Bluetongue Midge's 12 Hour Flight To The UK

Main Category: Veterinary
Also Included In: Water - Air Quality / Agriculture
Article Date: 07 Mar 2008 - 2:00 PDT

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An article in this week's issue of The Veterinary Record explains how the midge that carried bluetongue virus to the UK probably surfed the air currents above the North Sea for between nine and 12 hours to deliver its payload from Belgium.

Meteorologist John Gloster, and colleagues from the Met Office and the Institute for Animal Health at Pirbright, have examined the meteorological conditions leading up to the first British case of the disease in a Highland cow near Ipswich on September 15, 2007.

Their study confirms that the most likely time of arrival of infected midges was overnight on August 4 to 5, 2007, following a transit time of between nine and 12 hours. Light winds, initially from the north and then from the south east, picked up midges in the Ostend region of Belgium and carried them at about 50 metres above the North Sea towards the UK.

Gloster believes that although the virus survived over the winter of 2006/07 in north-west Europe it is not inevitable that it will do the same in the UK this year. However, a warm winter may enhance the likelihood of survival. An effective vaccination programme could significantly reduce the impact of the disease in 2008, but the authors warn that timing is critical, and if the disease were to take hold before livestock are vaccinated, it may spread across the UK.

They also warn that the UK is at risk of further introductions of virus from the continent. A 10 year study of wind directions has revealed that for about 100 hours each month it blows in the right direction to carry a midge from the continent. Combined with suitable temperatures, this could lead to a repeat of the events of August 2007. Should currently uninfected areas of the continent, perhaps further to the west, be affected by bluetongue, livestock on the south coast of the UK and in the Channel Islands would be at increased risk of becoming new centres of the disease.

Gloster says that 'the coming months will be an anxious time for all of those involved in cattle and sheep farming. The main question is whether the virus has overwintered and we should have that answer to that over the next few weeks. It's certainly possible that the disease could easily re-establish in the coming months'.

1. Bluetongue is a disease of animals but not humans. It affects all ruminants, including sheep, cattle, deer, goats and camelids. It does not affect horses or pigs. Sheep suffer the worst affects but cattle are the main reservoir of the virus that is spread by certain types of biting midges (genus Culicoides). Bluetongue was first discovered in South Africa but has since been found in most countries in the tropics and sub tropics. Since 1999 there have been widespread outbreaks in southern Europe. In 2006 the disease reached Germany, Belgium, France, the Netherlands and Luxembourg and in 2007 infections increased from around 2,000 to 45,000 holdings. Vaccination is seen as key to controlling the disease. The timing of vaccine arrival, its speedy administration and take up by the farming community will influence the spread of the virus over the country.

2. The Veterinary Record is the British Veterinary Association's official journal and has been published since 1888. It delivers news, comment, letters and clinical research papers on a wide range of veterinary topics to the profession.

3. Reference: J Gloster, L Burgin, C Witham, M Athanassiadou & P. Mellor (2008) Bluetongue in the United Kingdom and northern Europe in 2007 and key issues for 2008. The Veterinary Record, March 8, vol 162, No 10, pp 298-302

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