Experts issue biosecurity plea after avian influenza is found in sheep in Yorkshire backyard flock

Further tests are being carried out on the virus that infected the Yorkshire sheep.

While Government officials withheld the location of the outbreak, earlier this month highly pathogenic avian influenza H5N1 was confirmed in commercial poultry at three premises near Sandhutton, west of Thirsk. In each case a 3km Protection Zone and a 10km Surveillance Zone were put in place around the premises.

The other most recent outbreaks confirmed in Yorkshire include at a farm near Langtoft, north of Driffield, on February 26, three premises near Holme on Spalding Moor on February 18 and two premises near Market Weighton and another near Pocklington early last month.

Professor Ian Brown, group leader at the Pirbright Institute, said the detection of H5 highly pathogenic avian influenza in the mammary gland of a sheep was “not an unexpected finding”.

He added: “It is too early to consider whether such virus is capable of onward spread within sheep but this was an isolated small holding with a small number of birds and sheep.”

Associate professor in virology Dr David Allen, said people needed to avoid touching dead or sick wild birds they found.

He said: “Current evidence suggests the circulating avian-origin influenza viruses do not spread easily to humans, so the risk to the general public remains very low. However, but people should be aware of advice to not touch any dead or sick wild birds they find.”

Experts said swift action to identify the virus had reduced the chance of it evolving genetic changes and spreading, as has happened in the US after the virus was detected in cattle.

Bird flu outbreaks have been confirmed in more than 900 herds across 16 states and the virus in a harmless form has been detected in supermarket milk.

Government officials said the case was detected in a sheep undergoing heightened surveillance due to the previous poultry outbreak, and experts said it seemed reasonable to infer the sheep was infected by close contact with infected birds or fomites from them on the same farm.

Infectious disease epidemiologist Prof James Wood said the Yorkshire sheep represented the first case of a domesticated animal getting infected with avian influenza H5N1 over the five years or so of the current epidemic in wild birds and poultry.

He added: “The case appears to have worrying parallels with the dairy cattle situation in the US, but also some reassuring differences. The case is one in which a mammary infection was found, as in the US cattle, but thankfully no within farm spread has been found. In the US, transmission between cattle is thought to have been mostly from the milking process.”

NFU President Tom Bradshaw said: “While the risk to the nation’s livestock population remains low, it’s vital that all keepers of domesticated poultry, cattle, sheep and goats maintain high standards of biosecurity and remain vigilant for any signs of disease.”

Biosecurity