The Centers for Disease Control and Prevention for weeks has reassured the public that an outbreak of bird flu in dairy cattle poses only low risk to most people. But in a summary on Friday, the Atlanta-based agency wrote that it is preparing for the “possibility of increased risk to human health.”
CDC officials have said that while workers in dairy barns with apparently infected cows have been infected with the bird flu virus, there is no evidence of person-to-person transmission in the U.S.
Seema Lakdawala, a virologist and influenza expert at Emory University, has an eponymous lab — the Lakdawala lab — studying how influenza viruses could spread under different conditions including different temperatures but also how factors like a person’s age and vaccination may influence how influenza viruses can spread from one person to another.
A renowned bird flu expert, Lakdawala and other researchers in her lab are currently studying how exactly the virus — also known as H5N1 or “avian influenza” — is spreading. Her lab is zeroing in on strategies to prevent the spread of the virus, including a recommendation that dairy farm workers wear face shields.
Lakdawala was recently part of a team of researchers at Emory and the University of Pittsburgh who reported that the H5N1 virus now infecting dairy cows can persist and remain infectious in unpasteurized milk and on milking equipment surfaces for a long time. This route could be allowing the virus to spread among cows but may also be how dairy farmers are being infected, she said.
Photo credit: Jack Kearse, Emory Health Sciences Photography
Photo credit: Jack Kearse, Emory Health Sciences Photography
The Atlanta Journal-Constitution interviewed Lakdawala on May 23 to discuss bird flu in humans and why this virus needs to be taken seriously.
Questions and answers have been edited for length and clarity.
Q: What was your first thought when you heard about more human cases associated with this current outbreak?
I will tell you one way I’m not surprised: The first is, what has become evident over the past few weeks and months since the detection of the avian influenza virus in cattle, is that there is a high amount of virus that is shed in the milk. ... Humans come into contact with cattle on these farms, and they’re milking these animals, interacting with the animals at face height ... including (exposure to) potentially contaminated milk.
(Inside a dairy barn, milking takes place in what is known as a “parlor.” They are often built in a way that puts cows’ udders at eye level for the workers who attach and remove milking equipment. Some parlors milk as many as 96 cows an hour, with workers in close proximity to the raw milk.)
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This is probably the tip of the iceberg. There are probably so many infections (in humans) that we have already missed; that they’ve cleared it and luckily they didn’t transmit to other people. But what is happening is two things: the virus is adapting in its new host, cattle; and it’s constantly trying to spillover into humans because these lactating cattle have to be milked every day. People have to interact with these animals.
Q: How do you think bird flu is spreading from cows to people exactly?
A: When these cows are milked, a lot of aerosol is getting produced. There’s also a lot of spray of milk that happens from the splatter of the milk during the process, and the milk can get sprayed into someone’s face. And then there’s when cows are leaking before the milking claws are attached to the teats of the cow. There’s contamination on the equipment and they can touch that and then touch their eye.
Q: According to the Centers for Disease Control and Prevention, a nasal swab from the worker in Michigan had tested negative for the virus, but an eye swab sent to the agency tested positive. What could that indicate about how the virus can spread?
A: There are very few studies that are really looking at conjunctivitis and influenza infections.
I know there’s ongoing testing to look at the potential for onward transmission from human to human, understanding a lot of these migrant workers at farms live in really tight cramped spaces. And maybe more interaction would allow for close-range transmission.
Maybe there isn’t as much contact via the eye as there would be otherwise. ... The larger concern for me is how is the virus is going to adapt in (the eye.)
As these viruses — and this has been my concern the whole time — as they continue to have access to humans, there’s this huge interface between cattle and people and they are constantly testing this space.
The virus can change in the eye. Maybe it’s only in a couple of people. But those viruses adapt.
So what we really need to do is prevent these infections from ever happening.
Q: What do you think must happen now?
A: What I want is one, for all dairy workers to wear face shields to protect all of the mucous membranes (of the eyes, mouth and nose).
Two, we need to be offering vaccines from our stockpile to dairy farmworkers and veterinarians working at dairy farms because they also face the potential of high amounts of the virus as well. Third, I think we need to do more testing to get a handle on how widespread this is, and that includes testing at farms without any cases.
We should pause the movement of all cattle until we better understand the risks of spreading the disease at different stages in their lactation cycle, which includes milking periods and dry (off periods).
Q: What do you say to your friends and family in Georgia about bird flu? Do they need to do anything differently?
A: I love my milk and we went for ice cream three times this week. The thing I tell family and friends is I am not concerned about my own or my child’s consumption of milk products that are pasteurized.
I do not recommend anyone ever consume raw milk, and not necessarily because of H5N1 but for all the other pathogens that can be transmitted from the milk of cows that pasteurization kills.
Q: Health officials have said the risk to the general public is low. There have been no cases in Georgia in cattle or people. So why do you think people need to care about this?
A: The reason I think it’s important that we care is because we don’t want to go into lockdown.
No one wants the emergence of a novel virus. And so we need to be vigilant, we need to advocate for all the government agencies and all of the farm owners and all of the people who work on the cattle, all these frontline individuals, to take this on. No one wants another pandemic.
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