甲型肝炎病毒感染的血清流行病学研究

对543例城、乡正常人群甲肝IgG抗体的IAHA检测指出阳性率为64.8%。男女差异无显著性（P>0.05）。约半数感染人群发生在10岁以前，到成年时已超过80%。农村较城市更高（P<0.001），多数感染（73.2%）发生在10岁以下的小年龄人群，城市感染则多发生在较大年龄人群，与农村不同。表明甲肝感染普遍而严重。包括幼儿在内的青少年应是防止甲肝感染的主要对象，控制这些易感人群集中单位的爆发流行，是降低甲肝发病的有力措施。成人的群体免疫力较强，主要是及时发现，处理好散在发生的甲肝患者及其密切接触的易感人群，防止造成流行是有积极意义的。     

广州市正常人群甲型病毒性肝炎抗体水平调查

作者1988年12月至1989年6月在广州市进行了甲型病毒性肝炎抗体水平调查,抗-HAV检测用ELISA方法。调查正常人群1 663例,抗-HAV阳性率65.1%。各区、县的抗-HAV阳性率差异很大,最高为90.2%,最低为46.7%。抗-HAV阳性率,农村地区(79.3%)显著高于城区(53.9%),散居幼儿(46.5%)显著高于托幼幼儿(20.8%);4岁以下幼儿中男孩(39.0%)显著高于女孩(13.3%)。0~10岁抗体阳性率在15.4%至44.4%之间起伏,其中0~4岁组为29.7%,10~49岁随年龄增长而上升,高峰值在45~49岁。50岁以上缓慢下降。呈甲肝中发区流行图象模式。     

Cost analysis of two strategies for preventing hepatitis A virus infection in Spanish travellers to developing countries.

Our objectives were to assess the prevalence of anti-hepatitis A (HAV) antibodies in Spanish travellers to developing countries and to carry out a cost analysis to allow the comparison of two vaccination strategies. Adult subjects were selected from among travellers to developing countries. Information was obtained on age, sex, destination, previous vaccination against HAV and having received immunoglobulin. Blood specimens were obtained for anti-HAV antibody determination. A total of 485 travellers were studied. The prevalence of anti-HAV antibody was 30.5% (95% CI 26-35). Antibody prevalence was inversely correlated with age: 9.8% in 18-25 years of age, rising to 75.4% in those 41-55 years of age. Cost analysis determined that the critical value of prevalence for vaccination with HAV vaccine was 37.5%. It was concluded that the youngest Spanish travellers lack anti-HAV antibodies. Vaccination without screening in those < or = 35 years of age and screening before vaccination for those > 35 years, are the preferred alternatives.     

The seroepidemiology of hepatitis A and B in a Japanese town.

Sera collected from 1,118 healthy children and adults aged between four years and 90 years during the period 1989 to 1990, were tested for serological markers of hepatitis A virus (HAV) [antibody to HAV (anti-HAV)] and hepatitis B virus (HBV) [hepatitis B surface antigen (HBsAg) and antibody to hepatitis B surface antigen (anti-HBsAb)]. The overall prevalence rates of anti-HAV, HBsAg, and anti-HBV were 20.2%, 0.36%, and 5.1%, respectively. No body was found to be positive for anti-HAV below 30 years of age but more than 70% of the adults aged 50 years or over were positive for anti-HAV. The level of exposure of HAV infection is declining in Japan and paradoxically at the same time a vast majority of people are becoming susceptible to more severe illness. The fall in prevalence of HBsAg possibly represents the positive impact of ongoing vaccination programs and other preventive measures against HBV.     

Hepatitis A in Peru. The role of children

A serologic survey in 1983-1984 evaluated the presence of hepatitis A antibody (anti-HAV) and hepatitis A immunoglobulin M antibody (anti-HAV IgM) in 3,251 adults and 811 children in the jungle and coastal areas of Peru. All subjects were asymptomatic. Adults had a 98% positive anti-HAV rate except for naval cadets, who had a 76% rate. Children had an 82% positive anti-HAV rate, increasing from 30% at one year of age to 100% at eight years of age. Anti-HAV IgM was present in 27% of children one to four years of age who had antibody and was not present in those older than 12. The vast majority of Peruvian adults are immune to hepatitis A, and children with asymptomatic infection play a significant role in the transmission of this disease.     

Cost analysis of two strategies for hepatitis A vaccination of hospital health-care personnel in an intermediate endemicity area.

The aim of the study was to carry out a cost analysis to allow the comparison of the cost of two vaccination strategies against Hepatitis A in health-care personnel. A total of 423 health-care workers were recruited at one General Hospital of Madrid, Spain. Blood specimens were obtained for anti-HAV antibody determination. The prevalence of anti-HAV antibody was 40% (95% CI: 35-45) and it was directly correlated with age. Cost analysis determined that the critical value of prevalence for vaccination with HAV vaccine was 23%. In hospital health-care workers < or =30 years in age, vaccination with HAV vaccine (without screening) would be the less costly strategy. In those >30 years in age, it would be less costly to screen for anti-HAV antibody first and vaccinate those who are antibody-negative.     

Prevalence of antibody to hepatitis A and hepatitis B viruses in selected populations of the South Pacific.

Five island populations representing the three major cultural groups of the South Pacific--Polynesia, Micronesia, Melanesia--were studied for prevalence of antibody to hepatitis A virus (anti-HAV) and of antibody to the core antigen of hepatitis B virus (anti-HBc). Sera were collected in the late 1950s and early 1960s, selected where possible for appropriate age and sex distributions, and were tested by radioimmunoassay. Rather marked differences in prevalence were observed. Anti-HBc patterns confirmed that HBV is endemic in the Pacific populations. Furthermore, the patterns differed somewhat from each other and did not correlate with ethnogeographic area. Prevalence of anti-HAV was high in all populations studied. A Unique pattern was found for the island of Ponape (Micronesia): In a Ponape population bled in 1963, anti-HAV was not detected in any individual under 20 years of age, but almost all individuals over that age were found to be seropositive. On testing a second group of sera collected in 1975, all individuals aged 14--21 years were found to be antibody positive, indicating that HAV had returned to Ponape sometime prior to 1975. There was no significant difference in the prevalence of HAV or HBV infection between males and females in any of the populations studied.     

孩尔来福甲肝灭活疫苗接种幼龄儿童后3年抗体追踪观察

目的为了观察幼龄儿童(1～4岁)接种孩尔来福(Healive)甲型肝炎灭活疫苗3年后的甲肝病毒抗体滴度和下降规律.方法对河北某山区农村曾接种500 U/剂(0,3和0,6免疫程序)甲肝灭活疫苗的幼龄儿童连续3年采血,用敏感的酶联免疫吸附试验(ELISA)方法,检测其血清中的抗甲肝病毒抗体.结果初免后1年内为抗体快速下降期,以后缓慢下降;至第3年检测时,全部接种对象仍保持甲肝抗体阳性;0,3和0,6程序组甲肝抗体滴度值＞200 mU/ml的分别为61.5%和73.2%.结论Healive甲肝灭活疫苗诱导的抗体在免后3年检测仍保持较高水平.     

Detection of antibodies against hepatitis A in blood spots dried on filter paper. Is this a reliable method for epidemiological studies?

Diluted dried blood drops on filter paper were compared with serum samples as a specimen source for qualitative anti-HAV antibody determination by ELISA. A total of 298 serum samples and dried blood drops were collected from a population of healthy adolescents (15.3 +/- 1.2 years old). The prevalence of anti-HAV antibody obtained by testing serum samples was 7.7% (95% CI:4.8 10.1). Compared with serum sampling the sensitivity and specificity of diluted dried blood drops were 91.3 and 99.3%. The positive and negative predictive values were 91.3 and 99.3%, respectively, and the likelihood ratios of positive and negative results were 91 and 0.09. It is proposed that this test represents a reliable procedure for anti-HAV antibody testing.     

Prevalence of antibody to hepatitis A virus in drinking water workers and wastewater workers in Texas from 1996 to 1997

To determine if wastewater workers had a higher prevalence of antibody to hepatitis A virus (anti-HAV) than drinking water workers, a convenience sample of Texas wastewater and drinking water workers was evaluated for risk factors by questionnaire and tested for anti-HAV. A total of 359 wastewater and 89 drinking water workers participated. Anti-HAV positivity was 28.4% for wastewater and 23.6% for drinking water workers. After adjustment for age, educational attainment, and Hispanic ethnicity, the odds ratio for the association between anti-HAV positivity and wastewater industry employment was 2.0 (95% confidence interval, 1.0 to 3.8). Among wastewater workers, never eating in a lunchroom, > or = 8 years in the wastewater industry, never wearing face protection, and skin contact with sewage at least once per day were all significantly associated with anti-HAV positivity in a model that adjusted for age and educational attainment. Wastewater workers in this study had a higher prevalence of anti-HAV than drinking water workers, which suggested that wastewater workers may have been at increased risk of occupationally acquired hepatitis A. Work practices that expose workers to wastewater may increase their risk.     

Delayed hypersensitivity. A critical evaluation of five recall antigens in a large reference population

The reactivity to five recall antigens, candida, mumps, PPD, varidase and trichophyton and the corresponding diluents was tested in 840 healthy persons aged between 17 and 101 years. Candida antigen was tested in a lower (l) and a higher (h) dose. The size of reactions did not follow a Gaussian distribution and we therefore used the 10th and 5th percentiles instead of standard deviation to define the limits between positive, weak and negative reactions. The number of positive reactions to each of candida-h, mumps, PPD and varidase was between 80 and 95 per cent in patients less than 60 years of age and above this age it varied between 0 and 85 per cent. The number of positive reactions to candida-l and trichophytin was low in all ages. The reactivity was regarded as normal if there was a positive reaction i.e.sum of right angle diameters >10 mm to atl east one antigen, relatively anergic if there was only a weak reaction (7-9 mm) and anergic if there was a negative reaction (0-6 mm) to all antigens. A normal reaction was found in 100 per cent of subjects up to 60 years of age, and in 95 per cent up to 30 years. Among those with normal reactivity, positive results were found with candida-h alone in between 67-93 per cent, candida-h + mumps between 92-100 per cent and candida + mumps + PPD in 100 per cent irrespective of age.     

Sex-related differences in immunoglobulin M and in total antibody response to hepatitis A virus observed in two epidemics of hepatitis A

Sixty symptomatic and 42 asymptomatic cases of hepatitis A detected during two epidemics on the Greek island of Crete in autumn-winter, 1978-1979 were tested for serum total and immunoglobulin M (IgM) specific antibody to hepatitis A virus (anti-HAV and IgM anti-HAV) by commercially available solid phase radioimmunoassays. All cases of symptomatic hepatitis A tested during the first eight weeks from onset were IgM anti-HAV positive with a geometric mean titer of 1:3,575 at 0-28 days from onset. The probability of positivity declined progressively thereafter: a 50% level was reached on the 128th day from onset and the geometric mean titer dropped to 1:317 in samples obtained after the 85th day from onset. Asymptomatic patients had a significantly shorter duration of IgM response than symptomatic ones and three months from onset the prevalence of IgM anti-HAV was only 33% in the former compared to 95% in the latter (p less than 0.0001). A significantly higher prevalence of IgM anti-HAV and higher titers of total and IgM specific anti-HAV was observed in females than in males. IgM anti-HAV was positive in 12 (57%) of 21 samples from females compared to three (12.5%) of 24 samples from males, collected after the 85th day from onset (p less than 0.01). Five months from onset, the cumulative probability of IgM anti-HAV positivity in females was 38% compared to 0% in males (p less than 0.05).     

Are homosexual males a risk group for hepatitis A infection in intermediate endemicity areas?

The purpose of this study was to examine the prevalence of antibody against hepatitis A (anti-HAV) in a population of homosexual men compared with that of heterosexual men in an area of intermediate HAV endemicity (Madrid, Spain). A total of 148 patients were recruited in a Sexually Transmitted Diseases Clinic: 74 homosexuals (mean age of 28 +/- 5 years) and 74 heterosexuals (29 +/- 5 years). The prevalence of anti-HAV antibody was 47% and 43% for homo- and heterosexuals, respectively. Among the factors evaluated (age, sexual orientation and practices, travel to high HAV endemicity areas) oral-anal contact was significantly associated with a higher prevalence of anti-HAV antibody (odds ratio, 2.8; 95% confidence interval, 1.1-7.4; P = 0.03). These results indicated that in an area of intermediate endemicity young homosexual men are not at increased risk of having acquired hepatitis A infection than heterosexuals. Oral-anal contact is an independent risk factor that influences the presence of anti-HAV antibody, regardless of sexual orientation.     

Hepatitis A antibodies: prevalence and persistence in a group of Mexican children

The prevalence of antibodies against hepatitis A virus (anti-HAV) was evaluated in sera from 275 asymptomatic infants and children under the age of five years and in 46 maternal-cord serum pairs, followed by sera obtained thereafter each month from the first to the fifth month of life in 29, 17, 9, 9 and 7 infants (a total of 163 serum samples). Anti-HAV was found in all cord blood sera, but its prevalence declined progressively to 0% among 19 infants aged eight months. Four (25%) of 16 children aged one year had positive anti-HAV and the antibody prevalence was 89% in children five years old. Recent hepatitis A infection shown by circulating anti-HAV immunoglobulin M was detected in five infants under the age of two months and with frequencies ranging from 19-67% in one- and five-year-old children. It was concluded that in children living in Mexico City, hepatitis A infections occur at an earlier age and at higher rates than in children in other cities, especially those in developed countries.     

The changing epidemiological pattern of hepatitis A in an urban population of India: Emergence of a trend similar to the European countries

The present study was undertaken to determine the seroprevalence of the antibody against hepatitis A virus (IgG anti-HAV) in an urban population sample from Delhi (India) and to assess any change in the epidemiological pattern of HAV infection in this part of the world. A total of 500 healthy subjects were enrolled and divided into groups on the basis of age, sex and per capita income and evaluated for the presence of IgG anti HAV antibodies using a commercially available kit. The mean age of all the subjects was 32.6 ± 13.2 yr. and the male:female ratio was 1.5:1. The overall prevalence of IgG anti-HAV in all subjects was 71.2% (356/500). The prevalence in subjects >35 years (92.1% [186/202]) was significantly higher than that in subjects <35 years (92.1% [186/202]) was significantly higher than in subjects <35 years (57% [170/298]). No statistically significant difference was observed between male and female subjects (71.4% [217/304] vs. 70.9% [139/196]) or between subjects belonging to middle and low socioeconomic groups (68.9% [135/196] vs. 72.7% [221/304]). These findings when compared with the results that were obtained in 1982, showed a decreasing prevalence of IgG anti-HAV, most significantly in younger age groups (16–35 years). Thus, we may conclude that the seroepidemiology of hepatitis A virus infection in urban population of India seems to be changing with seroprevalence in the younger population approaching a figure similar to that of the more developed European countries.     

Antibody against hepatitis A in seven European countries. I. Comparison of prevalence data in different age groups.

Using a solid phase radioimmunoassay, antibody to hepatitis A virus (anti-HAV) was determined in 3890 sera from populations in seven European countries. Prevalence of anti-HAV was lowest in Scandinavian countries and highest in Greece and France. Antibodies were found in 77 (13%) of 602 blood donors in Sweden, in 29 (17%) of 175 blood donors and women taking birth control pills in Norway, in 273 (39%) of 700 blood donors in Switzerland, in 262 (52%) of 505 blood donors in Holland, in 365 (55%) of 661 accident patients in West Germany, in 452 (75%) of 600 blood donors in France and in 530 (82%) of 647 persons in Greece. Prevalence of anti-HAV increased with age in all populations tested, indicating nearly total exposure to HAV in persons over 19 years of age in Greece and in persons over 39 years of age in West Germany, Holland and France. Antibody was found more frequently in rural than in urban populations in Greece and Switzerland. Calculation of the age-specific incidence of HAV infections suggests a remarkable decline in the exposure rate in the last few decades.     

A large outbreak of hepatitis A in a day-care center: association with non-toilet-trained children and persistence of IgM antibody to hepatitis A virus

In early summer, 1979, a large outbreak of hepatitis A occurred in an Oklahoma day-care center. A total of 41 cases were confirmed, all in adults. Of the 115 non-employee households represented by children in the center, 19 households (16.5%) had one or more cases of hepatitis. Hepatitis occurred in 29% of the households with at least one non-toilet-trained child, compared to 2% of the households without such a child (p = 0.00004). At least four (15%) of 27 center employees had hepatitis. Of 26 cases tested serologically, all were positive for hepatitis A antibody (anti-HAV), and 24 of these 26 were also positive for anti-HAV of immunoglobulin class M (anti-HAV IgM), at an average time after onset of illness of 80 days (range, 38-142 days). Three of ten persons remained anti-HAV IgM-positive 164 days after onset.     

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.     

Hepatitis A control in a refugee camp by active immunization

An outbreak of hepatitis A occurred among children of a refugee camp in Croatia. In order to disrupt the outbreak, we decided to vaccinate children from 1 to 15 years of age in the camp, in addition to intensified general preventive measures. Assuming high prevalence of hepatitis A virus antibodies within this population, we conducted anti-HAV testing of the children eligible for vaccination. Of 108 children tested, 74 (68.5%) were anti-HAV positive. We vaccinated 34 children. One month after vaccination 31 previously negative children were tested for anti-HAV and 30 of them were found positive, suggesting a seroconversion rate of 96.8%. One child fell ill 5 days after vaccination, after whom no new cases of hepatitis A occurred. Thus we conclude that active immunization is a successful means of stopping an outbreak of hepatitis A.     

Seroepidemiology of hepatitis A in voluntary blood donors from Pune, western India (2002 and 2004-2005)

Recently, a changing pattern of hepatitis A epidemiology has been reported in the Indian population indicating a rise in the rate of hepatitis A infection among adults. The study's objective was to assess anti-HAV prevalence in voluntary blood donors from middle and high socioeconomic strata. Serum samples collected from voluntary blood donors from Pune city and its suburbs in the years 2002 and 2004-2005 were tested for anti-HAV IgG antibodies. Serum samples collected during 2004-2005 were examined for anti-HAV IgM antibodies. Positive samples were tested for HAV-RNA. Agewise anti-HAV positivity was significantly low in adults aged 18-25 years (90.4%) compared to those aged >25 years (97.4%) (P<0.01). A decline in anti-HAV prevalence was significant in 2004-2005 compared to that in 2002 (96.5% vs. 92.1%) (P<0.01). Overall, in both adult age groups, the proportion of anti-HAV positivity was remarkably low in the high socioeconomic group (HSG) (88.96%) compared to that of the middle socioeconomic group (MSG) (95.86%) (P<0.01). Anti-HAV IgM positivity was not significant (~1%), however, presence of HAV-RNA in one of the samples indicated the possibility of horizontal transmission of HAV. Increase in seronegativity to HAV in HSG implicates a rise in the susceptible pool and indicates the need for vaccination against hepatitis A.