Many U.S. dairy farms have not yet increased health protections against bird flu for employees during an outbreak in cows, according to workers, activists and farmers, worrying health experts about the risk for more human infections of a virus with pandemic potential.

Epidemiologists are concerned the virus could potentially spread and cause serious illnesses as farmers downplay the risk to workers while employees are not widely aware of cases in U.S. cattle.

The U.S. government said on Wednesday that a second dairy worker contracted bird flu since cattle first tested positive in late March and that investigators are looking into whether the person was wearing or offered protective equipment.

AUSTRALIA REPORTS NEW BIRD FLU CASE AT POULTRY FARM AS GLOBAL CONCERNS RISE

Nearly 24,000 farms sell milk around the country, and they offer varying protections to staff. Lobby group the National Milk Producers Federation said it encouraged farms to use protective equipment in line with federal recommendations and heard of increased worker protections.

Three dairy workers, seven activists and two lawyers who assist farm employees told Reuters that dairy owners have not offered equipment like face shields and goggles to staff who spend 10- to 12-hour days side-by-side with cows. Three large dairy companies with tens of thousands of cows declined to comment on their procedures.

The workers - all based in New York, a major dairy producer - said they heard of the new illness affecting cattle through the media or community organizers, not their employers. One, 39-year-old Luis Jimenez from Mexico, said last week it was business as usual.

"They're not doing anything," he said.

The U.S. Centers for Disease Control and Prevention in April and May advised workers to use personal protective equipment (PPE) if they may be exposed to sick livestock, after a Texas dairy worker tested positive for bird flu. On May 6, the agency asked states to make equipment available to workers.

CDC wants "to make sure that farm workers across the country, whether they are at a farm with an affected herd or not, have access to PPE," said Nirav Shah, principal deputy director, last week.

New York state said it is assessing CDC's recommendation and has not yet distributed equipment. Texas, New Mexico and Colorado, where cattle were infected, said they distributed equipment to eight dairies combined. Kansas, Idaho and Wisconsin said they have equipment, but no farmers asked for it.

Michigan, where the second dairy worker tested positive, said many farms have protective gear but the state is coordinating a way to make it available for those that need more.

Dairies became more aware of bird flu's risks in late April after the U.S. government began requiring that cows test negative before crossing state lines, said Emily Yeiser Stepp, who oversees a National Milk Producers Federation program that covers workforce development.

Still, "reaching out into some of our rural networks takes a little longer," she said when told of workers who said they were not informed of recommendations for protective equipment.

The U.S. confirmed bird flu in dairy cattle in nine states. Scientists have said they believe the outbreak is more widespread based on findings of H5N1 particles in about 20% of retail milk samples.

Bird flu has caused serious or fatal infections globally among people in close contact with wild birds or poultry. In cows, the U.S. Department of Agriculture said it believes unpasteurized milk is the primary vector for transmitting the virus, though officials do not know exactly how it spreads.

Health experts advise dairy workers to wear gloves and disposable coveralls that can block milk splashes on their bodies or clothing.

Jimenez said his coworkers are under pressure to work so quickly that they sometimes do not have time to wash their hands before meals and often drive home in their work clothes.

Workers attach and detach milking equipment on cows, putting their faces close to unpasteurized milk. Most are immigrants and many do not have health insurance.

"When you're milking, splashes can't be avoided. When it splashes in our eyes, we wash it out with water," said another New York worker, who requested anonymity because he is undocumented.

Lucas Sjostrom, a farmer and executive director of the Minnesota Milk Producers Association, uses robotic machines to attach milking equipment to cows, but said he is being extra conscious that human workers wear gloves while transporting unpasteurized milk. Minnesota has not reported bird flu in cows.

In Indiana, another state without confirmed cases, farmer Steve Obert said he has not increased precautions for workers, though that could change if his herd tests positive. Extra protective equipment is not comfortable to wear, he added.

"We're rather isolated and I don't think the risk is really great," said Obert, executive director of the industry group Indiana Dairy Producers.

The infected Texas worker suffered conjunctivitis and broken blood vessels that turned his eyes scarlet red, according to a photo published in the New England Journal of Medicine. He reported wearing gloves when working with cows but not respiratory or eye protection, the journal said.

Scientists are watching for changes in the virus that could make it spread more easily among humans. Epidemiologists said it could cause more serious illnesses if it mutates or infects someone with a compromised immune system.

Some dairies with infected cows have resisted allowing federal officials on their farms because of financial concerns, said Gregory Gray, a University of Texas Medical Branch professor studying cattle diseases.

The CDC said it would like to test more farm workers, but it is not required.

New Mexico had anecdotal reports of workers with symptoms similar to conjunctivitis, but most were not tested, according to internal state documents that were dated April 26 and obtained by Reuters under a public records request. The workers were not tested because they did not seek healthcare, the New Mexico Department of Health said.

Policy changes are needed to encourage workers to seek treatment, such as emergency income assurance for those who test positive, said Brian Castrucci, an epidemiologist and CEO at health policy group the de Beaumont Foundation.

"I don't want to wait until we have a dead dairy farm worker until we ratchet up what we're doing," he said.