anti-HAV Seroprevalence Research Articles

Convenience is the key to hepatitis A and B vaccination uptake among young adult injection drug users

Background Despite CDC recommendations to vaccinate injection drug users (IDUs) against hepatitis A virus (HAV) and hepatitis B virus (HBV) infections, coverage remains low. Vaccination programs convenient to IDUs have not been widely implemented or evaluated. We assessed whether convenience and monetary incentives influenced uptake of free vaccine by 18–30-year-old IDUs in five U.S. cities. Methods IDUs recruited from community settings completed risk behavior self-interviews and testing for antibodies to HAV (anti-HAV) and hepatitis B core antigen (anti-HBc). Vaccine was offered presumptively at pre-test (except in Chicago); on-site availability and incentives for vaccination differed by site, creating a quasi-experimental design. Results Of 3181 participants, anti-HAV and anti-HBc seroprevalence was 19% and 23%, respectively. Although 83% of participants were willing to be vaccinated, only 36% received ≥1 dose, which varied by site: Baltimore (83%), Seattle (33%), Los Angeles (18%), New York (17%), and Chicago (2%). Participation was highest when vaccine was available immediately on-site and lowest when offered only after receiving results. Monetary incentives may have increased participation when on-site vaccination was not available. Conclusion IDUs were willing to be vaccinated but immediate, on-site availability was critical for uptake. Convenience should be a key consideration in designing strategies to increase vaccine coverage among IDUs.

Seroepidemiology of hepatitis A and hepatitis B virus in Luxembourg

A prospective seroepidemiological survey was carried out in Luxembourg in 2000-2001 to determine the antibody status of the Luxembourg population against hepatitis A virus (HAV) and hepatitis B virus (HBV). One of the objectives of this survey was to assess the impact of the hepatitis B vaccination programme, which started in May 1996 and included a catch-up campaign for all adolescents aged 12-15 years. Venous blood from 2679 individuals was screened for the presence of antibodies to HAV antigen and antibodies to hepatitis B surface antigen (anti-HBs) using an enzyme immunoassay. Samples positive for anti-HBs were tested for antibody to hepatitis B core antigen (anti-HBc) using a chemiluminiscent microparticle immunoassay to distinguish between individuals with past exposure to vaccine or natural infection. The estimated age-standardized anti-HAV seroprevalence was 42.0% [95% confidence interval (CI) 39.8-44.1] in the population >4 years of age. Seroprevalence was age-dependent and highest in adult immigrants from Portugal and the former Yugoslavia. The age-standardized prevalence of anti-HBs and anti-HBc was estimated at 19.7% (95% CI 18.1-21.3) and 3.16% (95% CI 2.2-4.1) respectively. Anti-HBs seroprevalence exceeding 50% was found in the cohorts targeted by the routine hepatitis B vaccination programme, which started in 1996. Our study illustrates that most young people in Luxembourg are susceptible to HAV infection and that the hepatitis B vaccination programme is having a substantial impact on population immunity in children and teenagers.

Declining hepatitis A seroprevalence: a global review and analysis

Hepatitis A virus (HAV) is spread by faecal-oral contact or ingestion of contaminated food or water. Lifelong immunity is conferred by infection or vaccination, so anti-HAV seroprevalence studies can be used to indicate which populations are susceptible to infection. Seroprevalence rates are highly correlated with socioeconomic status and access to clean water and sanitation. Increasing household income, education, water quality and quantity, sanitation, and hygiene leads to decreases in HAV prevalence. Japan, Australia, New Zealand, Canada, the United States, and most European nations have low anti-HAV rates. Although anti-HAV rates remain high in most Latin American, Asian, and Middle Eastern nations, average seroprevalence rates are declining. Surveys from Africa generally indicate no significant decline in anti-HAV rates. Because the severity of illness increases with age, populations with a high proportion of susceptible adults should consider targeted vaccination programmes.

Task profile and risk of occupational hepatitis A infection in sewerage workers.

The aim of the study was to assess to what extent parameters of task-related occupational exposure influence anti-hepatitis A virus (anti-HAV) seroprevalence in sewerage workers, using a new instrument for classification of exposure. A new instrument for the assessment of work-related infection hazards was developed based on expert interviews, evaluation of literature and theoretical considerations. It was included in a questionnaire for collecting detailed information on occupational exposure, safety awareness, safety behaviour and socio-demography. Anti-HAV status was assessed for all (n = 343) (non-vaccinated) study participants. Marked differences in task profile and task-related exposure within the group of sewerage workers were found, underlining the necessity of a detailed exposure analysis. In a multivariate model three risk factors that were related significantly to anti-HAV positivity were identified: age, country of origin and task-related exposure. Since task profiles and occupational exposure differ strongly within the job category of sewerage workers. evaluation of endangerment has to reflect individual task-related exposure. The task-exposure matrix developed and presented in this study is a practicable and valid instrument for exposure assessment and may be used for the exposure analysis of further biological agents in this working environment. Besides the known risk parameters age and origin, our study demonstrates a dose-response relationship between the degree of occupational exposure and the anti-HAV seroprevalence. Therefore, an effective worksite HAV-prevention programme should consider all technical, structural and educational measures that help to reduce individual exposure.

Change in hepatitis A virus seroepidemiology in southern Taiwan: a large percentage of the population lack protective antibody.

Hepatitis A, the predominant reported etiologic form of viral hepatitis in Taiwan, continues to be a disease primarily of children and young adults. A seroepidemiologic study was performed to assess the seroprevalence of hepatitis A (HAV) antibodies in the southern Taiwan general population in 1998 and is compared with results of a similar study in 1992. A total of 948 subjects (477 male and 471 female) with ages ranging from 0.3 to 63 years were stratified into 14 age-specific groups. The presence of anti-HAV antibodies was detected using a commercially available radioimmunoassay. Fifteen percent of the subjects were positive for anti-HAV antibodies, which is lower than that in 1992 (P < 0.001). Seroprevalences were 14.1% for males and 22.6% for females (P = 0.006). The pattern of anti-HAV seroprevalence was distinguishable from that found in 1992; minimum seroconversion occurred at ages ranging from 1 to 30 years. Prevalence of seropositive subjects decreased markedly for the < 1, 13-15, 16-19, 20-24, 25-29, and 30-39 year age groups in comparing 1998 with 1992. The current study demonstrates a continuing decline in the prevalence of HAV among children, adolescents, and young adults. The findings can be ascribed to the improvement of socioeconomic status and modernization of environmental sanitation. As a consequence of this changing trend of endemicity and the resulting lack hepatitis A antibodies among the general population in Taiwan, the risk of sudden major outbreaks is increased because of increasing international travel and immigration, particularly during and after natural disasters. HAV vaccination will be important for the prevention and control of HAV outbreaks in the community.

Hepatitis A and hepatitis B seroprevalence in 4 centers in Brazil

The prevalence of antibodies to hepatitis A and B virus was assessed in 3,653 subjects across four regions of Brazil. The anti-HAV and anti-HBc seroprevalence were 64.7% and 7.9%, respectively. The highest anti-HAV (92.8%) and anti-HBc (21.4%) rates were seen in the Northern region. In other regions, anti-HAV seroprevalence over 90% was only reached in the more elderly, indicating an intermediate endemicity and a significantly higher anti-HAV prevalence was seen in the low socioeconomic group between 1-30 years. With respect to anti-HBc seroprevalence an increase was seen in adolescents and there was a significantly higher anti-HBc prevalence in the lower socioeconomic group between 1-20 years. A 3.1% anti-HBc prevalence was seen in one-year-old infants, suggesting a vertical transmission. The major findings of this study indicate that the pre-adolescent and adolescent population in some Brazilian cities are at greatest risk from both hepatitis A and B infection, but for different reasons.

Hepatitis A shifting epidemiology in Latin America

In the past, Latin America was considered to be an area of high endemicity for hepatitis A virus (HAV) infection, with most people infected in early childhood. A seroepidemiological study was recently undertaken in six countries to determine whether this pattern has changed. The highest seroprevalence of antibodies to HAV (anti-HAV) was found in Mexico and the Dominican Republic. Analysis of the different age groups showed that at age 6–10 years, 30% of children in Chile and 54–55% in Brazil, Venezuela and Argentina had been infected, compared with almost 70% in Mexico and 80% in the Dominican Republic. At age 11–15 years, nearly 90% in Mexico and 91% in the Dominican Republic had been infected, compared with 54% in Argentina, 62% in Venezuela, 60% in Brazil and 70% in Chile. By age 31–40 years, over 80% of the populations in all six countries had been exposed to HAV. In all of the countries except Brazil and Venezuela, the seroprevalence of anti-HAV was significantly higher in females than in males. In Mexico, Argentina and Brazil, anti-HAV seroprevalence was significantly higher in the low socioeconomic groups than in the middle/high socioeconomic groups. The results show that there has been a shift from high to medium endemicity of HAV infection throughout Latin America, which may result in more clinical cases in adolescents and adults and a greater potential for outbreaks. The vaccination strategy for hepatitis A should thus be reviewed.

Seroprevalence of viral hepatitis in an older nursing home population.

To assess the prevalence of current or previous infection with viral hepatitis agents in an older nursing home population. A prospective cohort study. Three nursing homes in the greater St. Louis area affiliated with Saint Louis University. Older residents admitted to these facilities. Residents were interviewed and examined for evidence of hepatitis or liver disease. Serum samples were tested for hepatitis B surface antigen (HBsAg), antibody to hepatitis B core and surface antigens (anti-HBc and anti-HBs), antibody to hepatitis A virus (anti-HAV), antibody to hepatitis C virus (anti-HCV), and hepatitis G virus RNA (HGV RNA). Of 329 residents queried, 199 gave consent and were able to participate. The seroprevalence of hepatitis was: HBsAg 0%, anti-HBc 24.1%, anti-HBs 19.5%, anti-HAV 79.9%, anti-HCV 4.5%, and HGV-RNA 10.6%. Frequency of HAV infection increased significantly with age whereas HBV infection correlated with ethnic status and former occupation as a manual worker. A history of blood transfusion was associated with a higher rate of anti-HCV. End stage renal disease, present in 17 patients, was associated with anti-HBc, anti-HCV, and HGV RNA positivity but not with anti-HBs or anti-HAV positivity The seroprevalence of anti-HCV was surprisingly high in this population residing in skilled nursing facilities, and we recommend that all new patients admitted to this type of institution be screened for anti-HCV. The prevalence of HGV RNA was higher than in the general US blood donor population, but the significance of this finding remains uncertain.

Age-Specific Anti-Hepatitis A Virus Seroepidemiology in Italian Travelers: Indications for Anti-Hepatitis A Vaccination.

Background: Hepatitis A virus (HAV) circulation in the environment is decreasing in most industrialized Western countries. This decrease has lead to low seroprevalence rates in adults. As a consequence, many nonimmune unprotected travelers from areas of low prevalence are considered at risk of acquiring HAV infection when traveling to high HAV endemic areas in developing countries. The recent HAV inactivated vaccine has proved safe and effective, and its use in different geographic areas should be guided by local age-specific HAV seroprevalence rates. The aim of this paper is to describe the age-specific sero-epidemiology of HAV infection in travelers from a highly industrialized region in Northern Italy (Lombardy). Methods: Seven hundred and forty-four consecutive travelers aged from 20 to 59 years, subdivided in 10-year age groups, gave blood samples in the collaborative Health Centers in the Lombardy region and sera were tested for HAV IgG antibodies. A questionnaire was given to travelers that investigated alimentary habits and a history of previous travel. Results: Anti-HAV seroprevalence was 18.0%, 58.0%, 75.8%, and 89.5% in the 20-29, 30-39, 40-49, and 50-59 age groups, respectively. Age was the single most important determinant of anti-HAV seroprevalence. The influence of previous travels, eating shellfish, or ingestion of self-cultivated vegetables was ruled out by multivariate analysis. Conclusions: In the Lombardy region (Northern Italy), age specific anti-HAV seroprevalence rates are much higher than those reported in other Western European countries. The cost-benefit analysis suggested that travelers born after 1960 do not need serologic screening before vaccination. Whenever possible, however, HAV serologic screening is advisable for travelers born before 1960. However, the severity of the disease in older subjects, and the proved safety of HAV vaccination in immune subjects, may advise d'emblée HAV vaccination without prior screening, when serologic investigation is unfeasible because of lack of time or the unavailability of testing facilities.

Prevalence of Antibodies to Hepatitis A, B, C, and E Viruses in a Healthy Population in Leon, Nicaragua

A cross-sectional survey of the seroprevalence of hepatitis A virus (HAV), B (HBV), C (HCV), and E (HEV) antibodies in a healthy population in Leon, Nicaragua was conducted and associated with demographic data. The overall prevalence of antibodies to HAV was 94.6%, to HBV 6.5% and to HEV between 4.6% and 8.0%, whereas none of 399 tested subjects showed confirmed seropositivity to HCV. A high HAV seropositivity rate (72.7%) was observed even in the lowest age groups tested (2-4 years of age). In contrast, HBV and HEV seropositivity was observed mainly in adults, the seroprevalence in > 40-year-old individuals being 15.4% and 17.6%, respectively. The overall mean hepatitis B surface antigen carrier rate was estimated to be 0.9%, and in individuals more than 20 years of age, 2.0%. The prevalence of anti-HAV as well as anti-HEV was significantly higher in people having their water supply outside rather than inside the house. Furthermore anti-HAV seroprevalence correlated with lack of access to a flush toilet. Hepatitis B virus seropositivity was more frequent in people living in a crowded environment than in those living with few household members. These findings indicate that hepatitis A is a childhood infection in Nicaragua and that the spread of the infection is facilitated by poor socioeconomic conditions. In contrast, HBV infection is relatively infrequent in the country and HCV seems to be very uncommon. Hepatitis E virus infection may occur in all age groups and is apparently associated with water-borne transmission.

Risk of infection with hepatitis A, B or C, cytomegalovirus, varicella or measles among child care providers.

Employment as a child care provider has been suggested as an indication for hepatitis A virus (HAV) immunization; however, whether this occupational group is at increased risk of HAV infection is not well-defined. We obtained sera samples for testing for antibodies to hepatitis A, B and C, cytomegalovirus, varicella and measles from a sample of child care providers in King County, WA, and administered a questionnaire to assess employment characteristics and other potential risk factors for infection. We also compared the anti-HAV seroprevalence among providers with that of subjects in the Third National Health and Nutrition Survey, representative of the US general population. Thirteen percent (48 of 360) of providers were anti-HAV-positive (46% (22 of 47) of foreign born vs. 8% (26 of 313) of US-born (P < 0.001)). In multivariate analysis anti-HAV seropositivity was associated with foreign birth, age, income and Hispanic ethnicity but was not associated with characteristics of employment. Seroprevalence among US-born providers tended to be lower than that among Third National Health and Nutrition Survey subjects of similar age, sex, race and income. Sixty-two percent of providers were seropositive to cytomegalovirus, which was associated with nonwhite race, changing diapers > or = 3 days/week while at work and having a child in the household. Antibody prevalence was 1.4% to hepatitis B core antigen, 0.6% to hepatitis C, 94% to measles and 98% to varicella. The anti-HAV prevalence among US-born providers was low, and seropositivity was not associated with employment characteristics, indicating that occupational exposure to HAV is uncommon under non-outbreak circumstances.

Immunogenicity and efficacy of a killed hepatitis A vaccine in day care center children.

The objective of this study was to characterize the immune response of children after the use of two different vaccine doses and to evaluate whether vaccination benefits children attending day care centers in areas with high anti-HAV seroprevalence. The study was conducted in a day care center with a stable population in São Paulo, Brazil. Two groups of 20 children, all seronegative for hepatitis A antibodies, were assigned randomly to receive three times 0.5 and 1.0 ml of the vaccine, the second and third dose 1 and 6 months after the first dose, respectively. There were 27 children in the control group. All children in both vaccinated groups had protective levels of antibodies in the serum after two inoculations, and serious adverse reactions were not observed. In the eighth month of follow-up, a hepatitis A outbreak occurred in the day care center. Five children in the control group had high titers of IgM class anti-HAV, four with clinical manifestations of acute hepatitis. None of the vaccinated children developed symptoms or signs of hepatitis (P = 0.0125), and the estimate of vaccine efficacy was 100%. Two nonstudy children from the center also had clinical and serological evidence of acute hepatitis A. It is concluded that vaccination represents an important method for prevention of hepatitis A transmission in day care centers. The results of this pilot study justify further testing in larger groups.

Seroepidemiology of hepatitis E virus in the Egyptian Nile Delta.

The seroendemicity of hepatitis E virus (HEV) in an entire village population located in the Egyptain Nile Delta is described. Serum specimens were obtained from 68% of the total population of 1,850 villagers. The lack of serum specimen was greatest in the youngest age group (< 5). Commercially available enzyme immunoassays (EIA) for antibody to hepatitis A virus (anti-HAV), to hepatitis B virus core antigen (anti-HBc), to second-generation hepatitis C virus (anti-HCV) core and nonstructural antigen, and to hepatitis E virus (HEV) were used. Only repeated reactive sera were coded as positive. Stool specimens were examined for Schistosoma mansoni by the Kato method and standard methods for the examination of the liver and spleen by ultrasonography were used. Unadjusted for nonrespone, the seroprevalence of anti-HEV was 17.2% (SE +/- 1.1). Anti-HEV seroprevalence increased by age and was not associated statistically with any of the other viral markers including HCV. Anti-HAV seroprevalence was consistently > 95%, even in the youngest age group (< 5). The overall sero-endemicity of HEV was higher than reported elsewhere and appears not to have been introduced into the village population recently.

Hepatitis A antibody titres after infection and immunization: implications for passive and active immunization

Titres of antibodies against hepatitis A virus (HAV) were determined in patients, in donors, and in volunteers after active, passive, and combined immunization. Highest titres were found in recently infected persons: in 109 IgM anti-HAV positive persons, the geometric mean titre (GMT) was 15,400 mIU/ml. The GMT in 265 anti-HAV positive blood donors was 10,700 mIU/ml. The anti-HAV seroprevalence in 19,746 donors increases with age: at the age of 40 years, 50% have antibodies. Titres after active, passive, and combined immunization were studied in three groups: 51 persons received inactivated HAV vaccine at months 0, 1, and 6. The GMT after the booster was 3,400 mIU/ml at month 7. All persons produced more than 100 mIU/ml anti-HAV. Forty-nine persons received both 5 ml immunoglobulin and three vaccinations, yielding a GMT of 1,300 mIU/ml at month 7. One person in this group produced less than 100 mIU/ml anti-HAV. Forty-nine persons received 5 ml immunoglobulin intramuscularly. At day 5 the GMT was 96 mIU/ml. The estimated minimum protective level (10 mIU/ml) was reached in 3 months. Hepatitis A vaccination may supersede the use of immunoglobulin as prophylaxis for travellers to endemic areas. Passive immunization remains necessary for protection during outbreaks. The dosage regimen for passive immunization is based on old studies using preparations with unknown anti-HAV content. Concern regarding the antibody levels in immunoglobulin preparations is justified; the prevalence of HAV antibodies in developed countries continues to fall. Our results indicate that dosage regimens should be reconsidered. Dosage should be deduced logically from the anti-HAV antibody content of the immunoglobulin preparation.

Hepatitis A sero-epidemiology in Singapore: a changing pattern

Sera from 896 healthy volunteers between 15 and 56 years old were tested in 1987–1991 for immunoglobulin G antibody against the hepatitis A virus (IgG anti-HAV). The overall seroprevalence rate of IgG anti-HAV was 27%: it increased from 0·9% in the 10–19 years age group to 48·1% in the 40–49 years age group and was 100% in subjects over 50 years. There was no difference in anti-HAV seroprevalence between the sexes (29% among men and 26% among women) and races. A downward trend in anti-HAV seroprevalence was seen from 1987 (33%) to 1991 (21·4%). The level of exposure to the hepatitis A virus has decreased when compared with data obtained in 1975 and 1984–1985. Hepatitis A virus infection is no longer an infection of children and adolescents locally.

Hepatitis transmission among the Sioux Indians of South Dakota.

Hepatitis A continues to occur in cyclical community-wide epidemics on the Indian reservations of South Dakota. In June 1985 a population-based serosurvey for viral hepatitis involving 120 households was conducted at the Pine Ridge and Rosebud Sioux Indian reservations in South Dakota. The serosurvey was performed shortly after a large hepatitis A epidemic on the Pine Ridge reservation in 1983-84, and immediately before a large hepatitis A epidemic on the Rosebud reservation in 1985-86. The overall seroprevalence for antibodies to hepatitis A virus (anti-HAV) was 76.2 percent (Pine Ridge reservation 80.5 percent, Rosebud reservation 72.0 percent, relative risk = 1.12, 95 percent confidence interval = 1.01, 1.24). For age groups 0 to 4 years, 54.2 percent and 36.1 percent of children were seropositive at Pine Ridge and Rosebud, respectively. Seropositivity rose rapidly with age; by age 40, more than 90 percent of persons at both Pine Ridge and Rosebud were anti-HAV positive. Only 1.1 percent of persons tested were positive for hepatitis B markers. Anti-HAV seroprevalence rates in both communities are similar to rates observed in developing countries. The surprisingly high anti-HAV seroprevalence among young children at Rosebud, where clinical hepatitis A had been virtually absent in the previous seven years, indicates that high-grade silent transmission was taking place during the interepidemic period.