Detection of hepatitis A virus genotype IB variants in clams from Maputo Bay, Mozambique

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.

Characterisation of the environmental presence of hepatitis A virus in low-income and middle-income countries: a systematic review and meta-analysis

OBJECTIVE

To characterise the environmental presence of hepatitis A virus (HAV) in low- and middle-income countries (LMICs).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

EBSCOhost, PubMed, Scopus, ScienceDirect, Clinical Key and Web of Science were searched. Grey literature was sourced by searching the following electronic databases: Open Grey, National Health Research Database and Mednar.

ELIGIBILITY CRITERIA FOR INCLUDING STUDIES

Cross-sectional and ecological studies reporting HAV environmental presence and conducted in LMICs between January 2005 and May 2019, irrespective of language of publication.

DATA EXTRACTION AND DATA SYNTHESIS

Relevant data were extracted from articles meeting the inclusion criteria, and two reviewers independently assessed the studies for risk of bias. High heterogeneity of the extracted data led to the results being reported narratively.

RESULTS

A total of 2092 records were retrieved, of which 33 met the inclusion criteria. 21 studies were conducted in Tunisia, India and South Africa, and the rest were from Philippines, Pakistan, Morocco, Chad, Mozambique, Kenya and Uganda. In Tunisian raw sewage samples, the prevalence of HAV ranged from 12% to 68%, with an estimated average detection rate of 50% (95% CI 25 to 75), whereas HAV detection in treated sewage in Tunisia ranged from 23% to 65%, with an estimated average detection rate of 38% (95% CI 20 to 57). The prevalence of HAV detection in South African treated sewage and surface water samples ranged from 4% to 37% and from 16% to 76%, with an estimated average detection rates of 15% (95% CI 1 to 29) and 51% (95% CI 21 to 80), respectively. Over the review period, the estimated average detection rate of environmental HAV presence appeared to have declined by 10%.

CONCLUSION

The quality of included studies was fair, but sampling issues and paucity of data limited the strength of the review findings.

PROSPERO REGISTRATION NUMBER

CRD42019119592.

Alteration of host-pathogen interactions in the wake of climate change - Increasing risk for shellfish associated infections?

The potential for climate-related spread of infectious diseases through marine systems has been highlighted in several reports. With this review we want to draw attention to less recognized mechanisms behind vector-borne transmission pathways to humans. We have focused on how the immune systems of edible marine shellfish, the blue mussels and Norway lobsters, are affected by climate related environmental stressors. Future ocean acidification (OA) and warming due to climate change constitute a gradually increasing persistent stress with negative trade-off for many organisms. In addition, the stress of recurrent hypoxia, inducing high levels of bioavailable manganese (Mn) is likely to increase in line with climate change. We summarized that OA, hypoxia and elevated levels of Mn did have an overall negative effect on immunity, in some cases also with synergistic effects. On the other hand, moderate increase in temperature seems to have a stimulating effect on antimicrobial activity and may in a future warming scenario counteract the negative effects. However, rising sea surface temperature and climate events causing high land run-off promote the abundance of naturally occurring pathogenic Vibrio and will in addition, bring enteric pathogens which are circulating in society into coastal waters. Moreover, the observed impairments of the immune defense enhance the persistence and occurrence of pathogens in shellfish. This may increase the risk for direct transmission of pathogens to consumers. It is thus essential that in the wake of climate change, sanitary control of coastal waters and seafood must recognize and adapt to the expected alteration of host-pathogen interactions.

Survivability of low pathogenic (H9N2) avian influenza virus in water in the presence of Atyopsis moluccensis (Bamboo shrimp)

Low pathogenic avian influenza virus (LPAIV) exhibits an ecological climax with the aquatic ecosystem. The most widely prevalent subtype of LPAIV is H9N2. Wild aquatic birds being the natural reservoirs and ducks, the "Trojan horses" for Avian Influenza Virus (AIV), can contaminate the natural water bodies inhabited by them. The virus can persist in the contaminated water from days to years depending upon the environmental conditions. Various aquatic species other than ducks can promote the persistence and transmission of AIV; however, studies on the role of aquatic fauna in persistence and transmission of avian influenza virus are scarce. This experiment was designed to evaluate the survivability of H9N2 LPAIV in water with and without Atyopsis moluccensis (bamboo shrimp) for a period of 12 days. The infectivity and amount of virus in water were calculated and were found to be significantly higher in water with A. moluccensis than in water without A. moluccensis. The study also showed that A. moluccensis can accumulate the virus mechanically which can infect chicken eggs up to 11 days. The virus transmission potential of A. moluccensis requires further studies.

Synthetic peptides for the immunodiagnosis of hepatitis A virus infection

VP1, VP2 and VP3 molecules of hepatitis A virus are exposed capsid proteins that have shown to be antigenic and are used for diagnosis in recombinant-antigen commercial kits. In this study, we developed a sequence analysis in order to predict diagnostic peptide epitopes, followed by their spot synthesis on functionalized cellulose paper (Pepscan). This paper with synthetic peptides was tested against a sera pool of hepatitis A patients. Two peptide sequences, that have shown an antigenic recognition, were selected for greater scale synthesis on resin. A dimeric form of one of these peptides (IMT-1996), located in the C-Terminus region of protein VP1, was antigenic with a recognition frequency of 87-100% of anti-IgG antibodies and 100% of anti-IgM antibodies employing the immunological assays MABA and ELISA. We propose peptide IMT-1996, with less than twenty residues, as a cheaper alternative for prevalence studies and diagnosis of hepatitis A infection.

Enteric viruses in healthy children in Cameroon: viral load and genotyping of norovirus strains

Data regarding prevalence of noroviruses (NoVs) among asymptomatic persons are scarce. The current study carried out on samples from Cameroon describes the asymptomatic shedding of NoVs and other enteric viruses in healthy children and in adults infected with HIV but lacking symptoms of gastroenteritis. Enteric viruses were common with a prevalence of 53.7% in the children, and 35.5% in the adult participants. Multiple enteric viruses (2-5 agents) were detected in fecal samples from 65% of the children, and co-infection with NoV was demonstrated in almost all cases of multiple infections. NoV viral loads in the healthy children were within disease causing range and significantly higher than those observed in the adults (P < 0.01). Sequencing and genotyping of NoV strains by phylogeny showed a marked diversity within two distinct genogroups, GI and GII, and strains clustered with genotypes GI.3, GII.17, GII.8, and GII.4. Genetic similarities to recent outbreak strains from other continents suggest a rapid circulation of NoVs that includes healthy children, who may constitute a reservoir for pathogenic NoVs.

Marked genomic diversity of norovirus genogroup I strains in a waterborne outbreak

Marked norovirus (NoV) diversity was detected in patient samples from a large community outbreak of gastroenteritis with waterborne epidemiology affecting approximately 2,400 people. NoV was detected in 33 of 50 patient samples examined by group-specific real-time reverse transcription-PCR. NoV genotype I (GI) strains predominated in 31 patients, with mixed GI infections occurring in 5 of these patients. Sequence analysis of RNA-dependent polymerase-N/S capsid-coding regions (∼900 nucleotides in length) confirmed the dominance of the GI strains (n = 36). Strains of NoV GI.4 (n = 21) and GI.7 (n = 9) were identified, but six strains required full capsid amino acid analyses (530 to 550 amino acids) based on control sequencing of cloned amplicons before the virus genotype could be determined. Three strains were assigned to a new NoV GI genotype, proposed as GI.9, based on capsid amino acid analyses showing 26% dissimilarity from the established genotypes GI.1 to GI.8. Three other strains grouped in a sub-branch of GI.3 with 13 to 15% amino acid dissimilarity to GI.3 GenBank reference strains. Phylogenetic analysis (2.1 kb) of 10 representative strains confirmed these genotype clusters. Strains of NoV GII.4 (n = 1), NoV GII.6 (n = 2), sapovirus GII.2 (n = 1), rotavirus (n = 3), adenovirus (n = 1), and Campylobacter spp. (n = 2) were detected as single infections or as mixtures with NoV GI. Marked NoV GI diversity detected in patients was consistent with epidemiologic evidence of waterborne NoV infections, suggesting human fecal contamination of the water supply. Recognition of NoV diversity in a cluster of patients provided a useful warning marker of waterborne contamination in the Lilla Edet outbreak.

Genetic analysis of hepatitis A virus strains that induced epidemics in Korea during 2007-2009

Hepatitis A virus is one of the most prominent causes of fecally transmitted acute hepatitis worldwide. In order to characterize the viral agents causing an outbreak in Korea (comprising North and South Korea) from June 2007 to May 2009, we collected specimens and performed genotyping of the VP1/P2A and VP3/VP1 regions of hepatitis A virus. We then used a multiple-alignment algorithm to compare the nucleotide sequences of the 2 regions with those of reference strains. Hepatitis A virus antibodies were detected in 64 patients from 5 reported outbreaks (North Korea, June 2007 [n = 11]; Jeonnam, April 2008 [n = 15]; Daegu, May 2008 [n = 13]; Seoul, May 2009 [n = 22]; and Incheon, May 2009 [n = 3]). We found 100% homology between strains isolated from the Kaesong Industrial Region and Jeonnam. While those strains were classified as genotype IA strains, strains from Seoul and Incheon were identified as genotype IIIA strains and showed 98.9 to 100% homology. Genotype IIIA was also dominant in Daegu, where strains were 95.7 to 100% homologous. All hepatitis A virus strains isolated from the Kaesong Industrial Region, Jeonnam, Seoul, and Incheon belonged to a single cluster. However, strains from Daegu could be classified into 2 clusters, suggesting that the outbreak had multiple sources. This study indicates that hepatitis A virus strains of 2 different genotypes are currently cocirculating in Korea. Moreover, it documents an increasing prevalence of genotype IIIA strains in the country.

An outbreak of hepatitis A affecting a nursery school and a primary school

Between March and June 2008, 12 cases of hepatitis A were notified in Winchester. Cases were from a primary school and a nursery school with no direct linkage. Hepatitis A virus (HAV) RNA sequenced from nine cases confirmed the strain in both schools to be identical. The outbreak could have affected three other schools and a maternity unit and was controlled by immunization and screening of neonates in the maternity unit by dried blood spots. No neonates were infected and no further cases were reported until 5 months later when the index case's mother became infected with same strain of virus associated with the outbreak despite vaccination. Neither the source of the outbreak or the subsequent infection of the index case's mother was identified; however, with the timing of the cases continued transmission in the community by children with asymptomatic infection or a recurrent source cannot be ruled out.

Hepatitis A virus: serology and molecular diagnostics

The diagnosis of hepatitis A virus (HAV) infection is based on the detection of anti-HAV IgM. Shortcomings of this serological approach include the persistence of IgM after normalization of liver enzymes or its detection during polyclonal activation of the immune system due to unrelated viral infection or autoimmune diseases. Molecular diagnosis of HAV along with anti-HAV IgG avidity measurement are helpful in case of positive IgM where laboratory evidence of acute hepatitis is absent and there is no epidemiologic link to other cases. Molecular epidemiology allows us to determine whether viruses from different locations are related to each other and provides further understanding of viral epidemiology by identifying sources and transmission modes. It has been demonstrated that the rapid turnover of HAV strains in low-endemicity countries is caused by their introduction by travelers. Growing sequence databases allow for the identification of geographic origin of viral strains. Collaboration between surveillance laboratories, including database sharing, should be promoted for deeper investigation of outbreaks and improved prevention approaches.

Tracing of norovirus outbreak strains in mussels collected near sewage effluents

Noroviruses from mussels collected near sewage effluents were compared with local patient outbreak strains. Sequence analyses of RNA polymerase-capsid-poly(A)-3' (3.1-kilobase) regions confirmed the 99.9% similarity between genotype I.1 strains from mussels and patient strains from recreational-bathing outbreaks, indicating the potential usefulness of sentinel norovirus mussel studies in tracing human norovirus contamination of coastal waters.

Molecular characterization of hepatitis A virus isolates from Argentina

Hepatitis A, a vaccine preventable disease, is now of transitional or intermediate endemicity in Argentina, as the epidemiologic pattern of the disease has shifted with improvements in living conditions in some parts of the country. Increase in the susceptibility of older children and adults has led to increasing disease incidence. Molecular epidemiology has played an important role in the understanding of HAV infection by identifying modes of spreading and by permitting the monitoring of changes in circulating virus brought about by prevention programs. South American isolates characterized are limited. Eighty-two sporadic and outbreak isolates from Argentina were sequenced in the VP1/2A region of HAV genome over a 9-year period. All the isolates belonged to subgenotype IA. All our sequences grouped into two big clusters. Apparently, at least two lineages have been co-circulating in the same place at the same time. Despite great genetic variability, few point amino acid changes could be deduced. Four sequences showed an Arg --> Lys substitution at 1-297 which characterized the genotype IB at the amino acid level. Many isolates carried a conservative amino acid substitution Leu --> Ile at position 42 of the 2A domain, previously described as a possible fingerprint of HAV sequences in Brazil. The other rare changes have been found before, except for a 1-277 Asn --> Ser substitution displayed in two isolates that has not been previously reported. Argentina recently implemented universal vaccination in 1-year-old children. Molecular tools would be useful in an active surveillance program.