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TBE epidemiology in Germany (1997–1998)
Zentralblatt fUr
Zent.bl. Bakteriol. 289, 579-582 (1999) © Urban & Fischer Verlag http://www.urbanfischer.de/journals/zblbakteriol
Extended Summary
TBE Epidemiology in Germany (1997 -1998) Melanie Fiedler 1, Gundula Jager2, Reinhard Kaiser 3, and Michael Roggendorf1 1 2 3
Institut fur Virologie, Universitiitsklinikum Essen, Essen Max-von-Pettenkofer-Institut, Universitiit Munchen, Munchen Neurologische Klinik, Universitiit Freiburg, Freiburg
The first documented cases of tick-borne encephalitis (TBE) in Germany were noted in the 1960s. In order to assess the magnitude of the TBE problem in Germany and to study the epidemiology of this disease, distribution of a spe cial questionnaire to diagnostic laboratories and hospitals was initiated in 1974. As a result, approximately 1800 cases of TBE infection were reported during the period 1974-1998. More than 95 % of them occurred in southern German states of Bavaria and Baden-Wurttemberg. Figure 1 shows the num ber of recorded TBE cases in Baden-Wurttemberg and Bavaria in each year. The increase in the number of TBE cases in the 1980s and 1990s most prob ably can be attributed to a more intensified questioning performed in these periods and not to a real change in the epidemiology of this disease. The observed increase of the number of recorded TBE cases in the 1990s was higher in Baden-Wurttemberg than in Bavaria. One might suggest that the lower number of TBE infections in Bavaria reflects more intensive implemen tation of the immunisation program against TBE in this state during the last 10 years. An increase in the number of TBE cases in the 1990s has also been recorded in another southern German state. Overall, since 197941 autochthonous TBE cases were reported in Hesse, ranging from 4-12 cases per year; all these cases were reported from the Odenwald area (Table 1). In 1997 we organised two special surveys in order to analyse the number of TBE cases that occurred in Germany, especially in the states other than Baden-Wurttemberg and Bavaria. In the first survey 21006 questionnaires were distributed among internists, neurologists and paediatricians in practice, hospitals, and laboratories in the state of North-RhinelWestphalia. 721 0934-8840/99/289/5-7-579 $ 12.00/0
580
M. Fiedler et al. 1.50 200
Baden Wiirttemberg
150 100
e :z:
Fig.1. Annual numbers of TBE cases in Bavaria and Baden-Wiirttemberg from 1974 to 1998. Based on questionnaire surveys (n = 1750). * preliminary figures 2/99.
Table 1. Number of TBE cases reported in Hesse from 1979-1998 Year
1979-92 1994 1995 1996 1997 1998 Total:
Number of reported cases
4 6
8 7 12
4
41
(3.4 %) questionnaires were returned. Altogether, 17 TBE cases were reported in the 1980s and 1990s. Thirteen of these patients acquired their TBE infec tion while being in southern Germany, two in foreign countries, and in two cases the place where the TBE infection took place was not established. Thus, these data suggest that most TBE-patients from North-RhinelWestphalia acquired the infection elsewhere. In the second survey, 45867 questionnaires were sent to physicians practic ing outside Bavaria, Baden-Wiirttemberg, and North-RhinelWestphalia. 1988 (4.3 %) questionnaires were returned; 92 TBE were reported cases from the 1980s and 1990s. The first column of Table 2 shows the total number of re ported TBE cases from each state. The following two columns demonstrate in-
Recent TBE epidemiology in Germany
581
Table 2a. Number of TBE cases reported from German states other than Baden Wiirttemberg, Bavaria, and North-RhineIWestphalia (based on a questionnaire survey initiated in 1997) Total number of cases reported (acquired in 1980-1997) Berlin Bremen Brandenburg Hamburg Hesse Lower Saxony Mecklenburg-Western Pomerania Rhineland-Palatinate Saarland Saxony Saxony-Anhalt Schleswig-Holstein Thuringia
8 2 3
o 40 8
o
8 3 12 3 2 3
Table 2b. Number of reported TBE cases acquired in 1994-1997. The number of all reported cases and the subgroup of autochthonous cases are stated. Number of reported cases acquired in 1994-1997 total Berlin Bremen Brandenburg Hamburg Hesse Lower Saxony Mecklenburg-Western Pomerania Rhineland -Pala tinate Saarland Saxony Saxony-Anhalt Schleswig-Holstein Thuringia
autochthonous
7 2 1
1 0 1
29 6
23 0
5 3 9 3 2 3
1 1 4 2 0 2
582
M. Fiedler et al.
Table 3. TBE cases in Germany in 1997-1998 ("preliminary results) Area of infection
1997
1998<·
Bavaria Baden-Wurttemberg Berlin Hesse Rhineland-Palatinate Saxony Saxony-Anhalt Thuringia Foreign countries
51 132 1 12 2 1 4 3 5
23 104 2 4 0 0 0 0 1
Total:
211
134
fections recorded between 1994 and 1997, and the number of TBE infections acquired autochthonously. Analysis of these data indicates that not in all cases the infections was acquired locally in the state from which it was reported. For example, overall, 40 TBE cases were reported from Hesse. Twenty-nine of these cases occurred in 1994-1997, and six of them were acquired outside Hesse, but in other states (predominantly in Bavaria and Baden-Wiirttemberg). The tendency was even more pronounced in some eastern states of Germany. Thus, for example, only one of seven cases of TBE reported from Berlin, and four of nine cases recorded in Saxony, were acquired locally. In general, the re sults summarized in Table 2 suggest that TBE infections were only sporadical ly acquired in the northern and eastern states of Germany. Table 3 presents the distribution of TBE cases recorded in Germany in 1997-1998 according to our survey. 211 and 134 cases of TBE were reported in 1997 and 1998, respectively. During this period most infections occurred in Baden-Wiirttemberg, Bavaria, and Hesse. Sporadic cases were noted in Ber lin, Rhineland-Palatinate, Saxony, Saxony-Anhalt, and Thuringia. Several TBE cases were acquired by Germans during their stay in Austria or in east ern Europe. The new questionnaire surveys started in 1997, and they have confirmed the main observation of our previous studies, namely, that more than 95 % of all TBE cases in Germany have been acquired in the southern part of the country, especially in Baden-Wiirttemberg and Bavaria. Only a low number ofTBE cases occurred in other regions of Germany. In these areas most cases were acquired sporadically. In conclusion, one should note that the detailed study of the epi demiology of TBE in Germany is aggravated by a low number of reported cases. Key words: TBE, epidemiology, Germany Corresponding author: Melanie Fiedler, Universitatsklinikum Essen, Institut fur Viro logie, HufelandstraSe 55, D-45147 Essen
Zent.bl. Bakteriol. 289, 579-582 (1999) © Urban & Fischer Verlag http://www.urbanfischer.de/journals/zblbakteriol
Extended Summary
TBE Epidemiology in Germany (1997 -1998) Melanie Fiedler 1, Gundula Jager2, Reinhard Kaiser 3, and Michael Roggendorf1 1 2 3
Institut fur Virologie, Universitiitsklinikum Essen, Essen Max-von-Pettenkofer-Institut, Universitiit Munchen, Munchen Neurologische Klinik, Universitiit Freiburg, Freiburg
The first documented cases of tick-borne encephalitis (TBE) in Germany were noted in the 1960s. In order to assess the magnitude of the TBE problem in Germany and to study the epidemiology of this disease, distribution of a spe cial questionnaire to diagnostic laboratories and hospitals was initiated in 1974. As a result, approximately 1800 cases of TBE infection were reported during the period 1974-1998. More than 95 % of them occurred in southern German states of Bavaria and Baden-Wurttemberg. Figure 1 shows the num ber of recorded TBE cases in Baden-Wurttemberg and Bavaria in each year. The increase in the number of TBE cases in the 1980s and 1990s most prob ably can be attributed to a more intensified questioning performed in these periods and not to a real change in the epidemiology of this disease. The observed increase of the number of recorded TBE cases in the 1990s was higher in Baden-Wurttemberg than in Bavaria. One might suggest that the lower number of TBE infections in Bavaria reflects more intensive implemen tation of the immunisation program against TBE in this state during the last 10 years. An increase in the number of TBE cases in the 1990s has also been recorded in another southern German state. Overall, since 197941 autochthonous TBE cases were reported in Hesse, ranging from 4-12 cases per year; all these cases were reported from the Odenwald area (Table 1). In 1997 we organised two special surveys in order to analyse the number of TBE cases that occurred in Germany, especially in the states other than Baden-Wurttemberg and Bavaria. In the first survey 21006 questionnaires were distributed among internists, neurologists and paediatricians in practice, hospitals, and laboratories in the state of North-RhinelWestphalia. 721 0934-8840/99/289/5-7-579 $ 12.00/0
580
M. Fiedler et al. 1.50 200
Baden Wiirttemberg
150 100
e :z:
Fig.1. Annual numbers of TBE cases in Bavaria and Baden-Wiirttemberg from 1974 to 1998. Based on questionnaire surveys (n = 1750). * preliminary figures 2/99.
Table 1. Number of TBE cases reported in Hesse from 1979-1998 Year
1979-92 1994 1995 1996 1997 1998 Total:
Number of reported cases
4 6
8 7 12
4
41
(3.4 %) questionnaires were returned. Altogether, 17 TBE cases were reported in the 1980s and 1990s. Thirteen of these patients acquired their TBE infec tion while being in southern Germany, two in foreign countries, and in two cases the place where the TBE infection took place was not established. Thus, these data suggest that most TBE-patients from North-RhinelWestphalia acquired the infection elsewhere. In the second survey, 45867 questionnaires were sent to physicians practic ing outside Bavaria, Baden-Wiirttemberg, and North-RhinelWestphalia. 1988 (4.3 %) questionnaires were returned; 92 TBE were reported cases from the 1980s and 1990s. The first column of Table 2 shows the total number of re ported TBE cases from each state. The following two columns demonstrate in-
Recent TBE epidemiology in Germany
581
Table 2a. Number of TBE cases reported from German states other than Baden Wiirttemberg, Bavaria, and North-RhineIWestphalia (based on a questionnaire survey initiated in 1997) Total number of cases reported (acquired in 1980-1997) Berlin Bremen Brandenburg Hamburg Hesse Lower Saxony Mecklenburg-Western Pomerania Rhineland-Palatinate Saarland Saxony Saxony-Anhalt Schleswig-Holstein Thuringia
8 2 3
o 40 8
o
8 3 12 3 2 3
Table 2b. Number of reported TBE cases acquired in 1994-1997. The number of all reported cases and the subgroup of autochthonous cases are stated. Number of reported cases acquired in 1994-1997 total Berlin Bremen Brandenburg Hamburg Hesse Lower Saxony Mecklenburg-Western Pomerania Rhineland -Pala tinate Saarland Saxony Saxony-Anhalt Schleswig-Holstein Thuringia
autochthonous
7 2 1
1 0 1
29 6
23 0
5 3 9 3 2 3
1 1 4 2 0 2
582
M. Fiedler et al.
Table 3. TBE cases in Germany in 1997-1998 ("preliminary results) Area of infection
1997
1998<·
Bavaria Baden-Wurttemberg Berlin Hesse Rhineland-Palatinate Saxony Saxony-Anhalt Thuringia Foreign countries
51 132 1 12 2 1 4 3 5
23 104 2 4 0 0 0 0 1
Total:
211
134
fections recorded between 1994 and 1997, and the number of TBE infections acquired autochthonously. Analysis of these data indicates that not in all cases the infections was acquired locally in the state from which it was reported. For example, overall, 40 TBE cases were reported from Hesse. Twenty-nine of these cases occurred in 1994-1997, and six of them were acquired outside Hesse, but in other states (predominantly in Bavaria and Baden-Wiirttemberg). The tendency was even more pronounced in some eastern states of Germany. Thus, for example, only one of seven cases of TBE reported from Berlin, and four of nine cases recorded in Saxony, were acquired locally. In general, the re sults summarized in Table 2 suggest that TBE infections were only sporadical ly acquired in the northern and eastern states of Germany. Table 3 presents the distribution of TBE cases recorded in Germany in 1997-1998 according to our survey. 211 and 134 cases of TBE were reported in 1997 and 1998, respectively. During this period most infections occurred in Baden-Wiirttemberg, Bavaria, and Hesse. Sporadic cases were noted in Ber lin, Rhineland-Palatinate, Saxony, Saxony-Anhalt, and Thuringia. Several TBE cases were acquired by Germans during their stay in Austria or in east ern Europe. The new questionnaire surveys started in 1997, and they have confirmed the main observation of our previous studies, namely, that more than 95 % of all TBE cases in Germany have been acquired in the southern part of the country, especially in Baden-Wiirttemberg and Bavaria. Only a low number ofTBE cases occurred in other regions of Germany. In these areas most cases were acquired sporadically. In conclusion, one should note that the detailed study of the epi demiology of TBE in Germany is aggravated by a low number of reported cases. Key words: TBE, epidemiology, Germany Corresponding author: Melanie Fiedler, Universitatsklinikum Essen, Institut fur Viro logie, HufelandstraSe 55, D-45147 Essen