Rabies in the Federal Republic of Germany

Comp. Immun. Mi~rohiol. infect. Dis, Vol. 5, Nos. I 3. pp. 309 313. 1982. Printed in Great Britain.

RABIES

IN THE

FEDERAL

0147 9571/82/010309 05 $03.00/0 £~ 1982 Pergamon Press Ltd.

REPUBLIC

OF GERMANY

HELEN C. JACKSON Federal Research Institute for Animal Virus Diseases, P.O. Box 1149, D7400 Tuebingen, Federal Republic of Germany

During the present epizootic (sylvatic rabies), rabies has been present in the Federal Republic since 1950. In general rabies incidence is lower in the low lying land of the north and west. In the central Federal Republic, rabies incidence is higher east of the Rhine than to the west. In addition, the pattern of incidence appears to differ on either side of the river. Key words: Sylvatic rabies, rabies incidence, Federal Republic of Germany Abstract

LA RAGE EN REPUBLIQUE

FEDERALE

ALLEMANDE

Resume--Au cours de l'6pizootie actuelle de rage selvatique, cette maladie est reconnue en R6publique F6d+rale Allemande depuis 1950. Son incidence est g~n~ralement plus faible dans les zones de basse altidude du Nord et de l'ouest. Au centre de la Republique Fed6rale, l'incidence de la rage est plus forte fi l'Est du Rhin qu'fi l'Ouest. Par ailleurs, les caract6res de cette incidence semblent ~tre diff~rents de chaque c6t6 du fleuve. Mots-clef~: Rage selvatique, incidence de la rage, RSpublique Fbd6rale d'Allemagne

A rabies e p i z o o t i c in which the red fox (Vulpes vulpes) is the m a i n vector has s p r e a d over a large p a r t o f E u r o p e since 1940 [1, 2]. The F e d e r a l R e p u b l i c o f G e r m a n y first r e c o r d e d rabies in foxes ( d u r i n g this epizootic) in 1950; t o d a y it a p p e a r s endemic in m a n y regions o f the c o u n t r y . R a b i e s incidence in an a r e a d e p e n d s on fox p o p u l a t i o n density which is in t u r n a result o f the h a b i t a t (in this c o n t e x t h a b i t a t c o u l d include such variables as h u n t i n g practices a n d fox p o p u l a t i o n c o n t r o l m e t h o d s ) . A r e a s with a low rabies incidence have low fox p o p u l a t i o n densities [3]. These could be, for example, (a) areas where fox p o p u l a t i o n s are low because o f biological limitation, a n d (b) areas o f small g a m e h u n t i n g where fox p o p u l a t i o n s are k e p t artificially low. In o r d e r to begin a study o f rabies in relation to h a b i t a t , the rabies incidence d a t a at Kreis (county) level in all a n i m a l species was collected for the p e r i o d 1950-1980 [4]. MEAN INCIDENCE AT KREIS LEVEL

Mean rabies incidence lies between 0.0000 and 0.0982 rabies cases per km 2 per year (mean = 0.0185 rabies cases per km 2 per year; standard deviation = 0.0142) calculated from the year rabies was first recorded in the Kreis (Fig. 1). T h e lowest rabies incidence (0.0000-0.0020 cases per k m 2 p e r year) is f o u n d in n o r t h west N i e d e r s a c h s e n , the heavily industrialized western p a r t o f N o r d r h e i n W e s t f a l e n a n d s o u t h - e a s t Bayern. Incidence is highest ( m o r e t h a n 0.0300 cases per k m 2 per year) in s o u t h B a d e n - W u e r t t e m b e r g , s o u t h - w e s t Bayern a n d in the central F e d e r a l R e p u b l i c - - t h e western Kreise o f Hessen a n d the eastern Kreise o f N o r d r h e i n - W e s t f a l e n . 3o9

310

H.C. JACKSON

Fig. 1. Rabies cases per km2 per year at Kreis level (calculated from the year rabies first recorded in the Kreis), Key: ~ 0.0000 0.0020, ~]]T[]0.0021 0.0100,k-~-~ 0.0101- 0.0200, ~ 0 . 0 2 0 1 . 0 . 0 3 0 0 , ~ ' ~ 0.0301 0.1000.

In general, mean rabies incidence is lower in the low lying land in the north and west of the country than in the higher lying central region and southern parts of the country. PATTERNS OF RABIES INCIDENCE AT KREIS LEVEL Four quite distinct patterns of rabies incidence (Fig. 2, i iv)--the rabies case per km 2 plotted for every y e a r - - c a n be identified by eye: (i) rabies absent, or sporadic at low densities; (ii) rabies continuously present at low densities without sharply defined peaks of incidence; (iii) rabies continuously present with sharply defined peaks of incidence; (iv) rabies incidence sharply peaked and rabies often completely absent between peaks. The curves are not always a true reflection of the recorded rabies incidence; the size of a Kreis ranges from 35.9 km 2 to 2859 km 2 (mean=912.3 km2; standard deviation--503.5)

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Fig. 2. Characteristic types of rabies incidence. (i) Low, sporadic or absent, e.g. Mettmann, Passau. (ii) Continuously present with no marked peaks, e.g. Neustadt Waldnaab, Harburg, Celle. (iii) Continuously present with marked peaks, e.g. Werra- Meissner Kreis, Lindau a. Bodensee, Waldshut. (iv) Discontinuous incidence-marked peaks followed by periods of absence, e.g. Saarbriicken, S/idliche WeinstraBe, F/irstenfeldbruck.

and in larger Kreise, rabies may affect only a small area, or different areas at different times. In many areas of the Federal Republic however, neighbouring Kreise have similar patterns of rabies incidence, e.g. pattern (i) in north-west Niedersachsen; pattern (ii) in north-east Bayern; pattern (iii) in Hessen, and pattern (iv) in Rheinland Pfalz. CENTRAL FEDERAL REPUBLIC In the central part of the Federal Republic, the pattern of rabies incidence east of the river Rhine is quite different to that west of the Rhine. This difference could perhaps be explained by the Rhine acting as a barrier to the movement of the fox. In Fig. 3, four areas of the central Federal Republic are represented. In each area the pattern of rabies incidence is similar, whereas differences are clearly seen between areas. The areas (i), (ii), (iii), and (iv) of Fig. 3 are equivalent to the rabies incidence types (i), (ii), (iii) and (iv) of Fig. 4. All Kreise east of the Rhine in the central part of the Federal Republic were infected by rabies before 1960. Since then, rabies has been more or less continuously present (Fig. 4, iii) with most areas recording between 4 and 7 peaks of rabies incidence at intervals of 3 5 years. A different pattern is found in an area bounded by the Rhine on the west, the river Neckar in the south and the river Main in the north and east (Fig. 4, iv). Here two peaks

312

H.C. JACKSON

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Fig. 3. Diagrammatic representation of areas. (i), (ii), (iii) and (iv) equivalent to the areas of rabies incidence curve types (i), (ii), (iii) and (iv) of Fig. 4.

were recorded in the early 1960s; 1960 or 61 and 1964 or 65, followed by an almost complete absence until the 1970s when two more peaks were recorded; in 1973 75 and 1978-80. A very different pattern o f rabies incidence is found west o f the river Rhine. In some areas a very low incidence o f rabies was recorded during the 1950s; M a y e n - K o b l e n z , Donnersberg-Kreis and R h e i n - H u n s r u e c k , but the first peak o f rabies was not recorded

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Rabies in the Federal Republic of Germany

313

until 1964 or later. There have been only two peaks o f rabies incidence in most areas west of the Rhine, often with a complete absence of rabies between peaks (Fig. 4, i a n d ii). The first peak occurred in 1964~69 a n d the second in 1977-80.

REFERENCES 1. Wandeler, A., Wachend6rfer, G., F6rster, U., Krekel, H., Schale, W., Miiller, J. and Steck, F., Rabies in wild carnivores in central Europe I. Epidemiological Studies, Zbl. Vet. Med. B21, 735-756 (1974). 2. Steck, F. and Wandeler, A., The epidemiology of fox rabies in Europe, Epidemiol. Rev. 2, 71 96 (1980). 3. B6gel, K., Moegle, H., Knorpp, F., Arata, A., Dietz, K. and Dietzhelm, P., Characteristics of the spread of a wildlife rabies epidemic in Europe, Bull. WHO 54, 433-447 (1976). 4. Tierseuchenberichte, 1950-1980. Bundesrepublik Deutschland Tierseuchenbericht Amtliche Mitteilung des Bundesministers f/~r Ern/ihrung, Landwirtschaft und Forsten, Bonn.