| The period between March 1968 and December 1998 represented
three decades of fox rabies in France. Looking back over several years,
it is possible to evoke the characteristics of the descriptive epidemiology
(evolution in time and space) of this fox rabies ‘invasion’,
and the measures applied to control it. After two decades of semi-failures,
those measures eventually were successful thanks to the prophylactic ‘revolution’ represented
by oral vaccination of foxes against rabies [1].
Descriptive epidemiology of fox rabies in France (1968-1998)
The evolution of the yearly incidence of fox rabies in France is shown
in figure 1.
The evolution of the fox rabies front during the years when the enzootics
progressed (1968-1990) is shown in figure 2 [3].
From 1968 to 1975, the progression of the fox rabies front was uninterrupted
and the increase of incidence was exponential. From 1975, the progression
of the front slowed down. Epidemic waves were observed every 3-6 years
in the infected area.
Until 1990, the control efforts, which were mainly based on limiting
fox populations and vaccination of domestic animals, were unable to control
the disease. A retrospective study on 10 years [4] of the efficacy of
sanitary control measures on rabies incidence did not show any constant
efficacy.
From 1990, the yearly incidence decreased until the complete disappearance
of rabies in 1999. The enzootic area progressively shrank northwestwards
until it disappeared.
The success of the eradication programme was due to the change in policy
against rabies implemented in 1989.
The fight against fox rabies in France
For two decades, rabies prophylactic measures applied to foxes were mainly
based on attempts to reduce fox populations using various available
means, strongly opposed by ecologists, such as poisoning, rifle shooting,
gassing fox dens with chloropicrine, etc.
In France, the first actions ‘on-site’ oral vaccination of
foxes were carried out in 1986 along the borders with Belgium and Luxembourg.
The results were disappointing, unlike the more satisfying results obtained
in Switzerland [5].
In December 1998, the Scientific Commission of the National Federation
of Cattle Sanitary groups dedicated its annual meeting to rabies, gathering
together specialists from the National Rabies Laboratory (Nancy) and
Pasteur Institute (Paris). Vaccination of foxes against rabies was clearly
a topic of interest, and proposals were made to implement it on a large
scale in France. In 1989, the decision was made at the highest level
(by the prime minister) to adopt a strategy to surround the enzootic
area by a vaccination belt, followed by an action of forcing back infection
towards the north east.
The strategy was defined by the National Rabies Laboratory and the “Entente
Interdépartementale de la rage” (ERZ), which also organised
and implemented all the campaigns.
The immunity barrier to block the advance of the rabies front was set
up in 1989 and 1990, and ran from the Swiss border to the North Sea,
covering 54 792 km², nearly 41% of the enzootic area [6].
Vaccination areas were then progressively extended, moving up to the
northeastern borders [Figure 3]. The whole enzootic area was covered
by the autumn 1992 (192 418 km² treated in the year).
This systematic vaccination policy over the whole enzootic area achieved
the elimination of fox rabies within a few years, with the last case
being recorded at the end of December 1998.
The rules set up were:
- Vaccination in spring and in autumn in enzootic areas;
- Implementation of three successive vaccination campaigns in free areas
after the last recorded case;
- Application on extended areas all in one block with a sanitary cordon
representing a rabies-free territory of at least 30 km wide;
- Maintenance of increased alertness (continuous surveillance of rabies
by sampling, then analysing suspect animals) in areas considered rabies-free
in order to quickly react in case a cluster appears.
The efficacy of oral fox vaccination campaigns was increased thanks to
various procedures such as [7] :
- Extra vaccination by distributing baits in front of dens,
- Increase of bait density distributed (number by surface).
The intensive efforts carried out between 1989 and 1998 by the National
Rabies Laboratory and the ERZ yielded dramatic results. Every year that
followed 1998, safety measures were implemented along the German border.
From 1999 to 2003, nine oral vaccination campaigns (with only one campaign
in autumn 2003) were performed along the German border in order to avoid
recontamination of France.
France, along with other western European countries (such as Belgium,
Switzerland and Luxembourg), succeeded in eliminating fox rabies from
its territory, thanks to the methodical use of anti-rabies vaccination
of foxes [8]. Since 2000, France has been listed as rabies-free according
to the OIE criteria. France is faced with two potential rabies risks:
on one hand, the risk from bats, although the yearly incidence in recent
years (since 1989, year of the first bat rabies diagnosis, 20 bat rabies
cases all due to EBLV-1 virus on Eptesicus serotinus have been
recorded in France [9]) suggests that the situation has stabilised; and
on the other hand, the risk from imported dog rabies, as recently experienced
in Southern of France [10]. With the recent tightening of European regulations
[11] that now require anti-rabies vaccination for any transport of pets
between rabies-free countries, the fear is that illegal importation of
young cats and dogs acquired by travellers to rabies enzootic countries
(mainly in North Africa) will continue.
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