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Archive Number 20071030.3526
Published Date 30-OCT-2007
Subject PRO/AH> Bluetongue - Europe (51): BTV-8, vectors
BLUETONGUE - EUROPE (51): BTV-8, VECTORS
****************************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>

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]

******
[2] Switzerland: Basel, not Bern (correction)
Date: Tue 30 Oct 2007
From: Christian Griot <christian.griot@ivi.admin.ch>


re: Bluetongue - Europe (49): BTV-8, Switzerland: correction
------------------------------------------------------------
The farm is NOT located in the Canton of Bern but in the Canton of Basel. 
It is a mixed dairy and beef holding.

The cow, which I had seen, had typical BT symptoms and was in bad 
condition. The other animals did not show any clinical symptoms. 5 of them 
had been virus and antibody positive.

-- 
Christian Griot, DVM PhD
MPA University of Berne
Director Institute of Virology and Immunoprophylaxis (IVI)
Adj. Associate Professor Vetsuisse Faculty
National Exotic Disease Reference Laboratory
Sensemattstrasse 293
3147 Mittelhausern
Switzerland
<christian.griot@ivi.admin.ch>

[We are grateful to Professor Griot for the correction and for his 1st hand 
information on the Swiss outbreak of BTV-8. A similar correction has been 
received from Dr Florian Gutzwiller, who is gratefully acknowledged. - Mod.AS]

[see also:
Bluetongue - Europe (50): BTV-8, Switzerland 20071030.3522
Bluetongue - Europe (49): BTV-8, Switzerland 20071028.3504
Bluetongue - Europe (48): BTV-8 20071026.3488
Bluetongue - Europe (47): BTV-8, Italy, NOT 20071022.3441
Bluetongue - Europe (46): BTV-8, UK, Italy (susp., RFI) 20071020.3421
Bluetongue - Europe (45): BTV-8 20071017.3400
Bluetongue - Europe (44): BTV-8, sheep 20071016.3392
Bluetongue - Europe (43): BTV-8, Denmark, OIE 20071016.3389
Bluetongue - Europe (42): BTV-8, Denmark, UK 20071014.3375
Bluetongue - Europe (41): BTV-8, Netherlands, Denmark 20071013.3360
Bluetongue - Europe (40): BTV-8, UK, experimental 20071012.3344
Bluetongue - Europe (39): BTV-8, EU, UK 20071011.3336
Bluetongue - Europe (38): BTV-8, EU, UK 20071009.3317
Bluetongue - Europe (37): BTV-8, EU, UK 20071008.3311
Bluetongue - Europe (36): BTV-8, EU, UK 20071005.3296
Bluetongue - Europe (35): BTV-8, EU, UK, vaccination 20071003.3267
Bluetongue - Europe (17): BTV-8, Germany, vectors 20070719.2315
2006
---
Bluetongue - Europe (14): new vector 20061024.3042
Bluetongue - Europe (11): vector 20061016.2978]

.................arn/mj/sh


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