Possible risk factors for the transmission of hepatitis E virus and for the severe form of hepatitis E acquired locally in Hokkaido, Japan

Fulminant liver failure from acute autochthonous hepatitis E in France: description of seven patients with acute hepatitis E and encephalopathy

Fulminant hepatitis E has not been well characterized in industrialized countries. The aim of this study was to prospectively describe patients with acute hepatitis E presenting as fulminant hepatic failure, i.e. with encephalopathy and prothrombin index <50%. Between February 1997 and April 2005, seven patients with encephalopathy were diagnosed with acute hepatitis E using viral RNA detection. These patients were compared with 33 patients diagnosed with a mild form (absence of encephalopathy) of acute hepatitis E during the same time period. Patients were 65 +/- 11 years old. Five were active drinkers and six had chronic liver disease. All hepatitis E virus sequences evaluated (5/7) were of genotype 3. All patients but two died (71%). Four patients had no travel history. When compared with patients with a mild form of acute hepatitis E, active alcohol abuse and chronic liver disease were more frequent in patients with the severe form. Duration of hospitalization was longer. Aspartate transferase and bilirubin levels were significantly higher. Prothrombin index and accelerin levels were lower and death was more frequent. Acute nontravel-associated hepatitis E can appear as fulminant hepatitis with encephalopathy and coagulation disorders. Prognosis is severe and this may be due to the age at which it occurs and frequent underlying chronic liver disease.

Genetic variability and evolution of hepatitis E virus

Hepatitis E virus (HEV) is the sole member of the genus Hepevirus in the family Hepeviridae. HEV is transmitted primarily by the fecal-oral route, and water-borne epidemics are characteristic of hepatitis E in many developing countries in Asia, Africa and Latin America where sanitation conditions are suboptimal. Accumulating lines of evidence indicate that HEV-associated hepatitis also occurs domestically among individuals in industrialized countries, that there are animal reservoirs of HEV such as domestic pigs and wild boars, and that hepatitis E is a zoonosis. Based on the extensive genomic variability among HEV isolates, HEV sequences have been classified into four genotypes: genotype 1 consists of epidemic strains in developing countries in Asia and Africa; genotype 2 has been described in Mexico and several African countries; genotype 3 HEV is widely distributed and has been isolated from sporadic cases of acute hepatitis E and/or domestic pigs in many countries in the world, except for countries in Africa; and genotype 4 contains strains isolated from humans and/or domestic pigs exclusively in Asian countries. This paper reviews current knowledge on the genomic variability, geographic distribution and zoonotic aspects of HEV as well as the clinical significance of genotype and evolution of HEV.

Use of serological assays for diagnosis of hepatitis E virus genotype 1 and 3 infections in a setting of low endemicity

Because of the occurrence of genotype 3 hepatitis E virus (HEV) in regions of low endemicity, it is important to validate the currently used serological assays for diagnosing infections with viruses belonging to this lineage, since these assays only use antigens derived from genotype 1 and 2 viruses. We evaluated the Genelabs enzyme-linked immunosorbent assay (ELISA) and the RecomBlot from Mikrogen for the detection of HEV-specific immunoglobulin M (IgM) and IgG under conditions of low endemicity. We compared test results of 16 patients with locally acquired genotype 3 HEV, 8 genotype 1 patients, 167 healthy controls from the general population, and 101 cases with hepatitis due to other viral causes. The measured specificities of the ELISA (98%) and the RecomBlot (97%) were comparable to those given by the manufacturer for IgM but were significantly lower for IgG (93% by ELISA and 66% by immunoblotting, versus reported values of 98% for ELISA and 95% for blotting). Antibody levels detected following infections with genotype 3 were lower than those following genotype 1 infections except for those measured in the IgM ELISA. Reactivity to the four antigens used in the immunoblot assay were analyzed and showed differences in the IgM immunoblot reactions between genotype 1 patients and genotype 3 patients. The ORF3 antigen was the most specific antigen. The specificity could be improved by a combined testing regimen with confirmation by immunoblotting of all positive ELISA results and by raising the cutoff of the IgG immunoblot assay without loss of sensitivity. We conclude that a combination of ELISA and immunoblotting is needed for acceptable specificity and sensitivity of HEV assays under conditions of low endemicity.

[Acute hepatitis E in Madrid: description of 18 cases]

INTRODUCTION

Hepatitis E virus (HEV) is the main cause of non-A non-B enterically transmitted hepatitis in underdeveloped countries but is rare in industrialized areas. However, in the last few years, several sporadic autochthonous hepatitis E cases have been reported in Europe and no risk factors, such as visiting to endemic areas, could be found in these patients.

OBJECTIVE AND PATIENTS

Twelve patients with sporadic autochthonous hepatitis E (no risk factors such as traveling to endemic areas) and six imported cases (travel to Nepal, Santo Domingo, China, Brazil and Ecuador) were studied between June 1999 and December 2005.

RESULTS

HEV infection was diagnosed in patients with symptoms of acute hepatitis and the presence of IgG and IgM antibodies in serum with no other markers of hepatitis. HEV infection is probably overlooked in industrialized countries.

CONCLUSIONS

This diagnosis should be suspected in patients with acute hepatitis and anti-HEV antibodies in serum without known risk factors such as traveling to endemic areas.

Hepatitis E indigenous to economically developed countries: to what extent a zoonosis?

PURPOSE OF REVIEW

Hepatitis E, a disease transmitted by hepatitis E virus, is increasingly recognized as being indigenous to affluent, temperate-zone countries. Issues pertaining to disease acquisition and hepatitis E virus infection, particularly in Western countries, are reviewed and highlighted.

RECENT FINDINGS

Clinical hepatitis E in the West, as in Japan, manifests more commonly in older people (>60 years) and in men, but fulminant hepatitis appears less frequent than in Japan. There, specific gastronomic and culinary risk factors associated with disease are being identified, but in the West, data implicating hepatitis E as being foodborne have yet to emerge. While hepatitis E virus subgenomic sequences in Western case patients are found to be closely related to swine hepatitis E virus, a porcine linkage to their infection remains to be established. Weak associations between occupational contact with pigs and risk of infection have been noted. Findings from earlier studies implicating animals that cohabitate with humans as reservoirs, and sewage as vehicles of infection await confirmation.

SUMMARY

Hepatitis E indigenous to developed countries is a distinct clinico-epidemiological entity. Humans, animals, food and the environment contribute and interact to cause human disease, and to sustain hepatitis E virus endemicity and enzooticity.

Distinct changing profiles of hepatitis A and E virus infection among patients with acute hepatitis, patients on maintenance hemodialysis and healthy individuals in Japan

To compare the epidemiologic profiles of hepatitis A virus (HAV) and hepatitis E virus (HEV) infections in Japan, the prevalence of clinical or subclinical HAV and HEV infections was investigated serologically and molecularly among 128 consecutive patients (age, mean +/- standard deviation, 37.5 +/- 14.7 years) who contracted acute hepatitis between 1989 and 2005 in a city hospital, and among 416 hemodialysis patients (60.1 +/- 12.6 years) and 266 medical staff members (34.6 +/- 11.4 years) at the same hospital, using stored periodic serum samples collected since the start of hemodialysis or employment, respectively. Between 1989 and 1995, among 93 patients with acute hepatitis, 51 (54.8%) were diagnosed with hepatitis A and only one patient with hepatitis E. Between 1996 and 2005, however, among 35 patients, only 3 (8.6%) were diagnosed with hepatitis A and 2 (5.7%) with hepatitis E. Although subclinical HEV infection was recognized in four hemodialysis patients (one each in 1979, 1980, 1988, and 2003) and two medical staff members (1978 and 2003) in previous studies, none of the 191 hemodialysis patients who had been negative for anti-HAV at the start of hemodialysis contracted HAV infection during the observation period of 7.6 +/- 6.4 years. Only one (0.4%) of the 246 medical staff members who had been negative for anti-HAV at the start of employment acquired hepatitis A during the observation period of 7.9 +/- 8.0 years: none had subclinical HAV infection. Clinical or subclinical HEV infection has occurred rarely during the last three decades, while HAV infection has markedly decreased at least since 1996.

Development and validation of an improved RT-PCR assay with nested universal primers for detection of hepatitis E virus strains with significant sequence divergence

Recent studies revealed that hepatitis E virus (HEV) genomes are more variable than previously thought and well-conserved regions suitable for designing universal primers are limited. In this study, based on alignment of 70 full-length HEV sequences of genotypes 1-4, a part of the ORF2/ORF3 overlapping region was found to be the best target region for PCR amplification of various HEV strains. Using the newly designed primers, an RT-PCR method (ORF2/3-137 PCR) that amplifies a 137-nucleotide (nt) sequence within the ORF2/ORF3 overlapping region and is capable of amplifying all known HEV sequences was developed. When compared with the previous RT-PCR method (ORF2-457 PCR) that amplifies a 457 nt ORF2 sequence, ORF2/3-137 PCR was two to three times more sensitive than ORF2-457 PCR upon testing serial dilutions of three HEV RNA-positive serum samples. The ORF2/3-137 PCR assay could detect viraemia in five patients with acute or fulminant hepatitis E 3-14 days longer than ORF2-457 PCR after disease onset. All 41 ORF2-457 PCR-positive serum samples of various genotypes tested positive for HEV RNA by the ORF2/3-137 PCR assay. Since the amplicons of ORF2/3-137 PCR contain variable sequences, a phylogenetic tree of the ORF2/3-137 products could clearly distinguish the different HEV genotypes.

Analysis of the full-length genome of genotype 4 hepatitis E virus isolates from patients with fulminant or acute self-limited hepatitis E

It was suggested that hepatitis E virus (HEV) genotype 4 is associated more closely with the severity of hepatitis E than genotype 3, although the virological basis remains unknown. The aim of this study was to examine whether genomic differences among genotype 4 HEVs are responsible for the development of fulminant hepatitis. Full-length sequences of genotype 4 HEVs from three patients with fulminant hepatitis and six patients with acute self-limited hepatitis were determined. The sequences were analyzed with those of 13 genotype 4 HEV isolates whose entire nucleotide sequence is known. Analysis of 22 full-length sequences (fulminant hepatitis, 5; acute hepatitis, 17) revealed that C at nt 1816 and U at nt 3148 (U3148), both of which do not change the amino acid sequences, were significantly associated with fulminant hepatitis (P = 0.0489, respectively). When partial nucleotide sequences containing nt 1816 or nt 3148 were determined in 16 additional HEV isolates of genotype 4, a closer association between U3148 and fulminant hepatitis (P = 0.0018) was observed. The comparison of 86 HEV isolates of all four genotypes showed that U3148 had a stronger association with fulminant hepatitis than other nucleotides at nt 3148 (P = 0.0006). Patients infected with HEV with U3148 had a significantly lower value of the lowest prothrombin activity (P = 0.0293). Nt 3148 is located within the RNA helicase domain, and 22-nt sequence including nt 3148 was well conserved among all genotypes. A silent substitution of U3148 in HEV may be associated with the development of fulminant hepatitis. Further studies are needed to clarify the underlying mechanism.

Molecular tracing of Japan-indigenous hepatitis E viruses

The ancestor(s) of apparently Japan-indigenous strains of Hepatitis E virus (HEV) was probably of foreign origin, but it remains unclear when and from where it made inroads. In this study, 24 genotype 3 and 24 genotype 4 HEV strains recovered in Japan each showed a significant cluster, clearly distinct from those of foreign strains, in the phylogenetic tree constructed from an 821 nt RNA polymerase gene fragment. The evolutionary rate, approximately 0.8 x 10(-3) nucleotide substitutions per site per year, enabled tracing of the demographic history of HEV and suggested that the ancestors of Japan-indigenous HEV had made inroads around 1900, when several kinds of Yorkshire pig were imported from the UK to Japan. Interestingly, the evolutionary growth of genotype 3 in Japan has been slow since the 1920s, whereas genotype 4 has spread rapidly since the 1980s. In conclusion, these data suggest that the indigenization and spread of HEV in Japan were associated with the popularization of eating pork.