Fulminant or subfulminant non-A, non-B viral hepatitis: the role of hepatitis C and E viruses

Challenges in Diagnosis and Therapeutic Approach of Acute on Chronic Liver Failure-A Review of Current Evidence

Acute-on-chronic liver failure (ACLF) is a syndrome characterized by acute and severe decompensation of chronic liver disease (CLD) correlated with multiple organ failure, poor prognosis, and increased mortality. In 40-50% of ACLF cases, the trigger is not recognized; for many of these patients, bacterial translocation associated with systemic inflammation is thought to be the determining factor; in the other 50% of patients, sepsis, alcohol consumption, and reactivation of chronic viral hepatitis are the most frequently described trigger factors. Other conditions considered precipitating factors are less common, including acute alcoholic hepatitis, major surgery, TIPS insertion, or inadequate paracentesis without albumin substitution. Host response is likely the primary factor predicting ACLF severity and prognosis, the host immune response having a particular significance in this syndrome, together with the inflammatory cascade. The management of ACLF includes both the prevention of the precipitating factors that lead to acute liver decompensation and the support of vital functions, the prevention and management of complications, the estimation of prognosis, and the opportunity for liver transplantation.

Susceptibilidad genética y aclaramiento viral de la infección por Virus de la Hepatitis C

El virus de la hepatitis C (VHC) sigue siendo una de las principales causas de hepatitis crónica en el mundo occidental. Del 15 % al 40 % de los individuos con infección aguda por VHC logran el aclaramiento viral espontáneo; sin embargo, los factores y variables asociadas a este fenómeno no están completamente descritas. El análisis de los mecanismos de patogénesis de la infección por VHC es indispensable para identificar los factores y variables implicadas en el aclaramiento espontáneo o en la persistencia de la infección. En algunos estudios se han documentado los factores del huésped asociados al aclaramiento viral espontáneo durante la infección aguda, entre ellos el polimorfismo del gen de la interleucina -28 (IL28B) que codifica para el interferón lambda 3 (IFNL3). El objetivo de este artículo es realizar una revisión de la literatura sobre la fisiopatología de la infección por el VHC y describir la evidencia acerca del papel de los polimorfismos en el gen IL28B y su impacto en el proceso de aclaramiento viral espontáneo, así como en otros aspectos de la historia natural y el tratamiento de la infección.

Chronic Hepatitis C: Acute Exacerbation and Alanine Aminotransferase Flare

The hepatitis C virus (HCV) causes acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma, as well as extrahepatic manifestations such as malignant lymphoma. Currently, direct-acting antiviral agents (DAAs) against HCV infection can lead to a sustained virological response (SVR) in almost all HCV-infected patients. In this review article, we discuss acute exacerbation and alanine aminotransferase (ALT) flare in patients with chronic HCV infection. Although acute liver failure caused by HCV infection is rare, careful attention should be paid to the cases with ALT elevation during the natural course of chronic HCV infection. HCV genotype 2 infection, the use of rituximab, and a higher dose of corticosteroid are factors associated with HCV acute exacerbation and ALT flare. Treatment regimens for cancer have been interrupted or changed due to ALT flare due to HCV infection in some patients undergoing chemotherapy for cancer. The pathogenesis of HCV acute exacerbation and ALT flare could involve cellular as well as humoral immune responses. In the DAA era, the earlier introduction of DAAs may prevent chronic HCV-infected patients with acute exacerbation and ALT flare from developing into a more severe form, although DAAs may not be effective for all of them.

Natural History of Hepatic and Extrahepatic Hepatitis C Virus Diseases and Impact of Interferon-Free HCV Therapy

The hepatitis C virus (HCV) infects 71.1 million persons and causes 400,000 deaths annually worldwide. HCV mostly infects the liver, causing acute and chronic necroinflammatory damage, which may progress toward cirrhosis and hepatocellular carcinoma. In addition, HCV has been associated with several extrahepatic manifestations. The advent of safe and effective direct-acting antivirals (DAAs) has made the dream of eliminating this public health scourge feasible in the medium term. Prospective studies using DAA-based regimens have shown the benefit of HCV clearance in terms of both liver- and non-liver-related mortality.

Clinical Outcome and Viral Genome Variability of Hepatitis B Virus-Induced Acute Liver Failure

Acute hepatitis B virus (HBV) infection remains a frequent cause of acute liver failure (ALF) worldwide. ALF occurs in 0.1%-0.5% of infected patients. The aim of this study was to scrutinize the outcome of patients with HBV-induced ALF and mutational patterns of HBV variants, which might contribute to ALF. From 2005 to 2016, 42 patients were treated for HBV-induced ALF in the University Hospital Essen, Germany. Clinical and virological data from these patients were collected. As a control, 38 patients with acute hepatitis B (AHB) without liver failure were included. The HBV genome was sequenced by next-generation sequencing (NGS). Mutations that were found by NGS were analyzed in vitro. Of 42 patients, 8 had ALF without spontaneous recovery (NSR): Seven patients underwent liver transplantation (LT) and one patient died before LT. Of 42 patients, 34 (81%) had spontaneous recovery (SR) and cleared the infection, achieving either anti-HBs seroconversion or hepatitis B surface antigen (HBsAg) loss. HBV genotype (GT)-D was the most frequent GT in patients with ALF. Mutations in HBV core, preS2, and small hepatitis B surface antigen (SHB) were more frequent in patients with ALF-NSR compared with those with ALF-SR or AHB. Amino acid deletions (del; 16-22 and 20-22) in preS2 and SHB mutation L49R were exclusively detected in patients with ALF-NSR. In vitro analyses reveal that these mutations did not influence HBsAg secretion or infectivity. Conclusion: HBV GT-D and increased variability in HBV core, preS2 region, and SHB are associated with a worse clinical outcome of acute HBV infection.

Role of N-acetylcysteine treatment in non-acetaminophen-induced acute liver failure: A prospective study

BACKGROUND/AIMS

Acute liver failure (ALF) is a rare but severe medical emergency. To date, there is no established treatment for non-acetaminophen-induced acute liver failure (NAI-ALF) other than liver transplantation, and little is known about the use of N-acetylcysteine (NAC) in NAI-ALF. A randomized case control study was conducted with the aim to determine the effect of NAC on the mortality of NAI-ALF patients, as well as to evaluate the safety and efficacy of NAC use.

PATIENTS AND METHODS

A total of 80 patients diagnosed with NAI-ALF were included in the study. Forty patients received NAC infusion for 72 h whereas the control group received placebo. The variables evaluated were demographic characteristics, signs and symptoms, biochemical parameters, and clinical course during hospitalization.

RESULTS

The two groups (NAC and control) were comparable for various baseline characteristics (such as etiology of ALF, INR, alanine aminotransferase, creatinine, albumin, and grade of encephalopathy), except for age. Although majority of patients had undetermined etiology (32.5% in NAC group and 42.5% in control group), the second main cause was acute hepatitis E and drug or toxin-induced ALF. The mortality decreased to 28% with the use of NAC versus 53% in the control group (P = 0.023). The use of NAC was associated with shorter length of hospital stay in survived patients (P = 0.002). Moreover, the survival of patients was improved by NAC (P = 0.025). Also, drug-induced ALF showed improved outcome compared to other etiologies.

CONCLUSION

The findings of the study recommend the use of NAC along with conventional treatments in patients with NAI-ALF in non-transplant centers while awaiting referrals and conclude the use of NAC as safe.

Hepatitis C virus JFH-1 strain infection in chimpanzees is associated with low pathogenicity and emergence of an adaptive mutation

The identification of the hepatitis C virus (HCV) strain JFH-1 enabled the successful development of infectious cell culture systems. Although this strain replicates efficiently and produces infectious virus in cell culture, the replication capacity and pathogenesis in vivo are still undefined. To assess the in vivo phenotype of the JFH-1 virus, cell culture-generated JFH-1 virus (JFH-1cc) and patient serum from which JFH-1 was isolated were inoculated into chimpanzees. Both animals became HCV RNA-positive 3 days after inoculation but showed low-level viremia and no evidence of hepatitis. HCV viremia persisted 8 and 34 weeks in JFH-1cc and patient serum-infected chimpanzees, respectively. Immunological analysis revealed that HCV-specific immune responses were similarly induced in both animals. Sequencing of HCV at various times of infection indicated more substitutions in the patient serum-inoculated chimpanzee, and the higher level of sequence variations seemed to be associated with a prolonged infection in this animal. A common mutation G838R in the NS2 region emerged early in both chimpanzees. This mutation enhances viral assembly, leading to an increase in viral production in transfected or infected cells.

CONCLUSION

Our study shows that the HCV JFH-1 strain causes attenuated infection and low pathogenicity in chimpanzees and is capable of adapting in vivo with a unique mutation conferring an enhanced replicative phenotype.

Acute and chronic liver insufficiency

The term “liver insufficiency” denotes a break down in the functions of the liver. The syndrome of functional liver failure covers a wide spectrum of clinical, biochemical and neurophysiological changes. In principle, liver insufficiency can occur without previous liver damage as well as with already existing liver disease. It is characterized by a deterioration in the synthesizing, regulatory and detoxifying function of the liver. This final stage of liver disease terminates in hepatic coma.

Hepatitis A as an etiologic agent of acute liver failure in Latin America

BACKGROUND

This prospective, multicenter study examined the importance of hepatitis viruses as etiological agents of acute liver failure (ALF) and the outcome of ALF cases in Latin American children and adolescents.

METHODS

The study was conducted for minimum 12 months in 9 centers in Argentina, Brazil, Chile, Colombia, Costa Rica, and Mexico during 2001-2002. Hospitalized patients aged 1-20 years with a suspected diagnosis of ALF were included in the study and tested for serologic markers for hepatitis A, B, and C viruses.

RESULTS

Of the 106 patients enrolled, 88 were included in the analysis. Median age was 5 years, and 55% with ALF were aged 1-5 years. A total of 37 individuals (43%) tested positive for anti-hepatitis A virus (HAV) immunoglobulin M (IgM) as marker of acute HAV infection; one was positive for anti-hepatitis B core antigen IgM and negative for hepatitis B surface antigen. None had markers of hepatitis C virus infection. Mortality rates in the overall study cohort (45%) and for those who tested anti-HAV IgM positive (41%) were similar. Forty-one percent of all patients and 46% of those positive for anti-HAV IgM underwent transplantation. The mortality rate in those with liver transplantation was half of that in patients who were not transplanted (28% versus 57%).

CONCLUSIONS

HAV was the main etiologic agent of ALF in the population studied.

A retrospective autopsy study of histopathologic spectrum and etiologic trend of fulminant hepatic failure from north India

Background

Fulminant hepatic failure (FHF) is rapidly fatal and liver transplant is the treatment of choice. The condition is known for its heterogeneity of defining criteria, clinical presentation, histologic spectrum and etiologic factors. The etiology of FHF varies widely, some of which includes viral hepatitis, drug overdose and idiosyncratic drug reactions. The identification of the etiology of FHF is critically important, because it influences the management. A histopathological classification of FHF has not been reported earlier in the literature.

Methods

The current study was conducted retrospectively on 224 autopsies at a tertiary care hospital in India. In all of these cases the liver was examined grossly and microscopically. Clinical findings, serological data and immunohistochemical findings were correlated with the morphological subtypes and a consensus morphological classification was formulated.

Results

Young females, especially those in the reproductive age group were most susceptible to the disease. Hepatotropic viruses and drugs were the likely causes in most of the patients. Clinical presentation is important, as delayed onset of encephalopathy or the subacute FHFs lead to maximum mortality. After careful gross and microscopic examination the morphological findings of FHF were divided into four distinct categories. Histologic typing can sometimes be misleading if solely made on H & E slides without application of special stains.

Conclusion

Fulminant hepatic failure is a medical emergency, proper histological categorization can help in deciding the treatment modalities.

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.

Acute liver failure: a review

Since publication of the first descriptions of acute liver failure (ALF) as a distinct clinical entity in the 1950's, the understanding of the pathophysiologic mechanisms involved and the management options have increased substantially. ALF still represents a major challenge for todays hepatologists, because it can rapidly lead to multiorgan failure and death that may be preventable with appropriate intervention. This article summarizes the basic patho-physiology underlying ALF, compares epidemiologic trends in the United States, the United Kingdom, and the Far East, and reviews prognostic markers and treatment options for ALF.

Fulminant hepatic failure

The rare but potentially devastating clinical syndrome of fulminant hepatic failure has as its components severe encephalopathy and finally cerebral edema, hemodynamic instability, renal failure, coagulopathy, profound metabolic disturbances and a particular susceptibility to bacterial and fungal infection. Despite advances in medical management, fulminant hepatic failure in its most severe form carries a high mortality rate unless urgent orthotopic liver transplantation is carried out. However, availability of cadaveric donor organs is limited and, due to the rapidly progressive clinical course in many cases, a substantial proportion of patients will die or develop contraindications to transplantation before the procedure can be performed. Consequently, recent interest has centred on living donor transplantation and the possibility of providing temporary liver support, either through auxiliary partial organ transplantation, extracorporeal perfusion or transplantation of hepatocytes, to allow time for either a liver graft to become available or native liver regeneration, on which spontaneous survival ultimately depends, to occur.

Case fatality rate of acute viral hepatitis in Italy: 1995-2000. An update

BACKGROUND

Fulminant hepatic failure is the most serious complication of viral hepatitis. Although this event occurs rarely, it may be fatal.

AIMS

To evaluate the case fatality rate (several deaths divided by number of cases x 100) for each viral hepatitis type in Italy from 1995 to 2000.

PATIENTS

Acute hepatitis cases identified by the surveillance system for acute viral hepatitis, which covers approximately 58% of the Italian population.

RESULTS

Twenty-five deaths (0.1%) occurred among the 18 460 acute viral hepatitis cases observed from 1995 to 2000, a rate threefold lower than the 0.3% reported during the period 1985-1994. The highest case fatality rate (0.4%) was seen for acute hepatitis B (18 deaths among 4257 cases). Only one death (0.01%) occurred among the 11 063 acute hepatitis A cases and two deaths (0.1%) among the 1536 acute hepatitis C cases. No deaths were observed among the 309 acute hepatitis A cases superimposed on chronic HBsAg carriers and the 166 superimposed on chronic HCV carriers. Intravenous drug use (22.2% of cases) and other parenteral exposures (22.2% of cases) were the most frequent non-mutually exclusive sources of infection reported by subjects who died of acute hepatitis B.

CONCLUSIONS

Analysis of surveillance system data from 1995 to 2000 indicates that, in Italy, deaths due to acute viral hepatitis are rare, but most commonly observed with acute hepatitis B. There is no evidence that acute hepatitis A may be fatal in chronic HBsAg or HCV carriers. The overall better survival rate may probably reflect improvements in the treatment of fulminant hepatitis in the last few years in Italy.

Aetiology and prognostic factors in acute liver failure in India

The early prognostic indicators for acute liver failure in endemic zones for hepatitis E virus have not been determined. All consecutive patients with acute liver failure from a geographically defined region endemic for hepatitis E virus were studied over the period April 1989-April 1996. Demographic, clinical and biochemical parameters were recorded at presentation and serum samples were analysed for known viral hepatitis (A-E) markers. Multiple parameters were compared in survivors and non-survivors in a univariate analysis. All significant factors on univariate analysis were entered into a stepwise logistic regression analysis to identify independent variables of prognosis. The sensitivity and specificity of significant prognostic factors was then assessed. A total of 180 [69 males and 111 females: age (mean +/- SD) 31.1 +/- 14.7 years] with acute liver failure were studied. Of these, 131 (72.8%) patients died. Hepatitis E virus was the aetiological cause in 79 (43.9%) patients, while hepatitis A virus, hepatitis B virus, hepatitis C virus and non-A, non-E agent/'s could be incriminated in four (2.1%), 25 (13.9%), 13 (7.2%) and 56 (31.1%) patients respectively. Of 83 women in childbearing age, 49 (59.0%) were pregnant, 33 (67.3%) of these were in the third trimester. Forty-seven (95.8%) pregnant women had HEV infection. Nine variables differed significantly between survivors and non-survivors on univariate analysis. Of these, four variables which predicted the adverse outcome on multivariate analysis were non-hepatitis-E aetiology, prothrombin time >30 s, grade of coma >2 and age >40 years in that order of significance. Pregnancy per se or duration of gestation did not adversely affect the prognosis. In endemic areas, hepatitis E virus is the commonest cause of acute liver failure. Acute liver failure occurs in a high proportion of pregnant women, mostly in third trimester. Early predictors of a poor outcome are non-E aetiology, prothrombin time >30 s, grade of coma >2 and age >40 years.

Spontaneous viral clearance in patients with acute hepatitis C can be predicted by repeated measurements of serum viral load

Early interferon (IFN) therapy prevents viral persistence in acute hepatitis C, but in view of the resulting costs and morbidity patients who really need therapy have to be identified. Twelve consecutive patients with acute hepatitis C (9 women, 3 men, mean age: 39.5 +/- 18.8 y, genotype 1: 7, genotype 3a: 3, 2 could not be genotyped) were studied. The sources of infection were medical procedures in 6, sexual transmission in 3, and intravenous drug abuse in 3 patients. Viral load was measured by Cobas Amplicor HCV Monitor v2.0 (Roche Diagnostic Systems, Branchburg, NY). The time from infection to clinical symptoms was 43.3 +/- 8.6 (mean +/- SD) days. Eight patients cleared hepatitis C virus (HCV) spontaneously and remained HCV-RNA negative with a follow-up of 9.0 +/- 3.9 months. In these patients viral load declined fast and continuously. The time from exposure to HCV-RNA negativity was 77.4 +/- 25.3 and from the first symptoms was 34.7 +/- 22.1 days. In 4 patients HCV-RNA levels remained high or even increased. Two of them became sustained responders to treatment initiated after a 6-week observation period. The 2 remaining patients were not treated (one because of contraindications for IFN, the other declined therapy) and are still HCV-RNA positive. In conclusion, patients with acute icteric hepatitis C have a high rate of spontaneous viral clearance within the first month after the onset of symptoms. IFN therapy appears only needed in patients who fail to clear the virus within 35 days after onset of symptoms. By this approach, IFN therapy was not necessary in two thirds of patients with acute hepatitis C.

Epidemiological characteristics, risk factors, and clinical manifestations of acute non-A-E hepatitis

A substantial proportion of acute non-A, non-B hepatitis was of unknown etiology and was termed non-A-E hepatitis. Analysis of the clinical features is needed while attempting to identify the causative agent(s). In this study, the clinical and biochemical features of 53 patients who were admitted to hospital with acute non-A-E hepatitis were compared with a cohort of patients with acute hepatitis C (n = 70) and E (n = 5). In acute non-A-E hepatitis, the sex ratio was 34:19, and ages ranged from 21 to 76 years (median 49). Biochemical tests [median (range)] revealed albumin 3.6 (2.2-4.4) g/dl, AST 714 (193-2311) U/l, ALT 896 (310-3,000) U/l, bilirubin 11.2 (0.9-36.3) mg/dl, and prothrombin time > 1.1 (0-11.5) seconds. No patients reported parenteral exposures or household contact. Forty-five percent had severe hepatitis (i.e., albumin < 3 g/dl, bilirubin > 15 mg/dl or prothrombin time > 3 sec), including 3% with fulminant hepatitis. Chronic evolution was noted in 7%. These features were similar to those of hepatitis C or E, except for a significantly high frequency of parenteral exposures (20%), household contact (16%), and chronicity (70%) in hepatitis C. In conclusion, there is no obvious parenteral risk factor identified in acute non-A-E hepatitis. Clinical severity is similar to that of hepatitis C at least in hospitalized patients, but the rate of chronic evolution is much lower.

Sequence analysis of hepatitis C virus isolated from a fulminant hepatitis patient

Although hepatitis C virus (HCV) is a major cause of non-A non-B hepatitis, its pathogenic role in fulminant hepatitis remains controversial. A 32-year-old man contracted hepatitis. Serum ALT concentration was reached to 6,970 IU/L, the lowest prothrombin time value was 16% and jaundice and stage II encephalopathy were developed. HCV RNA was detected in this patient by reverse transcription polymerase chain reaction in sera at the acute phase, and it was undetectable during the remission phase when anti-HCV was found. The entire genome of infected HCV was recovered, cloned, and sequenced from this patient, and compared with the clones of six other chronic hepatitis patients. Phylogenetic analysis revealed a clustering around genotype 2a and a deviation from the other 2a chronic hepatitis strains. Calculating the genetic distance in each subgenomic region revealed that the 5'untranslated region (5'UTR), core, nonstructural (NS) 3, and NS5A were severely deviated. Of 20 clones of the hypervariable region (HVR), 17 showed an identical sequence with the others showing a difference of only one amino acid. HCV was isolated from a fulminant hepatitis patient and its entire genome was recovered; a clustering around genotype 2a was observed, but the sequence deviated especially in 5'UTR, core, NS3, and NS5A; and monoclonality of the HVR sequence was found not only in the fulminant hepatitis patient but in a certain percentage of chronic hepatitis patients.

Lack of known hepatitis virus in hepatitis-associated aplastic anemia and outcome after bone marrow transplantation

Viral infection has been shown to induce aplastic anemia, unidentified types of hepatitis being the most common cause for aplastic anemia-associated viral hepatitis. The survival rate for this group of patients after bone marrow transplantation with stem cells from an HLA-matched sibling is not well known. The aim of this study was to determine the prevalence of hepatitis G virus (HGV) and transfusion transmitted virus (TTV) infection in non-A, non-B, non-C hepatitis associated-aplastic anemia (HAAA) patients, and to define the role of bone marrow transplantation (BMT) as a therapeutic modality for this disease. Sixty-eight patients (43 males and 25 females) with aplastic anemia, underwent allogeneic BMT at the Hadassah University Hospital between 1981 and 1997. Onset of hepatitis was defined as jaundice and elevated alanine aminotransaminase (ALT) levels. Onset of aplastic anemia was defined as the first date on which varying degrees of pancytopenia occurred: hemoglobin level below 10 g/dl, WBC below 2 x 10(9)/l and low platelet count 10 x 10(10)/l. Serial serum samples from HAAA patients were assayed for virological and/or serological markers of hepatitis A, B, C, D, E, G viruses, TTV and parvovirus B19. Seventeen of the 68 patients with aplastic anemia (25%) suffered from hepatitis, 12 males and five females, ages 5 to 36 years. The mean interval between onset of hepatitis and first indication of aplastic anemia was 62 days (range 14-225 days). The development of aplastic anemia was unrelated to age, sex or severity of hepatitis. Ten of the 17 patients (59%) achieved complete ALT recovery prior to the diagnosis of aplastic anemia. Serum samples were available for 15 patients; none had evidence of acute or active hepatitis A, B, C, D, E, G and TTV virus infection at the time of diagnosis. Parvovirus B19 DNA sequences were not detectable in 10 of 12 tested cases; two positive results were detected in serum samples obtained after blood transfusion, making the analysis of these positive results difficult. All 17 patients underwent BMT. The mean post-BMT follow-up period was 38 months (range 1 day-123 months), five patients (30%) died 1 to 160 days post BMT, and 12 (70%) are alive 31 to 123 months after BMT. Relapsing hepatitis was not observed in any of the patients. In conclusion, HAAA is a disease of the young and the etiologic agent associated with HAAA remains unknown. HGV, TTV and parvovirus B19 sequences were not detected in any of the HAAA cases. The survival rate after BMT with stem cells from an HLA-matched sibling is similar to that for patients with non-hepatitis-associated aplastic anemia.

Acute liver failure: established and putative hepatitis viruses and therapeutic implications

Any virus that can cause an acute hepatitis will, on occasion, give rise to acute liver failure. Such infections can be separated into those due to the primary hepatitis viral infections A to E and those where hepatitis occurs as part of a systemic viral infection, as with infection with, for instance, Epstein-Barr virus, cytomegalovirus, Varicella zoster virus, adenovirus and Herpes simplex virus. In general, the frequency with which the different hepatitis viruses are responsible for acute liver failure is related to their underlying prevalence in particular countries. An apparent exception is the striking geographical variation in the reported prevalence of acute liver failure due to hepatitis C virus infection, with a much higher proportion of cases generally attributed to this agent in Japan and Taiwan than in Western countries. Recent work has focused on the possible importance of mutant hepatitis B viral strains, co- and super-infection with known hepatitis viruses and certain newly described agents that may account for otherwise unexplained cases of acute liver failure. Despite an improved understanding of the pathogenesis of complicating cerebral oedema and advances in general supportive care, it is likely that the most severely affected patients with acute liver failure due to viral causes will survive only with liver transplantation, at least until approaches for promoting adequate liver regeneration are successfully developed and implemented.

Acute hepatic failure: a Western perspective

Acute hepatic failure (AHF) is an uncommon, devastating syndrome, which results in death or the need for liver transplantation in more than 50% of cases. While AHF has numerous causes, most cases are due to viral hepatitis and drug toxicity or idiosyncratic reactions. A significant group with indeterminate causation remains, despite careful investigation. In many of these cases a viral aetiology is suspected, although yet not proven. Major differences exist in the aetiology of AHF between the West and Eastern countries. A wider range of aetiologies exists in the West. Common causes include acetaminophen toxicity and idiosyncratic drug reactions, while viral hepatitis is less frequent. Hepatitis E infection is rarely seen in Western countries in contrast to its high prevalence in the East. The mainstay of AHF management is supportive care in an intensive care unit. Liver transplantation is now the standard of care in many Western liver units for individuals who have a less than 20% probability of survival. Lack of availability of donor livers at short notice remains a significant problem. Methods of liver support used while waiting for a donor liver or for the native liver to regenerate include bioartificial livers, extracorporeal liver-assist devices, extracorporeal whole organ perfusion (human and transgenic pig) and hepatocyte transplantation. The effectiveness of these methods remains unproven and awaits controlled clinical trials. Both transplantation and liver-support methods require specialized units and expensive and complicated equipment. Further research is necessary to identify modalities of therapy that would be effective as well as widely accessible.

Natural history of acute hepatitis C

To study the short- and long-term outcomes of acute hepatitis C, three groups of patients were enrolled. Of 26 patients with acute hepatitis C, 18 (69%) maintained HCV viraemia and 8 had cleared virus naturally at 12 months after the onset. Normalization of ALT was seen in all 8 patients with acute resolving hepatitis, but in only 1 (5%) of the 18 patients with chronic HCV infection (P< 0.001). Changes in liver histology were analysed in 43 patients with acute hepatitis C who underwent repeated liver biopsy. The mean score of the fibrotic stage was 0.9 within 1 year of the onset, and it increased gradually up to 3.5 at 30 years from the onset (0.1 grade/year). The fibrotic stage increased more rapidly in patients aged more than 50 years. In 115 patients, the mean duration between blood transfusion and the diagnosis of HCC increased significantly (P< 0.001) in accordance with increasing age at blood transfusion; 35 +/- 5.3 years in patients aged less than 30 years, 30 +/- 4.9 years in those aged between 30 and 40 years, and 25 +/- 6.8 years in those aged more than 40 years. In conclusion, approximately 70% of patients with acute hepatitis C develop chronic hepatitis. Once patients develop chronic hepatitic fibrosis of the liver, it progresses over several decades, faster in older patients.

Fulminant hepatic failure in acute hepatitis C: increased risk in chronic carriers of hepatitis B virus

BACKGROUND/AIMS

The role of hepatitis C virus (HCV) in fulminant hepatitis remains controversial. This study was conducted to investigate the risk of fulminant hepatitis C in relation to HCV genotypes and concurrent infection of other viruses.

PATIENTS

109 HCV RNA positive patients from 334 consecutive cases hospitalised to a medical centre in northern Taiwan for overt acute viral hepatitis were prospectively evaluated.

METHODS

HCV RNA was detected by a combined reverse transcription-polymerase chain reaction assay. HCV genotypes were analysed using a genotype specific probe based assay in the 5' untranslated region.

RESULTS

39 patients tested positive for hepatitis B surface antigen but negative for IgM antibody to hepatitis B core antigen, indicating concurrent chronic hepatitis B virus (HBV) infection. Twelve patients were hepatitis G virus (HGV) RNA positive. Genotyping of HCV disclosed 1b in 93, 1b mixed with 2a/2c or 1b mixed with 2b in 11, and not classified in five. Serum titres of HCV RNA were <10(5) copies/ml in 77, 10(5)-10(7) copies/ml in 25, and >10(7) copies/ml in seven. Eleven patients (10.1%) had fulminant hepatitis as a complication. Development of fulminant hepatitis did not correlate with age and gender of the patients, concurrent HGV infection, HCV genotypes, or serum titre of HCV RNA. However, the incidence (95% confidence interval) of fulminant hepatitis in patients with underlying chronic HBV infection was 23. 1% (9.9 to 36.3%), which is significantly higher than in those without (2.9% (-1.0 to 6.8%)). In 39 patients with concurrent chronic HBV infection, the clinical and virological characteristics showed no significant difference between those with fulminant hepatitis and those without.

CONCLUSIONS

Acute hepatitis C in patients with concurrent chronic HBV infection is associated with a substantial risk of fulminant hepatitis.

The Significance of Hepatitis G Virus in Serum of Patients With Sporadic Fulminant and Subfulminant Hepatitis of Unknown Etiology

Excluding acute hepatic failure caused by drugs, the etiology of fulminant hepatitis (FH) remains unknown in many patients. There are conflicting data about a possible pathogenic role for the hepatitis G virus (HGV) in patients with cryptogenic fulminant hepatitis (non–A-E FH). We investigated the presence of circulating HGV in 36 patients with well-documented non–A-E fulminant and 5 patients with subfulminant hepatitis from 3 geographic locations in the United States. Serum HGV RNA was determined by reverse transcriptase-polymerase chain reaction using primers from the NS5 region of the HGV genome. HGV RNA was also measured before and after liver transplantation in 5 patients and at different time points in 7 patients. Serum samples were recoded and reanalyzed for HGV RNA using different primer sets to assess the validity of the HGV RNA assay. HGV was present in serum of 14 of the 36 patients (38.8%) with non–A-E fulminant hepatitis. Twenty percent of patients from the Northeast, 11% of the patients from the Southeast, and 50% from the Mid-Atlantic regions of the United States had circulating HGV RNA. The use of therapeutic blood products was significantly associated with the presence of serum HGV RNA (P < .02). Retesting for HGV RNA with different primers was positive in all but 1 case. HGV RNA is not causally related to non–A-E fulminant hepatitis. The finding of HGV RNA in serum from these patients is likely related to the administration of blood product transfusion after the onset of fulminant hepatitis.

The Significance of Hepatitis G Virus in Serum of Patients With Sporadic Fulminant and Subfulminant Hepatitis of Unknown Etiology

Excluding acute hepatic failure caused by drugs, the etiology of fulminant hepatitis (FH) remains unknown in many patients. There are conflicting data about a possible pathogenic role for the hepatitis G virus (HGV) in patients with cryptogenic fulminant hepatitis (non–A-E FH). We investigated the presence of circulating HGV in 36 patients with well-documented non–A-E fulminant and 5 patients with subfulminant hepatitis from 3 geographic locations in the United States. Serum HGV RNA was determined by reverse transcriptase-polymerase chain reaction using primers from the NS5 region of the HGV genome. HGV RNA was also measured before and after liver transplantation in 5 patients and at different time points in 7 patients. Serum samples were recoded and reanalyzed for HGV RNA using different primer sets to assess the validity of the HGV RNA assay. HGV was present in serum of 14 of the 36 patients (38.8%) with non–A-E fulminant hepatitis. Twenty percent of patients from the Northeast, 11% of the patients from the Southeast, and 50% from the Mid-Atlantic regions of the United States had circulating HGV RNA. The use of therapeutic blood products was significantly associated with the presence of serum HGV RNA (P &lt; .02). Retesting for HGV RNA with different primers was positive in all but 1 case. HGV RNA is not causally related to non–A-E fulminant hepatitis. The finding of HGV RNA in serum from these patients is likely related to the administration of blood product transfusion after the onset of fulminant hepatitis.

Minimal role of GB virus-C/hepatitis G virus in fulminant and subfulminant hepatitis in Taiwan

BACKGROUND

The role of GB virus-C/hepatitis G virus (GBV-C/HGV) in fulminant hepatitis (FH) and subfulminant hepatitis (SFH) remains unclear.

METHODS

Thirty-two FH or SFH patients, with adequate clinical information and serum specimens, were studied. Serum samples were tested for hepatitis markers and genomes of hepatitis A-E viruses, as well as GBV-C/HGV.

RESULTS

Of the cases of FH/SFH studied, one (3%) was caused by anti-tuberculosis agents, 26 (81%) had hepatotropic virus infection, and five (16%) had no identifiable cause. Of the 26 patients with hepatotropic virus infection, five had acute hepatitis B infection (one with acute hepatitis D virus (HDV) co-infection), one had acute hepatitis C infection, 16 were hepatitis B surface antigen carriers with reactivation or superimposed by unidentified agent(s) (two had triple virus infections), three were hepatitis B carriers with HDV superinfection, and one had GBV-C/HGV infection in addition to exposure to halothane. GBV-C/HGV-RNA was detected in only three of 32 patients (9%) and all had a history of blood transfusion or co-existing causative factors. Of the 26 patients with hepatotropic virus infection, 18 were tested for antibodies against GBV-C/HGV envelope protein and seven were reactive, suggesting past infection.

CONCLUSIONS

The role of GBV-C/HGV in causing FH and SFH is minimal in Taiwan and HBV infection remains the major aetiology. These findings also suggest the existence of as yet unrecognized agents, responsible for such catastrophic illnesses.

Fulminant hepatic failure

Fulminant hepatic failure is a disease of varied causes and a high mortality rate. A sudden onset, jaundice, hepatic encephalopathy, and multiorgan failure are the hallmarks of this syndrome. The management of patients with FHF requires a multidisciplinary approach and intense monitoring. The availability of liver transplantation has provided the means to rescue such patients from near-certain death. Early prognostication and timely availability of donor livers are requirements for a successful outcome. The development of effective artificial liver support devices may greatly prolong the window of opportunity to provide a donor liver, or alternatively, to allow the native liver to regenerate.

The distribution of HBV, HCV and HGV among livers with fulminant hepatic failure of different aetiology

BACKGROUND/AIMS

The aim of the study was to assess the impact factor of HCV and HGV in fulminant hepatic failure.

METHODS

The 5'-untranslated regions of HCV RNA and HGV RNA and a segment of the core antigen sequence of HBV were amplified after extracting the nucleic acids from snap-frozen tissue aliquots from explanted livers of 26 consecutive patients undergoing orthotopic liver transplantation for fulminant hepatic failure preoperatively diagnosed as either autoimmune (n=2), HAV/HBV (n=8), toxic (n=4) or aetiologically unknown (n=12).

RESULTS

HCV RNA was detected in five of 26 (19.2%) livers with fulminant hepatic failure. All five HCV RNA-positive livers belonged to the group of non-toxic, non-autoimmune liver failure (n=20), three of them were found in the group of liver failure with unknown aetiology (n=12) and two in the group of HBV-associated liver failure (n=7), making an HCV incidence of 25%, 25% and 28.6%, in the different groups, respectively. HGV RNA was detected in 10 of 17 (58.8%) explants and in all four groups of fulminant hepatic failure as defined preoperatively. HBV DNA was identified in six livers of 26 patients (23.1%) with fulminant hepatic failure. Neither HCV RNA nor HBV DNA was detected in the livers of patients with toxic or autoimmune fulminant hepatic failure.

CONCLUSIONS

These results indicate that HBV and HCV, but not HGV, play an aetiologic role in fulminant hepatic failure. HCV-positive cases were concentrated either in the group of otherwise unexplained fulminant hepatic failure or in the group of HBV fulminant hepatic failure. HGV-positive cases, on the other hand, were found within all four preoperatively defined groups, indicating a role as cofactor rather than as single aetiologic agent.

Idiopathic dilated cardiomyopathy: lack of association with hepatitis C virus infection

OBJECTIVE

To determine whether there is an association between hepatitis C virus (HCV) infection and dilated cardiomyopathy in a well defined area of north western Greece; such an association has been reported elsewhere.

DESIGN

Evaluation of consecutive patients with chronic HCV infection for the presence of clinical or subclinical manifestations of dilated cardiomyopathy by history, physical examination, and non-invasive laboratory procedures (ECG, chest x ray, and echocardiography) before the initiation of interferon alpha treatment; investigation for HCV infection markers in patients with dilated cardiomyopathy by enzyme and immunoblot assays (antibodies to HCV) and the reverse transcriptase polymerase chain reaction (HCV RNA).

SETTING

A tertiary referral centre for patients with chronic hepatitis and dilated cardiomyopathy.

PATIENTS

102 patients with well defined chronic HCV infection and 55 patients with well established dilated cardiomyopathy were evaluated.

MAIN OUTCOME MEASURES

The need for HCV testing in patients with dilated cardiomyopathy, or follow up for heart disease in patients with chronic HCV infection.

RESULTS

None of the patients with chronic HCV infection had clinical or subclinical evidence of dilated cardiomyopathy from history and laboratory findings. None of the patients with dilated cardiomyopathy was positive for antibodies to HCV or viraemic on HCV RNA testing.

CONCLUSIONS

The study neither confirms the findings of other investigators, nor indicates a pathogenic link between HCV and dilated cardiomyopathy. For this reason, at least in Greece, testing for HCV in patients with dilated cardiomyopathy or follow up for heart disease in HCV patients appears unnecessary. Genetic or other factors could be the reason for this discrepancy if previously reported associations between HCV and dilated cardiomyopathy or hypertrophic cardiomyopathy were not coincidental.

Hepatitis C virus infection: Review and implications for the dentist

OBJECTIVE

The purpose of this report was to review the current literature on hepatitis C virus infection, with particular attention to the aspects of interest for dental health care staff.

MATERIAL AND METHODS

The authors searched original research and review articles on specific aspects of hepatitis C virus infection, including articles on virology, epidemiology, transmission, diagnosis, natural history, extrahepatic manifestations, therapy and oral aspects of hepatitis C virus infection. The relevant material was evaluated and reviewed.

RESULTS

Hepatitis C virus is an RNA virus that is present throughout the world and has major geographic variations. The virus, transmitted mainly by means of blood contact, causes chronic hepatitis in up to 80% of cases and may give rise to hepatic cirrhosis and hepatocellular carcinoma in a significant proportion of patients. Although it is of limited efficacy, interferon alpha is currently the drug of choice in the treatment of the infection. Hepatitis C virus infection is associated with a number of extrahepatic manifestations that may include oral diseases such as lichen planus or sialadenitis. Although there are documented cases of nosocomial transmission to health care workers after percutaneous exposure, the prevalence of hepatitis C virus among dental staff members is probably similar to that in the general population.

CONCLUSION

Hepatitis C virus infection is a relatively common infection worldwide (1.4% in the US general population) that causes significant chronic hepatic disease. The dentist is thus likely to face a growing number of patients with a diagnosis of hepatitis C virus infection. For this reason it is essential for dental health care workers to be aware of the principal features of the disease and of its oral and dental implications.

Detection of hepatitis C and E virus genomes in sera of patients with acute viral hepatitis and fulminant hepatitis by their simultaneous amplification in PCR

A study was undertaken to investigate the role of hepatitis C virus (HCV) and hepatitis E virus (HEV), either alone or together, in the causation of sporadic acute viral hepatitis (AVH) and fulminant hepatitis (FH) by simultaneous detection of their genomes in serum samples using the reverse transcription and nested polymerase chain reaction (RT-PCR). A total of 50 patients were enrolled in the study of which 34 had AVH and 16 had sporadic FH. The serum samples were first tested for hepatitis B surface antigen (HBsAg) and immunoglobulin (Ig)M antibodies against hepatitis A virus (HAV), hepatitis B core antigen (HBcAg) and HEV and also antibodies against HCV using commercially available enzyme-linked immunosorbent assay (ELISA) kits. All samples were then subjected to RT-PCR using primers for both HCV and HEV simultaneously in the same reaction mixture. Hepatitis C or hepatitis E was diagnosed when either the antibodies or PCR or both were positive for the respective viruses. Evidence of hepatitis C was present in six of the 34 (17.6%) cases of AVH and two out of 16 (12.5%) cases of FH. Four patients in the AVH group and one of the fulminant hepatic failure (FHF) group were found to be positive by PCR and the rest by serology. But as a sole aetiological agent, HCV infection was found in only one (2.9%) case of AVH and in none of the FHF cases. Evidence of HEV infection was found in 22/34 (64.7%) and 8/16 (50%) cases of AVH and FHF, respectively. Excluding co-infection with other viruses, HEV was found to be the sole aetiological agent in 15/34 (44.1%) of AVH and 7/16 (43.7%) cases of FHF. In five (10%) (four AVH and one FHF) of the 50 cases, evidence of infection with both HCV and HEV was present. But only in two of these five cases, genomes of both HCV and HEV were co-amplified. In seven (four AVH and three FHF) out of 50 (14%) cases, no known viral agent could be detected. Our results suggest that HEV is the most common aetiological agent for both acute viral hepatitis and fulminant hepatic failure and that HCV is a rare cause of acute liver diseases although along with other viruses, evidence of either present or past HCV infection may be present in a substantial number of cases. Furthermore, advanced-stage pregnancy appears to be a potential risk factor for HEV infection and high rate of mortality in women. The study suggests that the method of simultaneous amplification of both HCV and HEV genomes could reduce the time, labour and cost involved in diagnostic work up of acute liver disease patients.

Prevalence of GBV-C and hepatitis G virus variants in patients with fulminant hepatic failure in Japan

BACKGROUND/AIMS

Whether GB virus C and hepatitis G virus participate in fulminant hepatic failure is controversial. We studied the prevalence of the viral RNA in 48 patients. There were possible routes of infection, including blood transfusion, in 22 patients (group 1), and no risk factors in the other 26 (group 2).

METHODS

We assayed serum viral RNA with reverse transcription and nested polymerase chain reactions. Serum was obtained at admission, and after transfusion in group 2.

RESULTS

Five (10%) serum samples from group 1 at admission had viral RNA of the 5'-untranslated region, and three of these samples had viral RNA of the NS3/helicase region. All five patients had transfusions before sampling. Two (4%) samples from group 2 were positive by both tests only after transfusion. Of two patients, one with non-A-E fulminant hepatic failure survived. Her serum alanine aminotransferase did not increase further after transfusion, but did stay above the reference range during follow-up. The other patient, with infection with hepatitis B virus detected at admission, died. After transfusion, his alanine aminotransferase did not increase further. Partial nucleotide sequences of GB virus C and hepatitis G virus from three fulminant hepatic failure patients and five control patients with chronic hepatitis C were compared with published sequences. A viral variant causing fulminant hepatitis, suggested elsewhere, was not found, nor was all of a characteristic pattern of six mutations found elsewhere.

CONCLUSIONS

GB virus C and hepatitis G virus may cause hepatitis, but probably not severe hepatitis such as fulminant hepatic failure.

Clinical manifestations of hepatitis C

Hepatitis C is a common cause of viral hepatitis that progresses to chronic infection in the majority of patients. Clinically, the infection is generally asymptomatic, but it may present with a wide variety of symptoms. Cirrhosis, hepatocellular carcinoma, cryoglobulinemia, auto-antibodies, and glomerulonephritis have been strongly associated with HCV. There is a probable association with autoimmune disease and NHL. More information is needed to determine whether lichen planus, PCT, and other disorders are part of the growing clinical spectrum or just coincidental associations with chronic liver disease.

Non-A, non-B, non-C hepatitis: its significance in pediatric patients and the role of GB virus-C

OBJECTIVES

To delineate the importance of non-A, non-B, non-C (non-ABC) hepatitis, and the role of GB virus C (GBV-C) in children.

METHODS

From 1980 to 1995, acute-onset viral hepatitis was diagnosed in 166 inpatients and categorized into type A, B, C, and non-ABC hepatitis according to the serologic markers or the results of polymerase chain reaction assay for HBV DNA or HCV ribonucleic acid (RNA) in the National Taiwan University Hospital. Non-ABC hepatitis was diagnosed in 57 patients (34%). GBV-C RNA was investigated by reverse transcription and nested polymerase chain reaction in 32 of the 57 patients with non-ABC hepatitis. The clinical and laboratory features of patients with acute non-ABC hepatitis were compared with the features of those with acute hepatitis A and B.

RESULTS

The degree of abnormality in aminotransferase activities was milder in patients with non-ABC hepatitis than in those with hepatitis B; chronicity was noted in 12%. Fulminant hepatitis occurred in 16%, and the mortality rate was 56%. Young age carried a significantly higher risk of having a fulminant course (1.9 +/- 0.2 years of age vs 6.4 +/- 5.1 years of age in acute course; p < 0.05). Compared with fulminant hepatitis B, fulminant non-ABC hepatitis had a trend of a longer interval from onset to death (119.2 +/- 144.8 vs 15.2 +/- 8.4 days; p = 0.079). GBV-C RNA was detected in only two of the patients tested, both of whom had received transfusions; one had persistent viremia and fluctuating aminotransferase values.

CONCLUSIONS

Non-ABC hepatitis plays an important role in the etiology of pediatric viral hepatitis; however, the role of GBV-C is minor. A search for other unknown viral agent(s) responsible for non-ABCG hepatitis is needed.

Selection of prognostic factors of acute hepatitis type non-A, non-B for patient listing for liver transplantation

The aim of this study was to select prognostic factors from information available on admission in order to list patients for liver transplantation before the onset of hepatic encephalopathy in patients with fatal hepatitis type non-A, non-B. Information regarding patient profile and biochemical data obtained on admission was analyzed by multiple stepwise logistic regression, and independent prognostic factors related to death were selected. Four parameters were selected as independent prognostic factors. Patient age (over 50 years), serum total bilirubin level (over 10 mg/dl), peripheral leukocyte count, and prothrombin time were independently related to death. Positive predictive value, negative predictive value, and predictive accuracy were 0.86, 0.79, and 0.84, respectively. Our model is able to predict a patient's fatal outcome much earlier than other currently used models. It will be helpful for early referral to a transplant center.

Case fatality rate of acute hepatitis in Italy: results from a 10 year surveillance

Using data from the surveillance system for acute viral hepatitis we have evaluated the case fatality rate of viral hepatitis in Italy. 71 deaths (0.3%) occurred among the 21,553 reported acute viral hepatitis cases from 1985-1994. None reported history of exposure to drugs or toxins. The highest case fatality rate was observed for B and NANB hepatitis (0.5%). One death occurred among the 6,353 (0.02%) hepatitis A cases and 1 among the 909 (0.1%) anti-HCV positive NANB hepatitis cases. The case fatality for Delta hepatitis was 0.2% (1/422). Case fatality rate was similar in both sexes; increasing with age; 0.03% were < 15 years of age, 0.1%, 15-24 year-old, and 0.5%, > or = 25 years. Subjects older than 24 years of age accounted for 81.4% of total deaths. Intravenous drug use, blood transfusion and other parenteral exposures were the three most frequent non-mutually exclusive sources of infection reported by subjects who died from B and NANB hepatitis. These findings indicate that the survival rate of acute B and NANB hepatitis is lower than that of acute hepatitis A; moreover in Italy, as in other Western countries, acute HCV seems to cause liver failure only rarely.

Hepatitis C virus: molecular biology and genetic variability

The pathogenetic mechanisms of hepatitis C virus (HCV) infection are poorly known. An understanding of HCV biology and the potential clinical impact of HCV genetic variability is essential to managing, treating, and preventing HCV infections. HCV is a member of the Flaviviridae viral family. Its genome is a positive, single-strand RNA molecule. The structure of the HCV particles is poorly known due to the lack of an efficient cell culture system as well as a striking heterogeneity in density. The core protein may have a regulatory role on both viral and cellular gene expression. The mechanisms of HCV-RNA replication may include synthesis of negative strand intermediates, which drive synthesis of new positive RNA genomes. New procedures have been developed to better identify and characterize the HCV-RNA genome. The mechanisms of HCV persistence are currently unknown, although it is known that HCV chronicity develops despite humoral and cellular responses to HCV proteins. HCV-RNA shows significant genetic variability with an estimated rate of nucleotide change of approximately 10(-3) substitutions/site/year. Currently, three major HCV genotypes and three to seven minor subtypes can be distinguished. The geographical distribution of these genotypes and subtypes varies significantly. It appears that poor clinical response to interferon (IFN) is more common with HCV genotype 1. In addition, some studies have shown an association between chronic infection, severe chronic hepatitis, and cirrhosis with subtype 1b. Further, there is evidence for a potential direct effect of HCV in liver carcinogenesis, with subtype 1b possibly being an independent risk factor for hepatic carcinoma development. HCV-RNA circulates as a population of RNA molecules, which creates a heterogeneity referred to as "quasispecies." It is possible that some HCV strains might have direct clinical implications. It may be that highly heterogeneous populations observed prior to treatment might correlate with a lower rate of response to IFN therapy.

The natural history of hepatitis C

The natural history of hepatitis C is complex and still poorly known. Hepatitis C virus (HCV) replication can be detected very soon after exposure and, at least in the transfusional setting, it persists indefinitely in up to 90% of the cases. While liver damage during the acute phase of hepatitis is almost invariably mild (fulminant cases are exceptions), chronic sequelae of HCV infection may be severe in the long run. Chronic hepatitis C, in fact, is a long-lasting indolent process which leads to cirrhosis in approximately 20% of all infected patients. Hepatocellular carcinoma is a well-recognized complication of old infections, as are a number of extrahepatic manifestations, including type II cryoglobulinaemia. The determinants of the severity of the liver disease are still unclear. However, the risk of cirrhosis seems to be greater for patients with old infections, those infected with the genotype 1b and those with associated conditions. The latter are a heterogeneous and increasing group of 'problem' patients, including patients who are co-infected with the human immunodeficiency virus (HIV1), or who are being treated with cytotoxic or immunomodulating drugs. Data suggest that the natural history of hepatitis C is altered in patients with associated conditions, and this might have an impact on strategies of patient management and treatment.