Four farm workers, who work at the same poultry farm, were infected with bird flu on Monday, increasing the total number of cases to eight, according to officials Centers for Disease Control and Prevention in the United States.

The cases come, simultaneously, with a worrisome outbreak of the virus among cattle, which has also resulted in human infections.

A fifth case is also suspected but must still be analyzed to be confirmed.

For the American public, the risk is still “low,” according to the CDC. In addition to conjunctivitis, the affected workers reported experiencing “flu-like symptoms.”

In the United States, a surprising twist to the bird flu outbreak was discovered in the spring: cows were suddenly contracting the disease, which had previously only affected poultry and birds. Human cases of bird flu climb to 8 in US

The first human infection via a cow was announced on April 1, in the state of Texas.

Two other cases were then reported in Michigan, and in early July, another case was found in Colorado.

That western US state is now seeing the disease spread among both livestock and poultry.

Despite the rarity of human cases, experts are concerned about the increasing number of afflicted creatures.

They worry that widespread distribution may facilitate the development of a virus mutation that would enable human-to-human transmission.

The CDC renewed its call for precautions for workers in contact with infected cows or poultry.