Familiar clustering and spreading of hepatitis delta virus infection

Hepatitis D virus infection in a large cohort of immigrants in southern Italy: a multicenter, prospective study

Background

Since few data are available in the literature on the prevalence of anti-Delta-positive subjects in immigrant populations, the aim of the present study was to evaluate the demographic and virological characteristics of HDV infection in a large cohort of immigrants living in southern Italy.

Methods

Between January 2012 and February 2020 all immigrants attending one of the 5 first- level centers were enrolled and screened for HBsAg, the HBsAg-positive for anti-Delta and if positive, for HDV-RNA and HDV genotype.

Results

Of the 3521 immigrants observed in the study period, 3417 (97.0%) agreed to be screened; they were mainly males (61%), with a median age of 27 years (IQR 8–74) and came prevalently (58%) from sub-Saharan Africa.

Of the 3417 patients enrolled, 319 (9%) subjects were HBsAg-positive, and of those, 8 (2.5%) were anti-Delta-positive. No difference in the demographic and epidemiological characteristics was observed between the anti-Delta-negative vs -positive. Of the 8 anti-Delta-positive subjects, only one was HDV-RNA-positive (viral load: 7050 IU/mL), genotype 1, with clinical signs of cirrhosis.

Conclusions

the present study showed a prevalence of HDV of 2.5% in a large cohort of asymptomatic immigrants, suggesting the need for screening campaigns for viral infections including delta hepatitis in this population.

Supplementary Information

The online version contains supplementary material available at 10.1007/s15010-022-01938-0.

Acute Delta Hepatitis in Italy spanning three decades (1991-2019): Evidence for the effectiveness of the hepatitis B vaccination campaign

Updated incidence data of acute Delta virus hepatitis (HDV) are lacking worldwide. Our aim was to evaluate incidence of and risk factors for acute HDV in Italy after the introduction of the compulsory vaccination against hepatitis B virus (HBV) in 1991. Data were obtained from the National Surveillance System of acute viral hepatitis (SEIEVA). Independent predictors of HDV were assessed by logistic-regression analysis. The incidence of acute HDV per 1-million population declined from 3.2 cases in 1987 to 0.04 in 2019, parallel to that of acute HBV per 100,000 from 10.0 to 0.39 cases during the same period. The median age of cases increased from 27 years in the decade 1991-1999 to 44 years in the decade 2010-2019 (p < .001). Over the same period, the male/female ratio decreased from 3.8 to 2.1, the proportion of coinfections increased from 55% to 75% (p = .003) and that of HBsAg positive acute hepatitis tested for by IgM anti-HDV linearly decreased from 50.1% to 34.1% (p < .001). People born abroad accounted for 24.6% of cases in 2004-2010 and 32.1% in 2011-2019. In the period 2010-2019, risky sexual behaviour (O.R. 4.2; 95%CI: 1.4-12.8) was the sole independent predictor of acute HDV; conversely intravenous drug use was no longer associated (O.R. 1.25; 95%CI: 0.15-10.22) with this. In conclusion, HBV vaccination was an effective measure to control acute HDV. Intravenous drug use is no longer an efficient mode of HDV spread. Testing for IgM-anti HDV is a grey area requiring alert. Acute HDV in foreigners should be monitored in the years to come.

The medical impact of hepatitis D virus infection in Uzbekistan

BACKGROUND & AIMS

The hepatitis B virus (HBV) is endemic in Uzbekistan but the medical impact of infection with the HBV-dependent hepatitis D virus (HDV) is unknown in the Country. An Hepatology Center was recently established at the Institute of Virology in Tashkent, which has set up a database enlisting patients with chronic viral liver disorders from all over Uzbekistan; it provides an observatory on the current scenario of viral hepatitis in the Country.

METHODS

The prevalence of HBV monoinfection, hepatitis C virus (HCV) infection and HDV superinfection on hepatitis B surface antigen (HBsAg)-positive cirrhosis was determined in 6589 patients with viral cirrhosis collected in the last 3 years.

RESULTS

Of 1089, 1150 and 1455 carriers of the HBsAg with cirrhosis recruited in 2016, 2017 and 2018, 834 (76.5%), 926 (80.5%) and 1224 (84%) respectively, had antibody to the HDV. In 2016, 2017 and 2018, the prevalence of HDV infection has been 41%, 45% and 49.1% respectively, largely exceeding the prevalence of HBV monoinfection (12.5%, 11% and 9.3% respectively) and surpassing the prevalence of HCV in 2017 and 2018 (44% and 41.5% respectively). The median age of the patients with HDV cirrhosis was 39 years, distinctly lower than that of HBV and HCV patients (46 and 55).

CONCLUSIONS

Superinfection with the HDV is present in over 80% of the HBsAg-positive cirrhosis in Uzbekistan. The HDV appears to be the major cause of advanced viral liver disease and of juvenile cirrhosis in the Country.

HDV infection in immigrant populations

AIMS

Little data have been published so far on the epidemiological aspects of hepatitis D virus (HDV) infection in immigrant populations and even poorer is the information on the virological, phylogenetic, and clinical aspects of this infection in these populations. This review article, aimed primarily at physicians caring for immigrants, summarizes the information available on HDV infection and analyzes data on this topic concerning the immigrant populations.

METHODS AND RESULTS

The prevalence of HDV infection in HBsAg-positive immigrants varies according to the country of origin. For example, in immigrants from sub-Saharan Africa, this prevalence is higher in those born in Equatorial Guinea (24.4%) than those from other African countries (10.3%). The epidemiological impact of HDV infection linked to migratory flows is a function of the different endemicity between countries of origin and countries in which a new existence has been established. This impact is high when immigrants from areas endemic to HDV infection (eg, Equatorial Guinea) settle in areas of low endemicity (eg, Germany or England, with a prevalence of around 4%), while the impact is lesser or nonexistent if the migratory flows are directed toward countries with intermediate endemicity (eg, Italy and Greece, with a prevalence of around 10%).

CONCLUSION

This impact of immigration on HDV epidemiology can be strong when HDV endemicity is high in the country of origin and low in the host country and slight when immigrants move to high or medium endemic countries.

Hepatitis delta infection in Italian patients: towards the end of the story?

BACKGROUND

The endemicity of hepatitis delta virus infection in Italy has decreased in the last decades.

AIM

To evaluate the current epidemiology of chronic delta infection in Italy and to compare the present findings with the corresponding figures from the previous studies.

METHODS

A cross-sectional study involving 16 referral centres scattered all over the country in 2014.

RESULTS

Out of the 513 hepatitis B surface antigen-positive subjects enrolled, 61 (11.9%) were anti-delta positive, with a sex ratio (M/F) of 2.05. The majority (80.3%) of them was 50 years or older, while the proportion of subjects younger than 30 years of age was as low as 3.3%. No difference was detected by geographical area of residence. The presence of liver cirrhosis was diagnosed in 52.4% of cases. In comparison to previous studies, a further shift towards the oldest age groups and an increasing proportion of subjects having liver cirrhosis among all anti-delta-positive subjects are observed.

CONCLUSIONS

Currently, hepatitis delta infection mostly affects old people who have an advanced but indolent liver disease, reflecting a survival effect. The defective hepatitis delta virus is near to disappear in the country, where it has been discovered in the second half of 70s.

Stochastic modelling of intra-household transmission of hepatitis C virus: evidence for substantial non-sexual infection

OBJECTIVE

To simulate the probability of HCV transmission from an HCV seropositive index patient to susceptible household contacts through non-sexual exposures.

METHODS

A modified Reed-Frost stochastic simulation model was used to assess the probability of HCV transmission from an HCV seropositive index patient to susceptible household contacts through non-sexual exposures. This mathematical model does not require the specification of infection onset times for individual, nor is it necessary to identify the chains of household infections. Therefore, this model can be used with serologic data on detected asymptomatic infections. The HCV serological data on 341 non-sexual household contacts of 86 HCV seropositive index patients were used in this simulation study. The frequency distribution of HCV infection of susceptibles for each household size of 4-8 initial susceptibles was calculated. A maximum likelihood procedure was used to estimate the non-sexual household transmission parameter for HCV infection for the range of household sizes studied and was used in 1000 stochastic iterations. The goodness-of-fit test was carried out to compare the observed proportions of households where HCV transmission occurred to one or more initial susceptible with mean expected simulated proportions of such households with varying sizes ranging from 4 to 8 initial susceptibles.

RESULTS

The maximum likelihood estimates (90% probability interval (PI)) of binomial probability of HCV transmission within households with varying number of initial susceptible non-sexual household contacts ranged from 0.248 (90%PI: 0.031, 0.560) to 0.164 (90%PI: 0.011, 0.440) for household size of 4 and 8 respectively. The χ(2) goodness-of-fit test of observed and mean expected simulated proportions of households wherein at least one of the susceptibles was infected revealed good fit for households of all sizes examined (P ≥ 0.96). In a household, the probability of HCV transmission from the index HCV seropositive patient to susceptible via non-sexual contacts tended to decrease linearly as the household size increased from four to seven.

CONCLUSION

Intra-household HCV transmission through non-sexual contacts may have substantial impact on HCV transmission and needs to be considered in an HCV control program.

Natural Course and Treatment of Hepatitis D Virus Infection

Hepatitis D virus (HDV) is a subviral satellite with hepatitis B virus (HBV) as its natural helper virus. After entry into hepatocytes, it utilizes host cellular enzymes to replicate by a double-rolling-circle mechanism. HDV is most often transmitted by contact with contaminated blood and body fluid, similar to HBV infection. Approximately 5% of the global HBV carriers are coinfected with HDV, leading to a total of 10-15 million HDV carriers worldwide. HDV infection can occur concurrently with HBV infection (coinfection) or in a patient with established HBV infection (superinfection). The pathogenesis of HDV remains controversial. A decline in the prevalence of both acute and chronic hepatitis D (CHD) has been observed worldwide. At present, therapy for chronic HDV infection is by the use of interferon-alpha. Compared to chronic hepatitis B or C, CHD treatment requires a higher dosage and a longer duration of treatment, and post-treatment relapses are common. In order to prevent the progression of CHD and its related morbidity and mortality, more effective treatments are needed.

Transition of care between paediatric and adult gastroenterology. Chronic viral hepatitis

Chronic viral hepatitis is a common disease. More than 500 million people have chronic viral hepatitis worldwide. These diseases are due to chronic infection with hepatitis B virus, hepatitis D virus or hepatitis C virus. Chronic viral hepatitis is responsible for severe complications: cirrhosis and hepatocellular carcinoma, which are responsible for major morbidity and mortality worldwide. The prognosis of chronic viral hepatitis depends on the rate of progression of fibrosis, which varies widely from one patient to another. Some factors, such as gender, age, alcohol consumption and immune status, influence the progression of fibrosis. In recent years, treatment of chronic viral hepatitis has markedly improved-especially in chronic hepatitis C, with more than 50% of patients having a sustained response with the combination of pegylated interferon and ribavirin. Also, in chronic hepatitis B, new drugs are available, or being evaluated, and combination therapy could dramatically change future therapeutic strategies.

Intrafamilial transmission of hepatitis delta virus: molecular evidence

BACKGROUND/AIMS

Epidemiologic studies have suggested that transmission of hepatitis delta virus (HDV) occurs by intrafamilial routes in some populations in southern Italy, where HDV infection is endemic. To further evaluate intrafamilial transmission of HDV, we obtained the partial sequence of the viral genome from HDV-RNA positive members of families in which two or more immediate family members were positive for HDV-RNA.

METHODS

The region analyzed was the semi-conserved region from nucleotides 908 to 1265. Sequences obtained from family members were compared with those obtained from a control group of 20 unrelated patients.

RESULTS

The mean genetic divergence among HDV isolates was 2.8 +/- 1.7% within the 9 families analyzed, and 7.6 +/- 2.2% among the control group of unrelated individuals (p < 0.0001). A Receiver Operating Characteristic curve and Youden Index were used to define a cut-off value of 3.5% to discriminate sequence variations calculated within families and in the control group.

CONCLUSIONS

The data indicate that in most family units, HDV-infected members harbored nearly identical strains of HDV, and provide molecular support that HDV infection can be transmitted within the family. Such spreading among family members highlights the role of inapparent transmission through personal contacts.

Spread of hepatitis C virus infection within families. Investigators of an Italian Multicenter Group

In 1995, the intrafamilial spread of hepatitis C virus (HCV) was evaluated among 1379 household contacts of 585 HCV antibody-positive HCV RNA-positive subjects (index cases) in Italy. All index cases were patients with histologically proven chronic liver disease. The presence of antibodies to HCV (anti-HCV) was assessed by third-generation enzyme-linked immunosorbent assay (ELISA); the polymerase chain reaction (PCR) was used to test for HCV RNA. The overall anti-HCV prevalence among household contacts of index cases was 7.3% (101/1379); it was 15.6% in spouses and 3.2% in other relatives (P < 0.05; odds ratio (OR), 6.5; 95% confidence interval (CI), 3.5-8.6). Spouses married to index cases for longer than 20 years had a significantly higher anti-HCV prevalence than those married 20 years or less (19.8% vs 8.0%; P< 0.05; OR, 2.8; 95% CI, 1.5-5.3). Parenteral risk factors were more likely to be reported in anti-HCV positive than in anti-HCV negative household contacts. After adjustment for confounders by multiple logistic regression analysis, age greater than 4 5 years (OR, 3.1; 95% CI, 1.6-5.3) and any parenteral exposure (OR, 3.7; 95% CI, 1.7-8.1), were the only independent predictors of the likelihood of anti-HCV positivity among household contacts. Spouses versus other relatives and length of marriage were both no longer associated. These findings suggest that sexual transmission does not seem to play a role in the intrafamilial spread of HCV infection.

Hepatitis D virus

The hepatitis D virus (HDV) relies on the helper hepatitis B virus (HBV) for the provision of its envelope, which consists of hepatitis B surface antigen (HBsAg). The RNA genome of HDV is a circular rod-like structure due to its extensive intramolecular base-pairing. HDV-RNA has ribozyme activity which includes autocatalytic cleavage and self-ligation properties, essential in virus replication via the rolling circle mechanism. Replication of the RNA is thought to be effected by cellular RNA polymerase II. Hepatitis D antigen (HDAg) is the only protein encoded by HDV-RNA and its long and short forms have a regulatory role in the replication and morphogenesis of the virus. Superinfected HBV carriers who become chronically infected with HDV are at increased risk of developing cirrhosis. Attempts to treat such carriers with interferon have not been particularly successful. In recent years the epidemiology of HDV has changed primarily due to the impact of HBV vaccination in preventing an increase in the pool of susceptible individuals. Copyright 1998 John Wiley & Sons, Ltd.

Long-term interferon-alpha treatment of children with chronic hepatitis delta: a multicentre study

We assessed the efficacy of prolonged interferon-alpha (IFN) therapy in children with chronic hepatitis caused by hepatitis delta virus (HDV) by treating 26 paediatric cases with IFN-alpha 2b (5 MU m-2, then 3 MU m-2 three times weekly for 12 (medium-term group MTG) or 24 months (long-term group, LTG). Compliance and tolerability were acceptable. At the end of therapy a complete biochemical response [normalization of alanine aminotransferase (ALT)] occurred in 12 children (5/13 in MTG and 7/13 in LTG). A relapse occurred after stopping IFN in 10 cases (five in MTG and five in LTG). Two patients from the LTG had normal liver function tests during 12 months of follow-up. Six of the eight hepatitis B e antigen (HBeAg) positive children lost HBeAg, while all six hepatitis B virus (HBV) DNA positive patients lost HBV DNA during treatment. HBeAg reappeared later in two children. HDV RNA, present in 10/10 cases of MTG before treatment, persisted after 12 months IFN therapy in 3/10. One year after stopping therapy, 8/10 patients were again HDV RNA positive. Two children cleared hepatitis delta antigen (HDVAg) from the liver. No significant improvements in liver histology were seen in both groups. Our experience suggests that IFN-alpha treatment in children with chronic type D hepatitis has a transient effect, and long-term treatment does not appear to induce a greater therapeutic benefit in terms of biochemical and virological response.

Incidence and risk factors of acute Delta hepatitis in Italy: results from a national surveillance system. SEIEVA Collaborating Group

The incidence of hepatitis Delta virus in the general Italian population was estimated by a specific surveillance system for acute viral hepatitis over the period 1987-1992. The hepatitis Delta virus incidence rate declined from 3.1/1,000,000 inhabitants in 1987 to 1.2/1,000,000 in 1992. Males predominated (83.8% of cases); the sex ratio was 5.2. Only 2.5% of cases occurred in subjects younger than 15 years. There were 119 (49.4%) coinfections of Delta and B hepatitis and 122 (50.6%) Delta superinfections in chronic HBsAg carriers. Jaundice was present in 83.6% of cases. The hospitalization rate was 97.5%; median stay in hospital was 25 days (range 1-98 days). The results of multivariate analysis showed that a history of intravenous drug abuse (odds ratio 34.9; confidence interval 95% = 16.8-72.5), household contact with an HBsAg+ carrier (odds ratio 10.7; confidence interval 95% = 4.36-23.30) and a history of two or more sexual partners within the previous 6 months (odds ratio 2.44; confidence interval 95% = 1.34-4.43) were independent risk factors associated with Delta hepatitis. No association was found with the other risk factors considered, such as blood transfusion, surgical intervention, hospitalization, other percutaneous exposures, dental therapy, contact with an icteric case, and household contact with an i.v. drug abuser. These findings indicate that, in Italy, Delta hepatitis currently has a minor impact. In addition to intravenous drug abuse and household contact with an HBsAg+ carrier, heterosexual activity appears to be an efficient route of HDV transmission.

Risk of liver cirrhosis and hepatocellular carcinoma in subjects with hepatitis B and delta virus infection: a study from Kure, Japan

To investigate the effect of hepatitis delta virus (HDV) superinfection on the long-term outcome of Japanese subjects with chronic hepatitis B virus (HBV) infection, we examined the presence of antibodies to hepatitis delta antigen (anti-HD) in serial serum samples collected from 1127 subjects with chronic HBV infection. The subjects were followed for at least 36 months (mean: 121.3 months) between 1973 and 1991. Among 69 cases where anti-HD was detected, eight (12%) developed liver cirrhosis (LC) and six (9%) developed hepatocellular carcinoma (HCC). However, among 1058 cases without anti-HD, there were 43 patients (4%) who developed LC and 29 (3%) who developed HCC. The prevalence of LC and HCC was significantly higher among the cases with anti-HD than those without anti-HD. The proportion of LC and HCC per 1000 person years was 10.46 and 7.84, respectively among cases with anti-HD, and 4.05 and 2.73 among those without anti-HD, respectively. The overall relative risk of LC and HCC was 2.58 and 2.87, respectively; 95% confidence interval (CI): LC, 1.14-5.13; HCC, 1.03-6.23. These results indicate that in the Kure district in Japan, where HDV infection of persons infected with HBV is about 6%, such superinfection increases the risk of LC and HCC.

Delta hepatitis: molecular biology and clinical and epidemiological features

Hepatitis delta virus, discovered in 1977, requires the help of hepatitis B virus to replicate in hepatocytes and is an important cause of acute, fulminant, and chronic liver disease in many regions of the world. Because of the helper function of hepatitis delta virus, infection with it occurs either as a coinfection with hepatitis B or as a superinfection of a carrier of hepatitis B surface antigen. Although the mechanisms of transmission are similar to those of hepatitis B virus, the patterns of transmission of delta virus vary widely around the world. In regions of the world in which hepatitis delta virus infection is not endemic, the disease is confined to groups at high risk of acquiring hepatitis B infection and high-risk hepatitis B carriers. Because of the propensity of this viral infection to cause fulminant as well as chronic liver disease, continued incursion of hepatitis delta virus into areas of the world where persistent hepatitis B infection is endemic will have serious implications. Prevention depends on the widespread use of hepatitis B vaccine. This review focuses on the molecular biology and the clinical and epidemiologic features of this important viral infection.

The epidemiology of hepatitis delta infection in Italy. Promoting Group

The epidemiology of HDV infection in Italy was assessed in a retrospective study involving 1556 HBsAg chronic carriers on their first presentation at one of the 35 Liver Units in 1987. Total anti-HD was detected in 23.4% of HBsAg carriers and was significantly more frequent in southern than in northern Italy (26.6% vs. 19.1%, p less than 0.01). Age distribution showed that 73% of the anti-HD-positive subjects, but only 56% of the anti-HD-negative subjects, were under 40 years of age (p less than 0.01). Anti-HD prevalence increased with the severity of the liver disease from 3.8% in healthy carriers to 42.5% in cirrhosis. No geographical statistical difference was found among HBsAg healthy carriers or subjects with chronic persistent hepatitis (CPH), while among patients with chronic active hepatitis (CAH) or cirrhosis anti-HD prevalence was much higher in the south (p less than 0.01). The various potential risk factors were evaluated by multiple logistic regression analysis. HDV infection was independently related to young age, residence in the south, i.v. drug abuse, a large family and household contact with an anti-HD-positive carrier. No association was found with blood transfusion or male homosexuality. These findings confirm that HDV infection is endemic in Italy, particularly in some southern areas, where intrafamily contact probably at a young age may favour the spread of the infection.

Smouldering hepatitis B virus replication in patients with chronic liver disease and hepatitis delta virus superinfection

Hepatitis B virus deoxyribonucleic acid (HBV-DNA) was studied by Southern blot analysis in liver biopsy specimens from 75 HBsAg-positive patients with chronic liver disease living in southern Italy. Twenty-seven of the patients were hepatitis delta virus (HDV) superinfected. Intrahepatic HBV-DNA was detected in 54 (72%) patients, 32 (59%) of them with replicative forms. The presence of replicative forms was directly related to liver HBcAg and inversely related to liver HDAg, as shown by multivariate analysis. However, 14 patients with intrahepatic HBV-DNA non-replicative pattern and about half of HDV-infected patients were liver HBcAg and/or serum HBV-DNA positive, mostly in low amounts. Histological inflammatory activity was strongly related to liver HBcAg expression regardless of HDV superinfection, as confirmed by multivariate analysis. Our results confirm previous studies about the concordance between intrahepatic HBV-DNA replicative pattern and liver HBcAg expression and about inhibition by HDV of high-level HBV replication. However, they suggest that low-level HBV replication may have an important role in causing liver damage also among HDV-infected patients, in a population where the spreading of HBV and HDV is a naturally occurring event.

Hepatitis delta virus as a global health problem

As a defective virus requiring helper functions of the hepatitis B virus (HBV), the hepatitis delta virus (HDV) develops only in patients with hepatitis B surface antigen (HBsAg); its presence aggravates the course of the underlying HBV infection. There is no specific prophylaxis against HDV, and its inactivation kinetics by physical and chemical agents are largely unknown. Thus, prevention of HDV in the HBsAg carrier at risk of superinfection is limited to environmental and barrier measures only. As normal persons are efficiently protected from HDV by hepatitis B vaccination, the risk of HDV is another indication for hepatitis B vaccination of at-risk individuals.

Interleukin-2, interleukin-2 receptor and gamma-interferon synthesis by peripheral blood mononuclear cells in chronic hepatitis delta virus infection

The behaviour of the immune system during liver damage caused by chronic hepatitis delta virus (HDV) infection was evaluated by assessing, in 16 patients with HBsAg+ chronic liver disease and HDV superinfection (15 HBeAg-, 1 HBeAg+), phytohaemagglutinin (PHA)-induced interleukin-2 synthesis and interleukin-2 receptor expression, PHA and staphylococcal enterotoxin B (SEB)-induced gamma-interferon synthesis and, in some cases, the presence of hepatitis B virus DNA (HBV-DNA) within peripheral blood mononuclear cells (PBMC). The results were compared to those obtained in 13 patients without HBV replication (i.e., serum HBV-DNA and liver HBcAg-negative), in 15 with HBV replication (i.e., serum HBV-DNA and/or liver HBcAg-positive) with chronic liver disease without HDV superinfection, and in 15 HBsAg-negative healthy control subjects. The lymphokine pattern in HDV infection was comparable to that of healthy subjects and of HBV non-replicating patients without HDV superinfection. Interleukin-2 receptor expression and gamma-interferon synthesis were however significantly decreased in HDV-negative patients with active HBV replication. HBV-DNA was detected in PBMC from 8 of 23 patients, without any correlation with the lymphokine pattern. Our results suggest that in HDV-related chronic liver disease, immune system alterations are unlikely. HDV superinfection does not affect the occurrence of HBV-DNA sequences within the leukocytes. HBV-DNA in PBMC does not interfere with the interleukin-2 system nor with the gamma-interferon response in HBV- and HDV-related chronic liver disease.

Hepatitis delta virus (HDV) infection and disease

The conformational and biologic properties of the hepatitis delta virus (HDV), a defective RNA hepatotropic pathogen dependent on obligatory helper functions provided by the hepatitis B virus (HBV), are different from the properties of conventional RNA animal viruses but resemble in many aspects the characteristics of the satellite RNAs and satellite viruses of higher plants. The HBsAg coat provided to HDV by HBV makes the defective virus transmissible via the vectors and modes of transmission of the ubiquitous helper; alike HBV, HDV is prevalent in tropical and subtropical areas and in the Mediterranean basin. In contrast to HBV, HDV is highly pathogenic and its infection aggravates the underlying HBV infection upon which it thrives. The defective pathogen has been recognized worldwide as a major cause of fulminant hepatitis and of severe chronic hepatitides leading to cirrhosis and liver failure. There is yet no established therapy for this ominous disease.

Perinatal transmission of hepatitis B virus-associated hepatitis D virus

Sera from 185 HBsAg carrier, pregnant Saudi women were tested for HBeAg, antibody to HBeAg (anti-HBe) and for antibody to hepatitis D virus (anti-HDV); 9.7% of the carrier mothers were anti-HDV-positive and the majority of them (94.4%) were anti-HBe-positive. Follow-up of 17 infants of anti-HDV-positive carrier mothers until about 7 months of age showed no evidence of perinatal transmission of HDV. Age-specific prevalence of anti-HDV in 280 Saudi carriers showed that infection with HDV is infrequent in infants and is mainly acquired during the second and third decades of life, which suggests that transmission of HDV is predominantly horizontal.

Delta and non-A, non-B hepatitis viruses

A review is given on the current knowledge of the hepatitis delta virus (HDV), the only hepatotropic non-A and non-B (NANB) virus characterized, although the infection it causes requires infection with hepatitis B virus (HBV). Studies in chimpanzees have provided the most data now available on the putative NANB agents. Histologic and electron microscopic changes occurring in HDV and NANB hepatitis have been shown to be comparable, and some biologic, epidemiologic and clinical features are similar. However, the lack of cross-protection between NANB and HDV hepatitis in cross-challenge transmission experiments and the lack of hybridization between HDV-RNA and nucleic acids from NANB material indicate that HDV and the putative NANB agents are minimally, if at all, related.

Delta hepatitis in Lebanon. Prevalence studies and a report on six siblings with chronic delta-positive active hepatitis

The prevalence of delta infection in Lebanon is reported for the first time. Delta antigen and antibody were screened for in serum of 43 patients consecutively seen in hospital, 22 with acute hepatitis B (anti-HBc IgM-positive), and 21 with histological evidence of chronic active hepatitis, 6 of whom were brothers in a sibship of eleven. Twenty asymptomatic HBsAg carriers without clinical or biochemical evidence of liver disease were similarly studied. None of the asymptomatic carriers or acute hepatitis B patients had markers of delta infection. In contrast, delta antibody in high titre (greater than 1:5000) was found in 12 (57%) of the patients with chronic active hepatitis, including all six brothers. Five sisters in the sibship were anti-HBs-positive without evidence of liver disease, suggesting a horizontal mode of transmission of the delta virus, as a superinfection on a hepatitis B carrier state. Excluding the sibship, delta infection was present in 6 of 15 (40%) chronic active hepatitis patients. This prevalence is similar to other Middle Eastern countries. Delta infection was associated with severe liver disease.

Epidemiology of hepatitis delta virus (HDV) infection

Markers of hepatitis delta virus (HDV) infection have been detected all over the five continents. Geographical prevalence varied heavily: HDV infection is very rare in Far East Asia, but extremely frequent in Arabian countries, in Romania and in certain Indian populations of South America. In Europe and in the USA the infection is widely spread among high risk groups such as intravenous drug abusers and haemophiliacs.

Delta hepatitis--present status

The hepatitis delta virus (Delta) is a defective RNA pathogen dependent for replication on obligatory helper functions provided by the hepatitis B virus (HBV). The virion is a particle of 35-37 nm, which encloses within a HBsAg coat the RNA genome and the Delta antigen, the specific immunologic expression of the new pathogen. Infection is diagnosed by the presence of Delta antigen in liver and the finding of antibody to Delta in serum. The virus is infectious for primates but can also adapt to non-primates. Distribution is world-wide with peak prevalence in the Mediterranean basin, the Middle East and areas of Africa. Transmission occurs by direct parenteral inoculation and by non-parenteral routes linked to close body contacts. Delta is highly pathogenic and a cause or an aggravating factor of HBsAg-positive liver disease. Infection superimposed on acute HBV hepatitis may induce a fulminant illness. Superinfection of carriers of HBsAg may convert a previously asymptomatic carrier in a carrier with chronic hepatitis, or accelerate the downward clinical course of chronic underlying HBV disease. Carriers of HBsAg probably represent the reservoir of the virus.