A second Michigan farmworker has contracted the H5 avian influenza virus, likely from infected dairy cattle, the state health department announced Thursday. The person was treated with antiviral medication for respiratory symptoms and is recovering.
As with the first human bird flu case in Michigan, which was announced May 22, the state health department would not disclose on which farm the person worked, in which county the infection occurred or even which region of the state is involved.
"It's just to protect farm and worker privacy. These are small towns," said Chelsea Wuth, a spokesperson for the Michigan Department of Health and Human Services.
Wuth did say, however, that Michigan's two infected farmworkers are employed at separate farms in a county (or counties) with a known dairy cattle H5N1 outbreak. There does not appear to be human-to-human spread of the virus at this time.
As of Thursday, there were 23 outbreaks in dairy cattle herds in 10 Michigan counties: Allegan, Barry, Calhoun, Clinton, Gratiot, Ingham, Ionia, Isabella, Montcalm and Ottawa, according to the state Department of Agriculture and Rural Development.
What's distinct about the latest case is that the worker reported upper respiratory tract symptoms, including cough without fever, and eye discomfort with watery discharge, the U.S. Centers for Disease Control and Prevention reported.
The other two known human cases of cow-to-human transmission of highly pathogenic H5N1 influenza — in Michigan and Texas farmworkers — reported conjunctivitis, more commonly known as pinkeye, as their only symptom.
"Most influenza presents as a respiratory virus," said Joe Coyle, deputy state epidemiologist and director of the MDHHS Bureau of Infectious Disease, "so that's not necessarily terribly surprising. But this is the first case that has had these types of symptoms in the country. And, generally speaking, with something like influenza and respiratory viruses, when you have respiratory symptoms, you're more likely to spread the virus than if it was just conjunctivitis like the previous case we had in Michigan and the one in Texas.
"It is a new presentation, and it's something that we'll definitely be looking at ... to see if this represents a different mutation of the virus that's causing these types of symptoms, or is it really the same virus but just a different route of transmission with respect to the human exposure."
The CDC reported that the person was treated with the antiviral drug oseltamivir, better known as Tamiflu, and is isolating at home. None of the person's contacts have developed symptoms and all are being monitored for symptoms and also have been offered antiviral medication.
"No other workers at the same farm have reported symptoms, and all staff are being monitored," the CDC reported Thursday.
Dr. Natasha Bagdasarian, the state's chief medical executive, said the newest case of avian influenza in a Michigander was identified through a swift public health response that encourages farm owners and workers to report even mild symptoms and provides access to testing.
“With the first case in Michigan, eye symptoms occurred after a direct splash of infected milk to the eye," she said in a statement. "With this case, respiratory symptoms occurred after direct exposure to an infected cow. Neither individual was wearing full personal protective equipment (PPE).
"This tells us that direct exposure to infected livestock poses a risk to humans, and that PPE is an important tool in preventing spread among individuals who work on dairy and poultry farms. We have not seen signs of sustained human-to-human transmission, and the current health risk to the general public remains low.”
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The risk is higher for people who have prolonged or close contact with infected birds, cattle or other animals and for people who spend time in environments contaminated by infected birds or other animals, the CDC said.
That includes not only poultry and cattle farmers and workers, but also those who work in slaughterhouses, people who have backyard flocks, veterinarians and veterinary staff, and others who work in animal and public health.
"Given the extent of the spread of this virus in dairy cows, additional human cases in people with higher risk exposures would not be surprising," the CDC said in a statement released Thursday. "A CDC priority right now is to prevent additional cases of A(H5N1) infections in dairy herd workers, who are at higher risk of exposure."
The agency urges people to avoid consuming raw milk and to stay away from sick animals along with potentially contaminated surfaces and water (such as ponds, bogs and troughs) on farms with potentially infected animals. It also suggests avoiding contact with the udders of lactating dairy cattle; the feces, bedding or litter of potentially infected animals, and the carcasses of animals — especially birds and livestock — that have died from an unknown cause.
Those who must work around infected animals are urged to wear such PPE as a waterproof apron, respirator mask, safety goggles or a face shield, gloves, a head covering and boots or boot covers.
The first Michigan case of the H5N1 influenza virus in a human was identified through the text messaging surveillance program MDHHS developed that allows farmworkers to report daily whether they have any symptoms that could be tied to bird flu, Coyle said.
But with the second case, detection came about through collaboration between state agriculture workers and public health.
When MDARD identifies infected cattle herds, state agricultural workers reach out to the farm owners, Coyle said.
"We asked MDARD, 'When you do that first outreach to the farm, can you please let the farm owner or the producer know that local public health will be following up?' " he said. "One of the critical questions that they're going to ask is: 'Do you have any sick people?' And so when MDARD started to make that initial outreach to the farm, and local public health followed up, the producer said, 'Oh, yes, there has been someone who has been sick.'
"It was through the public health follow-up with the farm that we were able to identify that person as being ill and then rapidly worked to get them tested."
Specimens were collected from the farmworker and tested by the state Bureau of Labs. The CDC said it confirmed the H5 infection Wednesday night, and genetic sequencing is underway to determine whether there are any concerning changes to the virus.
Sequencing of the virus that infected the first Michigan dairy farmworker showed a mutation that allows mammals to be infected with this strain of bird flu more easily, the CDC reported last week, but did not contain changes that would likely make it easier for the virus to spread from human to human.
Contact Kristen Shamus: kshamus@freepress.com. Subscribe to the Free Press.
