ABERDEEN, S.D. — The flu and other winter illnesses have led to a shortage of blood in parts of the Dakotas and Minnesota, and recent blizzard conditions have hindered efforts to collect more.

Molly Vetter, center manager of United Blood Services in Aberdeen, S.D., says a blizzard about a week ago cost the organization’s six Dakotas offices about 300 units of blood.

She said that the problems are likely to continue. On Monday, a mobile unit that was supposed to go to Fullerton, N.D., was canceled because of the weather. Illnesses, especially the flu, have also hindered people from being able to donate.

United Blood needs about 500 donations a day to supply 93 hospitals in the Dakotas and part of Minnesota.