Highly pathogenic avian influenza, commonly called bird flu, has increasingly spread to mammals and infected hundreds of people, raising concerns that it may lead to human-to-human transmission and turn into a new pandemic.

Sheep were added to the list of mammals that can get infected with bird flu on Monday, with the United Kingdom government announcing a first case had been detected at a farm in northern England.

Bird Flu Outbreak: World’s First Case of Avian Influenza Found In Sheep

Pigs represent a particular concern for the spread of bird flu because they can become co-infected with bird and human viruses, which could swap genes to form a new, more dangerous virus that can more easily infect humans.

Some of the mammals such as dairy cows and sheep are farmed and so interact closely with humans, increasing the threat of transmission, while others have much less contact with people.

CDC Confirms New Strain Of Bird Flu In Nevada Dairy Worker

Recently, a new strain of bird flu wiped out a Mississippi poultry farm. After the virus was detected, all the birds died or were executed (culled). This new strain of a highly pathogenic bird flu known as H7N9 occurred in chickens raised for breeding. None of the birds entered the food supply.

According to USDA rules, however, routine and periodic testing of breeder birds for low-pathogenic avian influenzas is required. In 2017, an outbreak of H7N9 occurred along the Mississippi flyway, probably starting in late February, but reported only in March. A summary report of the outbreak suggested the virus was introduced via wild birds. –Los Angeles Times

Immunity from the flu could allegedly help humans stave off the major symptoms of the bird flu, while some members of the current ruling administration have suggested allowing bird flu to run its course to offer natural immunity.

Kennedy Wants To Stop Culling Birds For Natural Immunity