Officials say an outbreak of cholera in Nigeria's northwest Zamfara state has infected 536 people and killed 50 in the past week.
Medical director of the state hospital, Dr Labaran Anka, blamed contaminated water in rural areas that have no clean running water. Villagers rely on handmade ponds where animals and people share water.
Anka said more than 420 patients have been treated and discharged since the first victims arrived Friday.
Medical authorities also have reported a cholera outbreak that had killed eight people by Monday, in a village of central Plateau state overcrowded with refugees from communal violence.
Cholera is caused by filth and dirty water. UN figures indicate half of Nigeria's 160 million people do not have safe water and a third do not have proper sanitation.