Conclusions

ANAs were detected frequently and transiently in patients with AHA, especially after their peak-ALT day. The presence of ANAs may not be associated with the clinical outcome of AHA, but simply with AHA status on the ANA assay day.

Heat Inactivation of Hepatitis A Virus in Shellfish Using Steam

Shellfish are an important cause of foodborne viral illness. Consumer-friendly cooking recommendations for shellfish could improve food safety and decrease the risk for infection from contaminated products. Thermal inactivation parameters were established for hepatitis A virus (HAV) in mussels and validated with cooking experiments. Steaming for only 2-5 min was not sufficient to inactivate HAV in mussels in all layers of a steamer. Steaming mussels for 6 min was sufficient to inactivate HAV in all layers. These cooking guidelines produce shellfish with a reduced risk for foodborne virus transmission.