20th October 2007

On 22 September the Institute for Animal Health (IAH) identified the presence of bluetongue in a sick cow in Suffolk. This is the first ever recorded case of bluetongue in the UK. The bluetongue virus in Suffolk and adjacent areas is serotype 8, the same as in Belgium and neighbouring countries.

Scientists of the Met Office and IAH believe that the midges responsible for starting the outbreak arrived in early August 2007, having been carried by easterly winds across the sea from Belgium or the Netherlands.

 

Since the spread of bluetongue virus serotype 8 to Belgium and neighbouring countries in 2006 , scientists have feared that warm easterly winds from that region would bring infected midges to the south-easterly counties of England. Such winds usually occur four to seven times a month between May and October, although conditions would not necessarily be ideal for successful spreading of the midges on each of these occasions

 

Research in IAH, with collaborators in the Universities of Cambridge and Liverpool, had predicted that conditions in England would be suitable for the growth and spread of the virus.

 

John Gloster, on secondment from the Met Office to the IAH Pirbright Laboratory, and colleagues has been monitoring wind direction in western Europe on a daily basis since August 2006.

 

Overnight on 4/5 August was considered ideal in respect of conditions for midge take-off, safe transit and landing in the Suffolk area: warm conditions would have encouraged the midges to become airborne, winds were easterly during the nine to twelve hour transit, and then light in strength once the midges had crossed the UK coast.

 
Plume trajectories

Plume Trajectories

 Culicoides midges are most active in the evening. Therefore each evening John Gloster and colleagues made calculations to predict where wind-borne midges would have arrived by 06.00, had they become air-borne between 18.00 and 21.00 on the previous evening. The figure shows the air plume that is believed to be the one that brought bluetongue virus-infected midges to eastern counties during the night of August 4/5.
 

Following confirmation of bluetongue on a farm near Baylham, Suffolk, James Barber and Chris Sanders of IAH set up a mobile Automatic Weather Station (AWS) at the first infected premises. Hourly observations of temperature, wind speed and direction, relative humidity and precipitation are being regularly accessed from Pirbright. The data will be used to monitor the likely midge development in the area and help to identify areas for further spread of disease in the area.

 
IAH automatic weather station Baylam farm
Institute for Animal Health’s Automatic Weather Station at the farm near Baylham where bluetongue was first identified in Britain.
John Gloster analysing weather data
The Met Office’s John Gloster analysing weather data at the IAH’s Pirbright Laboratory.
 
 

For more information about the outbreaks of bluetongue virus serotype 8 in northern Europe see especially http://www.iah.bbsrc.ac.uk/bluetongue/.
To speak with our bluetongue experts, contact:
Dr Dave Cavanagh at the Institute for Animal Health’s press office:
mobile 07789 941568 (message can be recorded);
office 01635 577241 (message can be recorded);
email dave.cavanagh@bbsrc.ac.uk.