Surging cases of cholera, dengue and malaria are overwhelming hospitals in war-torn Sudan, aid workers say.

Health infrastructure has been devastated by more than two years of civil war and millions of people are living without access to adequate sanitation, providing the ideal conditions for diseases spread by mosquitoes and contaminated water.

Cases of dengue and malaria in particular have surged after flooding and the breakdown of sewage systems created breeding grounds for the insects.