Nebraska has canceled all poultry events through May 1 as bird flu cases shoot up throughout the state. The state confirmed its fourth case of the flu on Saturday, though it was the first case to arise from a backyard flock instead of a commercial coup. Bird flu rates have risen rapidly since it was first confirmed in Indiana last month; since then, 18 states in total have confirmed its presence and 13 million chickens and turkeys have been killed, according to the Associated Press. The flu is considered highly contagious, though most symptoms are similar to that of regular influenza. The CDC said the cases are not indicative of a larger public health crisis.