Desperately needed aid has reached remote islands and coastal villages in Fiji left devastated after a powerful cyclone killed at least 29 people.
Aid workers are warning of possible outbreaks of Zika and dengue viruses in the wake of Cyclone Winston.
Both of the viruses are carried by mosquitoes, which will breed in the stagnant water left by the storm.
“The threat of dengue and Zika in the coming days in Fiji is real,” said Chris Hagarty, senior health programme manager at Plan International Australia.
“The period immediately following a disaster of this scale can be a particularly dangerous one.”
There also fears the number of dead in the nation of 900,000 people could rise when communications resume with the smaller islands that were hit.
Aerial footage of outlying islands taken by the Royal New Zealand Air Force – and posted on the Fiji government’s website – shows whole villages flattened and flooded after winds of up to 200mph tore through the archipelago of 300 islands.
Thousands of Fijians live in tin or wooden shacks in low-lying coastal areas.
Authorities have warned of “catastrophic” damage to Koro Island, Fiji’s seventh-largest island, and more than 8,000 people are sheltering in evacuation centres across the country.
British student Frazer Diver, who travelled to Fiji on his gap year, said locals looked after him and his friends when they were stranded for two days in the village of Rakiraki in Viti Levu with little food and water.
He told Sky News they wanted to raise awareness of the plight of the villagers who helped them.
Mr Diver described the aftermath of the cyclone as “surreal, like being on a film set”.
“There were roofs in the front of the hotel trees uprooted, and pure chaos, and everyone seemed to be amazed, just as we were, seeing the extent of the damage,” he said.
He added: “These locals were willing to give up so much for us, even though their lives had been turned upside down.”
Prime Minister Frank Bainimarama has said his government is doing all it can, amid growing criticism of the slow response in some areas.
Fiji’s international airport has reopened and an evacuation team was sent to outer islands to provide urgent support and supplies, such as water and hygiene kits, medicines and access to shelter.