Right now people can't easily infect each other with bird flu; could that change?

The CDC reports that the current risk of bird flu to humans is low, but stresses the need for more testing, especially in dairy farms where the virus is spreading. The H5N1 bird flu virus has been found in American dairy cows across multiple states. There have been three mild human cases in the US, all involving dairy workers. The agricultural industry faces challenges with testing, as many do not want it done. Scientists are monitoring the virus's mutations, which have infected various mammal species globally. The USDA assures that cooked beef and pasteurized milk remain safe for consumption.

What challenges are faced in testing for bird flu in the agricultural industry?

What does the USDA say about the safety of consuming cooked beef and pasteurized milk in relation to bird flu?