The convergence of multiple flu strains in one animal can allow new virus strains to form—just as they did in past pandemics.

With the approach of fall and cooler weather across the United States, officials say the risk posed by the H5N1 bird flu virus could rise — and they’re taking steps to prevent the creation of a hybrid flu virus that could more easily infect humans.

Several labs will work with federal health authorities to develop a test for avian influenza, as the number of human cases rise across the country.