Published Date: 2017-11-19 19:26:30
Subject: PRO/AH/EDR> Bluetongue - Europe (09): France, bovine, serotype 4, assessment
Archive Number: 20171119.5453613
BLUETONGUE - EUROPE (09): FRANCE, BOVINE, SEROTYPE 4, ASSESSMENT
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Date: Sat 18 Nov 2017 [accessed]
Source: DEFRA Veterinary & Science Policy Advice Team - International Disease Monitoring. Ref: VITT/1200 BTV-4 in France [edited]
Preliminary Outbreak Assessment: Bluetongue virus (BTV-4) in France
On 6 Nov 2017, France reported a single case of BTV-4 in a bovine in Haute Savoie region (OIE, 2017). The animal in question tested positive for virus under the framework of pre-movement testing and has been humanely destroyed. Disease control measures are in place around the holding of origin, including surveillance and mandatory vaccination in the surrounding 20-km control and 100-km prevention zones and surveillance in the additional 50-km surveillance zone. The location of the holding of origin is close to the Italian and Swiss borders, and the respective authorities in each country have been notified, as the zones also cover part of their territory.
According to the French Authorities, the animal in question was a 15-day old veal calf which had been born in the Haute Savoie and then moved to a fattening farm in Allier region (via an assembly centre in the Loire region), where testing was carried out, prior to being moved to Spain. The animals at the fattening farm are also being tested.
The origin of disease is not known. BTV-4 has been circulating at high levels on the islands of Corsica and Sardinia this year  and was present earlier in the year in Northeast Italy. Vaccination is mandatory on Corsica and particularly for any animals which leave the restriction zone. The cases in NE Italy were likely a result of spread from the neighbouring countries in the Balkans and SE region of Europe, where disease was circulating widely in previous years.
Surveillance around the infected calf's place of origin is being carried out, and it will be interesting to understand the origin and infection status of the dam. BTV-4 is not known to be transplacentally transmitted, unlike BTV-8 (Darpel et al., 2009), but without understanding the full viral characteristics, it is too early to speculate. In experimental infections, passaged strains of BTV-1 and field strains of BTV-2 have been demonstrated to cause transplacental infection in sheep foetuses (van der Sluijs et al., 2013; Rasmussen et al., 2013). In terms of other disease sources, the distance from other areas reporting BTV-4 is probably too far for windborne transmission of midges without other cases being reported from other locations in between.
This new outbreak in France has no impact on the current risk level for the UK. Although inactivated BTV-4 vaccine is authorised for use in the EU, it is not currently available for distribution in the UK, except under a Special Import Certificate, but if the risk increases, the Veterinary Medicines Directorate are able to grant a marketing authorisation should the need arise.
We will continue to monitor the current situation in France and disseminate any further updates from the French Authorities, particularly with regards to the most recent cases and the BTV-4 situation.
Castleview English Longhorns
Gut Laach, D-52385 Nideggen, Germany
[The official report to the OIE, submitted on 7 Nov 2017, presented the site of the outbreak as "Orcier, Haute-Savoie," and indicated that the sample was taken "in the framework of a movement." More details are available in the above DEFRA assessment: the veal calf was born in the Haute Savoie region (Eastern France, on the Swiss border), moved to an assembly centre in the Loire region (about 500 km distance), then transported to a fattening farm in Allier region (central France; 200-250 km distance), where testing for BT, required since the 15-day-old calf was destined for export to Spain, seems to have been carried out (or applied earlier? Correction will be welcomed).
This is an enigmatic case. On top of the suspected in-utero (transplacental) infection on the holding of origin, the possibility of post-partum infection, there or elsewhere, including iatrogenic infection, deserves to be ruled out. - Mod.AS
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