Víctor Rodríguez Prieto & José Manuel Sánchez-Vizcaíno
SUAT-UCM
Updated on May 11th, 2012
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The emergence of a new previously unknown virus has created an international sanitary alert, especially in the European context. This virus, called "virus Schmallenberg", classified as a negative single-stranded RNA virus, belongs to the family Bunyaviridae and is responsible for causing primarily a reproductive disease in ruminants in northern Europe.
In six months eight countries of the European Union have been affected, causing infection in almost 4,400 ruminants, with a morbidity rate less than 2%. On March 12th, 2012, Spain notified the first outbreak of Schmallenberg disease in a sheep farm in Córdoba (Andalusia).
Clinical findings are characterized by the appearance of fetuses with congenital malformations such as arthrogryposis, torticollis or brain hypoplasia, passing virtually unnoticed in adults. It is believed to be transmitted, like many bunyaviruses, by midges of the genus Culicoides, the same vectors that transmit the famous bluetongue virus. In fact, the region where outbreaks have originated and their geographical extent resemble the outbreaks of bluetongue serotype 8, occurred in the same countries since August 2006.
Multiple antibody-based diagnostic techniques are in design, as well as a vaccine against the virus, since infected animals show significant rates of neutralizing antibodies, encouraging data for the control of infection. Through metagenomics, a newly introduced diagnostic technique, the sequence of viral isolates has been identified. This pathogen is related to with other Orthobunyavirus members of the Simbu serogroup circulating in Asia, Oceania, America and Africa.
Although further epidemiological investigations are needed, this virus may alledgely be a variant of any of these Orthobunyavirus circulating in Africa. How it entered northern Europe is unknown. In fact, there are many uncertainties about the extent of this infection: how many animals will be affected, how long cases will continue to appear and how far the infection will spread. Cases are expected to continue increasing up to June 2012 due to the long clinical silence (since an infected midge bites a pregnant female and the moment of parturition when congenital malformations are observed) Therefore, and due to the first outbreak reported in Cordoba, Spanish Ministry of Agriculture, Food and Environment (MAGRAMA) will promote surveillance and control measures to address the potential infection.
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More information:
“Notes on Schmallenberg disease” (Spanish text)
