Hepatitis E: an overview

Hepatitis E as a cause of adult hospitalization in Bangladesh: Results from an acute jaundice surveillance study in six tertiary hospitals, 2014-2017

In the absence of reliable data on the burden of hepatitis E virus (HEV) in high endemic countries, we established a hospital-based acute jaundice surveillance program in six tertiary hospitals in Bangladesh to estimate the burden of HEV infection among hospitalized acute jaundice patients aged ≥14 years, identify seasonal and geographic patterns in the prevalence of hepatitis E, and examine factors associated with death.

We collected blood specimens from enrolled acute jaundice patients, defined as new onset of either yellow eyes or skin during the past three months of hospital admission, and tested for immunoglobulin M (IgM) antibodies against HEV, HBV and HAV. The enrolled patients were followed up three months after hospital discharge to assess their survival status; pregnant women were followed up three months after their delivery to assess pregnancy outcomes. From December’2014 to September’2017, 1925 patients with acute jaundice were enrolled; 661 (34%) had acute hepatitis E, 48 (8%) had hepatitis A, and 293 (15%) had acute hepatitis B infection. Case fatality among hepatitis E patients was 5% (28/589). Most of the hepatitis E cases were males (74%; 486/661), but case fatality was higher among females—12% (8/68) among pregnant and 8% (7/91) among non-pregnant women. Half of the patients who died with acute hepatitis E had co-infection with HAV or HBV. Of the 62 HEV infected mothers who were alive until the delivery, 9 (15%) had miscarriage/stillbirth, and of those children who were born alive, 19% (10/53) died, all within one week of birth. This study confirms that hepatitis E is the leading cause of acute jaundice, leads to hospitalizations in all regions in Bangladesh, occurs throughout the year, and is associated with considerable morbidity and mortality. Effective control measures should be taken to reduce the risk of HEV infections including improvements in water quality, sanitation and hygiene practices and the introduction of HEV vaccine to high-risk groups.

In the absence of reliable surveillance data on the burden of hepatitis E in endemic countries, we conducted a hospital-based acute jaundice surveillance study over a two and a half year period in six tertiary hospitals in Bangladesh. The study confirms that HEV infections occur throughout the year, and is a major (34%) cause of acute jaundice in tertiary hospitals in Bangladesh. Three-quarters of the acute hepatitis E cases were male, and HEV infection was higher among patients residing in urban areas than patients in rural areas (41% vs 32%). The overall case fatality rate of acute HEV infections in hospitals was 5%, but was higher among pregnant women (12%). Hepatitis E patients who died were more likely to have co-infection with HAV or HBV than the HEV infected patients who did not die. Fifteen percent of HEV infected mothers had miscarriage/stillbirth. Of the children who were born alive, 19% died, all within one week of birth. Considering the high burden of hepatitis E among hospitalized acute jaundice patients, Bangladesh could take control measures to reduce this risk including improvements in water quality, sanitation and hygiene practices and the introduction of hepatitis E vaccine in high-risk areas.

The Impact of Emerging Infectious Diseases on Chinese Blood Safety

Emerging infectious diseases (EIDs) have always been one of the major threats to public health. Although the implementation of mandatory testing for 4 classical transfusion-transmitted infectious-human immunodeficiency virus, hepatitis B virus, hepatitis C virus, and syphilis-has reduced the transfusion risk of these pathogens, the potential threat of various EID agents and their constantly evolving variants to blood safety in China is not fully understood. This review presents 9 representative EID agents that are autochthonous and epidemic nationally or regionally in China. The epidemiologic status and distribution of these EID agents among donors and/or healthy populations are summarized. The potential risks of these EID agents to blood safety are discussed. The review also explores strategies to strengthen hemovigilance systems and studies to further evaluate the impact of EID agents on blood safety.

Shellfish-Associated Enteric Virus Illness: Virus Localization, Disease Outbreaks and Prevention

Numerous outbreaks of shellfish-borne enteric virus illness have been reported worldwide. Most notable among the outbreaks are those caused by NoV and HAV. Lessons learned from outbreak investigations indicate that most outbreaks are preventable. Anthropogenic sources of contamination will continue to invade shellfish growing waters. Shellfish, by their very nature, will continue to bioconcentrate these contaminants, including enteric viruses. There is no quick fix for enteric virus contamination of shellfish; however, vigilance on behalf of the industry, regulatory agencies, and the consumer could substantially reduce the incidence of illness. Enhanced monitoring in all areas of shellfish production, harvesting, distribution, and processing would help to reduce viral illnesses. Pollution abatement and improved hygienic practices on behalf of the industry and consumers are needed. Improved analytical techniques for the detection of enteric viruses in shellfish will lead to enhanced shellfish safety and better protection for the consumer and the industry. Better reporting and epidemiological follow-up of outbreaks are keys to reducing the transmission of foodborne viral infections. It is anticipated that recent advances in analytical techniques, particularly for NoV, will lead to better monitoring capabilities for food and water and a reduction in the incidence of enteric virus illness among shellfish consumers.

Opportunistic intruders: how viruses orchestrate ER functions to infect cells

Viruses exploit the functions of the endoplasmic reticulum (ER) to promote both early and later stages of their life cycle, including entry, translation, replication, assembly, morphogenesis and egress. This observation reveals a shared principle that underlies virus–host cell relationships.

Viral entry often requires disassembly of the incoming virus particle. This is best exemplified in the case of polyomavirus entry, in which ER-associated machineries are hijacked to disassemble the virus and promote entry to the cytosol en route to the nucleus.

Many enveloped viruses, such as HIV and influenza virus, co-opt the ER-associated protein biosynthetic machinery to translate their genome and produce structural proteins that are necessary for the formation of virus particles and non-structural proteins that are essential during genome replication.

Replication of the viral genome, particularly for positive-sense RNA ((+)RNA) viruses including hepatitis C virus (HCV), dengue virus (DENV) and West Nile virus (WNV), occurs in virus-induced membranous structures that are most often derived from the ER. The formation of these structures requires morphological changes to the ER membrane, involving membrane rearrangements that are induced by viral non-structural proteins that are targeted to the ER.

As virus assembly is often coupled to genome replication, the assembly process frequently relies on the ER membrane. This strategy is seen for both RNA and DNA viruses.

Morphogenesis of assembled virus particles can also take advantage of the ER. This is best observed in the non-enveloped rotavirus, for which a transient enveloped intermediate is converted to the mature and infectious particle in the lumen of the ER.

After maturation in the ER, progeny virus particles egress the host through the ER-dependent secretory pathway, which provides a physical conduit to the extracellular environment.

The overall observations that the ER actively promotes all steps of viral infection have therapeutic implications. The development of chemical inhibitors of selective ER-associated components is emerging as a potential avenue of antiviral therapy, provided that these inhibitors have minimal toxicity to the host cell.

Many host structures are vital for viral infection and the endoplasmic reticulum (ER), in particular, is essential. In this Review, Tsai and colleagues highlight examples of subversion of the ER by diverse viruses to promote all stages of their life cycle, from entry to egress.

Viruses subvert the functions of their host cells to replicate and form new viral progeny. The endoplasmic reticulum (ER) has been identified as a central organelle that governs the intracellular interplay between viruses and hosts. In this Review, we analyse how viruses from vastly different families converge on this unique intracellular organelle during infection, co-opting some of the endogenous functions of the ER to promote distinct steps of the viral life cycle from entry and replication to assembly and egress. The ER can act as the common denominator during infection for diverse virus families, thereby providing a shared principle that underlies the apparent complexity of relationships between viruses and host cells. As a plethora of information illuminating the molecular and cellular basis of virus–ER interactions has become available, these insights may lead to the development of crucial therapeutic agents.

Hepatitis E vaccine immunization for rabbits to prevent animal HEV infection and zoonotic transmission

Hepatitis E virus (HEV) infection has become a significant global public health concern as increasing cases of acute and chronic hepatitis E are reported. HEV of animal origin was proved to be a possible source of human infection and a previous study showed that the recent licensed HEV 239 vaccine can serve as a candidate vaccine to manage animal sources of HEV infection. However, previous immunization strategy for rabbits was the same as that for human, which is too costly to conduct large-scale animal vaccination. In an effort to reduce the costs, three vaccination schemes were assessed in the present study. Forty specific pathogen-free (SPF) rabbits were divided randomly into five groups with eight animals for each and inoculated intramuscularly with different doses of HEV 239 and placebo, respectively. All animals were challenged intravenously with swine HEV-4 and rabbit HEV of different titers 7 weeks after the initial immunization and then fecal virus excretion was monitored for 10 weeks. The results indicated that immunizing rabbits with two 10μg doses of the vaccine is superior to vaccination with two 20μg doses or a single 30μg dose, which can protect rabbits against homologous and heterologous HEV infection. These findings could enable implementation of large-scale animal vaccination to prevent rabbit HEV infection and zoonotic transmission.

Hepatitis E: the West of Scotland experience

BACKGROUND AND AIMS

Hepatitis E virus is traditionally regarded as a virus of the developing world and is emerging as a leading cause of non-A/B/C hepatitis. We wished to investigate locally acquired transmission of hepatitis E in the West of Scotland and compare our use of traditional serology versus polymerase chain reaction since the introduction of polymerase chain reaction in 2007.

METHODS

Clinical details provided on specimens of blood positive for hepatitis E virus by serology or polymerase chain reaction were collated and analysed.

RESULTS

Since 2007, 30 samples were hepatitis E virus-positive by serology or polymerase chain reaction. Polymerase chain reaction positivity was generally associated with positive serology although four samples were polymerase chain reaction-negative and strongly positive by serology. Interestingly, one-quarter of cases were likely to represent endogenous transmission of the infection.

CONCLUSIONS

Polymerase chain reaction is valuable in reliably diagnosing hepatitis E virus. However, serology is valuable for diagnosing resolved infection. There may be a high level of undiagnosed locally acquired hepatitis E virus in Scotland.

[Hepatitis E virus: A new entity]

Hepatitis E virus (HEV) is a RNA enterically transmitted virus that causes large waterborne epidemics of acute hepatitis E in endemic regions (Asia and Africa). Sporadic hepatitis E is an emerging disease in developed countries such as France. The majority of acute hepatitis E in France is indigenous (non travel-associated) and is due to infection with HEV genotype 3. Diagnosis is made on the presence of specific serum antibodies and on viral RNA detection in serum or stools. Characteristic pathological signs of acute hepatitis E are severe intralobular necrosis, polymorph inflammation and acute cholangitis in portal tract with numerous neutrophils. Severe forms of hepatitis are associated with underlying chronic liver disease such alcoholic disease. In immunocompetent patients, HEV causes acute resolutive hepatitis and there is no chronic evolution. Conversely, chronic hepatitis E is frequent in immunocompromised patients with a risk of rapid evolution to cirrhosis. Histologic lesions of chronic hepatitis E are similar to those observed in patients chronically infected with hepatitis C virus with dense lymphocytic portal infiltrate, constant peacemeal necrosis and fibrosis.

Excretion of hepatitis E virus by pigs of different ages and its presence in slurry stores in the United Kingdom

Five faecal samples were collected from four different stages of production at each of 10 pig farms in the Yorkshire Humberside area of the UK, and samples of slurry were collected from nine of the farms. All the samples were tested for hepatitis E virus (HEV) RNA by a nested reverse transcriptase PCR. At least one sample from the pigs on each of the farms tested positive for hev; its prevalence in the 10 herds varied from 5 per cent to 35 per cent and its mean prevalence was 21.5 per cent. The mean prevalence in pigs aged three to five weeks was 26.0 per cent, in pigs aged 10 to 12 weeks 44.0 per cent, in pigs aged 22 to 24 weeks 8.9 per cent, and in adult dry sows 6.0 per cent. Two of the nine slurry lagoons tested positive for HEV RNA. Phylogenetic analysis of the sequence data indicated that the strains of the virus were of genotype 3 and closely related to strains detected in other pigs and in human beings in the UK.

Hepatitis E: an emerging infection in developed countries

Hepatitis E is endemic in many developing countries where it causes substantial morbidity. In industrialised countries, it is considered rare, and largely confined to travellers returning from endemic areas. However, there is now a growing body of evidence that challenges this notion. Autochthonous hepatitis E in developed countries is far more common than previously recognised, and might be more common than hepatitis A. Hepatitis E has a predilection for older men in whom it causes substantial morbidity and mortality. The disease has a poor prognosis in the context of pre-existing chronic liver disease, and is frequently misdiagnosed as drug-induced liver injury. The source and route of infection remain uncertain, but it might be a porcine zoonosis. Patients with unexplained hepatitis should be tested for hepatitis E, whatever their age or travel history.

A national survey of acute hepatitis E in France

BACKGROUND

Few data are available on the incidence, risk factors and contamination pathways involved in acute indigenous hepatitis E in developed countries.

AIMS

To draw up an overall picture of hepatitis E cases, to confirm whether or not the majority of the cases were indigenous and to attempt to identify the risk factors and contamination pathways involved in hepatitis E.

METHODS

This study was performed in the framework of a national network (ANGH) including 96 participating centres. The 19 centres with at least one case of acute HEV reported a total number of 53 cases.

RESULTS

A decreasing South-to-North geographic gradient was observed. A nonspecific clinical profile was observed in many cases. Acute hepatitis E was of indigenous origin in 90% of the patients. The most relevant and/or frequent possible risk factors among the 47 indigenous metropolitan cases were water consumption from a personal water supply, uncooked shellfish consumption and the recent acquisition of a pet pig.

CONCLUSIONS

This national survey confirmed that acute indigenous hepatitis E is an emerging disease in developed countries such as France, and suggests that various risk factors are responsible for acute indigenous hepatitis E contamination in non-endemic countries.

Routes of transmission of swine hepatitis E virus in pigs

Hepatitis E virus (HEV) is believed to be transmitted by the fecal-oral route in pigs. To date, in experiments, HEV has been transmitted successfully only by the intravenous or intrahepatic route. To assess the route of HEV transmission, 27 pigs were separated into nine groups of three pigs. Positive-control pigs were inoculated intravenously with swine HEV and served as the source of HEV for the other groups. Uninoculated contact pigs were placed in the positive-control group. On three consecutive days, naive pigs were inoculated using samples collected from the positive-control pigs at 9, 10, and 11 days postinoculation. The tonsils and nasal mucosa of each positive-control pig were swabbed and that swab was used to rub the tonsils and nasal and ocular mucosa of naive pigs. The positive-control pigs were also injected with bacterin, and the same needle was used to immediately inject naive pigs. Feces were collected from positive controls and fed by oral gavage to naive pigs. Weekly fecal and serum samples from each pig were tested for anti-HEV antibodies and HEV RNA. All positive-control pigs shed the virus in feces; two pigs were viremic and seroconverted to anti-HEV. All contact control pigs shed the virus in feces; two seroconverted and one became viremic. One of three pigs in the fecal-oral exposure group shed the virus in feces and seroconverted. Pigs exposed to the contaminated needles or the tonsil and nasal secretion swabs remained negative. This is the first report of experimental fecal-oral transmission of HEV in swine.

Evidence for the presence of hepatitis E virus in pigs in the United Kingdom

Samples of serum, tissue and faeces from two pig herds in England were examined for hepatitis E virus by reverse-transcriptase PCR (RT-PCR), and a virus strain from each herd was partially sequenced. Eleven of 42 faecal samples and 16 of 21 tissue samples from two pigs were positive for the virus by RT-PCR. Analysis of two unique but closely related nucleotide sequences obtained from the two herds showed that the viruses clustered in genotype III (6) with a human strain of the virus from an autochthonously acquired case of acute hepatitis in the UK. An ELISA based on recombinant open reading frame 2 (ORF-2) was used to detect antibodies to hepatitis E virus in 256 pig sera from the UK; 85.5 per cent of the samples were positive, compared with 58 per cent of similar samples from Swedish pigs and 23.5 per cent of samples from Dutch pigs.

Development of a molecular method to identify hepatitis E virus in water

Hepatitis E virus (HEV) causes an infectious form of hepatitis associated with contaminated water. By analyzing the sequence of several HEV isolates, a reverse transcription-polymerase chain reaction method was developed and optimized that should be able to identify all of the known HEV strains. When tested under laboratory conditions, this method was able to detect low levels of five diverse HEV variants. In addition, internal controls were constructed so that any PCR inhibition could be detected. Finally, virus-spiked environmental water samples were analyzed successfully with these assays.

Acute hepatitis E virus infection presenting as a prolonged cholestatic jaundice

Hepatitis E virus (HEV) is an enteric virus that usually causes a self-resolving hepatitis; although, it may be fatal, especially in pregnant women. Although HEV is endemic in Israel, there have been no recent local outbreaks. We report the case of a 70-year-old man who presented with painless jaundice. Ultrasound and abdominal computed tomography scan revealed gallstones, with no evidence of cholecystitis and no dilatation of the intra-or extrahepatic bile ducts. An open cholecystectomy was performed with intraoperative cholangiography. There was no evidence of choledocholithiasis. A subsequent endoscopic retrograde cholangiopancreatography was normal. His bilirubin level subsequently increased to a maximum of 25 mg/dL, and his gamma-glutamyl-transferase level reached 1,400 U/L. There was no evidence of any autoimmune or metabolic disease, and routine viral serology was normal except for immunoglobulin G to hepatitis A virus. A liver biopsy revealed an acute cholestatic picture. The jaundice resolved slowly after a period of 6 months. Hepatitis E virus RNA was isolated from the acute-phase serum and was not detectable in the convalescent serum. This case is a unique example of chronic cholestatic jaundice that we think is caused by acute HEV infection.

Late medical complications and fatigue in Hodgkin's disease survivors

PURPOSE

Long-term medical complications, such as cardiac, pulmonary, and thyroid dysfunction, are frequent among Hodgkin's disease survivors (HDSs). Chronic fatigue is also highly prevalent among HDSs. Few studies have explored possible etiologic explanations for fatigue. The aim of this study was to explore whether late cardiac, pulmonary, and thyroid complications after curative treatment for Hodgkin's disease (HD) may explain the high level of fatigue among HDSs.

PATIENTS AND METHODS

Four-hundred fifty-nine patients treated for HD at the Norwegian Radium Hospital from 1971 to 1991 were included in a cross-sectional, follow-up study of subjective health status. Fatigue (physical [PF] and mental), was measured by the Fatigue Questionnaire. A subcohort of the HDSs (116 patients) treated from 1980 to 1988 were included in a separate study in which long-term cardiac, pulmonary, and thyroid complications were assessed. All patients had received radiotherapy, and 63 patients had received additional chemotherapy. The present study comprised 92 patients (mean age, 37 years; range, 23 to 56 years) who participated in both studies.

RESULTS

HDSs with pulmonary dysfunction were more fatigued than HDSs with normal pulmonary function (PF 10.9 v 8.9; P <.05). Gas transfer impairment was the most prevalent pulmonary dysfunction, and three times as many patients with gas transfer impairment reported chronic fatigue (duration, 6 months or longer), compared with patients without pulmonary dysfunction (48% v 17%, P <.01). No associations were found between cardiac sequelae or hypothyroidism and fatigue.

CONCLUSION

Pulmonary dysfunction is associated with fatigue in HDSs. Cardiac sequelae was not associated with fatigue in HDSs. We question the absence of an association between thyroid complications and fatigue.

A review of hepatitis E virus

Hepatitis E virus (HEV) is a major cause of outbreaks and sporadic cases of viral hepatitis in tropical and subtropical countries but is infrequent in industrialized countries. The virus is transmitted by the fecal-oral route with fecally contaminated drinking water being the usual vehicle. Hepatitis resulting from HEV infection is a moderately severe jaundice that is self-limiting in most patients. Young adults, 15 to 30 years of age, are the main targets of infection, and the overall death rate is 0.5 to 3.0%. However, the death rate during pregnancy approaches 15 to 25%. Death of the mother and fetus, abortion, premature delivery, or death of a live-born baby soon after birth are common complications of hepatitis E infection during pregnancy. Hepatitis E virus is found in both wild and domestic animals; thus, HEV is a zoonotic virus. The viruses isolated from swine in the United States or Taiwan are closely related to human HEV found in those areas. The close genetic relationship of the swine and human virus suggests that swine may be a reservoir of HEV. In areas where swine are raised, swine manure could be a source of HEV contamination of irrigation water or coastal waters with concomitant contamination of produce or shellfish. Increasing globalization of food markets by industrialized countries has the potential of introducing HEV into new areas of the world. The purpose of this review is to cover certain aspects of hepatitis E including the causative agent, the disease, diagnosis, viral detection, viral transmission, epidemiology, populations targeted by HEV, and the role of animals as potential vectors of the virus.

Diagnostic value of immunoglobulin G (IgG) and IgM anti-hepatitis E virus (HEV) tests based on HEV RNA in an area where hepatitis E is not endemic

Acute hepatitis E (AHE) has rarely been reported in industrialized countries, but the rate of seroprevalence of hepatitis E virus (HEV) antibodies (anti-HEV) is inappropriately high. The sensitivity and specificity of the assay used to test for immunoglobulin G (IgG) and IgM anti-HEV have not been well established in areas where hepatitis E is not endemic (hereafter referred to as "nonendemic areas"). We collected serum samples from 13 AHE patients, 271 healthy subjects, and 160 other liver disease patients in Taiwan to test for HEV RNA by reverse transcription (RT)-PCR and for IgG and IgM anti-HEV by enzyme-linked immunosorbent assays. The sensitivities of IgG and IgM anti-HEV (relative to RT-PCR) were 86.7 and 53.3%, respectively. The specificities of IgG and IgM anti-HEV assays for diagnosing AHE were 92.1 and 98.6%, respectively. The rate of seroprevalence of IgG anti-HEV was 11% among healthy subjects in this nonendemic area, and it increased with age. In summary, IgG anti-HEV is a good diagnostic test for screening for AHE in nonendemic areas. The high rate of prevalence of anti-HEV in healthy subjects indicates that subclinical infection may exist.

HEV identified in serum from humans with acute hepatitis and in sewage of animal origin in Spain

BACKGROUND/AIMS

Hepatitis E virus (HEV) is an enterically transmitted pathogen that appears sporadically in non-endemic countries. We studied HEV as a causal agent of acute hepatitis cases in the Spanish population, and the role of pigs as an animal reservoir.

METHODS

The presence of HEV-RNA was analysed by nested polymerase chain reaction in 37 serum samples from patients with acute viral hepatitis, 48 porcine serum samples, 6 pig faecal samples and 12 slaughter-house sewage samples. Presence of antibodies was also tested in porcine sera.

RESULTS

HEV-RNA was found in 3 human serum samples from patients presenting IgG anti-HEV antibodies. Nucleotide sequence analysis identified 2 strains with 93.4% identity, phylogenetically most closely related to the Greece1 isolate, and more closely related to North American and other European strains than to those from endemic regions. HEV-RNA was also detected in slaughterhouse sewage mainly from pigs, presenting 92-94% nucleotide similarity compared to the strains detected in the human sera. Twenty-five per cent of the pigs tested presented IgG anti-HEV antibodies.

CONCLUSIONS

These data suggest that the HEV could be more widespread than previously thought, and present new evidence of the close relationship between HEV strains detected in pigs and those from acute hepatitis patients.

Risk of hepatitis E infection to travelers

Hepatitis E virus (HEV), previously referred to as enterically transmitted non-A, non-B hepatitis, is a major cause of epidemic hepatitis and acute, sporadic hepatitis in endemic areas of the world. The existence of HEV was suspected based upon epidemiological grounds for many years. However, it was only in the early 1990s that confirmation occurred when two prototype strains of HEV from Burma and Mexico were sequenced.1-3 Outbreaks of HEV infection as well as sporadic transmission commonly occur in Asia, Africa, Central and South America, the Middle East, and the Republics of the former USSR. Southeast Asia seems to be a particularly high HEV endemic region. HEV is transmitted via the fecal-oral route, and contaminated drinking water is a common source of infection.4 Many of the large outbreaks have occurred after heavy rains and flooding.4 During interepidemic periods sporadic infections occur frequently. This suggests a constant environmental reservoir, allowing for transmission between epidemics. The existence of a zoonotic reservoir for the virus is likely. HEV has been detected in a number of species, including swine, rats, and chicken.

Hepatitis viruses A, B, C, D, E and G: implications for dental personnel

BACKGROUND

This article provides dental personnel with a brief overview of the different types of viral hepatitis, including their epidemiology, clinical features, prevention and treatment. It also explores the ramifications of these diseases for the practice of dentistry. DESCRIPTION OF THE CONDITION: Viral hepatitis is an inflammation of the liver caused by one of at least six distinct viruses. The hepatitis A and E viruses, or HAV and HEV, are enterically transmitted viruses that produce acute disease only. The hepatitis B, C and D viruses, or HBV, HCV and HDV, are most efficiently transmitted by infected blood, but also can be transmitted by exposure to other infectious bodily fluids. These three viruses can cause acute or chronic hepatitis. People with chronic viral hepatitis can develop chronic liver disease, cirrhosis and hepatocellular carcinoma. The hepatitis G virus was recently identified, and its ability to cause clinically significant acute or chronic hepatitis is unknown.

CONCLUSIONS

Dental health care workers, or DHCWs, should be concerned primarily with HBV, HCV and HDV, as occupational exposure to these pathogens places them at risk of developing acute or chronic infections. Vaccines and immune globulins are available and effective in protecting against infections with HAV, HBV and HDV, but not HCV.

CLINICAL IMPLICATIONS

DHCWs should become knowledgeable about viral hepatitis. They should be vaccinated against hepatitis B. Adherence to infection control measures will help prevent occupational transmission of all bloodborne pathogens, including hepatitis viruses.

Characterization of a strain of infectious hepatitis E virus isolated from sewage in an area where hepatitis E is not endemic

Raw sewage samples from an area where hepatitis E is not endemic (Barcelona, Spain) were analyzed by reverse transcriptase-PCR followed by nested PCR. One of the 37 tested samples showed a positive result for hepatitis E virus (HEV). The detected strain was amplified by inoculation into rhesus monkeys, and the course of the infection was studied by analyzing serological and biochemical parameters and by monitoring the presence of HEV in serum and feces. Fecal suspensions from the rhesus monkeys were used as the source of viral particles for sequence analysis. Eighty percent of the genome of the isolated strain, named BCN, was sequenced and found to be phylogenetically related to Asian (Indian) strains, with a 98% nucleotide identity with an isolate from Madras, India. Since this was a single isolation we cannot conclude that HEV is regularly present in the sewage. However, the finding of viable HEV in sewage has implications for contamination of the environment and shellfish by HEV and must be considered in the diagnosis of viral hepatitis in regions of nonendemic hepatitis.

The pregnant traveler

The care of the pregnant traveler is both challenging and rewarding. It requires clinical information and skills that are derived from many disciplines. This article reviews preparatory guidelines for safe travel by the pregnant mother and her most important travel companion, the developing fetus. Issues considered are pretravel risk assessment, immunizations, and prevention of travelers' diarrhea and hepatitis. The safety and efficacy of malaria chemoprophylaxis in the present context of widespread multidrug-resistant malaria is discussed, and guidelines are offered for both prevention and treatment. A safety profile of commonly used travel medications, antibiotics, and antiparasitic drugs is reviewed.

Hepatitis E virus in Nepal: similarities with the Burmese and Indian variants

Hepatitis E has been the predominant type of acute hepatitis in Nepal both in adults and children, in sporadic and epidemic forms. We examined six hepatitis E virus (HEV) isolates obtained during an 8-year period, from 1987 to 1995, in the Kathmandu valley of Nepal. Analysis of portions of the putative helicase, polymerase and capsid genes demonstrated close genetic relatedness among themselves (> 96.4% identity) and with the Burmese (> 95.5%) and Indian (> 95.3%) isolates, and less so with the African (> 94.4%) and the Chinese (> 91%) isolates within the Asian genotype. Phylogenetic analysis placed the Nepali isolates in the Burma-India evolutionary branch and showed that the oldest isolate, TK78/87 was more similar to the Burmese isolates whereas the most recent isolates were closer to the Indian ones. Assuming no frameshifts, the Nepali isolates showed high amino acid conservation, but also unique changes when compared to other HEV isolates. Amino acid residue 614 of the capsid protein was identified as a possible marker to distinguish the Burma-Nepal-India from the China-Central Asian Republics subgenotype, and the Mexico genotype.