Bird flu confirmed in Wyoming dairy cattle

The spread of Highly Pathogenic Avian Influenza into dairy cows has now been confirmed in Wyoming, making it one of 12 states to be affected by this recent outbreak.

Instances of bird flu appearing in cattle began near the end of March, when animals from two Texas herds tested positive.

At this time, the Centers for Disease Control believe the spread is linked to the movement of cattle, rather than through wild birds, with further local spread between dairy farms.

Over 90% of affected farms reported thickened or clotted milk from the animals, while over 80% reported abnormal lactation and decreased consumption of feed.

More than 60% of affected farms are known to have continued moving animals off the farm after the onset of clinical signs.

Nearly all farms with poultry present noted sick or dead poultry and over half of farms with cats said the same. Around a third observed sick or dead wild birds within 30 days prior to the onset of clinical signs.

Shared equipment that is not cleaned between uses is thought to have contributed to the spread, as are shared personnel and visitors such as veterinarians and contract haulers.

So far, morbidity among infected cows has been less than 10% on average, while mortality and culling has been less than 2%.

Lactating cows appear to be the most highly affected.

The number of human cases of bird flu has now risen to four since the outbreak began in 2022. While the first person to be infected was exposed to poultry, the most recent have been reported since the beginning of April and were all exposed to dairy cows.

The most recent case, in Michigan, was the first human case in the United States to report symptoms of acute respiratory illness.

Because all infected humans were directly exposed to infected animals, the CDC has not changed its risk assessment from “low”.

However, the CDC recommends personal protective equipment when interacting with potentially infected animals and avoiding close, long or unprotected exposure to sick or dead animals, including wild birds, poultry, other domestic birds and other wild or domestic animals, including cows.

In addition, the CDC avoids unprotected exposure to animal waste, bedding, raw milk or materials that have been touched by or close to animals that are suspected to be infected.