Re: Switzerland-Bluetongue
BLUETONGUE - EUROPE (50): BTV-8, SWITZERLAND
Date: Mon 29 Oct 2007
Source: OIE WAHID (World Animal Health Information Database) Disease
Information 2007; 20(44) [edited]
<
http://www.oie.int/wahid-prod/public.php?page=weekly_report_index&admin=0>
Bluetongue, Switzerland
Information received on (and dated) 29 Oct 2007 from Mr Hans Wyss, chief
veterinary officer, Schwarzenburgstrasse 161, Swiss Federal Veterinary
Office, Liebefeld Berne, Switzerland
Summary
Report type: immediate notification
Start date: 26 Oct 2007
Date of confirmation of event: 28 Oct 2007
Date submitted to OIE: 29 Oct 2007
Reason for notification: 1st occurrence of a listed disease
Manifestation of disease: clinical disease
Causal agent: bluetongue virus, serotype 8
Nature of diagnosis: suspicion, clinical, laboratory (basic), laboratory
(advanced)
Report pertains to: entire country
New outbreaks
Summary of outbreaks
Total outbreaks: 1 (BT_CH_1)
Outbreak location: Bettingen, Basel-Stadt
Date of start of outbreak: 26 Oct 2007
Outbreak status: continuing (or date resolved not submitted)
Epidemiological unit: farm
Affected animals
Species: cattle
Susceptible: 19
Cases: 6
Deaths: 0
Destroyed: 1
Slaughtered: 0
Affected population: 9 suckler cows, 6 cows serological and virological
positive, one cow with clinical signs. Additionally, there are 10 dairy
cows on the farm, tested negative. Animals from the neighbouring farm have
also been tested with negative results.
Outbreak statistics
Species: cattle
Apparent morbidity rate: 32 per cent
Apparent mortality rate: 0 per cent
Apparent case fatality rate: 0 per cent
Proportion susceptible removed*: 5.26 per cent
* Removed from the susceptible population either through death,
destruction, or slaughter
Epidemiology
Source of infection: vectors
Epidemiological comments:
Switzerland has declared the whole country as
restriction zone according to EU regulations since 9 Oct 2007. Now a 20 km
(12 mile) infection zone has been established according to EU legislation.
Vaccination is currently not allowed, but may be permitted according to the
future situation.
Diagnostic test results:
Laboratory name and type: Institut fuer Viruskrankheiten und
Immunprophylaxe IVI (National laboratory)
Species: cattle
Test: enzyme-linked immunosorbent assay (ELISA)
Test date: 27 Oct 2007
Result: positive
Species: cattle
Test: real-time PCR (polymerase chain reaction)
Test date: 28 Oct 2007
Result: positive
--
communicated by:
ProMED-mail
<
promed@promedmail.org>
[In ProMED-mail posting "Bluetongue - Europe (49): BTV-8, Switzerland
20071028.3504," Basel was erroneously replaced by Bern. We regret the
error. - Mod.AS
Basel, which is located very close to the French and Germany borders with
Switzerland (see interactive map at
<
http://healthmap.org/promed?v=46.8,8.2,5>) lies well within the bluetongue
restriction zone, so it is not surprising to receive notice of an outbreak.
For a map of the restriction zones across Europe, see
<
http://ec.europa.eu/food/animal/diseases/controlmeasures/BlueTongue_RestrictedZones.jpg>.
The report mentions that vaccine use is presently prohibited. It is to be
hoped that a good hard freeze will occur, eliminate the midge vector, and
provide some respite at least until next year (2008). A thorough risk
assessment process can then be undertaken to decide on whether vaccine can
be part of an ongoing control strategy. With the spread of BTV-8 to
Scandinavia and now Switzerland, an optimal control plan is imperative. -
Mod.PC]:tiphat:
http://tinyurl.com/358ohg
In this update:
[
1] Europe: BTV-8 vectors
[2] Switzerland: Basel, not Bern (correction)
******
[1] Europe: BTV-8 vectors
Date: Tue 30 Oct 2007
Source: FMD & CSF Coordination Action website: presentation given at the
2nd International Disease Control Workshop, Brussels, 18 Oct 2007 [extract,
edited]
<
http://www.fmd-and-csf-action.org/second-international-disease-control-workshop/R%20Meiswinkel.pdf>
The following presentation on the updated entomological aspects of the
current BTV-8 epizootic in Europe, deserves the attention of subscribers. -
Mod.AS]
R Meiswinkel, C Staubach, E Dijkstra, P Leijs.
Overview of the bluetongue
situation in Europe with emphasis on the _Culicoides_ vectors. presentation
given at the 2nd International Disease Control Workshop, Brussels, 18 Oct 2007
-----------------------------------------
a.
Marked changes in vector abundances
1. In southern Holland in 2006 _C. dewulfi_ comprised 17 per cent of the
midges captured (and _C. obsoletus_ 68 per cent); the reverse occurred this
year [2007] with _C. dewulfi_ now dominant. If this applied elsewhere in
northern Europe then it might partly explain the intensity of the outbreak
this season.
2. There is no explanation for the increased abundances of _C. dewulfi_ and
may have been the case also in 2006 (but occurred before entomological
monitoring was implemented).
3. Nevertheless, the Obsoletus Complex has remained the most widespread
vector in 2007. Therefore, like in 2006, 2 or more species of _Culicoides_
appear to be driving the epidemic forward.
4. Like last year [2006], _C. pulicaris_ has NOT once been dominant in
collections.
5. _C. imicola_ has NOT been found amongst more than 500 000 _Culicoides_
captured. In a sense this is dire news demonstrating that _Culicoides_
endemic to Europe can disseminate BTV and on a vast scale.
b. The revelation that vector species are also diurnally active raises 2
points
1. Is BTV being transmitted during the day when animals are still at pasture?
2. Given this possibility, is it sufficient to monitor for _Culicoides_
using blacklight traps only?
c.
The attack of livestock by day and at night, both indoors and outdoors,
complicates our fight against BT, and at this juncture vector control holds
little promise in our quest to halt the spread of the disease.
Conclusions
-----------
1. In 2007 BT continued to spread and included a jump across the English
Channel. The BT restriction zone now covers an area of almost one million
sq/km (386 102 sq/mi).
2. There are no obvious geographical or topographic boundaries that might
halt the dramatic advance of BTV-8. This makes it likely that it will
continue to spread in 2008 (and beyond) until it reaches the (as yet
unknown) limits of its range.
3. This is daunting when it is considered that vector _Culicoides_ (and
ruminant hosts) occur across the entire Holarctic Region.
4.
The Holarctic includes the Mediterranean Basin where _C. imicola_ lies
in wait, and North America, where outbreaks of BT and epizootic
haemorrhagic disease of deer virus (EHDV) (another _Culicoides_-borne
pathogen) are occurring also.
5. Warmer winters in future will add to the conundrum by promoting rather
than suppressing virus survival and vector longevity.
--
communicated by:
ProMED-mail rapporteur Mary Marshall
[Subscribers are encouraged to download the entire presentation [from the
URL above], and are referred to Dr Meiswinkel's previous contribution in
ProMED-mail posting
20061024.3042. - Mod.AS]:tiphat:
http://tinyurl.com/2wmzbk
