Cholera has killed 58 people in Guinea-Bissau since the middle of June and infected more than 4,000 others, with the disease spreading through islands off its Atlantic coast, a health ministry official said on Sunday.

“There have been around 70 cases of cholera declared every day in the Simao Mendes hospital in (the capital) Bissau since the outbreak started on June 11,” the official said, declining to be named.

The disease - an intestinal infection spread by contaminated water and food - had also taken hold on the Bijagos islands, a thinly-populated archipelago belonging to the former Portuguese colony, the official said.

Guinea-Bissau has received medical supplies from Portugal to fight the outbreak as well as $100,000 from China. Cholera can quickly cause severe dehydration and death although many who die could have been saved by a simple mix of water and salts.