Schmallenberg virus – An emerging disease

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Germany, the Netherlands and Belgium have reported that a newly detected virus has circulated in the 2nd semester of 2011 amongst livestock ruminants, causing non-specific clinical signs in cattle and congenital malformations, mainly in sheep and more seldom in cattle and goats. In January 2012, both the Netherlands and Belgium reported to the OIE outbreaks of congenital malformations in newborn animals caused by this virus. These outbreaks were most likely caused by transmission of virus by insect vectors that occurred in summer and early autumn during pregnancy. Some countries in Europe have made this virus notifiable
The virus in question belongs to the Bunyaviridae family, genus Orthobunyavirus, serogroup Simbu  and has been tentatively named "Schmallenberg virus." This virus belongs to a vector-transmitted group of viruses thus direct transmission from animal to animal is unlikely. Vertical transmission from dam to newborn via the intrauterine route does occur as with other similar viruses. This group of viruses very often are associated with mild clinical signs of disease or with subclinical infection in ruminants.
There is currently no serological test. Thus the undetected subclinical cases of infection in ruminants may be many more than what has been reported.
Although the virus is not presently considered to be zoonotic, it cannot be completely excluded at this stage.

Small ruminants are economically important in the Caribbean. Thus, countries should assess their risk if they imported in 2011 from Europe inapparently infected cattle, sheep and goats.

by Victor Gongora, Chair of Epidemiology WG


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