Schmallenberg orthobunyavirus
Schmallenberg virus is the informal name given to an orthobunyavirus related to Shamonda virus, which has not been given a formal name as of January 2012[update], initially reported in November 2011 to cause fetal congenital malformations and stillbirths in cattle, sheep, and goats.[1]
It appears to be transmitted by midges (Culicoides spp.) which are likely to have been most active in causing the infection in the northern hemisphere summer and autumn of 2011, with animals subsequently giving birth from late 2011.[1]
The virus is named after Schmallenberg, in North Rhine-Westphalia, Germany, from where the first definitive sample was derived.[1] It has also been detected in Lower Saxony in Germany [2], as well as in the Netherlands, Belgium, France, Luxembourg, Italy, Denmark and the United Kingdom.[3]
The virus has been recognised by the European Commission's Standing Committee on the Food Chain and Animal Health[1] and the Friedrich-Loeffler-Institut (German Research Institute for Animal Health)[2]. A risk assessment in December 2011 did not consider it likely to be a threat to human health[4], as other comparable viruses are not zoonotic[2].
It was confirmed as present in the UK on 22 January 2012, having been formally identified in four sheep farms in Norfolk, Suffolk and East Sussex.[5] By 27 February 2012, the disease was reported in other counties in the south of England including the Isle of Wight, Wiltshire, West Berkshire, Gloucestershire, Hampshire and Cornwall. [6] It is likely that it was carried to Eastern England by midges from mainland Europe,[5] a possibility previously identified as a risk by DEFRA.[5]
The Animal Health and Vetinary Laboratories Agency (AHVLA)has an archive page with the most current updates on the Schmallenberg Virus[7].
Immunity can possibly be acquired naturally against SBV. It is possible that the seasonality of the infection cycle would not entail a second epidemic circulation next year, due to the shortness of the viraemic period (about 4 to 6 days post exposure, longer in affected foetuses). Vaccination is a possible option for controlling the disease as a vaccine exists for the similar virus Akabane.[8].
Symptoms
The virus causes two different profiles of Schmallenberg:
These symptoms have occurred during the period when the disease vectors (mosquitos, sandflies, midges) are active, during the summer and autumn of 2011, mainly affecting cattle.
- Stillbirths and birth defects in sheep, cattle and goats
Congenital malformations in newborn sheep, goats and calves are the most obvious symptoms. In many cases, the mother apparently has not presented symptoms of illness. These cases have occurred from December 2011, especially in sheep. The major malformations observed were: scoliosis, hydrocephalus, arthrogryposis, hypoplasia of the cerebellum and an enlarged thymus.[9]
Diagnosis
Blood samples from live animals with suspicious symptoms are taken for analysis. Dead or aborted fetuses suspected of having the virus are sampled by taking a piece of the brain or spleen for analysis. The samples are tested with the RT-PCR for Schmallenberg virus that has been developed by the Friedrich-Loeffler Institute in Germany.[9] A commercial kit is now available from AdiaVet[10] which targets the L region of the tripartite ssRNA genome of the virus[11].
References
- ^ a b c d New Animal Virus Takes Northern Europe by Surprise, Kai Kupferschmidt, sciencemag.org (AAAS), 13 January 2012, accessed 16 January 2012
- ^ a b c Schmallenberg Virus: New Orthobunyavirus in cattle, updated 10th January 2012, accessed 16 January 2012
- ^ http://web.oie.int/wahis/public.php?page=weekly_report_index&admin=0
- ^ Risk assessment: New Orthobunyavirus isolated from infected cattle and small livestock ─ potential implications for human health, European Center for Disease Prevention and Control, 22 December 2011, accessed 17 January 2012
- ^ a b c Carrington, Damian (23 January 2012). "Schmallenberg virus confirmed on farms in the UK". Guardian. Retrieved 23 January 2012.
- ^ BBC News - Schmallenberg livestock virus hits 74 farms in England.
- ^ http://www.defra.gov.uk/ahvla/tag/Schmallenberg/
- ^ SMC(UK) Fact Sheet on Schmallenberg virus
- ^ a b Programa nacional de vigilancia epidemiológica frente al virus de Schmallenberg. Ministerio de Agricultura Alimentación y Medio Ambiente (España), 2012. Consultado el 8 de febrero de 2012
- ^ SBV - Schmallenberg Virus PCR Detectction Kit
- ^ Genbank: Schmallenberg virus RdRp gene for RNA-dependent RNA polymerase, segment L, genomic RNA, isolate BH80/11-4
External links
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