What are the distances the virus can travel on the wind?
• The distance virus can travel on the wind and still cause an infection depends on environmental factors such as humidity, wind speed etc., the amount of virus produced, and the type and number of potential hosts downwind of the virus-producing animals. The virus seems to travel particularly long distances over water (up to 250km/156 miles) has been reported) although not nearly so far over land. Pigs produce much more virus than do cattle or sheep, while cattle are the species most likely to be infected by breathing in airborne virus. A recent study indicated that small numbers of sheep or cattle (e.g. ten infected animals) would not be infective more than about 100 metres (110 yards) downwind and even for 100 cattle or sheep producing virus, only cattle would be likely to be infected as little as 700 m (half a mile) downwind. At the other end of the scale, 1000 fully infective pigs could theoretically infect cattle 300 km downwind. Cattle are the domestic species infected most easil
