Natural horizontal transmission of HCV in microepidemic town in Japan

Hepatitis C: an epidemiological review

The aim of the study was to analyse the current literature regarding the mode of transmission of HCV and its global prevalence in different groups of people. A systematic review of the literature on the epidemiology of hepatitis C from 1991 to 2000 using computerized bibliographic databases which include Medline, Current Content and Embase. The prevalence of hepatitis C virus (HCV) varies tremendously in different parts of the world, with the highest incidence in the Eastern parts of the globe compared with the Western parts. Furthermore, certain groups of individuals such as intravenous drug users are at increased risk of acquiring this disease irrespective of the geographical location. Although the main route of transmission is via contaminated blood, curiously enough in up to 50% of the cases no recognizable transmission factor/route could be identified. Therefore, a number of other routes of transmission such as sexual or household exposure to infected contacts have been investigated with conflicting results. Hepatitis C infection is an important public health issue globally. Better understanding of routes of transmission will help to combat the spread of disease. In order to prevent a world wide epidemic of this disease, urgent measures are required to (i) develop a strategy to inform and educate the public regarding this disease and (ii) expedite the efforts to develop a vaccine.

Molecular epidemiology of hepatitis C virus infection in an area endemic for community-acquired acute hepatitis C

The southern district of N city (U area), Yamagata Prefecture, is highly endemic for hepatitic C virus (HCV) infection. Around 20% of the general population are positive for antibodies to HCV (anti-HCV). Community-acquired, acute non-A, non-B hepatitis was epidemic from 1967 to 1972 in this area. Our previous study revealed that these people are actually infected with HCV, but a relationship between this outbreak and the high positivity rate of anti-HCV in the U area has not been shown. We followed up 15 anti-HCV-positive individuals who developed hepatitis during the epidemic and used the serum collected to conduct molecular evolutional analysis to reveal the characteristics of the HCV epidemic in the U area. HCV genotypes in the U area were also analyzed. Phylogenetic analysis of the HCV core gene sequences showed that the subjects' HCV sequences were closely related and derived from the same cluster. All subjects were infected with HCV genotype 1b, which was frequently detected with a high positivity of over 80% of HCV-infected individuals in the U area. These results confirm that the community-acquired hepatitis C epidemic occurred around three decades ago through an unidentified route, and suggest that this episode may result in a continuing increase in the number of HCV-1b positive patients in this small area.

Heterosexual transmission of hepatitis C virus among married couples in southwestern Japan

The heterosexual transmission of hepatitis C virus (HCV) remains controversial, and data from general populations are scanty. In this cross-sectional study, we assessed the seroprevalence of antibodies to hepatitis C virus (anti-HCV) and the presence and genotype of HCV-RNA among 109 married couples within an endemic, community-based Japanese population. Overall, 25% of the husbands and 32% of the wives had anti-HCV. Spouses with anti-HCV-positive partners were around 2 times more likely to have anti-HCV than spouses with anti-HCV-negative partners (p = 0.01). Of 6 couples in which both spouses had HCV-RNA, however, 3 presented discordant HCV genotypes (type 1b vs. 2b). The couples' anti-HCV concordance status was not significantly influenced by the presence or absence of HCV-RNA among anti-HCV-positive partners (odds ratio [OR]: 0.8 for wives, 0.6 for husbands), nor by the length of marriage, the number of pregnancies or the use of contraceptives. No significant associations with anti-HCV were observed for serum markers of sexually transmitted agents, including human T-lymphotropic virus (OR = 1.1, 95% confidence interval [CI] 0.5-2.3), Treponema pallidum (OR = 0.7; CI 0.1-6.1) and hepatitis B virus (OR = 1.6; CI 0.9-3.0). Our results suggest that the clustering of HCV infection among specific couples within this endemic population may not be attributable to heterosexual transmission. Follow-up studies are necessary to determine the risk of heterosexual transmission of HCV in endemic areas.

Epidemiology of hepatitis C virus infection in an area of Southern Italy

BACKGROUND/AIMS

Hepatitis C virus (HCV) has been recognized as a major cause of liver disease, but little is known about its diffusion at population level. To estimate the prevalence and incidence of HCV infection and to explore potential risk factors at population level, an epidemiologic study was carried out.

METHODS

A cohort was built up in 1985, on a random sample of the population of Castellana, a small town in southern Italy (Bari province), and followed up until 1993. HCV ELISA II and RIBA HCV 2.0 were used as screening and confirmatory tests, respectively.

RESULTS

The overall anti-HCV prevalence was 26.0% (511/1969) at enrollment. The HCV infection incidence rate was 34.2x100,000 person-years (3 cases/8766 persons-years). A secular trend (referent born before 1930; born 1930-39 Odds Ratio (OR) 0.72, 95% Confidence Interval (95% CI) 0.56-0.94; born 1940-49, OR 0.33, 95% CI 0.25-0.44; born 1950 or after, OR 0.15, 95% CI 0.09-0.23) and geographical pattern (referent born outside Bari province; born in Bari province, OR 1.71, 95% CI 0.93-3.16; born in Castellana G, OR 2.29, 95% CI 1.29-4.05) were found by logistic regression analysis after controlling for several confounding factors.

CONCLUSIONS

The high prevalence, moderate incidence, and marked decrease in HCV infection in the cohort of birth in a population without known risk factors suggest that an epidemiological transition has been operating at population level since the 1950's.

Sporadic transmission of hepatitis C

At the present time, people having contracted hepatitis C are not warned about the possible ways in which they can transmit this disease to others. This greatly increases the risk of sporadic transmission of the virus. Public health and medical authorities should institute programs to inform all such afflicted persons how to avoid communicating the disease to others.

Injection with nondisposable needles as an important route for transmission of acute community-acquired hepatitis C virus infection in Taiwan

A prospective case-controlled study was conducted in order to determine the transmission route of community-acquired hepatitis C virus (HCV) infection in Taiwan. Thirty-eight consecutive patients (25 men and 13 women) with acute community-acquired HCV infection and 76 age (within 3 years)- and sex-matched healthy control subjects without HCV infection were enrolled. Serum anti-HCV was tested by second generation immunoassay. The sera of 26 family members from 12 families of index patients were also tested for anti-HCV. A questionnaire covering the history of blood transfusion, surgery, intravenous drug abuse, prostitute contact, dental procedures, injection, acupuncture, tattooing, and ear-piercing was conducted among patients and control subjects. Univariate analysis revealed injection with nondisposable needles was an independent risk factor (P = 0.02, odds ratio = 4.17, 95% confidence interval = 1.24-14.47) associated with HCV infection. Other risk factors were not significant. Only 2 (7.7%) family members of index patients had an anti-HCV. In conclusion, more vigorous effort to prohibit the use of nondisposable needles should be promoted to interrupt the spread of community-acquired HCV infection in Taiwan. Of note, a significant number of patients (34.2%) contracted HCV infection without identifiable risk factors. Unidentified routes need to be investigated.

Epidemiologic survey and genetic analysis of endemic hepatitis C virus infection in a Japanese town with a high prevalence of hepatitis B virus carriers

Mass screening for hepatitis C virus antibody was carried out in 875 inhabitants (313 men and 562 women) of a town in Japan with a high rate of hepatitis B virus infection. The overall rate of positivity for anti-HCV was 8.8% (6.4% in men and 10.1% in women). The rate of positivity for hepatitis B virus surface antigen was 11.2%. Five subjects (0.6%) were positive for both markers. HCV-RNA was detected in 65 (88.4%) of 77 individuals who were positive for anti-HCV and in 1 (1.5%) of 60 individuals negative for anti-HCV. The genotype of the HCV genome was determined by PCR analysis using type-specific primers in 60 individuals. HCV type 1b was detected in 51 subjects (85%), type 2a in 3 subjects (5%), and type 2b in 6 subjects (10%). None of the individuals was infected with more than one genotype. The nucleotide sequences of the partial nonstructural 5 region of HCV type 1b genotype obtained from 6 individuals showed at least 92.0% homology in the nucleotide sequence, and 94.8% homology in the amino acid sequence. Homology among these clones was greater than their homology with previously described type 1b sequences. The findings suggest that there was a specific local origin of HCV infection, although it was not possible to identify any single source of HCV infection. The results also indicate that presence of asymptomatic HCV carriers.

Evaluation of sexual transmission in patients with chronic hepatitis C infection

BACKGROUND

The transmission of hepatitis C virus (HCV) by parenteral exposure is well documented. However, a proportion of patients with acute or chronic HCV infection have an unknown source of infection.

OBJECTIVES

The purpose of this study is to evaluate the role of sexual transmission in HCV infection.

STUDY DESIGN

68 patients (median age, 50 years) with chronic hepatitis C and their spouses were tested for the presence of antibody to HCV (anti-HCV) by multi-antigen and chimeric C25 antigen enzyme immunoassays and for HCV RNA by the polymerase chain reaction. Information on sexual activity and risk factors for HCV infection were obtained from all couples via a questionnaire.

RESULTS

All index patients were positive for both anti-HCV and HCV RNA. Antibody to HCV was detected in four (5.9%) of their spouses. One anti-HCV-positive spouse had a history of blood transfusion while the other three (4.4%, 95% CI = 1.5-12.2%) had no known risk factors for HCV infection and thus may have been exposed to HCV via sexual transmission. Two of these 3 spouses had positive serum HCV RNA and had identical HCV genotype to the index patients. The length of sexual exposure was significantly longer in the couples who both were anti-HCV-positive than in patients whose spouses were anti-HCV negative (median: 25 vs. 10 years, P = 0.02, Mann-Whitney test). In our 68 index patients, 96% had antibodies to the recombinant proteins from the C22 (core) and C33C (NS3) regions, and 82% and 76% had antibodies to the proteins from the NS5 and C100-3 (NS4) regions. Identical anti-HCV profiles were noted in two of the four anti-HCV-positive couples.

CONCLUSIONS

Our results indicate that sexual transmission, although uncommon, should be considered as a risk factor for HCV infection, especially in spouses who have had long-term intimate relationships with a chronic hepatitis C patient.

Transmission of hepatitis C in an isolated area in Japan: community-acquired infection. The South Kiso Hepatitis Study Group

BACKGROUND/AIMS

The spread of hepatitis C virus (HCV) infection not due to drug needle sharing or transfusion is largely unknown in communities. A search for risk factors for HCV infection in an endemic area might elucidate inapparent modes of transmission.

METHODS

We conducted screening for hepatitis virus markers and parenteral exposures to blood among 435 inhabitants in an isolated area known for its endemicity for non-A, non-B hepatitis and in a nonendemic area with 1542 inhabitants.

RESULTS

The prevalence of hepatitis B surface antigen was the same in both areas. The prevalence of antibody to HCV verified by the recombinant immunoblot assay was 32.4% in the highly endemic area and 2.3% in the nonendemic area (P < 0.001). Risk factors for HCV infection in the highly endemic area were complex but included folk remedies such as acupuncture and "vacuuming" for congested blood in muscle by the use of a warm glass bottle.

CONCLUSIONS

Folk remedies such as acupuncture and cutting of the skin using nonsterilized knives should be considered as possible routes of HCV transmission not associated with blood transfusion or sharing of drug paraphernalia.

Prevalence of hepatitis C virus infection in the household contacts of patients with HCV-related chronic liver disease

It is still controversial whether the familial environment plays a role in the diffusion of HCV infection. The aim of this study was to evaluate the prevalence of anti-HCV positivity in the household contacts of patients with HCV-related chronic hepatitis. Nearly all the household contacts of 113 subjects with anti-HCV+ chronic hepatitis (100/113 spouses and 260/290 children) were investigated. Anti-HCV was determined by means of ELISA II and was confirmed by RIBA II. Anti-HCV positivity was found in 27% of the spouses and in 1.9% of the children. Prevalence of anti-HCV positivity in spouses correlated positively with the duration of the marital status. Seventeen/32 (53.1%) of anti-HCV-positive subjects were found to have chronic hepatitis. This study indicates that intrafamilial diffusion of HCV infection is mostly accounted for by horizontal, in particular spouse to spouse, transmission and that spouse to spouse transmission of HCV infection correlates positively with the duration of marital status.

Intrafamilial transmission of hepatitis C virus: the important role of inapparent transmission

To evaluate the intrafamilial transmission of hepatitis C virus (HCV) 104 index patients with type C chronic liver disease and their 307 family contacts were interviewed. After a questionnaire on the risk factors of parenteral exposure, blood samples were obtained and tested for liver biochemistry and anti-HCV antibody by enzyme-linked immunosorbent assay (Abbott II). Overall, 52 family contacts (17%) were positive for anti-HCV, indicating a higher anti-HCV prevalence among family contacts than among the general population in Taiwan. The anti-HCV prevalences in parents, spouses, children, and other contacts of the patients were 54% (14/26), 28% (25/91), 6.9% (10/143), and 6.4% (3/47), respectively. The contacts of index patients had increasingly greater risk of HCV infection when they became older and had lived longer with index patients. All family contacts were divided into two groups categorized by whether the index patients had or did not have a history of parenteral exposure. Among 126 family contacts of the 42 patients without parenteral exposure, blood transfusion and surgery were the factors significantly associated with HCV infection in these family contacts (odds ratio = 7.26, 95% confidence interval = 2.32-32.67; odds ratio = 3.95, 95% CI = 1.29-12.11, respectively). Risk factors were not significantly associated with HCV infection among 181 family contacts of the 62 index patients with parenteral exposure. It is concluded that the index patients without parenteral exposure appeared to have acquired the disease from HCV-infected family members with risk factors. Most of the index patients had a history of parenteral exposure and in turn served as the source of the disease for family members.

Intrafamilial transmission of hepatitis C virus

The intrafamilial transmission pattern of hepatitis C virus (HCV) was examined in 118 family members of 61 index patients with type C chronic liver disease using anti-HCV antibodies and HCV RNA assay. The study subjects consisted of eight parents, 49 spouses, 50 children, eight siblings and three other relatives. The positivity rates of anti-C100, anti-JCC, second-generation anti-HCV and HCV RNA were 6.8, 12.7, 12.7 and 11.0%, respectively. Positivity in one or more anti-HCV antibody assay was detected in 3/24 (12.5%) father-child pairs, 3/17 (17.6%) mother-child pairs, 2/8 (25%) sibling pairs, 6/38 (15.8%) husband-wife pairs and 2/13 (15.4%) wife-husband pairs. In spouses, positivity for anti-HCV antibody or HCV RNA was observed after 40 years of age. None of 11 spouses married < 15 years was positive for any anti-HCV assay or HCV RNA. In spouses whose age was > 50 years and duration of marriage was > 25 years, anti-HCV or HCV RNA was frequently detected (32.0%). However, when seven pairs involving four spouses, one mother-daughter pair and two sibling pairs were subtyped, the same HCV subtypes were found in only four pairs (type II in three pairs and type III in one pair). Further, the agreement rate between anti-HCV and HCV RNA was > 90%. These results suggest that intrafamilial transmission of HCV, revealed by the subtyping method, is considered lower than the percentage of positivity for anti-HCV antibodies or HCV RNA in family members of patients with type C chronic liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Sexual transmission of hepatitis C virus and HIV-1 infection in female intravenous drug users

We examined the relationship between the presence of antibody to HCV and sexually transmitted diseases in 151 female, intravenous drug users aged 17-43 years. Anti-HCV was present in 49 of 66 HIV-1-negative women (74.2%), and 63 of 85 HIV-1-positive women (74.1%). Anti-HCV seropositivity was significantly related to sexually transmitted infections (Ureaplasma urealyticum infections excluded) in HIV-1-seronegative women, but not in HIV-1-positive women. Also, in HIV-1-negative subjects. Trichomonas vaginalis infections (and infections with M. hominis) were significantly related to anti-HCV seropositivity, and a positive relation between the number of sexual partners and the presence of anti-HCV was demonstrated. In HIV-1-positive subjects a shared use of needles and syringes was more likely, and an increased parenteral exposure to HCV may decrease the relative contribution by sexual transmission. However, in HIV-1-negative subjects, sexual transmission of HCV appears to be both a possible and important means of transmission.

Risk factors for hepatitis C virus infection in blood donors: a case-control study

OBJECTIVE

To investigate risk factors for hepatitis C virus (HCV) infection in Sydney blood donors.

DESIGN

Blood donors confirmed to be positive for HCV antibodies were compared with blood donors with a positive result of a screening assay, but whose HCV antibody status had not been confirmed. A questionnaire on sexual, parenteral and other potential risk factors was administered to both groups.

SETTING

Blood Transfusion Service in Sydney.

PARTICIPANTS

The study enrolled 220 donors who had confirmed HCV infection, and 210 donors who did not.

RESULTS

The relative risk associated with injecting drug use was 63 (95% confidence interval, 19-260) when comparison was made with all other donors. Among donors who did not report injecting drug use, a significant, independent increase in risk was found in association with having had a tattoo. Among donors who did not give a history of parenteral exposure, there was a significantly greater risk in people with more than one life-time sexual partner than in those with at most one partner.

CONCLUSION

A history of injecting drug use was elicited as the most important risk factor in Sydney blood donors with antibodies to hepatitis C. Having had a tattoo, and an increased number of lifetime sexual partners were also independently associated with HCV infection.

High prevalence of hepatitis C virus infection in aborigines in Taiwan

In Taiwan, the epidemiological status of HCV infection is similar to those observed in other areas of the world, with 1.0% prevalence among adult volunteer blood donors and high prevalences among the high risk groups, by the detection of anti-HCV with synthetic peptide antigens. However, unusually high prevalences, 35.1%, 15.8% and 14.2%, were observed among adult populations in three of the five aboriginal communities. No difference in sex specificity was noted. In 37 (75.0%) of the 48 anti-HCV-positive cases, HCV-RNA was detected by reverse transcription polymerase chain reaction (RT-PCR) assay. None of such particular risk factors as tattooing, sexual promiscuity, operation, blood transfusion, nor intravenous drug abuse could be accounted for this high prevalence of HCV infection. No helpful supporting evidence for ethnic specificity was noted, either. Although a possible sexual transmission between spouses was observed, it is unlikely to be the main cause of the high prevalence in these aboriginal communities. We conclude that the unusually high prevalence of HCV infection observed in some aboriginal communities in Taiwan could be ascribed to poor anti-septic medical practice derived from insufficiency of medical personnel and facilities in these communities as compared with the other regions in Taiwan at the time before twenty years ago.