Hepatitis A in Swedish travellers Erik Nordenfelt
The incidence of hepatitis A is very low in Sweden. It has been shown that the prevalence of antibodies to hepatitis A virus is 6.6% in individuals 50 O00 for travel to the Mediterranean part o f Europe, ~ lOOfor travel to Africa and ~ 300Jot travel to Asia. Keywords: Hepatitis A; immune globulin; traveller
INTRODUCTION
RESULTS
The prevalence of antibodies against hepatitis A (antiHAV) is very low in Sweden. In an investigation of the distribution of anti-HAV among Swedes without a history of jaundice ~ a frequency of 6.6% was seen in individuals < 40 years of age. Of 54 children and adolescents < 20 years, none had detectable anti-HAV. Because of the very low level of natural immunity, immune globulin (Ig) has been widely used as prophylaxis for hepatitis A among travellers going to areas where this infection is endemic. It is mandatory for physicians in Sweden to report cases of hepatitis A infection to the national register. The source of infection is also registered. A significant number of the registered cases have been contracted in association with travel outside the Nordic countries. Hepatitis A in Swedish travellers to endemic areas has already been reported for 1970-19842,3. This is a report on the situation for the period 1985-1990.
The number of reported cases of hepatitis A infection has declined from 628 in 1985 to ~ 250 cases annually during the last four years (Figure 1). Sweden has 8.5 million inhabitants. The attack rate per 100 000 inhabitants has thus declined from 7.3 to around 3 during this period. The number of cases infected in association with travel have been rather consistent at ~ 140 annually in the period 1985-1990. This means that at the beginning of this period ,~ 20%, and at the end 60%, of the registered hepatitis A cases were associated with travel. With slight variation during the period, about onethird of the total cases were each associated with travel either in Europe or to Asia (Table 1).
MATERIALS
AND METHODS
The national register of notifiable infectious diseases (Epidemiologiska Avdelningen, SBL, Stockholm) was the source of information regarding the number and source of hepatitis A infections. The Swedish Tourist Board (Sveriges Turistr~d, Sverigehuset) and the Statistical Year Book 1990 were the sources of statistics on travel and population. Kabi Pharmacia AB, gave the information regarding sale and use of Ig.
60C
30G
1985
1986
1987
1988
1989
1990
Year
Department of Medical Microbiology, University of Lund, SOIvegatan 23, S-223 62 Lund, Sweden 0264-410X/92/100S73-02 © 1992Butterworth-HeinemannLtd
Figure 1
Number of cases of hepatitis A in Sweden. _J, Total; J ,
associated with travel
Vaccine, Vol. 10, Suppl. 1, 1992 $73
Hepatitis A in Swedish travellers. E. Nordenfelt Table 1 Number of hepatitis A infections associated with travel to different continents per year Travelto
1985
Africa 31 Europe 37 North and South America 13 Asia 43 Unspecified (more than one) Total 124
1 9 8 6 1 9 8 7 1 9 8 8 1 9 8 9 1990 16 43 14 52 4 129
14 42 12 61 3 132
20 53 23 55 5 156
41 53 13 45 5 157
26 62 17 50 1 156
The age groups 0 14, 15 30, 3 1 4 5 and >45 years each account, with slight variation, for 25% of the cases. Until 1988 there was a steady rise in foreign travel. Between 1984 and 1988 there was a rise of 40% in passengers on international charter flights. It was estimated that in 1985 ~ I million Swedes went to the Mediterranean area of Europe. In 1989 and 1990 this figure increased to ~ 2 million. In 1989 the estimated total number of tourist travels outside the Nordic countries was 5.2 million tourist and 1.3 million business, a total of 6.5 million. In 1990 the total number of travels was the same but the number of tourist travels were lower (4.9 million) and business travels higher (1.6 million). Ig has been widely used as prophylaxis against hepatitis A infection but the use has declined. The statistics of total sales for lg show that the number of doses sold remained at the same level during 1986-1990 in spite of the rise in the number of travels. In the beginning of the 1980s ~ 45% of travellers to the mediterranean area of Europe received Ig 4. As the number of travellers to that area has doubled, it can be estimated that ~ 25% now use specific prophylaxis. Travellers to Africa and Asia use prophylaxis at a ratio estimated to be ~ 95%L Based on travel statistics and the estimations of doses of Ig used for prophylaxis, a risk ratio expressed as the number of travellers who did not receive Ig per case of hepatitis A infection can be calculated (Table 2). This risk ratio is ~ 5000 for travel to the Mediterranean part of Europe, ~ 100 for travel to Africa, and ~ 300 for travel to Asia.
DISCUSSION Hepatitis A in Swedish travellers has been studied and reported earlier for 1970 1984 e-~. In these investigations, the incidence of hepatitis A infection among travellers to the Mediterranean area of Europe could be seen to decrease dramatically from one case per 3000 travellers without lg in 1970 1972 to I in 20 000 in 1982-'. The results from the estimations in this report further confirm this decline. This must reflect a changing epidemiology of hepatitis A infection in this arca. The risk of Swedish travellers acquiring hepatitis A when going to remote destinations such as Africa and Asia seems to be the same during the periods studied. The number of cases with travel-associated hepatitis A has been stable and low during the last five years, although it forms a predominant part of the total number of hepatitis A cases in Sweden. The relative incidence of hepatitis A among travellers has, however, diminished as the total number of travellers has risen. Thus it must be concluded that the present routines for Ig prophylaxis against hepatitis A infection among Swedish travellers have worked satisfactorily.
ACKNOWLEDGEM
ENTS
The information and help from Dr Rolf Alsterlund, Epidemiologiska Avdelningen, SBL, Stockholm, Mr Lars Viddn, Sveriges Turistr~,d, Stockholm and Dr Bertil Eriksson, Kabi Pharmacia AB, Stockholm is gratefully acknowledged.
REFERENCES 1
Iwarson, S., Fr6sner, G., Lindholm, A. and Norkrans, G. The changed epidemiology of hepatitis A infection in Scandinavia. Scand. J. Infect Dis. 1978, 10, 155-156 Christenson, B. Epidemiological aspects of acute viral hepatitis A in Swedish travellers to endemic areas. Scand. J. Infect Dis. 1985, 17, 5-10 Christenson, B. Hepatit A hos svenska utlandsresen&rer - en epidemiologisk 6versikt. Lakartidningen 1986, 83, 2309--2310 Sparf, M. Enkat om reseprofylax. Kabijournalen 1984, 3, 85-86
Table 2 Hepatitis A cases among Swedish travellers to different areas. Risk ratio is number of travellers without Ig prophylaxis per case of hepatitis A infection 1989
1990
Travel to
No. of cases
Total No. of travellers per million
Risk ratio
No. of cases
Total No. of travellers per million
Risk ratio
Mediterranean area of Europe Africa Asia
29 41 48
2.2 0.1 0.3
~ 57 000 ~ 100 >_300
24 26 44
1.8 0.05 0.3
~-.56 000 z 100 ~. 300
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V a c c i n e , Vol. 10, Suppl. 1, 1992
The incidence of hepatitis A is very low in Sweden. It has been shown that the prevalence of antibodies to hepatitis A virus is 6.6% in individuals 50 O00 for travel to the Mediterranean part o f Europe, ~ lOOfor travel to Africa and ~ 300Jot travel to Asia. Keywords: Hepatitis A; immune globulin; traveller
INTRODUCTION
RESULTS
The prevalence of antibodies against hepatitis A (antiHAV) is very low in Sweden. In an investigation of the distribution of anti-HAV among Swedes without a history of jaundice ~ a frequency of 6.6% was seen in individuals < 40 years of age. Of 54 children and adolescents < 20 years, none had detectable anti-HAV. Because of the very low level of natural immunity, immune globulin (Ig) has been widely used as prophylaxis for hepatitis A among travellers going to areas where this infection is endemic. It is mandatory for physicians in Sweden to report cases of hepatitis A infection to the national register. The source of infection is also registered. A significant number of the registered cases have been contracted in association with travel outside the Nordic countries. Hepatitis A in Swedish travellers to endemic areas has already been reported for 1970-19842,3. This is a report on the situation for the period 1985-1990.
The number of reported cases of hepatitis A infection has declined from 628 in 1985 to ~ 250 cases annually during the last four years (Figure 1). Sweden has 8.5 million inhabitants. The attack rate per 100 000 inhabitants has thus declined from 7.3 to around 3 during this period. The number of cases infected in association with travel have been rather consistent at ~ 140 annually in the period 1985-1990. This means that at the beginning of this period ,~ 20%, and at the end 60%, of the registered hepatitis A cases were associated with travel. With slight variation during the period, about onethird of the total cases were each associated with travel either in Europe or to Asia (Table 1).
MATERIALS
AND METHODS
The national register of notifiable infectious diseases (Epidemiologiska Avdelningen, SBL, Stockholm) was the source of information regarding the number and source of hepatitis A infections. The Swedish Tourist Board (Sveriges Turistr~d, Sverigehuset) and the Statistical Year Book 1990 were the sources of statistics on travel and population. Kabi Pharmacia AB, gave the information regarding sale and use of Ig.
60C
30G
1985
1986
1987
1988
1989
1990
Year
Department of Medical Microbiology, University of Lund, SOIvegatan 23, S-223 62 Lund, Sweden 0264-410X/92/100S73-02 © 1992Butterworth-HeinemannLtd
Figure 1
Number of cases of hepatitis A in Sweden. _J, Total; J ,
associated with travel
Vaccine, Vol. 10, Suppl. 1, 1992 $73
Hepatitis A in Swedish travellers. E. Nordenfelt Table 1 Number of hepatitis A infections associated with travel to different continents per year Travelto
1985
Africa 31 Europe 37 North and South America 13 Asia 43 Unspecified (more than one) Total 124
1 9 8 6 1 9 8 7 1 9 8 8 1 9 8 9 1990 16 43 14 52 4 129
14 42 12 61 3 132
20 53 23 55 5 156
41 53 13 45 5 157
26 62 17 50 1 156
The age groups 0 14, 15 30, 3 1 4 5 and >45 years each account, with slight variation, for 25% of the cases. Until 1988 there was a steady rise in foreign travel. Between 1984 and 1988 there was a rise of 40% in passengers on international charter flights. It was estimated that in 1985 ~ I million Swedes went to the Mediterranean area of Europe. In 1989 and 1990 this figure increased to ~ 2 million. In 1989 the estimated total number of tourist travels outside the Nordic countries was 5.2 million tourist and 1.3 million business, a total of 6.5 million. In 1990 the total number of travels was the same but the number of tourist travels were lower (4.9 million) and business travels higher (1.6 million). Ig has been widely used as prophylaxis against hepatitis A infection but the use has declined. The statistics of total sales for lg show that the number of doses sold remained at the same level during 1986-1990 in spite of the rise in the number of travels. In the beginning of the 1980s ~ 45% of travellers to the mediterranean area of Europe received Ig 4. As the number of travellers to that area has doubled, it can be estimated that ~ 25% now use specific prophylaxis. Travellers to Africa and Asia use prophylaxis at a ratio estimated to be ~ 95%L Based on travel statistics and the estimations of doses of Ig used for prophylaxis, a risk ratio expressed as the number of travellers who did not receive Ig per case of hepatitis A infection can be calculated (Table 2). This risk ratio is ~ 5000 for travel to the Mediterranean part of Europe, ~ 100 for travel to Africa, and ~ 300 for travel to Asia.
DISCUSSION Hepatitis A in Swedish travellers has been studied and reported earlier for 1970 1984 e-~. In these investigations, the incidence of hepatitis A infection among travellers to the Mediterranean area of Europe could be seen to decrease dramatically from one case per 3000 travellers without lg in 1970 1972 to I in 20 000 in 1982-'. The results from the estimations in this report further confirm this decline. This must reflect a changing epidemiology of hepatitis A infection in this arca. The risk of Swedish travellers acquiring hepatitis A when going to remote destinations such as Africa and Asia seems to be the same during the periods studied. The number of cases with travel-associated hepatitis A has been stable and low during the last five years, although it forms a predominant part of the total number of hepatitis A cases in Sweden. The relative incidence of hepatitis A among travellers has, however, diminished as the total number of travellers has risen. Thus it must be concluded that the present routines for Ig prophylaxis against hepatitis A infection among Swedish travellers have worked satisfactorily.
ACKNOWLEDGEM
ENTS
The information and help from Dr Rolf Alsterlund, Epidemiologiska Avdelningen, SBL, Stockholm, Mr Lars Viddn, Sveriges Turistr~,d, Stockholm and Dr Bertil Eriksson, Kabi Pharmacia AB, Stockholm is gratefully acknowledged.
REFERENCES 1
Iwarson, S., Fr6sner, G., Lindholm, A. and Norkrans, G. The changed epidemiology of hepatitis A infection in Scandinavia. Scand. J. Infect Dis. 1978, 10, 155-156 Christenson, B. Epidemiological aspects of acute viral hepatitis A in Swedish travellers to endemic areas. Scand. J. Infect Dis. 1985, 17, 5-10 Christenson, B. Hepatit A hos svenska utlandsresen&rer - en epidemiologisk 6versikt. Lakartidningen 1986, 83, 2309--2310 Sparf, M. Enkat om reseprofylax. Kabijournalen 1984, 3, 85-86
Table 2 Hepatitis A cases among Swedish travellers to different areas. Risk ratio is number of travellers without Ig prophylaxis per case of hepatitis A infection 1989
1990
Travel to
No. of cases
Total No. of travellers per million
Risk ratio
No. of cases
Total No. of travellers per million
Risk ratio
Mediterranean area of Europe Africa Asia
29 41 48
2.2 0.1 0.3
~ 57 000 ~ 100 >_300
24 26 44
1.8 0.05 0.3
~-.56 000 z 100 ~. 300
S74
V a c c i n e , Vol. 10, Suppl. 1, 1992
