Deaths from malaria in Angola this year look set to surge past the numbers reported in 2015, as part of a spreading health crisis that includes one of the country's worst yellow fever outbreaks in decades — which the World Health Organization (WHO) said is of global concern.

Angola recorded 2,915 deaths from malaria in the first quarter of this year, compared with 8,000 for the whole of 2015 and 5,500 the previous year, WHO told Reuters on Monday.

"This new malaria outbreak has devastated the entire country, even in provinces that have low endemic prevalence we are seeing the spread and surge in cases," said WHO Angola representative Hernando Agudelo Ospina.

Ospina said uncollected garbage in Luanda, due to government budget cuts, and a record amount of rainfall had contributed to high cases of malaria, yellow fever, and chronic diarrhea. Angola's government budget has been slashed, debts are rising, and the currency has plummeted this year as depressed oil prices hit the finances of Africa's second largest crude exporter.

The yellow fever outbreak has gripped the country for several months now, killing at least 258 people in Angola, with 1,975 suspected cases of the mosquito-borne disease since December. It has already grown to become the worst outbreak in decades. The WHO has warned the epidemic poses a global threat.

"Cases of yellow fever linked to this outbreak have been detected in other countries of Africa and Asia," WHO director-general Margaret Chan said. "We are particularly concerned that large urban areas are at risk and we strongly urge all travelers to Angola to ensure they are vaccinated against yellow fever and carry a valid certificate."

The WHO's regional office for Africa said last week that there had been cases of yellow fever recorded in people who traveled from Angola to other countries. There have been 11 of these cases reported in China, 11 in the Democratic Republic of Congo (DRC), and 2 in Kenya. It said three further cases had been reported in Uganda, but these patients had no history of travel to Angola.

The WHO "is working with neighboring countries such as the DRC, Namibia, and Zambia to bolster cross-border surveillance with Angola and information sharing to prevent and reduce the spread of infection," it said.

Yellow fever is a virus carried and spread by mosquitos, but there are no treatments on the market. Symptoms include headache, fever, or chills. For some patients the virus can prove fatal.

Travelers to Angola must be vaccinated against yellow fever and carry a valid certificate to prove it, WHO announced on Tuesday. The UN health agency has advised that people are at the greatest risk of contracting the virus in large urban areas including the capital Luanda.

An epidemic that erupted in December has caused 1,975 suspected cases and killed 258 people since December, the WHO said in a statement. A nationwide vaccination program that began in February has reached 7 million people. But experts are warning the world's stocks of yellow fever vaccines are under severe pressure form the outbreak, with some calling for a radical switch in strategy to use a tenth of the normal dose and aim to cover more people.