4.2 million Iowa chickens infected, one flock to be culled

• Avian flu outbreaks have continued across the United States as authorities work to contain the spread.
• The virus was first detected in alpacas.
• The CDC has documented two cases of human infection with avian flu in 2024.

Avian flu outbreaks have continued across the United States as authorities work to contain the spread.

Although the outbreak likely began in chicken flocks and spread to dairy cows, there have been reports of the virus infecting other animals in several states. Two cases of the virus appearing in humans were reported despite ongoing testing, the Centers for Disease Control (CDC) said, and their symptoms were relieved by simple over-the-counter flu medications.

Commercial agricultural facilities have begun destroying infected herds in an attempt to stem the ongoing spread. Despite this, a new large-scale infection was reported in Iowa this week, affecting millions of laying hens.

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More than 4 million chickens will be killed

An outbreak of avian flu was detected Tuesday in Iowa in a commercial flock of 4.2 million chickens, according to the state Department of Agriculture.

The egg-laying flock, located in Sioux County, will be culled to prevent further spread. Since 2022, about 22.9 million birds from backyard flocks and commercial facilities have been destroyed to keep the virus at bay in Iowa, the nation’s top egg producer, according to data from the USDA.

Avian flu infection detected for the first time in alpacas

In addition to the unusual spread to dairy cows in recent months, avian flu has been detected in other animals, including barn cats found dead in infected facilities. And now we’ve found it in alpacas.

The U.S. Department of Agriculture’s National Veterinary Services Laboratories said Tuesday that a group of alpacas tested positive May 16 at an Idaho farm where poultry had previously tested positive and been destroyed.

This is the first known infection in alpacas, the USDA said.

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What is bird flu?

Avian flu, or bird flu, is a contagious infection that spreads among wild birds and can infect domestic poultry and other animal species. The virus is not often transmitted to humans, but sporadic infections have been reported. There are several strains, all belonging to type A influenza viruses.

The most common subtypes that can affect humans are A (H5N1), A (H7N9) and A (H9N2), according to the Cleveland Clinic. In humans, symptoms may resemble those of a typical flu, but may progress to more severe respiratory symptoms.

In birds, avian flu is very contagious and cases can range in severity from mild to very fatal. Infected birds shed viruses in their saliva, nasal secretions and droppings, meaning other birds can contract the virus through direct contact with these fluids or through contact with a contaminated surface.

The CDC has documented two cases of human infection with avian flu in 2024, one in a Michigan dairy farm worker and one in a Texas dairy farm worker. The two infected people only had symptoms of conjunctivitis or pink eye.

Avian influenza virus outbreak in dairy cows

The current outbreak of avian flu in cattle, which is affecting several states, likely began late last year.

At least 67 dairy cattle herds in nine states have been confirmed infected in nine states, including Colorado, Idaho, Michigan, New Mexico, North Carolina, Ohio and South Dakota.

In late April, the U.S. Food and Drug Administration announced that testing of dairy products had found remnants of the virus in one in five samples of commercial dairy products, but none contained a live virus capable of transmitting the disease.

As long as people consume pasteurized dairy products and cook poultry products to an appropriate temperature, mass-produced products will remain safe, the agency said.