Mozambican and international health workers raced Monday to contain a cholera outbreak in the cyclone-hit city of Beira and surrounding areas, where the number of cases has jumped to more than 1,000.

One person has died of cholera, while 97 patients remain in treatment centres, with the others released, Mozambique’s health director Ussein Isse announced. The new figures are an indication that cholera is spreading but is being brought under control, health workers say.

U.N. spokesman Stephane Dujarric said there is also a high risk of the spread of infectious diseases including those caused by insects like mosquitoes, with 276 malaria cases also reported in cyclone-affected areas,.

Story continues below advertisement

The overall cyclone death toll in Mozambique has risen to 518. With 259 deaths in Zimbabwe and 56 in Malawi, the three-nation death toll from Cyclone Idai now stands at more than 830. Authorities warn the tolls are preliminary as receding flood waters will expose more bodies.

Dujarric said more than 140,000 people in Mozambique are sheltering in 161 sites, including schools and community centres.

He said 11 emergency treatment centres for cholera victims have been established in Beira and other locations and nine are operational.

Mozambican workers have restored clean tap water to parts of Beira, a city of 500,000, although large areas of the urban centre still don’t have access to sanitary water, David Wightwick, the World Health Organization’s team leader in Beira, told The Associated Press while visiting a water treatment centre.

“A vaccination campaign against cholera, with 900,000 doses of the vaccine, will start Wednesday,” Wightwick said. “That should blunt the edge of this outbreak.”

More than two weeks after the cyclone hit Beira and swept across central Mozambique, about 98,000 people are in camps for displaced and “living under canvas,” he said.

“Cholera is our most immediate challenge,” said Wightwick, who added that getting adequate nutrition to the population and battling other diseases like malaria are also priorities.

Story continues below advertisement

In addition to Mozambican medics, health workers from Portugal, Denmark, Italy and China are helping respond to the crisis.

Sanitary water points and latrines are being constructed throughout Beira by the International Federation of the Red Cross, which has also established a field clinic in Macurungo, is constructing a field hospital in Nhamatanda and distributing relief supplies to 800 in Buzi, said the group’s spokeswoman, Jana Sweeny.

Cases of cholera, an acute diarrheal disease, have risen dramatically since the first five cases were confirmed last week. Cholera is spread by contaminated water and food. It can kill within hours but is relatively easy to treat.

The U.S. military joined the international humanitarian aid efforts to Mozambique by airlifting food and relief supplies from South Africa.

Round-the-clock flights are delivering supplies from the U.N. World Food Program from King Shaka International Airport in Durban, South Africa, U.S. Embassy spokesman Robert Mearkle said.

He said the commodities airlifted from Durban were from the World Food Program’s internal stock including rice, dried peas and vegetable oil.

Story continues below advertisement

“This lifesaving emergency food assistance will support approximately 160,000 people for one month,” Mearkle said.

As health responders stress the need for better disease surveillance, the United Nations’ deputy humanitarian co-ordinator in Mozambique, Sebastian Rhodes Stampa, has said all cases of diarrhea are being treated as though they are cholera.

Cholera is endemic to the region, and “it breaks out fast and it travels extremely fast,” he told reporters.

Doctors Without Borders has said other suspected cholera cases have been reported outside Beira in the badly hit areas of Buzi, Tica and Nhamathanda but the chance of spread in rural areas is smaller because people are more dispersed.

Mozambican officials have said Cyclone Idai destroyed more than 50 health centres in the region, complicating response efforts.

The United Nations has said some 1.8 million people need urgent help across central Mozambique’s sodden, largely rural region.

Story continues below advertisement

The U.N. Economic and Social Council has scheduled a special meeting in New York on Tuesday on the “Response to Cyclone Idai in Mozambique, Malawi and Zimbabwe.”