Consensus recommendations for managing asymptomatic persistent non-virus non-alcohol related elevation of aminotransferase levels: suggestions for diagnostic procedures and monitoring

A persistent increase in non-virus non-alcohol related aminotransferase levels can have multiple causes, which differ in terms of prevalence and clinical importance. In the general population, the most frequent cause is non-alcoholic hepatic steatosis, which can evolve into steato-hepatitis and cirrhosis. The treatment for steatosis and non-alcoholic steato-hepatitis consists of modifying lifestyles, whereas the effectiveness of drug treatment remains to be determined. Other much less frequent (yet not rare) causes of persistent non-virus non-alcohol related elevations in aminotransferase levels are celiac disease and hemochromatosis, whereas autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis, and alpha-1-anti-trypsin deficit are rare. Given that some of these conditions are susceptible to treatment, early diagnosis is important. No epidemiological data are available for evaluating the prevalence of elevated aminotransferase levels correlated with the toxicity of drugs or other xenobiotics, including herbal products. The present document, created by a panel of experts based on a systematic review of scientific evidence, is mainly geared towards physicians working in General Medicine and Transfusion Centres, who generally represent the first contact of persons with elevated aminotransferase levels. The document includes suggestions for diagnosing causes of persistent non-virus non-alcohol related increases in aminotransferase levels, considering the frequency and response to treatment. The conditions requiring specialized visits are also indicated.

Feasibility of vaccination in preventing secondary cases of hepatitis A virus infection

Although the secondary transmission of hepatitis A virus (HAV) infection is preventable through vaccination, it is not known whether the vaccination of household contacts is feasible. To this end, we conducted a prospective cohort study among the household contacts, 40 years of age or less, of all persons infected with primary HAV infection (index cases) and admitted to eight hospitals in southern Italy within 7 days of onset. Household contacts were vaccinated, and serum samples were taken at vaccination and after 14 and 45 days. Secondary cases were defined as those with IgM seroconversion occurring at least two weeks after enrollment. Coprimary cases were those assumed to have had the same exposure as the index case. Susceptible cases were those who were negative for both IgG and IgM. A total of 495 household contacts participated (acceptance rate of 65%); 65% were vaccinated within 4 days of admission of the index case and 95% within 7 days. At enrollment, 196 (39.6%) household contacts were immune (IgG-positive serum). During follow-up, 19 (3.8%) were IgM-positive: 13 (2.6%) were coprimary cases and 6 (1.2%; 95% CI: 0.2-3.2) secondary cases (5 identified at 14 days from vaccination and 1 at 45 days). Of the 241 susceptible cases, 192 (79.7%) had developed IgG antibodies at 14 days and only 3 (1.2%) did not develop IgG antibodies at 45 days. The 65% acceptance rate and the finding that 95% of the participating household contacts were vaccinated within 7 days of the index case's hospitalization indicate that timely vaccination is indeed feasible. The necessity of returning for the collection of blood samples probably decreased the acceptance rate.

Risk management of HBsAg or anti-HCV positive healthcare workers in hospital

Recommendations are made for controlling the transmission of the hepatitis B and hepatitis C viruses from healthcare workers to patients. These recommendations were based both on the literature and on experts' opinions, obtained during a Consensus Conference. The quality of the published information and of the experts' opinions was classified into 6 levels, based on the source of the information. The recommendations can be summarised as follows: all healthcare workers must undergo hepatitis B virus vaccination and adopt the standard measures for infection control in hospitals; healthcare workers who directly perform invasive procedures must undergo serological testing and the evaluation of markers of viral infection. Those found to be positive for: 1) HBsAg and HBeAg, 2) HBsAg and hepatitis B virus DNA, or 3) anti-hepatitis C virus and hepatitis C virus RNA must abstain from directly performing invasive procedures; no other limitations in their activities are necessary. Infected healthcare workers are urged to inform their patients of their infectious status, although this is left to the discretion of the healthcare worker; whose privacy is guaranteed by law. If exposure to hepatitis B virus occurs, the healthcare worker must undergo prophylaxis with specific immunoglobulins, in addition to vaccination.

Risk of parenterally transmitted hepatitis following exposure to surgery or other invasive procedures: results from the hepatitis surveillance system in Italy

BACKGROUND/AIMS

To evaluate the strength of association between parenterally transmitted viral hepatitis and specific types of invasive procedures.

METHODS

Data from the surveillance system for type-specific acute viral hepatitis (SEIEVA) during the period 1994-1999 were used. The association of acute hepatitis B virus (HBV) and hepatitis C virus (HCV) infection with the potential risk factors (odds ratios (OR)) was estimated comparing 3120 hepatitis B and 1023 hepatitis C cases with 7158 hepatitis A cases, used as controls, by multiple logistic regression analysis.

RESULTS

Most procedures resulted in being associated with the risk of acquiring acute HBV or HCV. The strongest associations were: for HBV infection, abdominal surgery (adjusted OR = 3.9; 95% confidence intervals (CI) = 2.0-7.5), oral surgery (OR = 2.7; 95% CI = 1.6-4.5) and gynaecological surgery (OR = 2.6; 95% CI = 1.2-5.5); for HCV infection, obstetric/gynaecological interventions (OR = 12.1; 95% CI = 5.6-26.3), abdominal surgery (OR = 7.0; 95% CI = 3.2-14.9) and ophthalmological surgery (OR = 5.2; 95% CI = 1.1-23.2). Biopsy and/or endoscopy were associated with HCV, but not with HBV infection.

CONCLUSIONS

Invasive procedures represent an important mode of HBV and HCV transmission. Since a large proportion of the adult general population is exposed to these procedures and an effective HCV vaccine is not yet available, non-immunological means of controlling iatrogenic modes of transmission are extremely important.

Niflumic acid and cutaneous reactions in children

In a case control study of adverse drug reactions in children, the odds ratio of developing a serious mucocutaneous event among users of niflumic acid, adjusted for concomitant use of all other drugs, was 4.9 (95% CI 1.9 to 12.8). Given the availability of safer analgesics and antipyretics, there is no indication, in our opinion, that requires the prescription of substances which bear an increased risk.

Vaccination policy against hepatitis A in Italy

In Italy, improved sanitation and living conditions have led to a decline in the rate of hepatitis A infection among children generating an increasing proportion of adults susceptible to this virus. Shellfish consumption is a major source of infection while person to person transmission is important in the spread of infection and in the maintenance of outbreaks. Thus prevention of secondary HAV infection is a crucial point. A randomised controlled trial of hepatitis A vaccine in household contacts of people with sporadic HAV infection in Italy has shown a protective efficacy of 82% (CI 20-96%). The two secondary infections in the vaccine group were symptomless, suggesting that the disease expression may be weaker in vaccinated subjects.

Efficacy of hepatitis A vaccine in prevention of secondary hepatitis A infection: a randomised trial

BACKGROUND

Hepatitis A vaccination stops outbreaks of hepatitis A infection, but its efficacy against infection after exposure has not been proven. We investigated the use of hepatitis A vaccine to prevent secondary infections with hepatitis A virus (HAV).

METHODS

We did a randomised controlled trial of hepatitis A vaccine in household contacts of people with sporadic HAV infection (index cases). Households (index cases and contacts) were randomly assigned to the vaccine group or unvaccinated group, according to the study week in which they were enrolled. All household contacts in the vaccine group received vaccination at the time of entry to the study.

FINDINGS

During 45 days of follow-up, secondary infection had occurred in ten (13.3%) of 75 households (two families had two cases each) in the untreated group and in two (2.8%) of 71 households in the vaccine group. The protective efficacy of the vaccine was 79% (95% CI 7-95). The number of secondary infections among household contacts was 12 (5.8%) of 207 in the unvaccinated group and two (1.0%) of 197 in the vaccinated group. Therefore, 18 individuals needed to be vaccinated to prevent one secondary infection.

INTERPRETATION

Hepatitis A vaccine is effective in the prevention of secondary infection of HAV and should be recommended for household contacts of primary cases of HAV infection.

Hepatitis B vaccination coverage among healthcare workers in Italy

In 1996, the vaccination coverage against hepatitis B virus among 3,157 healthcare workers in Italy was inversely related to the level of hepatitis B virus endemicity in the area of residence. Youngest age and lowest years of employment were independent predictors of the likelihood of vaccine acceptance.

Sexual transmission of hepatitis C virus and prevention with intramuscular immunoglobulin

The sexual transmission of hepatitis C virus (HCV) has long been debated. The prevalence of infected at-risk partners varies from 0% to 30%. In a prospective study, the risk of infection was quantified in steady heterosexual partners and the prophylactic effect of normal human polyvalent immune serum globulin (ISG) was evaluated. A total of 899 at-risk partners of HCV-infected patients were enrolled in a single-blind randomized controlled trial and assigned to receive every 2 month 4 mL of intramuscular ISG from unscreened donors (450 partners) or placebo (499 partners). Seven partners developed acute HCV infection (increased aminotransferase levels and appearance of HCV-RNA): six of the placebo group (incidence density [ID] 12.00/1,000 person year; 95% confidence interval [CI] 3.0 to 21.61), and only one of the ISG-treated group (ID 1.98/1,000 person year; 95% CI 0 to 5.86). The risk of infection was significantly higher in controls versus treated individuals (p = 0.03). Six couples had genotype 1b (85%), and one couple had genotype 1a; HCV sequence homology strongly supported sexual transmission. Our trial demonstrates that HCV infection can be sexually transmitted and quantifies the risk of sexual transmission: for every year of at-risk sexual relationship, almost 1% of the partners became infected. Intramuscular ISG is safe and well tolerated. Unlike ISG from screened donors, ISG from donors unscreened for anti-HCV contains high titers of anti-gpE1/gpE2 neutralizing antibodies and high neutralizing activity. Anti-HCV hyperimmune globulin could be prepared from anti-HCV-positive blood units and could be used to protect sexual partners and in other at-risk situations of exposure to HCV infection.

Correlation between virus genotype and chronicity rate in acute hepatitis C

BACKGROUND/AIMS

Forty-two patients with the diagnosis of acute hepatitis C virus hepatitis were studied to investigate the relationship between hepatitis C virus genotype and progression to chronic infection.

METHODS

The patients were followed for more than 1 year (mean age 29 years, male/female ratio 2.5). Intravenous drug use was documented in 15 cases, blood transfusion in four, surgical intervention, dental therapy or other parenteral exposure in 15, and unknown factors in the remaining eight. The evolution to chronicity was diagnosed on the basis of a persistent increase in transaminase levels, the presence of HCV-RNA and the histological pattern of chronic hepatitis.

RESULTS

The majority of cases presented hepatitis C virus infection of subtype 1a (38.1%) or 1b (33.9%). Six cases showed the presence of genotype 3a (14.3%). Subtype 2c was observed in three out of four cases infected with genotype 2. No significant association was demonstrated with documented risk factors. The overall chronicity rate was 59.5%. This value increased to 92% in individuals infected with genotype 1b. By multivariate analysis the age-adjusted odds ratio for infection with genotype 1b as compared with all other genotypes was 14.4 (95% confidence interval; 1.52-137). Moreover, significant differences (p= 0.0002) were present in this group for histological activity index (8.7 as compared with 5-7).

CONCLUSIONS

The results of this prospective study are consistent with an independent association between hepatitis C virus genotype 1b and a poor prognosis.

Ad hoc survey of hepatitis B vaccination campaign in newborns of HBsAg positive mothers and in 12-year-old subjects in southern Italy

The ongoing vaccination campaign against hepatitis B (HB) for newborns of hepatitis B surface antigen (HBsAg) positive mothers and for 12-year-old subjects was evaluated in Naples, Italy, an area of relatively high HB endemicity. Subjects were recruited by a random sampling procedure. Among 2060 pregnant women studied, 1887 (91.6%) were screened for HBsAg. HBsAg prevalence was 2.5% (47/1887). Immunoprophylaxis according to the protocol (immunoglobulins within 24 h plus vaccine within 7 days after birth) was administered in 26 (55.3%) out of the 47 newborns of HBsAg positive mothers; vaccination was delayed (later than 7 days after birth) for 14 (29.8%) infants; in the remaining seven newborns (14.9%) were not given immunoglobulins at birth. All infants were vaccinated. Out of the 1000 adolescents sampled 130 (13%) were not found due to an inaccurate census list; 727 (83.3%) of the 870 investigated had received a three-dose HB vaccine series. Overall, the HB vaccination program in Italy is working well. However, further efforts should be made to improve the efficacy and effectiveness of the campaign.

Sexual transmission of the hepatitis C virus and efficacy of prophylaxis with intramuscular immune serum globulin. A randomized controlled trial

OBJECTIVE

To estimate the risk of sexual transmission of hepatitis C and to assess the value of prophylaxis with periodic intramuscular immune serum globulin administration.

METHODS

Of 1102 steady heterosexual partners of patients with antibodies to the hepatitis C virus (HCV), 899 were enrolled in a single-blind, randomized, controlled trial. All the partners tested negative for antibodies to HCV and had normal baseline serum aminotransferase concentrations. The partners were assigned to receive 4 mL of 16% polyvalent immune serum globulin prepared from unscreened donors every 2 months (n = 450) or a placebo (n = 449). Tests for HCV infection were performed every 4 months.

RESULTS

Eight hundred eighty-four partners completed the study. Seven partners became infected with HCV: 6 in the control group (incidence density, 12.00 per 1000 person-years; 95% confidence interval, 3.0 21.61) and 1 in the immune serum globulin group (incidence density, 1.98 per 1000 person-years; 95% confidence interval, 0-5.86). The risk of infection was significantly higher for partners in the control group (P = .03): for each year approximately 1% of the partners became infected. Sequence homology studies strongly suggest the sexual transmission of HCV. All immune serum globulin lots used had high enzyme-linked immunosorbent assay titers of neutralizing antibodies to HCV envelope glycoproteins and high neutralization titers in the neutralization of binding assay.

CONCLUSIONS

Hepatitis C can be sexually transmitted. Immune serum globulin prepared from unscreened donors significantly reduced the risk. The treatment was safe and well tolerated. Because only immune serum globulin from unscreened donors (and not from those screened for HCV) contain anti-HCV neutralizing antibodies, hyperimmune anti-HCV immune serum globulin should be prepared from blood testing positive for antibodies to HCV, which is currently discarded.

Pre-S2 defective hepatitis B virus infection in patients with fulminant hepatitis

Controversial data were recently published concerning the association of hepatitis B virus (HBV) variants with fulminant hepatitis (FH). In this study, we first analyzed the complete nucleotide sequences of HBV genomes isolated from serum samples from a surgeon and his mother, who was accidentally infected by the son; both died of FH. The infecting viruses were genetically almost identical in both patients; all the clones examined carried a double nucleotide mutation in the start codon of the pre-S2 region that prevented the synthesis of the corresponding protein. Analyses of different serum samples from the son revealed only wild-type precore sequences in a high viremic serum, whereas hepatitis B e antigen (HBeAg)-defective strains were prevalent when the viremia had decreased. Subsequently, we extended the analysis to the viral genomes isolated from 18 additional patients with acute HBV infection and different clinical behaviors: 3 of 5 patients with FH and without previous liver disease had pre-S2 start codon mutations preventing pre-S2 protein synthesis, whereas none of the 13 control cases had similar genomic rearrangements. Analysis of the precore region showed that viral populations normally producing HBeAg were the only or the prevalent viral strains in all of these cases. In summary, our results support the hypothesis that the pre-S2 protein is not essential for HBV infectivity. They also show that infection by pre-S2-defective virus is frequently associated with FH, indicating that this variant might play a pathogenetic role in cases of acute liver failure. Finally, they suggest that the emergence of HBeAg-defective viruses might be a late event in the course of FH, occurring when HBeAg-producing viruses have been mostly cleared.

Risk factors for acute hepatitis B: a case-control study

Over the period 1989-1991 a case-control study was carried out in the area of Naples comparing 162 subjects with acute hepatitis B and 788 hospitalized control subjects. The results of multivariate analysis showed that surgical intervention (odds ratio 3.8; 95% CI 1.2-11.7), household contact with an hepatitis B surface antigen (HBsAg) positive carrier (odds ratio 2.7; 95% CI 1.1-6.7) and intravenous drug use (odds ratio 13.0; 95% CI 3.2-52.7) were risk factors independently associated with hepatitis B. No association was found with the other risk factors considered, such as blood transfusion, hospitalization, other percutaneous exposures, dental therapy, contact with an icteric case, barber shop shaving and two or more sexual partners. As a significant proportion of the general population undergoes surgical intervention, efficient procedures for sterilization of instruments should be implemented, together with the use of disposable materials, to control the spread of HBV infection in surgical settings.

Incidence rate and risk factors for HCV seroconversion among injecting drug users in an area with low HIV seroprevalence

We conducted a study on injecting drug users attending one of 3 drug treatment centres in Naples, to estimate HIV and hepatitis C virus (HCV) incidence rates and to identify risk factors for seroconversion. Incidence rates were estimated using as denominator the person-time of follow-up of participants who were negative for both HIV and HCV at enrollment and who were retested within 6-12 months. Information on risk factors was collected using a standardized questionnaire. A nested case-control analysis was performed comparing seroconverters with persistently HCV-negative individuals. None of the initially non-infected participants seroconverted for HIV, while the incidence rate for HCV infection was approximately 29 per 100 person-years. Analysis of risk factors showed that age > 28 years and injecting use of cocaine were associated with HCV seroconversion. The protective role of methadone treatment was also marginally significant. Our findings suggest that HCV infection may represent an important public health problem in areas with low HIV circulation. The identification of specific risk factors for HCV infection is needed to plan effective prevention strategies.

[The knowledge, attitudes and practice in regard to the risk for occupational HIV infection in a group of gynecologists from 3 Italian regions]

The risk of occupational infection by blood-borne pathogens has been well evaluated. However, a low perception of this risk among health care workers (HCWs) and a low compliance to infection control measures has been documented by several studies. During a meeting of gynecologists of Southern Italy, a survey of knowledge, attitudes and practices (K.A.P.) on HIV and other blood-borne viral infections was conducted among 143 obstetricians-gynecologists. 133 (93%) HCWs answered the questionnaire. 81% of them recalled almost one occupational exposure during their career and 54% almost two in the past year. Our data suggest a low knowledge about HIV and the other blood-borne viral infections and Universal Precautions (UP): only 16% of HCWs knew the rate of vertical transmission of HIV, less than 15% knew the rate of seroconversion after occupational exposure to HBV and HCV, and finally only 33% knew to which body fluids apply UP. Moreover, 93.7% of HCWs believed that HIV antibody screening of all patients is an effective strategy to reduce the risk of occupation HIV infection. More than 90% of gynecologists used to request HIV-antibodies to pregnant women, 21% after the first trimester. Although HCWs interviewed can not be considered representative of Italian gynecologists, our data suggest the need of an intensive training to increase gynecologists' knowledge about HIV, other blood-borne pathogens and the risk of occupational infections also in order to modify attitudes and practices.

Case control study of risk factors for hepatitis A: Naples 1990-1991. Hepatitis Collaborating Group

An increased incidence of hepatitis A was observed in Naples from 1990-1991. A hospital-based case-control study was carried out to evaluate the relative importance of various risk factors. A hundred and ninety-eight cases and 238 hospital controls were recruited during the study period. The strongest association was contact with a jaundiced person among children. A correlation was also shown for children and adults with raw shellfish consumption and pre-school nursery attendance or presence in the household of children attending pre-school nurseries. History of travel and intravenous drug use were risk factors for adult subjects. Considering the relative importance of the specific risk factors we found that 38% of the acute hepatitis A cases were attributable to contact with a jaundiced person, 15% to presence in the household of children attending pre-school nurseries and 28% to raw shellfish consumption.

Risk factors for acute non-A, non-B hepatitis and their relationship to antibodies for hepatitis C virus: a case-control study

A case-control study was carried out comparing 333 case subjects with non-A, non-B hepatitis and 1095 hospital control subjects. Of 333 case subjects, 197 (59%) were positive for hepatitis C antibody (anti-HCV). Excluding blood transfusion and intravenous drug use, surgical intervention and dental therapy were strongly associated with anti-HCV-positive cases: in particular, obstetric and gynecology surgical intervention was found to be strongly associated with HCV positivity (odds ratio [OR] = 32; 95% confidence interval [CI] = 7, 147). Raw shellfish consumption was a risk factor for anti-HCV-negative cases (OR = 2.2; 95% CI = 1.0, 5.1), thus suggesting an enterically transmitted virus in sporadic non-A, non-B hepatitis in Italy.

Understanding the dynamics of the HIV epidemic among Italian intravenous drug users: a cross-sectional versus a longitudinal approach

We studied annual human immunodeficiency virus (HIV) seroprevalence and incidence in a large number of intravenous drug users attending drug treatment centers in three Italian urban areas. We also evaluated risk factors for HIV seropositivity and for HIV seroconversion. The results showed that HIV prevalence and incidence are declining. HIV prevalence declined dramatically in study participants that were < 25 years old. Prevalent HIV cases were associated with older age and longer duration of intravenous drug use; however, short duration of drug use increased the risk of seroconversion. The findings of our study suggest that comparing cross-sectional and longitudinal data contributes to a better understanding of the dynamics of the HIV epidemic among intravenous drug users.

Hepatitis B in children in Italy: incidence and risk factors: SEIEVA Collaborating Group. Sistema Epidemiologico Integrato dell'Epatite virale Acuta

The objectives of the present report were to give a baseline picture of hepatitis B notification incidence rates in children before the campaign of mass vaccination for newborns and adolescents (12-13 years old), and to study the role of different risk factors. Data from a specific national surveillance system of acute viral hepatitis (SEIEVA, Sistema Epidemiologico Integrato dell'Epatite Virale Acuta) were used and acute hepatitis B cases were compared to acute hepatitis A patients with the case-control study method to estimate the associations with the considered risk factors. Since the system began, one hundred and sixty-three local health departments have joined SEIEVA covering 30% of the Italian population. The incidence of acute hepatitis B notifications among 0-14 aged children was 9 per 100,000 in 1985 and 1 per 100,000 in 1990. Such decline in incidence was observed in both the North and the South of Italy. Surgical interventions, dental therapy and household contacts with a HBsAg chronic carrier were found to be associated with acute hepatitis B. The point estimate of the odds ratio was 10 for the latter risk factor. Other preventive measures in addition to vaccination are needed to control the risk of hepatitis B infection and other parenteral diseases due to surgical intervention and dental therapy.

Hepatitis B mass immunization of adolescents: a pilot study in a community

The National Type Specific Hepatitis Surveillance System (SEIEVA) and seroepidemiological studies have shown that in addition to newborns from mothers who are carriers for hepatitis B surface antigen (HBsAg), adolescents are at high risk of acquiring type B hepatitis virus because of increasing importance of the heterosexual transmission of this virus. In order to evaluate logistic problems and acceptance rate of adolescents to mass vaccination against hepatitis B, a pilot study was carried out among all 7th grade children registered in the 9 schools of an hepatitis B endemic area located in the suburbs of Naples. After meetings held by the local health department with school teachers and parents, 1219 out of 1250 (97.5%) invited children received the first dose of hepatitis B vaccine; 1215 and 1209 received, respectively, the second and third doses. Anti-hepatitis B surface antigen (anti-HBs) values were studied in 406 subjects one month after the third dose, and 21 out of 406 (5.2%) had anti-HBs values less than 10 IU/L. We consider 95% of subjects with anti-HBs values greater than 9 IU/L a good achievement for a field vaccination program. The high acceptance rate of vaccination found in our study outlines the importance of active offer of vaccination combined with school involvement.

Decline of incidence of A, B and non-A, non-B hepatitis in Italy. Results of four years surveillance (1985-88). SEIEVA collaborating group

A specific surveillance system for acute viral hepatitis which uses weekly notification of cases and a standard risk factor questionnaire was started in Italy in 1984. From 1985 to 1988 153 Health Departments (27% of Italian population) joined the system. Estimated incidence of reported viral hepatitis was 30 per 100,000 in 1985 and 14 in 1988. The decline was impressive for hepatitis A, particularly in the south. Reduction of incidence was also evident for hepatitis B and Non-A, Non-B hepatitis, particularly in young adults. The decrease of viral hepatitis in Italy is consistent with recent seroepidemiological data. Shellfish consumption was the most frequent risk factor reported for hepatitis A cases at all ages. Hospitalization, surgical intervention, dental therapy and other percutaneous exposures still play a role in the transmission of parenteral hepatitis in Italy. Blood transfusions seem to be important only for Non-A, Non-B. Interventions other than vaccination to prevent B and Non-A, Non-B hepatitis due to hospitalization, surgical intervention, other percutaneous exposures and dental therapy are needed and can further contribute to the decline of hepatitis virus infection rates in Italy.

A village outbreak of hepatitis A: acquaintance network and inapparent pre-school transmission compared

A village outbreak of 38 cases of serologically confirmed hepatitis A is described. The epidemic curve was a propagative one and all of the cases occurred in primary school-age or pre-school children. In 1984 the incidence in this age group was 5,000 per 100,000, about 50 times the corresponding national rate. Although 21 of the cases attended the single primary school, these cases were not clustered within school years or classes and examination of onset dates showed only four cases could have resulted from case transmission within classes. A matched triplet case-control study was undertaken to measure the risk associated with prior contact with a case within the acquaintance network and the risk of household contact with either of the two pre-school nurseries where inapparent transmission may have been occurring. Whereas a similar proportion of cases and controls had direct or indirect contact with the nurseries, 48% of cases, compared with 9% of controls, reported a previous case of jaundice within 6 weeks amongst their acquaintance network (matched triplet analysis P less than .0001).