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ProMED-mail ► SCHMALLENBERG VIRUS - EUROPE (04): UK (ENGLAND), OVINE, INCREASED INCIDENCE, REQUEST FOR INFORMATION

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Published Date: 2017-03-01 18:49:50
Subject: PRO/AH/EDR> Schmallenberg virus - Europe (04): UK (England), ovine, increased incidence, RFI
Archive Number: 20170301.4873070
SCHMALLENBERG VIRUS - EUROPE (04): UK (ENGLAND), OVINE, INCREASED INCIDENCE, REQUEST FOR INFORMATION
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Date: Wed 1 Mar 2017, 6:10 am
Source: Agriland [edited]
http://www.agriland.ie/farming-news/schmallenberg-outbreaks-on-the-increase-in-england/


English livestock producers are being urged to submit lambs with suspected Schmallenberg virus (SBV) for post-mortem examination as the number of confirmed cases of the disease grows. The disease was recently detected in lambs on 4 holdings in the northeast of England, including Northumberland, by the post-mortem diagnostic service at John Warren ABP in Co. Durham.

The Schmallenberg virus was previously detected in the southwest of England last month [February 2017] and subsequently in North Yorkshire. It is capable of infecting pregnant sheep and cattle and causing severe malformations of foetuses in the womb. Importantly, the virus does not spread from animal to animal but, like the Bluetongue virus, is transmitted by midges, which infect the animals when they bite.

No, or very few, cases of SBV causing deformed calves or lambs were confirmed in 2014 or 2015, possibly as a result of immunity built up by animals following the 2011/2012 epidemic.

The possible increase in cases of the disease was predicted in a study carried out in 2015, Ben Strugnell, of Farm Post Mortem Ltd which operates the service at J Warren ABP, said. "The possible re-emergence of Schmallenberg was predicted following a study in autumn 2015 which tested young flock replacement sheep in the south of England, the results of which suggested that levels of immunity may have dropped.

"It is very important that, if producers encounter lambs with skeletal deformities, these are submitted for post-mortem examination so that appropriate samples can be taken to establish whether Schmallenberg is the cause.

"The best advice for producers is to contact their vet, who can provide information on the best way to arrange a post-mortem.

"At present there are no vaccines available for Schmallenberg and it is already too late to vaccinate sheep which are due to lamb in spring.

"However, it is important that we ascertain the true levels of the virus, because this will help determine whether there is a need to vaccinate later in the year," he said.

[Byline: Richard Halleron]

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[The Schmallenberg virus (SBV) was 1st detected in November 2011 in Germany from samples collected in summer/autumn 2011 from diseased (fever, reduced milk yield) dairy cattle. Similar clinical signs (including diarrhoea) were detected in dairy cows in the Netherlands where the presence of SBV was also confirmed in December 2011. Then, congenital malformations were reported in newborn lambs in the Netherlands, and SBV was detected in and isolated from their brain tissue. This was followed by the appearance of congenital malformations in cattle in the Netherlands and Germany.

The circulation of the virus, infecting (small and large) pregnant ruminants (cattle, sheep, goats) was recorded also in Belgium, UK, France, Luxembourg, Spain, Italy, Switzerland, Austria, Ireland and others, leading to typical malformations in their progeny. The involvement of SBV as causal agent of the stillbirths and congenital malformations was confirmed by positive PCR in the affected calves, lambs and kids. The incidence of malformation varied, depending on the stage of gestation at the time of infection and on the species. In some oestrus-synchronised sheep flocks, the incidence was high. However at the country level, the morbidity was not found to be very significant.

SBV belongs to the Bunyaviridae family, within the Orthobunyavirus genus. It is a member of the Simbu serogroup viruses, which includes Shamonda, Akabane, and Aino viruses. The Simbu viruses which are most related to SBV are Sathuperi and Douglas virus.

As experienced decades back in countries affected by Akabane and Aino viruses, such as Japan, Australia and Israel, the ruminant population remained immune for several years following an episode of the disease. In fact, natural infection of young animals prior to their 1st pregnancy is rather advantageous, rendering them natural immunity and preventing foetal infection/damage if/when exposed to the virus later during pregnancy.

Sheep, due to their relatively short pregnancy (5 months, compared to 9 in cattle) will be the 1st to demonstrate deformed offspring following their exposure to the SBV during pregnancy - earlier than pregnant cows which have been simultaneously exposed to the virus. The current information on the observations in UK sheep may serve as a forecast of the appearance of deformed calves during the coming months.

Inactivated SBV vaccines are available in some countries but their efficacy and cost/benefit ratio remains to be assessed. It would be interesting to obtain such information, as well as details on the vaccination program/schedule, from countries which have gathered experience, such as Japan, where Akabane vaccine is said to be used for many years. - Mod.AS

A HealthMap/ProMED-mail map can be accessed at: http://healthmap.org/promed/p/279.]

See Also

Schmallenberg virus - Europe (03): UK (England, Wales), ovine, bovine 20170211.4831904
Schmallenberg virus - Europe (02): UK (England, Wales, Scotland) bovine 20170204.4814854
Schmallenberg virus - Europe: Ireland (CO, LS) bovine, reemergence 20170106.4747269
2016
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Schmallenberg virus - Europe (02): UK (England, Wales), reemergence susp 20161214.4698989
Schmallenberg virus - Europe: Netherlands, Belgium, reemergence 20161023.4578989
2013
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Schmallenberg virus - Europe (27): UK (Scotland) update 20130630.1800385
Schmallenberg virus - Europe (18): UK (Scotland) bovine, 1st clin case 20130420.1660025
Schmallenberg virus - Europe (16): UK (Scotland) update 20130328.1608058
2012
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Schmallenberg virus - Europe (70): UK (N Ireland) 1st case 20121102.1387033
Schmallenberg virus - Europe (63): UK, update 20121011.1335963
Schmallenberg virus - Europe (60): Austria, UK, Belgium 20120926.1310236
Schmallenberg virus - Europe (54): UK, Switzerland 20120816.1246089
Schmallenberg virus - Europe (52): UK, update
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