Vanuatu has declared an outbreak of malaria with hotspots on four different islands across four different provinces.

The outbreak was reported on the islands of Santo, Malekula, Epi and Vanua Lava, though cases were being reported in other areas too.

Vanuatu's ministry of health said more than 500 cases had been recorded since January this year.

It is a significant rise in cases; only 322 cases were recorded in total during 2021. And medical experts warned they expect the high case numbers would continue to the end of 2022.

What to do to stay healthy?

The ministry called for everyone in the outbreak areas to wear insect repellant and cover up exposed skin where possible, with long-sleeved shirts and long pants. And to sleep under mosquito nets at night.

It also asked for everyone to clean up any standing water and areas mosquitos could breed, around houses.

Travellers were warned to talk to their doctor and get preventative medicine at least two weeks before arriving in the hotspots.

Almost all malaria cases in Vanuatu are caused by Plasmodium vivax parasites, and people should watch out for early symptoms: headaches, fever and chills, tiredness and body ache.

"Anyone with fever or symptoms of malaria should go to a health facility and get tested," the statement said.

In priority areas, authorities had increased community education and testing, and were handing out mosquito nets, spraying with insecticide around houses.

Current outbreak 'a step back'

The current high case numbers for malaria are still nothing like historic figures, but mark a tougher battle toward controlling the disease, and the goal of elimination, the ministry said.

Vanuatu typically recorded about 10,000 cases of malaria each year, 10 to 15 years ago, it said.

"Vanuatu has made excellent progress against malaria in the last 15 years and was approaching nationwide elimination".

"The [ministry] successfully eliminated malaria from Tafea province in 2017. Torba had two years with no reported local cases, and Penama has also had two years with no local cases.

"However, malaria transmission recently re-started ... in Torba, and transmission intensified in other areas."

The rise in case numbers was especially concerning as once case numbers had decreased and later increased in a population, international reports had shown the disease could be even more difficult to control again.

"Experience from other countries approaching malaria elimination is that if efforts are interrupted, malaria can quickly rebound back to high levels.

"This is because there is no immunity against malaria (with no vaccine available), health workers are unfamiliar with the disease, treatment may not be available or prescribed appropriately, and there is complacency to finish treatment."

For some of the areas where the outbreak had been declared, there were distinct zones with more concentrations of cases; including the north east and west coast of Espiritu Santo Island, the south east of Malekula Island, and the Sola area in the south east of Vanua Lava Island.