Bird flu has struck two northwest Iowa commercial turkey operations with 140,000 birds altogether, the Iowa Department of Agriculture reported.

Highly pathogenic avian influenza hit 100,000 turkeys at a commercial operation in Cherokee County and a 40,000-turkey flock in Sac County. Both cases were reported Tuesday.

They are the second and third commercial turkey flocks infected so far this month. The state reported Friday that a Buena Vista County facility with 40,000 turkeys had been infected.

So far this year, 26 Iowa backyard and commercial flocks, totaling nearly 15.7 million birds were destroyed to contain the deadly, highly contagious disease. Wild birds that migrate in the spring and fall can spread the virus through their droppings.

Iowa poultry producers have pushed biosecurity measures in an effort to keep the disease from their operations. The virus hasn't been a threat to U.S. residents and infected products have not entered the nation's food supplies, state and federal officials have said.

Donnelle Eller covers agriculture, the environment and energy for the Register. Reach her at deller@registermedia.com or 515-284-8457. 

This article originally appeared on Des Moines Register: Bird flu hits two commercial turkey flocks in northwest Iowa