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Published Date: 2012-08-06 14:46:20
Subject: PRO/AH> Schmallenberg virus - Europe (51): update, surveillance, classification
Archive Number: 20120806.1230364

SCHMALLENBERG VIRUS - EUROPE (51): UPDATE, SURVEILLANCE, CLASSIFICATION
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[1]
Date: 25 Jul 2012
Source: DEFRA, International Disease Monitoring, Reference: VITT/1200 Schmallenberg virus in North Europe [edited]
http://www.defra.gov.uk/animal-diseases/files/poa-schmallenburg-update-20120725.pdf

Update No.10 on Schmallenberg Virus in Northern Europe - Situation Assessment
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1. Disease Report
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Since our previous report in June 2012, the number of cases of deformities in young, newborn ruminants being reported has dropped significantly across Europe. Switzerland has now reported acute cases in adults in 2 cattle herds in Bern Canton as testing positive. This remains a low impact disease across Europe, with only a very low percentage of premises being affected. Total cases now stand at around 5500 across northern Europe, which is still less than 0.005 percent of [animals kept on] affected premises.

As we reported in the previous update, cases in the UK in sheep occurred as late as May 2012, which indicated that midges were still active and infectious in early 2012, and therefore the disease had over-wintered. Nevertheless, cases have still only been reported in the southeast, southwest and east of England. As time progresses, more detailed information on the impact is becoming available from various studies. For example, the French Centre for Epidemiology Resource (2012) has reported interim results of an on line survey on impact in both cattle and sheep farms, underpinning the EFSA report from April 2012 on low impact.

2 Situation Assessment
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In general, the inclement weather across parts of Northern Europe in the last few weeks is likely to have had only a small effect on midge activity and wind borne movement. Between May and July 2012, each county in the south of England, from Kent to Cornwall, would have been exposed to wind borne midges between 3 and 18 times a month, with Kent the most exposed county. The cold wet weather may have reduced the number of midges taking off, but this is clearly changing now that a more settled weather pattern is arriving. Therefore, we would encourage farmers to be vigilant and inform their private vet of any clinical signs in the adults, such as milk drop, diarrhoea, fever and inappetance.

The map [see at source URL, page 2] shows the affected regions from which cases have been reported, including those with acute cases in cattle. As outbreak locations are no longer being reported, they will no longer be shown on this map.

The table below is for positive SBV PCR tested cases across the EU according to Ministerial or Agency websites, official statistics or the recent EFSA report. It shows the number of PCR positive farms and includes those cases in adults in Switzerland identified as positive. (These data have been adjusted by ProMED-mail in line with the 3 Aug 2012 update available on the SBV web-site of the G. Caporale Zoosanitary Institute, Teramo, Italy, http://www.izs.it/IZS/Engine/RAServePG.php/P/358110010400/M/357410010300).

Country / Cattle / Sheep / Goat / others
Netherlands / 237 / 107 / 6
Belgium / 408 / 167 / 2
Germany / 871 / 866 / 49
France / 1505 / 1128 / 17
Italy / 3 / 0 / 5
Spain / 0 / 5 / 0
Luxembourg / 11 /6 / 0 /
Denmark / 3 / 0 / 0
Switzerland / 2 / - / -
UK (England & Channel Islands) / 53 / 220 / 0 / 3 (cattle + sheep)

The UK has reported in total 276 premises with SBV positive offspring: 220 in lambs and 53 in calves, with an additional 3 premises where affected lambs were 1st identified and then affected calves several weeks later.

The UK is also looking at the impact. An online survey was completed by sheep farmers across England and Wales, and results are being collated. In addition, Defra has started to conduct serological surveillance in certain regions of England and Wales to understand which counties have already been exposed to SBV and, therefore, where might be the most susceptible to further incursions. Using samples being taken from sheep and goats as part of the annual survey for brucellosis, some will be tested for SBV across the counties at the edge of the affected region or in counties where no infection was reported. This can only inform about exposure to SBV at the time when samples were taken and will not be a detailed structural epidemiological survey, but it will allow us to provide some information to farmers and livestock keepers about how far disease has spread. Cattle samples are not being taken, as it is clear the virus is present in both sheep and cattle; therefore, one informs the other. Additional information about cattle will come from reports of any acute clinical cases.

3 Conclusions
We urge farmers to report signs such as milk drop, fever and diarrhoea to their private vets, in particular along the edge of the risk area, if acute clinical signs are seen in cattle. Where the clinical signs of acute cases match the SBV case definition for cattle, samples from the counties where disease has not been reported before can be submitted for testing, and the SBV test will be paid for by Defra. We continue to urge farmers and animal keepers to report to their local private vets about signs of congenital deformities in newborn animals. There may still be cases in newborn animals, as we do not believe that transmission ceased entirely over the winter, and it is likely to still be circulating in Europe as well as the UK.

Defra will continue to pay for testing for SBV in deformed calves or lambs in the areas where disease has not been reported before. In counties where disease was reported on several premises over the last few months, we will collect data on cases but will not collect or pay for samples to be tested.

We will be reporting the results of the online questionnaire for impact on sheep farms.

We have started to test sheep samples from certain areas in England and Wales to give an approximate picture of how far disease has spread and expect to report results shortly.

[Byline: Helen Roberts]

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Communicated by:
ProMED-mail <promed@promedmail.org>

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[2]
Date: Mon 6 Aug 2012
Source: EID Journal Vol 18, No 9--September 2012 (Dispatch, Ahead of Print/In Press) [edited]
http://wwwnc.cdc.gov/eid/article/18/9/12-0716_article.htm

Schmallenberg Virus in Domestic Cattle, Belgium, 2012
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Abstract
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To determine prevalence of antibodies against Schmallenberg virus in adult cows and proportion of infection transmitted to fetuses, we tested serum samples from 519 cow/calf pairs in Belgium in spring 2012. Of cattle within 250 km of the location where the virus emerged, about 91 percent tested positive for IgG targeting nucleoprotein. Risk for fetal infection was about 28 percent.

Conclusions:
This study confirms that the emerging virus was absent from the area examined in spring 2011 and provides evidence that one year later, almost all adult cattle had seroconverted.

Furthermore, the results suggest that the risk for infection of the fetus in an immunologically naive herd is about 28 percent and that in utero infections can occur without sequelae visible at birth if the infection occurs when the fetus's immune system is mature enough to control virus spread. In the case of Akabane virus, the cow's natural immunity prevents subsequent infections of the fetus. It seems likely, therefore, that the Schmallenberg virus infection itself, and its resulting economic effects on farms in the regions concerned, might disappear in 2012.

Authors:
Mutien-Marie Garigliany, Calixte Bayrou, Deborah Kleijnen, Dominique Cassart and Daniel Desmecht; University of Liege, Liege, Belgium.

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Communicated by:
Sabine Zentis
Castleview Pedigree English Longhorns
Gut Laach
52385 Nideggen
Germany
<cvlonghorns@aol.com>

[It may be assumed that the situation unveiled in Belgium does not much differ from the one prevailing in other countries which have been initially infected by SBV during the 2011 season and where serosurveys may be under consideration or are already being applied. Serosurveillance in other, apparently unaffected parts of Europe is needed to define the susceptibility or otherwise of their ruminant populations. The vector season has already started; close clinical, serological, virological, and entomological monitoring are prescribed to obtain early information on the virus activity and unfold the 2012 SBV situation. One wonders whether such surveys may also contribute to the study of the route of SBV initial introduction into northwestern Europe in 2011.

Subscribers are also referred to the paper "Schmallenberg Virus as Possible Ancestor of Shamonda Virus," by K. V. Goller1, D. Hoper, H. Schirrmeier, T. C. Mettenleiter and M. Beer of the Friedrich-Loeffler-Institute, Riems, Germany, published as a dispatch ahead of print in EID Journal, Vol 18, No. 10, October 2012. The paper is available at http://wwwnc.cdc.gov/eid/article/18/10/12-0835_article.htm).

On the basis of their results of full-genome and serologic investigations, the authors suggest that SBV belongs to the species Sathuperi virus and is most likely not a reassortant but a possible ancestor of the reassortant Shamonda virus. They also suggest that Shamonda virus (SHAV) should be reclassified into the species Sathuperi virus and that the species should be renamed Peaton virus or Sango virus, and conclude: "These detailed insights into the phylogeny of SBV could be the basis for the development of efficient, cross-protective vaccines. Our results also highlight the importance of full-genome analyses to identify potential genetic reassortments and to investigate the evolutionary history of viruses with segmented genomes."

SBV evolvement in Europe during the 2012 vector season currently starting is anticipated with great interest. - Mod.AS

A HealthMap/ProMED-mail map can be accessed at: http://healthmap.org/r/1-q1.]

See Also