More than 100 people have died and over 5,000 have been infected in outbreaks of cholera, influenza and diarrhoea in remote parts of Papua New Guinea since last month.
A World Health Organisation official told Reuters the outbreaks have affected remote highland areas, as well as the major regional city of Lae and parts of the northern coast.
Some of these areas are very remote, with little communication or other infrastructure and often only reachable by helicopter.
Health officials say the figures could be substantially higher.
Health officials say it is thought to be the first recorded outbreak of cholera in Papua New Guinea and the strain of the water-borne disease has been identified as one widespread in Southeast Asia.
The influenza has been confirmed as seasonal influenza, not the new H1N1 strain which has been declared a global pandemic.