Published Date: 2012-05-06 22:34:39
Subject: PRO/AH/EDR> Schmallenberg virus - Europe (37): Epidemiology
Archive Number: 20120506.1124602
SCHMALLENBERG VIRUS - EUROPE (37): EPIDEMIOLOGY
A ProMED-mail post
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International Society for Infectious Diseases
Date: Fri, 4 May 2012
Source: EFSA supporting Publication 2012:EN-277 [edited]
"Schmallenberg" virus: analysis of the epidemiological data (April 2012)
Following a request from the European Commission, the European Food Safety Authority (EFSA) issued a technical report in February 2012 on likely epidemiological scenarios in Europe in relation to a recently detected virus provisionally named "Schmallenberg" virus (SBV) (Simbu serogroup, Bunyaviridae family, genus Orthobunyavirus), found in ruminants. The report also included guidance on data to be collected in Member States, with harmonised case definitions and reporting guidelines for a minimum dataset at herd/flock level and an extended dataset at animal level. This second epidemiological report presents the analysis of the submitted data (1 Aug 2011 - 16 Apr 2012), updating the previously published report on the epidemiological situation of SBV.
At present, 8 Member States (Belgium, France, Germany, Italy, Luxembourg, the Netherlands, Spain and United Kingdom) have confirmed cases of SBV. All affected Member States have reported the number of confirmed herds following viral detection by PCR, virus neutralisation test or serological confirmation and France, Italy, Luxembourg, the Netherlands, Spain and United Kingdom, have also reported the number of suspect herds. Switzerland reported herds where malformed offspring were tested by RT-PCR and the dams by serological testing, all results were negative. Ireland reported surveillance testing of herds and all herds were negative. Estonia reported that there have been no suspect or confirmed herds in the country. Moreover Demark and Norway reported suspect herds, in all herds foetuses/neonates were tested by RT-PCR and the results were negative. The total number of SBV confirmed herds in Europe as of the 16 April 2012 is 3444. No confirmed acute cases have been reported in adult animals in the year of 2012.
The data shows a decrease in the number of reports of SBV confirmed herds following a peak in week 9 (27 February - 4 March) of 2012. The decrease after week 9 is clearly observed in sheep in both numbers of confirmed and suspect herds. However in cattle there is no clear decrease and any drop in confirmed and suspect herds could be due to incomplete reporting for the month of April. The decrease in number of confirmed herds is most probably linked to the end of the lambing season in affected countries, the fact that lambs and goat kids born in April would have been in a stage of gestation potentially vulnerable to SBV when vector levels were low and other factors including reporting priorities in Member States.
The data available only allows an impact assessment based upon the comparison between the number of SBV confirmed herds and the total number of herds in each affected country by species. For all affected countries, the number of herds with at least one SBV confirmed animal is low in comparison with the total number of herds. This analysis should be interpreted cautiously since under-reporting or lack of diagnostic confirmation may affect the ratio.
The data provided allows an understanding of the temporal and geographical distribution of the SBV outbreak. In order to fully characterise the outbreak and the epidemiology of SBV in Europe, efforts to obtain comparable data on the number of herds tested, the number of newborns and foetuses within a herd with arthrogryposis hydranencephaly syndrome (AHS) type clinical signs and the number of animals within the herd tested by either direct or indirect laboratory methods are required. This could be achieved by following up selected herds or by performing a survey to properly evaluate the impact and magnitude of the spread of SBV infection. As more data becomes available the impact assessment for SBV (in particular within herd and local impact) could be subject to change.
[The Report's table of contents is the following:
Table of contents: p3
Background as provided by European Commission: p4
Terms of reference as provided by the European Commission: p4
1. Introduction: p5
2. Data collection activities in Member States and reporting to EFSA: p5
3. Minimum dataset - herd level: p6
3.1. Number of affected herds: p6
3.2. Temporal spread: p8
3.3. Spatial spread: p13
3.4. Characterization of affected herds: p15
3.5. Impact analysis: p18
4. Recommendations: p22
A. SBV Data Reporting Guidelines: p23
Subscribers are encouraged to download the full report at the source URL. -Mod. AS].
Date: Sat, 5 May 2012
Source: Veterinary Record 2012;170:453 doi:10.1136/vr.e3155 - News & Reports, Emerging Diseases [edited]
Serological ELISA for SBV currently being evaluated
Recent developments in the disease situation surrounding Schmallenberg virus (SBV) in northern Europe are discussed in the latest outbreak assessment from the International Disease Monitoring (IDM) team at Defra.
In the assessment, which was published on 23 Apr 2012, the IDM team says that AHVLA laboratories are currently validating a serological ELISA that has become commercially available in Europe. Defra is considering how the test could be used for surveillance and whether there is a potential cost-benefit to such use. The team adds that the geographical distribution of the disease is still restricted to north-west Europe, but that this could still change as more cattle that were infected last year continue to give birth, or as serological surveillance gives a clearer picture of past exposure.
The assessment also notes that infected midges, including _Culicoides dewulfi_ and _Culicoides obsoletus_, have been identified in Belgium, Denmark and Italy. Germany has reported finding antibodies to SBV in red and roe deer but, the IDM team says, the significance of this in terms of a potential wild reservoir host for SBV is not yet known. Meanwhile, investigations at the Robert Koch Institute in Germany of 60 sheep farmers who had been in close contact with infected animals had found no evidence of infection using an immunofluorescent antibody test and a serum neutralisation test. [In the meantime, human involvement has been further excluded by Dutch investigations; see ProMED archive number 20120501.1119639. - Mod.AS].
Regarding the pattern of infection, the IDM team notes that Germany, the Netherlands and Belgium continue to report outbreaks in cattle, but there have been fewer reports of affected sheep. The same pattern has been seen in the UK, it says, and coincides with the end of the lambing season in at-risk areas.
Noting that all of the cases confirmed in the UK have been found in counties that were within zones at risk of the incursion of infected midges in 2011, the IDM team adds: 'It should be noted that it is possible native midges also became infected at the same time over last summer and could have contributed to some of the infections'.
The AHVLA reported on its website that, by 30 Apr 2012, 254 farms in England had reported cases of SBV. Of these, 219 were sheep farms and 35 were cattle farms. [The respective figures as of 4 May were 256, 220 and 36. - Mod.AS].
The IDM team's latest outbreak assessment is available at <www.defra.gov.uk/animal-diseases/monitoring/>.