Maryland may be known for crabs, but it is also a major producer of broiler chickens and dairy products. So a recent spate of bird flu cases have public health officials on alert and watching for the impact on these multibillion dollar industries, as well as the health of the animals — and people.

The U.S. Centers for Disease Control and Prevention considers the threat to humans from the H5N1 strain low. But the virus is highly contagious and has already been found in dairy cows, poultry, backyard flocks, a variety of wild animals and a bunch of pet cats around the country. There have also been cases in dozens of people nationwide.

Maryland has reported cases of the “highly pathogenic” H5N1 avian influenza in Queen Anne’s and Caroline counties on the Eastern Shore, according to state officials. Two more cases were found in nearby Delaware.

Here is what’s important to know.

This is not the first bird flu outbreak. What’s different?

The CDC has confirmed cases on farms in multiple states. There have been 66 infections in people, largely linked to contact with infected animals since April. One person has died. Maryland officials found cases in chickens, but not in humans.

Andrew Pekosz, an influenza researcher at the Johns Hopkins Bloomberg School of Public Health, said this H5N1 strain may be a bigger threat to animals, and humans, than previous avian influenza outbreaks.

Most cases are in dairy cows, according to the CDC, but Pekosz said the virus has also been found in sea lions, bears, foxes, dolphins and wild migratory birds, which are likely spreading the virus. Domestic cats have been infected through raw milk and food and seem particularly at risk.

“That’s a concern because prolonged infection gives the virus a lot of opportunities to get better at growing in mammals,” said Pekosz, who is also a professor and vice chair of Hopkins’ Department of Molecular Microbiology and Immunology.

How is H5N1 being monitored? What happens when a case is found?

Both Maryland and federal officials are testing samples taken from animal farms and backyard flocks where cases are suspected.

Pekosz said H5N1 can kill chickens within two days of infection, so farmers know immediately they need to quarantine and cull sick flocks. Cases in dairy cows are less obvious, but a telltale sign is decreased milk production. Cows can be saved by isolating them and disposing of their milk during their recovery.

There are human tests for bird flu, but few people are tested beyond those with known exposures. Pekosz called the lack of human testing a “hole in the system.”

What’s the threat to animal and human health from an infection?

The CDC says that there has been no reported person-to-person spread of the virus, which means farmworkers and backyard flock owners are at the greatest risk. Those agricultural workers are being advised to wash their hands more often, sanitize their equipment and limit the number of visitors to their facilities.

However, there is a risk the virus will get stronger, infect more people and make more of them sicker, Pekosz said. Most current cases in humans lead to conjunctivitis, or pink eye, and not severe respiratory symptoms.

What do consumers need to know about consuming chicken, eggs and milk?

This virus “does not affect poultry meat or egg products, which remain healthy and safe to eat and handle,” said Maryland Department of Agriculture Secretary Kevin Atticks in a statement.

Pekosz said that’s because chickens likely die before their eggs or meat leave the farm. Cooking would kill the virus anyway.

That’s the same for drinking milk treated by pasteurization. Raw milk samples have shown live virus, Pekosz said, but in Maryland, it’s only sold for animal consumption. He warned that people and their pets should not drink raw milk.

“Raw milk is an issue because it seems to be something of a fad,” he said. “There is no benefit to raw milk. Pasteurization doesn’t reduce the nutritional value.”

Is there a vaccine for people or animals?

The federal government is preparing to test its own stockpile of a H5N1 vaccine in upcoming human trials, Pekosz said. Officials have also contracted for vaccines with manufacturers of mRNA vaccines, the kind made to protect against COVID.

Veterinary companies are working on producing a version of poultry vaccines used in other countries. Vaccinating chickens, however, could have trade implications because some countries ban their import, Pekosz said.

There also are antiviral treatments for humans if cases become severe.

“Generally, we are in a much better situation than with COVID, because we had none of this,” he said about the pandemic that killed more than a million Americans before it was controlled.

What are your biggest concerns?

The biggest effect so far has been on increased prices of chicken and eggs, pushed up by shortages.

Pekosz said he was concerned about the incoming Trump administration, which could include agency leaders who have promoted raw milk, criticized vaccines and mused about limiting infectious disease resources.

“The threat right now is low, but now is the time to act,” he said. “Once the virus is spreading from human to human it will be hard to stop.”