4.2 million Iowa chickens infected, flock to be culled


  • Bird flu outbreaks have continued across the U.S. as officials work to keep the spread at bay.
  • The virus was first found in alpacas.
  • The CDC has documented two cases of human bird flu infections in 2024.

Bird flu outbreaks have continued across the U.S. as officials work to keep the spread at bay.

Although the outbreak likely started among chicken flocks and spread to dairy cows, reports have emerged from several states that the virus has infected other animals. Despite continued testing, two human cases of the virus have been reported, according to the Centers for Disease Control (CDC), and their symptoms were alleviated by simple over-the-counter flu medications.

Commercial farming facilities have begun destroying infected herds in an effort to quell the ongoing spread. Yet a new large-scale infection was reported in Iowa this week, affecting millions of egg-laying chickens.

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More than four million chickens are expected to be killed

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

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

Bird flu infection found for the first time in alpacas

In addition to the unusual spread to dairy cows in recent months, bird flu has also been found in other animals, including barn cats found dead in infected facilities. And now it has been found 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, according to the USDA.

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What is bird flu?

Bird flu, or bird flu, is a contagious infection that spreads among wild birds and can infect poultry and other species. The virus does not often spread to humans, but sporadic infections have been reported. There are several strains, all of which belong to influenza A-type viruses.

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

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

The CDC has documented two cases of human bird flu infections in 2024, one in a dairy farm worker in Michigan and one in a Texas dairy farm worker. Both infected people showed only symptoms of conjunctivitis or pink eye.

Outbreak of the bird flu virus in dairy cows

The current outbreak of bird flu among cattle in multiple states likely began late last year.

At least 67 dairy 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 tests on dairy products found traces of the virus in one in five commercial dairy samples, but none contained live virus that could transmit the disease.

As long as people consume pasteurized dairy products and cook poultry products to the correct temperatures, mass-produced products remain safe, the agency said.

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