Bird flu spreads to more than 90 dairy farms in America

Avian influenza has now been found in hundreds of cattle across 12 different US states since it was first detected in dairy herds earlier this year.

At least 94 different herds have the H5N1 strain of the disease, while many more cases are likely to remain undetected.

The US Department of Agriculture has identified significant differences in the effects of the disease between farms, however, lactating cows are most highly affected.

See also: US reports human case of bird flu caught from cattle

Clinical observations found that, of the affected farms studied, more than 80% reported abnormal lactation and decreased feed consumption; and more than 90% reported thickened or clotted milk. Morbidity was less than 10% on average.

Michigan has been one of the worst hit states with 25 dairy herds affected by the outbreak.

Michigan Department of Agriculture and Rural Development director Dr Tim Boring said producers must implement robust biosecurity practices and create emergency preparedness plans.

“Implementing these measures must be the highest priority for every farm and agriculture worker. Working together, we can combat HPAI [highly pathogenic avian influenza] and reduce the long-term impacts on our dynamic food and agriculture industry,” he added.

Human cases

There have been three human cases of the virus found, all in farm workers who had direct contact with infected livestock.

However, the US Centre for Disease Control and Prevention says the human health risk assessment for the general public remains low.

The public in the US are being advised not to drink raw milk, avoid exposure to sick or dying animals, and take precautions if working in close proximity to infected animals.

USDA funding

The US Department of Agriculture (USDA) announced on 30 May it was providing an additional $824m (£650m) in funding to help control the virus in both poultry and livestock, and launch a voluntary dairy herd status pilot programme.

The USDA expects to see an increase in the number of positive cases as more testing takes place on farms through the pilot scheme.