The U.S. bird-flu outbreak in dairy cattle is much larger than official figures suggest due to farmers' reluctance to test their animals and risk the economic consequences of a positive result, according to Reuters interviews with dairy experts, veterinarians, and farmers in six states with known cases.

US undercounts bird flu in cattle as farmers shun testing
Farmers fear economic losses from positive tests, leading to under-reporting; USDA offers partial compensation

US to expand bird-flu testing of beef in slaughterhouses
The U.S. Department of Agriculture said on Tuesday it will expand bird-flu testing of beef entering the food supply as part of its response to the ongoing outbreak among dairy cattle, adding that U.S. beef and dairy products remain safe to consume.

Bird flu cases among farmworkers going undetected: study
A study posted online on Wednesday suggested that there are more farmworkers infected with bird flu than what has been reported.

US to spend $10 million to curb bird flu in farm workers
CDC plans vaccine push; says risk to general public remains low
The U.S. Centers for Disease Control and Prevention said on Tuesday it plans to spend $10 million to curb farm worker bird flu infections, including $5 million for seasonal flu vaccines, as part of its efforts to avoid further spread and mutation of the virus.

Light shed on bird flu spread in mammals
Researchers from Cornell University have determined how cows infected with H5N1 bird flu were able to spread the virus to other cows and mammals. In the study published in the journal Nature on July 24, scientists used genomic data, computer modeling, and data about the virus’s spread to show how infected cows from Texas spread bird flu […] Read more

Chicken culling, disposal raise concern as bird flu spreads in U.S.
The spread of bird flu among poultry and dairy farms has heightened some health experts' concerns that the process of killing and disposing of poultry infected with the virus may pose a risk to humans and livestock.

US CDC sends field team to aid Colorado’s bird flu response
The CDC, in a statement dated July 14, said its team of epidemiologists, veterinarians, clinicians and an industrial hygienist was working to support Colorado's assessment of the outbreak and the human cases.

Bird flu virus detected in Oklahoma dairy herd
Oklahoma has detected bird flu in a herd of dairy cattle, the state's agriculture department said on Friday, making it the 13th U.S. state to find the virus.

Explainer: How U.S. states are testing for bird flu
States in the U.S. are playing a key role in the nation's response to a growing outbreak of avian flu among dairy cattle that has also infected a small number of humans.
The states are chiefly responsible for testing cows and people for the virus, but they take different approaches. Scientists tracking bird flu are increasingly concerned that current surveillance efforts are not sufficient.

Bird flu strain in US cows shows minimal air spread in ferret study
The bird flu strain found in cows in the United States is not easily transmitted through the air among ferrets, a new study shows, although the scientist who led the work said it had shown some ability to spread this way.