TBE in Germany

Gerhard Dobler

E-CDC risk status: endemic

(data as of end 2023)

History and current situation

The beginning of research on TBE in Germany was influenced and inspired by the results and developments of TBE research in the former Czechoslovakia. There, TBE virus was detected in the Czechoslovak Republic in 1948. In Germany, the first evidence of the presence of TBE virus was found by Sinnecker and his group in the former German Democratic Republic (GDR).¹ The first virus strains were isolated also by Sinnecker’s group in the early 1960s.² In the former Federal Republic of Germany (FRG) TBE research started with research on TBE virus in the region of Franconia by Scheid and Ackermann.^3,4 In the region of Lower Franconia a virus was isolated which was called “Zimmern Virus” after the location of the isolation.⁵ Unfortunately, all these virus strains were lost but it can be assumed that they all belonged to the Western (European) subtype of TBE virus.

In the 1970s, a strong decrease of reported human TBE cases occurred in the former endemic areas of the German Democratic Republic.⁶ In Western Germany, only few studies were conducted on the geographic appearance of human TBE cases, mainly led by the company IMMUNO, the first producer of a TBE vaccine in Western Europe. No systematic epidemiological studies are available from this time. TBE was not reportable during this time.

In 2001, TBE became a reportable disease by the new Infection Control Act. From this time on, reliable data on the prevalence of TBE in Germany are available. In the era of molecular detection studies in different areas of Germany on the prevalence of TBE virus in ticks were conducted. In non-engorged ticks the prevalence rates vary depending on the tick stage from 0.1% to 0.5% (nymphs) up to 5% (adult stages).^7,8 The molecular characterization of a number of virus strains isolated from ticks in Germany shows that so far all known strains belong to the European subtype of TBE virus.⁸ Ixodes ricinus, the sheep tick, is the most important vector of TBE virus in Germany. In 2016, TBE virus was detected for the first time in Dermacentor reticulatus in the Federal State of Saxony. In 2016 and 2017 also for the first time in about 50 years two goat milk-borne outbreaks of TBE were registered in Germany (districts of Reutlingen, Tübingen, Baden-Württemberg).

In Germany, TBE is found mainly in the southern part, with the federal states of Bavaria and Baden-Württemberg comprising 80% to 90% of all reported human cases in Germany. There is an increasing number of districts in Saxony, Thuringia and for the first time in 2019 in Lower Saxony and Brandenburg which are classified as risk districts by the RKI. The annual reported human cases range from 200 to >550 (RKI, SurvStat). Seroprevalence rates before vaccination programs started in endemic areas in the human population ranged between 3% to 8% with high clustering in some human populations, indicating a highly focal geographic distribution with the endemic areas. Calculating the incidence of the overall German population is generally low (<0.1/100,000), but these figures may give a strongly underestimated risk for some districts in Southern Germany, where the highest incidence rates in Germany can reach incidence rates >10/100,000 in particular districts (e.g., Amberg, Bavaria and Ortenaukreis, Baden-Württemberg). Actual studies in the district of Ortenaukreis show that the prevalence of antibodies indicating infection (NS1 IgG) is 5.6% in a population of blood donors and subtracting the vaccinated (and therefore protected) portion, the prevalence of antibodies indicating infection was 12.8%.¹⁷

Overview of TBE in Germany

Table 1: Virus, vector, transmission of TBE in Germany
Viral subtypes, distribution	European TBEV subtype^7,8^,^13,14
Reservoir animals	Main vertebrate reservoir animals assumed – Myodes glareolus, Apodemus flavicollis, Apodemus agrarius, Apodemus sylvaticus, Microtus agrestis, Microtus arvalis, and Myodes glareolus; detailed information and studies missing.¹⁰
Infected tick species (%)	I. ricinus (0.1–5%); D. reticulatus (0.5%). (Chitimia-Dobler et al. submitted; Dobler, personal communication.)¹⁶
Dairy product transmission¹⁴	2016 first outbreak by goat milk and goat cheese for > 50 years in Germany; 2 patients; 2017 outbreak in school with 8 patients¹⁸

Table 2: TBE-reporting and vaccine prevention in Germany
Mandatory TBE reporting	All patients with confirmed TBE by serological methods (TBEV IgM ± IgG) or by virus detection are reported to the State Public Health Authorities and to the Federal State Public Health Authority (Robert Koch-Institute: www.rki.de)
Other TBE-surveillance	n/a
Special clinical features	Biphasic disease in about 50%. Risk groups: permanent inhabitants and visitors of highly endemic areas; mainly acquired during leisure activities 40% of patients meningoencephalitis, 10% meningoencephalomyelitis; No reliable data available on neurological sequelae; in a large study 40%–50% of patients with long-term sequelae; mortality rate 1%–2%⁹
Available vaccines	Encepur Erwachsene, Encepur Kinder (Bavarian Nordic), FSME-IMMUN Erwachsene, FSME-IMMUN Kinder (Pfizer)
Vaccination recommendations and reimbursement	All inhabitants and visitors of known endemic areas with a risk of tick contact; [STIKO recommendation (www.rki.de)]
Vaccine uptake by age group/ risk group/ general population	Vaccination rates in endemic areas 25% to 75%, depending on the district (Survey of the German Society of Consumption Research and personal seroprevalence studies).
Name, address/website of TBE National Reference Center	Robert Koch-Institute (Federal Authority of Public Health), Nordufer 20, 13353 Berlin, Germany (www.rki.de); Bundeswehr Institute of Microbiology, Neuherbergstrasse 11, 80937 München, Germany (gerharddobler@bundeswehr.org).

Figure 1: Burden of TBE in Germany over time

[The Center for Communicable Diseases and AIDS (2014). Available at: http://www.ulac.lt/ataskaitos]

Please note that TBE is not evenly distributed throughout Germany; in some specific areas of the country, TBE incidence may be >10/100,000 (see text for details).
[Robert Koch-Institute, SurvStat. Available at: http://survstat.rki.de/Content/Query/Create]

Source data

Year	Number of Cases	Incidence / 10⁵
1978	8
1979	1	<0.1
1980	32	<0.1
1981	30	<0.1
1982	97	0.17
1983	29	<0.1
1984	50	<0.1
1985	26	<0.1
1986	n.a.
1987	n.a.
1988	n.a.
1989	n.a.
1990	n.a.
1991	44	<0.1
1992	142	0.18
1993	118	0.15
1994	306	0.38
1995	226	0.28
1996	114	0.14
1997	211	0.26
1998	148	0.18
1999	115	0.14
2000	133	0.16
2001	255	0.31
2002	239	0.29
2003	277	0.34
2004	274	0.33
2005	432	0.52
2006	544	0.66
2007	239	0.29
2008	289	0.35
2009	313	0.38
2010	260	0.32
2011	424	0.52
2012	195	0.24
2013	420	0.52
2014	264	0.33
2015	221	0.27
2016	353	0.43
2017	485	0.59
2018	582	0.70
2019	443	0.53
2020	717	0.86
2021	421	0.51
2022	555	0.66
2023	474	0.58

Figure 2: Age and gender distribution of TBE in Germany, 2022

Robert Koch-Institute, SurvStat. Available at: http:// survstat.rki.de/Content/Query/Create

Source data

2010
Age Group (years)	Males	Females	Unknown	All
0-9	3	6		9
10-19	12	4		16
20-29	13	7		20
30-39	18	16		34
40-49	39	28		67
50-59	26	24		50
60-69	26	8		34
>70	23	7		30
2011
Age Group (years)	Males	Females	Unknown	All
0-9	19	7		25
10-19	19	13	1	33
20-29	18	8		26
30-39	15	23		38
40-49	76	42		118
50-59	62	25		87
60-69	34	18		52
>70	27	18		45
2012
Age Group (years)	Males	Females	Unknown	All
0-9	3	3		6
10-19	5	3		8
20-29	10	9		19
30-39	14	7		21
40-49	34	15		49
50-59	27	19		46
60-69	13	7		20
>70	17	9		26
2013
Age Group (years)	Males	Females	Unknown	All
0-9	17	5		22
10-19	22	5		27
20-29	25	15		40
30-39	26	24	1	51
40-49	47	36		83
50-59	53	35		88
60-69	33	17		50
>70	38	21		59
2014
Age Group (years)	Males	Females	Unknown	All
0-9	5	4		9
10-19	5	3		8
20-29	11	8		19
30-39	17	14		31
40-49	39	24		63
50-59	39	20		59
60-69	25	10		35
>70	27	13		40
2015
Age Group (years)	Males	Females	Unknown	All
0-9	5	4		9
10-19	11	5		16
20-29	11	6		17
30-39	11	6		17
40-49	17	23		40
50-59	30	21		51
60-69	27	12		39
>70	18	14		32
2016
Age Group (years)	Males	Females	Unknown	All
0-9	14	6		20
10-19	16	8		24
20-29	18	11		29
30-39	18	14		32
40-49	25	32		57
50-59	35	50		85
60-69	48	19		67
>70	28	11		39
2017
Age Group (years)	Males	Females	Unknown	All
0-9	13	7		20
10-19	14	14		28
20-29	22	13		33
30-39	36	16		52
40-49	43	27		70
50-59	81	52	1	134
60-69	52	25		77
>70	50	19		69
2018
Age Group (years)	Males	Females	Unknown	All
0-9	25	15		40
10-19	16	11		27
20-29	34	15		49
30-39	30	27		57
40-49	57	42		99
50-59	73	48	1	123
60-69	68	28		96
>70	66	25		91
2019
Age Group (years)	Males	Females	Unknown	All
0-9	16	4		20
10-19	19	6		25
20-29	23	14		37
30-39	26	15		41
40-49	39	29		68
50-59	58	48		106
60-69	47	37		84
>70	43	20		63
2020
Age Group (years)	Males	Females	Unknown	All
0-9	28	13		41
10-19	31	20		51
20-29	38	18		56
30-39	41	28		69
40-49	50	33		83
50-59	102	80		182
60-69	76	51	1	128
>70	75	28		103
2021
Age Group (years)	Males	Females	Unknown	All
0-9	16	6		22
10-19	21	3		24
20-29	19	10	1	30
30-39	30	19		49
40-49	31	17		48
50-59	59	49		108
60-69	48	24		72
>70	38	27		63
2022
Age Group (years)	Males	Females	Unknown	All
0-9	20	12		32
10-19	19	15		34
20-29	29	24		53
30-39	31	29		60
40-49	47	22		69
50-59	65	58		123
60-69	73	38		111
>70	44	29		73
2023
Age Group (years)	Males	Females	Unknown	All
0-9	10	5		15
10-19	16	9		25
20-29	24	8		32
30-39	31	26		57
40-49	32	25		57
50-59	62	47		109
60-69	64	37		101
>70	23	18		41

TBEV-isolation and TBE cases in Germany

Source data

Year of isolation	Strain name	Source of isolation	Location of isolation
1975¹¹	K23	Tick	Karlsruhe, Baden-Württemberg
2006⁸	AS33	Tick	Amberg, Bavaria
2007¹²	Salem	Monkey brain	Salem, Baden-Württemberg
2009^*	HM strains	Tick	Amberg, Bavaria
2011¹³	HB171/11	Tick	Heselbach, Bavaria
2014^**	Bottnang	Tick	Stuttgart, Baden-Württemberg
2016^*	HM-M1	Bank vole brain	Amberg, Bavaria
2016^,*	tbd	Tick	Aubachstrasse, Baden-Württemberg
2016¹⁵	tbd	Tick	Aubachstrasse, Baden-Württemberg
2017¹⁵	tbd	Tick	Schiltach, Baden-Württemberg
2017¹⁶		Tick (D. reticulatus)	Battaune, Saxony

*Dobler, personal communication; **Oehme, personal communication; ***Chitimia-Dobler, et al.¹⁶; tbd, to be determined.

Contact

Gerhard Dobler

gerharddobler@bundeswehr.org

Author

Gerhard Dobler

Citation

Dobler G. TBE in Germany. Chapter 13. In: Dobler G, Erber W, Bröker M, Chitimia-Dobler L, Schmitt HJ, eds. The TBE Book. 7th ed. Singapore: Global Health Press; 2024. doi:10.33442/26613980_13-13-7

References

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