The World Health Organization is urging travelers to Angola to get a yellow fever vaccination. An outbreak of the disease in the African country has killed at least 258 people.
WHO director-general Margaret Chan said large urban areas are at particular risk, and is strongly urging all travelers to Angola to ensure they are vaccinated against yellow fever.
The outbreak began in December in Angola's capital, Luanda, and has since spread to most of the country's provinces, with more than 1,975 suspected cases.
Chan also said, "Cases of yellow fever linked to this outbreak have been detected in other countries of Africa and Asia.”
The WHO Africa office noted yellow fever from Angola has been reported in China (11 cases), Democratic Republic of the Congo (10 cases with one in Kinshasa) and Kenya (two cases.)
Other cases were reported in Uganda, but WHO officials said travelers had no history of travelling to Angola.
The disease is transmitted by the same mosquito that spreads Zika and dengue viruses, but death rates are higher and 75 percent of the cases require admission to the hospital.
Yellow fever expert Jack Woodall, who formerly worked for the WHO and the U.S. Centers of Disease Control and Prevention, said he is worried the outbreak could spread rapidly along a major trucking route from DRC to Uganda's capital Kampala.
He called for intensified surveillance of this trade route and said vaccination of people living along it should be top priority.
The WHO launched a vaccination campaign in February targeting seven million people to try to prevent further spread of the disease. It has already become the worst outbreak in decades, officials said.