Vaccinating poultry against avian influenza is currently not allowed in the UK. The government says that strong biosecurity measures and culling are the most effective ways of fighting it. Meanwhile, there are concerns that poultry vaccinations might be linked to the virus evolving.

This latest outbreak is part of a broader epizootic that has swept across the United States, affecting not only poultry but also wild birds, mammals and humans.

The Virginia Department of Wildlife Resources is receiving increasing reports of sick or dead wild birds on the Eastern Shore.

Bird flu appears to be widespread among birds in Massachusetts, state health and environmental officials said Wednesday. The Division of Fisheries and Wildlife (MassWildlife), the Massachusetts Department of Agricultural Resources (MDAR) and the Massachusetts Department of Public Health (DPH) said bird flu -- also known as highly pathogenic avian influenza (HPAI) -- is suspected to be the cause of death in cases of both wild and domestic birds in several Massachusetts municipalities.

The number of bird flu cases in Central Massachusetts is relatively low, compared to a swath of the state that runs from Greater Boston to Southeastern Massachusetts. That message was delivered Wednesday during a virtual update from state health officials on the highly pathogenic avian influenza H5N1 virus.

Infectious disease experts say humans are unlikely to get the virus, and the biggest risk of infection remains through close, prolonged contact with a sick animal.

Six dead swans have been found in Worcester in a case of suspected bird flu. Worcester City Council said on Tuesday evening the birds had been found along a stretch of the River Severn between the cathedral and the railway viaduct.