In an investigation into mysterious illnesses in dairy cows in Texas, Kansas, and New Mexico, tests on unpasteurized milk and nasal swabs have revealed highly pathogenic avian flu in Kansas and Texas, according to a statement today from the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS).

The cow's symptoms included decreased milk production, low appetite, and other symptoms. APHIS said the infections were primarily seen in older dairy cows. The new development comes less than a week after Minnesota veterinary officials detected H5N1 avian flu in baby goats at a farm where the virus had been detected in a backyard poultry flock.

The Texas Department of Agriculture said today that the disease has been working its way through the Texas panhandle, puzzling the agriculture industry. It said the cows had flulike symptoms, including fever and thick and discolored milk.

Sporadic outbreaks continue to be reported in US poultry flocks, along with numerous H5N1 detections in a variety of wild birds across many states. Along with the unidentified illnesses, the farms had also reported dead wild birds on the properties. The virus was found in milk samples from sick cows at two dairy farms in Kansas and Texas and in an oropharyngeal sample from another dairy in Texas.

"Based on findings from Texas, the detections appear to have been introduced by wild birds," APHIS said, adding that initial testing by the National Veterinary Services Laboratory in Ames, Iowa, have found no changes that would make the virus more transmissible in humans.