A major outbreak of cholera in northern Nigeria has killed 42 people and hospitalised hundreds in the last two weeks, hospital authorities said on Wednesday.

Gravely dehydrated people lined the floors of the Infectious Diseases Hospital in Kano as the government told doctors to treat the victims free of charge.

“We have had 629 cases so far in the last two weeks of which 42 are confirmed dead,” said Ashiru Rajab, the hospital’s chief medical officer. More than 1,600 Africans have been killed this year by cholera, an intestinal infection spread by contaminated food and water, the World Health Organisation said earlier this month.

It causes severe diarrhoea and vomiting that leads to dehydration and sometimes death within 24 hours.

Cholera can largely be prevented by washing hands before handling food and avoiding contaminated drinking water. Many of those who die could be saved by a simple mixture of water and rehydration salts.