A prison inmate in a pre-release work program was the first recorded human case of the bird flu in the US

The first human case of the bird flu in the US has been reported by a prison inmate.

Almost 27 million chickens and turkeys have been killed to stop the spread of the bird flu, but the risk to humans remains low.

NBC News reported that the man was exposed to the H5N1 virus while working on a Colorado farm.

The outlet reported that a man was working at a farm while he was in the pre-release program. The other inmates in the program have not tested positive.

According to the Colorado Department of Public Health and Environment, the man had only one symptom, fatigue, and that it had cleared up after he took an oseltamivir drug. They identified him as younger than 40, but didn't give any information on his identity.

The department says that all inmates on the farm were given personal protective equipment and that all birds in the flock were euthanized.

The risk to Coloradans is low, according to Dr. Rachel Herlihy, state epidemiologist with the department.

The CDC has tracked the health of more than 2,500 people with exposure to H5N1 virus and this is the only case that has been found to date. The Centers for Disease Control and Prevention said in a statement that other people involved in the Colorado operation have tested negative for H5 virus, but they are being retested out of an abundance of caution.

He was the second person to test positive. The first was in the United Kingdom.

The CDC maintains that human risk is still low.

More than 880 human infections with earlier H5N1 viruses have been reported since 2003 worldwide, however, the predominant H5N1 viruses now circulating among birds globally are different from earlier H5N1 viruses.

The outbreak has hit more than thirty states and has resulted in an increase in egg prices as the strain continues to kill birds. Birds that catch it have a mortality rate of 90%.

The US is the hardest hit by the outbreak in seven years.

Rembrandt Enterprises roasted more than 5 million chickens because one of them tested positive for the virus. 250 workers were laid off after burying the chickens in pits.

The factory used a method to kill birds. It takes away air and then blasts the heat to over 100 degrees.

A Rembrandt worker told the Guardian that they cooked the birds alive.

Animal rights groups have criticized the practice of killing animals.

The organization says it can now see the widespread inherent cruelty for what it really is, demand accountability under the law, and remove our support from this industry by refusing to buy animal products.

The CDC says that cooking poultry and eggs to an internal temperature of 165 degrees kills off H5N1 viruses.

The CDC, Colorado's health department, and Animal Outlook did not respond to Insider's request for comment.