Risks of rheumatic diseases in first‐ and second‐generation immigrants in Sweden: A nationwide followup study

Objective

To examine whether there is an association between country of birth in first‐generation immigrants and first hospitalization for a rheumatic disease, and to study whether any such association remains in second‐generation immigrants.

Methods

In this followup study, the Swedish MigMed database at the Karolinska Institute in Stockholm was used to identify all primary hospital diagnoses of rheumatic diseases in first‐ and second‐generation immigrants in Sweden between January 1, 1964 and December 31, 2004. Incidence ratios, standardized with regard to age, geographic region, and socioeconomic status, were estimated by sex in first‐ and second‐generation immigrants.

Results

First‐generation immigrants from Iraq had a higher risk of rheumatoid arthritis than did subjects in the native‐born Swede reference group, and the risk of systemic lupus erythematosus was increased in immigrants from Iraq and Africa; these raised risks persisted in the second generation. The lower risk of rheumatoid arthritis in some first‐generation immigrants disappeared in the second generation. In groups of second‐generation immigrants, the risk of ankylosing spondylitis was similar to the risk in the corresponding parental groups. Polish‐born immigrants and second‐generation Yugoslavs and Russians showed a significantly increased risk of systemic sclerosis. The raised risk of systemic sclerosis did not persist in the second generation, but was clustered in groups involved in certain blue collar occupations.

Conclusion

Country of birth affected the risk of rheumatic disease. These findings indicate that both genetic and environmental factors are involved in the etiology of specific rheumatic diseases.

     

Does immigration contribute to decreasing CHD incidence? Coronary risk factors among immigrants in Göteborg,Sweden

Abstract. Dotevall A, Rosengren A, Lappas G, Wilhelmsen L (Sahlgrenska University Hospital at Ostra, Göteborg University, Göteborg, Sweden). Does immigration contribute to decreasing CHD incidence? Coronary risk factors among immigrants in Göteborg, Sweden. J Intern Med 2000; 247: 331–339. Objectives. To investigate if an increasing proportion of immigrants may have contributed to the decreasing trend in coronary heart disease (CHD) in Sweden during the last few decades and to analyse the cardiovascular risk factor pattern in immigrants compared to Swedish‐born subjects. Population and methods. CVD risk factors were investigated within the framework of the WHO MONICA project. A random sample of 1618 men and women aged 25–64 years responded to the invitation to a screening procedure including questionnaires and physical and laboratory examination. Data on myocardial infarctions (MI) were collected from the Göteborg Myocardial Infarction Register. Data from the City Council secretariat were used to estimate the number of immigrants in the total population. Results. In 1995, immigrants constituted 22.4% of the population between 25 and 64 years of age in Göteborg. The incidence of MI in immigrants, 21.7%, was similar to that in Swedish‐born subjects. Non‐Finnish immigrants reported more unemployment, low physical activity during leisure time and psychological stress than Swedish subjects. Immigrant men also smoked more. BMI and WHR were significantly higher in immigrant women and Finnish immigrants had higher blood pressure than Swedes. Total‐ and LDL‐cholesterol were higher in Finnish men. HDL‐cholesterol was significantly lower and s‐triglycerides significantly higher in non‐Finnish immigrants of both genders. Conclusion. The decreasing trend in CHD in Sweden during the last few decades is not due to an increasing number of immigrants from ‘low‐risk countries’. On the contrary, the immigrants in the present study seem to have a worse CVD risk factor profile than Swedes.     

Immigrants from the Middle‐East have a different form of Type 2 diabetes compared with Swedish patients

Aims To compare the clinical characteristics of Type 2 diabetes (T2DM) between immigrants from the Middle‐East and Swedish patients. Methods The study group included 450 consecutive patients with T2DM, 379 Swedish‐born aged 61 ± 12 years and 71 patients originally from the Middle‐East aged 50 ± 11 years from the diabetes clinic of Malmo University Hospital. Results Onset of diabetes had occurred 12 years earlier in the Middle‐East immigrants compared with the Swedish‐born patients (43 ± 10 vs. 55 ± 12 years, P < 0.001). Immigrants had lower fasting serum C‐peptide [0.7 (0.1–2.6) vs. 0.9 (0.1–4.0) nmol/l, P = 0.013], lower homeostasis model assessment (HOMA)‐β[1.7 (0.1–9.1) vs. 2.7 (0.1–59.0), P = 0.010], lower HOMA‐IR [0.4 (0.02–1.19) vs. 0.4 (0.01–2.8), P = 0.005] than the Swedish group. A first‐degree family history of diabetes was reported in 61% of immigrants, compared with 47% of Swedish‐born (P = 0.022). Conclusions Immigrants from the Middle‐East have an earlier onset, stronger family history and more rapid decline of pancreatic B‐cell function than Swedish patients, suggesting that they have a different form of T2DM compared with Swedish patients.     

Coronary heart disease risks in first- and second-generation immigrants in Sweden: a follow-up study

OBJECTIVES: To analyse whether there is an association between country of birth in first-generation immigrants and first hospitalization for or death from coronary heart disease (CHD) and to analyse whether this association remains in second-generation immigrants. DESIGN: In this follow-up study, the MigMed database at the Karolinska Institute, Stockholm, was used to identify all hospital diagnoses of and deaths from incident CHD in first- and second-generation immigrants in Sweden between 1 January 1987 and 31 December 2001. Incidence ratios standardized by age, geographical region and socio-economic status were estimated by sex in first- and second-generation immigrants; the reference group was Swedish-born people whose parents were both born in Sweden. SUBJECTS: The total Swedish population aged 25-69 years. RESULTS: First-generation immigrants from Finland, central European countries, other eastern European countries and Turkey had higher rates of CHD than men or women in the reference group. First-generation immigrant women born in southern Europe, other western European countries and Baltic countries had lower CHD risks than the reference group. Sons of both male and female first-generation immigrants showed CHD risks similar to or slightly higher than those of their parents. Amongst second-generation women, only subjects with Finnish fathers or mothers had higher risks of developing CHD than the reference. CONCLUSIONS: Increased risks of CHD found in some first-generation immigrant groups often persist in second-generation immigrant men. Healthcare professionals and policy makers should take this into account when designing and undertaking measures to prevent CHD.     

Gout in immigrant groups: a cohort study in Sweden

Our aim was to study the association between country of birth and incidence of gout in different immigrant groups in Sweden. The study population included the whole population of Sweden. Gout was defined as having at least one registered diagnosis in the National Patient Register. The association between incidence of gout and country of birth was assessed by Cox regression, with hazard ratios (HRs) and 95% confidence intervals (95% CI), using Swedish-born individuals as referents. All models were conducted in both men and women, and the full model was adjusted for age, place of residence in Sweden, educational level, marital status, neighbourhood socio-economic status and co-morbidities. The risk of gout varied by country of origin, with highest estimates, compared to Swedish born, in fully adjusted models among men from Iraq (HR 1.82, 95% CI 1.54–2.16), and Russia (HR 1.69, 95% CI 1.26–2.27), and also high among men from Austria, Poland, Africa and Asian countries outside the Middle East; and among women from Africa (HR 2.23, 95% CI 1.50–3.31), Hungary (HR 1.98, 95% CI 1.45–2.71), Iraq (HR 1.76, 95% CI 1.13–2.74) and Austria (HR 1.70, 95% CI 1.07–2.70), and also high among women from Poland. The risk of gout was lower among men from Greece, Spain, Nordic countries (except Finland) and Latin America and among women from Southern Europe, compared to their Swedish counterparts. The increased risk of gout among several immigrant groups is likely explained by a high cardio-metabolic risk factor pattern needing attention.     

Cohort effects on gender differences in alcohol dependence

Aims The present study investigated the presence of cohort effects on gender differences in the course, severity and symptomatology of DSM‐III‐R alcohol dependence in a community‐based sample. Design A comparison of substance‐related variables among men and women divided into two groups based on the median birth year of the sample was conducted. Participants Participants were 468 men and 132 women with life‐time alcohol dependence, the vast majority of whom were born between 1941 and 1960. Measurements Substance use and DSM‐III‐R substance use disorders were assessed by a structured interview administered in person. Findings Individuals born after 1951 had higher rates of alcohol dependence. Among individuals with alcohol dependence, those born after 1951 had an earlier onset and longer duration of alcohol‐related problems. Significant interactions indicated that these effects were stronger for women than men. Conclusions Risk for alcohol dependence appears to be rising in younger generations, and particularly for younger women, making them an important target group for prevention and treatment programs.     

Difference in prevalence of hepatitis B markers in children born either in Sweden or in Turkey of Assyrian immigrants

Sera from 95 children below 20 years of age born to Assyrian immigrants were tested for markers for hepatitis B virus (HBV). HBV markers were found in 26% of the study population. However, no markers were demonstrated in children born in Sweden. Of the 62 children born in Turkey or the Middle East 39% had HBV markers and 4 (6.5%) had HBsAg. Three of the 4 HBsAg+ children had anti-HBe and 1 HBeAg. These results suggest that the transmission of HB in Assyrians may be mainly horizontal rather than vertical. Children of Assyrian immigrants born in Sweden do not seem to constitute a risk group for transmission of HB, whereas those born in Turkey or the Middle East constitute the same risk as reported in a general population of Turks.     

Incidence of celiac disease among second-generation immigrants and adoptees from abroad in Sweden: evidence for ethnic differences in susceptibility

Abstract

Background and aims. The incidence of celiac disease (CD) shows large, worldwide variation. However, whether its causes are environmental (gluten-containing diet) or genetic (specific haplotype) have not been established. The aim of the present study is to examine the incidence of CD among second-generation immigrants and adoptees from abroad to disentangle genetic/ethnic versus environmental influences (assuming that immigrants have similar gluten exposures to native Swedes, and thus differ from them only in terms of their genetic background). Methods. Second-generation immigrants and adoptees from abroad were identified in the MigMed 2 Database and were followed until diagnosis of CD, death, or the end of study. Standardized incidence ratios (SIRs) were calculated among these immigrants with native Swedes as the reference group. Results. A total of 1,050,569 children were defined as second-generation immigrants and the overall SIR of CD (SIR = 0.89, 95% confidence interval 0.84–0.94) was significantly lower than that of native Swedes. The incidence of CD among children with parents from Western, Eastern, and Northern European countries was similar to that in native Swedes, but was lower for those with parents from low-prevalence countries, especially Eastern and Southeast Asian countries. A total of 51,557 children born in foreign countries were adopted by Swedes. Adoptees from Eastern Asia had a significantly decreased SIR of CD. Conclusions. The decreased incidence of CD in second-generation immigrants and some groups of adoptees from abroad strongly suggests that ethnic genetic heterogeneity may contribute to the worldwide variation in CD incidence.     

Cancer risk in patients with rheumatoid arthritis treated with anti–tumor necrosis factor α therapies: Does the risk change with the time since start of treatment?

Objective

To determine the short‐term and medium‐term risks of cancer in patients receiving anti–tumor necrosis factor α (anti‐TNFα) therapies that have proven effective in the treatment of chronic inflammatory conditions.

Methods

By linking together data from the Swedish Biologics Register, Swedish registers of RA, and the Swedish Cancer Register, we identified and analyzed for cancer occurrence a national cohort of 6,366 patients with RA who first started anti‐TNF therapy between January 1999 and July 2006. As comparators, we used a national biologics‐naive RA cohort (n = 61,160), a cohort of RA patients newly starting methotrexate (n = 5,989), a cohort of RA patients newly starting disease‐modifying antirheumatic drug combination therapy (n = 1,838), and the general population of Sweden. Relative risks (RRs) were estimated using Cox regression analyses, examining overall RR as well as RR by time since the first start of anti‐TNF therapy, by the duration of active anti‐TNF therapy, and by the anti‐TNF agent received.

Results

During 25,693 person‐years of followup in 6,366 patients newly starting anti‐TNF, 240 first cancers occurred, yielding an RR of 1.00 (95% confidence interval 0.86–1.15) versus the biologics‐naive RA cohort, and similar RRs versus the other 2 RA comparators. RRs did not increase with increasing time since the start of anti‐TNF therapy, nor with the cumulative duration of active anti‐TNF therapy. During the first year following the first treatment start, but not thereafter, dissimilar cancer risks for adalimumab, etanercept, and infliximab were observed.

Conclusion

During the first 6 years after the start of anti‐TNF therapy in routine care, no overall elevation of cancer risk and no increase with followup time were observed.

     

Alcohol-related and viral hepatitis C-related cirrhosis mortality among Hispanic subgroups in the United States, 2000-2004

Background: Hispanics have much higher cirrhosis mortality rates than non‐Hispanic Blacks and Whites. Although heavy alcohol use and hepatitis C virus (HCV) infection are two major risk factors for cirrhosis, no studies have systematically assessed the contribution of alcohol‐ and HCV‐related cirrhosis deaths to the total cirrhosis mortality for Hispanics as a whole and its variations across Hispanic subgroups. To fill this gap, this study presents the latest data on total cirrhosis mortality as well as its component alcohol‐ and HCV‐related cirrhosis mortality for all Hispanics and for Hispanic subgroups. Methods: The multiple‐cause approach was used to analyze data from the U.S. Multiple Cause of Death Data Files for 28,432 Hispanics and 168,856 non‐Hispanic Whites (as a comparison group) who died from cirrhosis as the underlying or a contributing cause during 2000–2004. Four major Hispanic subgroups were defined by national origin or ancestry, including Mexicans, Puerto Ricans, Cubans, and Other Hispanics. The cirrhosis deaths were divided into four distinctive cause‐of‐death categories: alcohol‐related, HCV‐related, both alcohol‐ and HCV‐related, and neither alcohol‐ nor HCV‐related. Age‐adjusted total cirrhosis death rates and percentage shares of the cause‐specific categories were compared across Hispanic subgroups and non‐Hispanic Whites. Results: Compared with non‐Hispanic Whites, all Hispanic subgroups except Cubans had much higher cirrhosis mortality. The age‐adjusted total cirrhosis death rates were twice as high for Puerto Ricans and Mexicans as for non‐Hispanic Whites. Alcohol‐related and HCV‐related cirrhosis death rates also were higher for most Hispanic subgroups than for non‐Hispanic Whites. Conclusions: Heavy alcohol use and hepatitis C viral infection are two important factors contributing to the high cirrhosis mortality among Hispanics. However, their relative contributions to total cirrhosis mortality varied by gender and Hispanic subgroup. This information is useful for targeted prevention and intervention efforts to address the excessive cirrhosis mortality in the Hispanic population.     

Socio‐economic status predicts drinking patterns but not alcohol‐related consequences independently

Aim To identify independent relationships between socio‐economic status and drinking patterns and related consequences and to identify socio‐economic groups at risk for heavier consumption. Design and setting Three comparable national telephone surveys were utilized: 1995, 2000 and 2004. The respondents were aged 18–65 years. Contextual information includes that a number of liberalized alcohol policy changes occurred over the time of the surveys. Results Educational qualification, income and occupation were associated independently with alcohol consumption. There were indications that the different dimensions of drinking (quantity and frequency) had different relationships with socio‐economic status (SES). For example, lower SES groups drank heavier quantities while higher SES groups drank more frequently. SES, however, did not play a major role predicting drinking consequences once drinking patterns were controlled for, although there were some exceptions. It was the lower‐to‐average SES groups that were at greater risk for drinking heavier quantities compared to other SES groups in the population (as they had sustained increases in the quantities they consumed over time where other SES groups did not). Conclusion Socio‐economic status was related independently to drinking patterns and there were indications that SES interacted differently with the different dimensions of drinking (quantity and frequency). For the most part, socio‐economic status was not related independently to the experience of alcohol‐related consequences once drinking patterns were accounted for. It was the lower‐to‐average SES groups that were at greater risk for drinking heavier quantities compared to other SES groups in the population.     

Increased incidence of cardiovascular disease in patients with rheumatoid arthritis: results from a community based study

Objective: To investigate the first-ever incidence of acute myocardial infarction and stroke in a community based RA cohort compared with the general population. Methods: The RA cohort consisted of all patients in a local RA register in Malmö, Sweden (n = 1022). The patients were recruited from private and hospital based rheumatology practices, and made up the absolute majority of patients with RA in the city. The general population of Malmö, aged 16 and above, served as controls. From the Swedish National Hospital Discharge Register and the national Swedish Causes of Death Register, information about all first-ever myocardial infarctions and strokes in Malmö residents between July 1997 and December 1999 was retrieved. The age and sex adjusted standardised morbidity ratio (SMR) of the two cohorts was calculated. Results: Fifty four patients with RA had first-ever myocardial infarctions or stroke during the study period, compared with 3862 subjects in the general population. The age and sex adjusted SMR was 161 (95% confidence interval (CI) 121 to 210). The first-ever incidence of cardiovascular disease was increased among female and male patients when studied separately. The increase of cardiovascular events in the RA cohort was mainly due to an excess of myocardial infarctions (n = 36; SMR = 176 (95% CI 123 to 244). Conclusion: Patients with RA in Malmö had an increased first-ever incidence of myocardial infarction or stroke compared with the general population. This confirms that cardiovascular comorbidity is of major importance in RA.     

Incidence of appendicitis according to region of origin in first- and second-generation immigrants and adoptees in Sweden. A cohort follow-up study

Background. Geographic variations in incidence of appendicitis and proportion of perforations suggest environmental or genetic etiological factors. We study incidence of appendicitis and proportion of perforations according to geographical origin in immigrants and international adoptees in Sweden. Methods. A cohort of 11,557,566 Swedish residents – 277,104 first- and 377,773 second-generation immigrants and 57,304 adoptees – was followed from 1988 till 2010. Differences in proportion of operation for perforated appendicitis and negative appendectomy and standardized incidence ratios (SIR) of perforated and non-perforated appendicitis associated with geographic origin was analyzed. Results. High incidence rates are seen in first- and second-generation immigrants from South America for perforated (SIR 1.58 and 1.81, respectively) and non-perforated appendicitis (SIR 1.18 and 1.22, respectively), and in adoptees from South America for non-perforated appendicitis (SIR 1.07). Low incidence rates are seen for perforated appendicitis in first-generation immigrants and adoptees from Asia (SIR 0.74 and 0.56, respectively), and for non-perforated appendicitis in immigrants from Africa and Asia (SIR 0.69 and 0.76 in first-generation, 0.51 and 0.74 in second-generation, respectively) and in adoptees from Asia (SIR 0.71). A high proportion of perforated appendicitis is associated with a low incidence rate of non-perforated appendicitis but no increase in the incidence rate of perforated appendicitis. Conclusions. The association of different incidence of appendicitis with geographic origin which remains over generations and is seen in adoptees suggest genetic etiologic factors. The proportion of perforation can be high without an increased incidence rate of perforation and is therefore an imperfect indicator of quality of care.     

Smoking cessation among daily smokers, aged 45-69 years: a longitudinal study in Malmö, Sweden

Objective To investigate differences in snuff consumption, socio‐demographic and psychosocial characteristics between baseline daily smokers who had remained daily smokers, become intermittent smokers or stopped smoking at the 1‐year follow‐up. Design, setting, participants and measurements A population of 12 507 individuals aged 45–69 years, interviewed at baseline in 1992–94 and at a 1‐year follow‐up, was investigated in this longitudinal study. The three groups of baseline daily smokers were compared to the total population according to socio‐demographic, psychosocial and snuff consumption characteristics. A multivariate logistic regression model was used to assess differences in psychosocial conditions, adjusting for age, sex, country of origin, marital status, education and snuff consumption. Findings Eighty‐six per cent of all baseline daily smokers remained daily smokers, 6.5% had become intermittent smokers and 7.3% had stopped smoking at the 1‐year follow‐up. The daily smokers who remained daily smokers were more likely to be born in other countries than Sweden, not married, have a lower educational level and poorer psychosocial conditions than the total population, while the socio‐demographic characteristics and psychosocial resources of those daily smokers who had become intermittent smokers or had stopped smoking were much more similar to the general population, with the exception of a higher snuff consumption, especially for intermittent smokers. Conclusions Daily smokers who remained daily smokers at the 1‐year follow‐up had poorer psychosocial assets, especially social participation, than baseline daily smokers who had become intermittent smokers or had stopped smoking, and the general population. The results suggest that low levels of social participation are a potent barrier against smoking cessation. Snuff consumption may explain a part of the increase in smoking cessation among men as opposed to women in Sweden.     

A prospective study of the association between smoking and later alcohol drinking in the general population

Aims To address the possible prospective association between smoking habits and risk of later heavy drinking in the adult population. Design Pooled population‐based long‐term cohort studies with repeated assessments of smoking and alcohol habits. Setting Copenhagen, Denmark. Participants A total of 14 130 non‐ to moderate drinkers at baseline, who attended re‐examination. Measurements Among the non‐ to moderate drinkers we addressed the relation between smoking habits at first examination and the risk of becoming a heavy and excessive drinker at follow‐up. Findings Level of tobacco consumption at first examination predicted an increased risk of becoming a heavy and excessive drinker in a dose‐dependent manner. Men who smoked more than 25 g of tobacco per day had adjusted odds ratios of 2.12 (95% confidence interval (CI): 1.44–3.11) and 3.95 (95% CI: 1.93–8.95) for becoming heavy and excessive drinkers, compared to participants who had never smoked. Equivalent estimates among women were 1.76 (95% CI: 1.02–3.04) and 2.21 (95% CI: 1.00–4.58), respectively. Conclusions This study suggests that tobacco use is associated quantitatively with later risk of heavier drinking.     

Glucose-lowering treatment and clinical results in 163 121 patients with type 2 diabetes: an observational study from the Swedish national diabetes register

Aims: To analyse clinical characteristics and treatment results in unselected type 2 diabetes mellitus (T2DM) patients, with non‐pharmacological treatment as well as the most commonly used pharmacological glucose‐lowering treatment regimens, in everyday clinical practice. Methods: In this population‐based cross‐sectional study, information was linked from the Swedish National Diabetes Register, Prescribed Drug Register and Patient Register. T2DM patients with non‐pharmacological treatment and T2DM patients continuously using the 12 most common pharmacological treatment regimens were included in the study (n = 163121). Results: There were statistically significant differences in clinical characteristics between the groups. Patients with insulin‐based treatment regimens had the longest duration of diabetes and more cardiovascular risk factors than the T2DM‐population in general. The proportion of patients reaching HbA1c ≤7% varied between 70.1% (metformin) and 25.0% [premixed insulin (PMI) + SU) in patients with pharmacological treatment. 84.8% of the patients with non‐pharmacological treatment reached target. Compared to patients on metformin, patients on other pharmacological treatments had a lower likelihood, with hazard ratios ranging from 0.58; 95% confidence interval (CI), 0.54–0.63 to 0.97;0.94–0.99, of having HbA1c ≤7% (adjusted for covariates). Patients on insulin‐based treatments had the lowest likelihood, while non‐pharmacological treatment was associated with an increased likelihood of having HbA1c ≤7%. Conclusion: This nation‐wide study shows insufficiently reached treatment goals for haemoglobin A1c (HbA1c) in all treatment groups. Patients on insulin‐based treatment regimens had the longest duration of diabetes, more cardiovascular risk factors and the highest proportions of patients not reaching HbA1c target.     

Alcohol use,heavy episodic drinking and subsequent problems among adolescents in 23 European countries: does the prevention paradox apply?

Aims According to the prevention paradox, a majority of alcohol‐related problems in a population can be attributed to low to moderate drinkers simply because they are more numerous than heavy drinkers, who have a higher individual risk of adverse outcomes. We examined the prevention paradox in annual alcohol consumption, heavy episodic drinking (HED) and alcohol‐related problems among adolescents in 23 European countries. Design and setting Survey data from the 2007 European School Survey Project on Alcohol and Drugs (ESPAD) among 16‐year‐old students were analysed. Participants A total of 38 370 alcohol‐consuming adolescents (19 936 boys and 18 434 girls) from 23 European countries were included. Measurements The upper 10% and the bottom 90% of drinkers by annual alcohol intake, with or without HED, and frequency of HED, were compared for the distribution of 10 different alcohol‐related problems. Findings Although the mean levels of consumption and alcohol‐related problems varied largely between genders and countries, in almost all countries the heavy episodic drinkers in the bottom 90% of consumers by volume accounted for most alcohol‐related problems, irrespective of severity of problem. However, adolescents with three or more occasions of HED a month accounted for a majority of problems. Conclusions The prevention paradox, based on measures of annual consumption and heavy episodic drinking, seems valid for adolescent European boys and girls. However, a minority with frequent heavy episodic drinking accounted for a large proportion of all problems, illustrating limitations of the concept. As heavy episodic drinking is common among adolescents, our results support general prevention initiatives combined with targeted interventions.     

Epidemiology of hepatitis A in children in Sweden 1979-1983

The incidence and transmission of hepatitis A in the Swedish child population was investigated for the period 1979-83. 47% (152/323) of the hepatitis A cases in children reported in Sweden 1979-83 occurred in children born to parents of foreign extraction. The annual incidence in Swedish children was extremely low (2/100,000) during this period, whereas the incidence was between 103 and 20 in children born to immigrants of Turkish, Yugoslavian, Asian or African extraction. A known transmission of hepatitis A to Swedish children occurred mainly from 3 sources; in 60 cases (35%) by exposure within the families; in 18 of these cases a family member had been abroad, visiting a country where hepatitis A is endemic; in 34 cases (20%) by exposure in a pre-school setting; and in 29 cases (17%) by exposure when travelling abroad. In 48 cases (28%) the exposure was unknown.