Schmallenberg disease fact sheet                05/03/2012

Current situation

The latest AHVLA update shows the number of confirmed cases of Shcmallenberg virus in the UK has risen to 92, of these 85 have been reported on sheep farms and seven on cattle farms. The cases are mainly in South and East of England, with infections reported in Berkshire, Cornwall, East Sussex, Essex, Hampshire, Hertfordshire, Isle of Wight, Kent, Norfolk, South Gloucester, Suffolk, Surrey, West Sussex and Wiltshire. The AHVLA, which has identified ‘high risk’ and ‘lower risk’ zones, is releasing updates on the disease situation twice weekly.

The disease is currently non-notifiable, although farmers have been asked to remain vigilant and report any abnormalities to local AHVLA laboratories, or, in Scotland, local SAC Disease Surveillance centres. [Information correct as of 27.02.2012]

Background

Schmallenberg virus, named for the German town where it was first identified in summer 2011, was first seen affecting stock in Germany and the Netherlands. Whilst it was first seen in cows, infections in sheep now outnumber cases on cattle farms.

Although European veterinary institutions and government labs are working together to increase understanding of the disease, little is currently known about SBV; its name remains provisional, and was only adopted in December 2011.

Spread

Schmallenberg virus is believed to be spread by biting insects, as is the case with other animal disease pathogens in its group (Simbu serogroup of viruses), such as Akabane and Shamonda viruses, which are transmitted by vectors, such as midges, mosquitoes and ticks. So far, none of the affected farms have reported importing animals during 2011 from the affected areas in mainland Europe, suggesting the virus was not transmitted by importing infected stock.

The extent of Schmallenberg’s spread in Europe is not yet clear, as the busiest period in the lambing season is still to come and infected cattle, which have a longer gestation period, will not yet be ready to give birth.

Defra’s International Disease Monitoring team and the AHVLA have identified areas at ‘very high risk’ of infection, where cases have already been confirmed, in the South East and Sourth West, areas at ‘medium risk’ covering much of the South of England, ‘low risk’, covering parts of the Midlands and South Wales, and ‘very low risk’ areas, including much of the Midlands, the North and Scotland.

It is thought that, as Schmallenberg may be reliant on insects, no new infections have occurred since late 2011.

As the virus can localise in the tissues of foetuses, it is uncertain as to whether there is potential for live actively infectious lambs, calves and goat kids in the spring, which could continue the spread of the infection. Although it is not currently clear whether the virus can spread from animal to animal, infected mothers appear to develop immunity after having been infected.

Distribution

There have currently been cases of Scmallenberg reported in seven European states. These are Belgium (144 cases), Northern France (277), Western Germany (737), Northern Italy (1), Luxembourg (1), The Netherlands (123) and Southern United Kingdom (92) [Data correct as of 27.02.2012]

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Current Schmallenberg Virus distribution in the UK 05.03.2011

Infection

The virus is thought to infect all ruminants and possibly camelids such as llamas and alpacas. Although it appears to affect sheep most commonly, and only sheep and cattle have been affected to date in the UK, cases have been reported in sheep cattle, bison and goats in continental Europe.

For cases which are currently coming to light, infection is thought to have occurred in late summer and autumn, when plumes of midges, which are thought to be the main vector for infection, were blown across the channel from infected countries in Northern Europe. There were a number of days in autumn 2011 when conditions were suitable to blow midges from Northern France as far as the southern counties of Wales.

There is not currently thought to be a risk to humans, though those handling stock have been advised to take appropriate cautions.

Pregnant women should not have contact with sheep and goats at lambing/kidding time due to risks of exposure to other disease causing organisms.

Symptoms

In Northern Europe, where the first cases were discovered, cattle infected with the virus were seen to suffer loss of condition, milk drop, loss of appetite, fever (pyrexia) and in some cases diarrhoea. The symptoms persisted for 2-3 weeks in cattle herds, with each infected animal experiencing symptoms for a number of days. However, some infected farms did not observe these symptoms.  

The disease has no apparent symptoms in infected sheep.

If pregnant animals are infected the virus has been known to cause spontaneous abortion, still birth and congenital abnormalities in foetuses, including bent or fused limbs, stiff joints and necks, damage to the spinal cord and brain abnormalities. Symptoms also include blindness, inability to feed and fitting in newborn animals.

Although the worst case reported in the UK so far has seen a 20 per cent loss of the lamb crop, cases in mainland Europe have resulted in losses up to 50 per cent.

Consequences

The effects of the virus have led to the introduction of export bans on animal products from infected regions in a number of countries. These include Mexico, Russia and India.

A number of Scottish farming groups have asked farmers to avoid buying lambs from infected regions, including the South of England and Northern Europe.

Losses from Schmallenberg are not currently covered by most insurance packages. Mortality cover will cover flocks affected by schmallenberg, though this is only usually in place for high value breeding stock.

Prevention

Currently little is known about the disease, although an AHVLA scientist has admitted that a vaccine could be two years away.

Useful contacts

AHVLA Disease Outbreak Information Line 0844 8844600 (more information on regional centres here)

Defra Helpline – 08459 335577

National Fallen Stock Scheme – 0845 0548888

SAC Disease surveillance centres 0131 535 3140 (more information on regional centres here)