More than 14 million people in Angola and Democratic Republic of Congo are to be vaccinated against yellow fever to prevent the national and international spread of the disease. The World Health Organization is coordinating the emergency vaccination campaign, calling it one of the largest ever attempted in Africa. Mass vaccination campaigns usually take between three to six months to plan; but, WHO says this campaign must begin by the start of the rainy season in September because the spread of yellow fever could become unstoppable. Spread by mosquitoes Yellow fever is a potentially deadly flu-like disease spread by mosquitoes. It causes a high fever and jaundice, a yellowing of the skin and eyes. The disease is not curable, but it can be prevented with the yellow fever vaccine. Since the outbreak of the disease in December, the WHO’s latest estimates put the number of dead at 369 in Angola and 16 in the DRC, with nearly 6,000 suspected and confirmed cases in both countries. Yellow fever usually occurs in remote rural areas where people are routinely vaccinated against the disease. The WHO says the current deadly outbreak is particularly worrisome because, for the first time, it is occurring in densely populated urban areas where immunity is very low and the risk of it spreading is high. International epidemic WHO spokesman Tarik Jasarevic tells VOA the risk of international spread also is of concern. “There is increasing urbanization, increasing mobility. There are environmental changes that may make international spread of mosquito-borne diseases…but we think that the outbreak is manageable if we can protect enough people with the vaccine ,” said Jasarevic. "So, the goal is that we prevent this event from becoming a public health emergency of international concern.” The mass vaccination campaign will take place in Kinshasa and along the DRC’s border with Angola. Jasarevic describes the scope of this campaign as unprecedented. “There are 17.3 million syringes that have to be shipped or air freighted to Democratic Republic of Congo; 41,000 health workers and volunteers have been mobilized with more than 500 vehicles to operate between more than 8,000 vaccination sites in Kinshasa and along the border,” said Jasarevic. The WHO says an emergency committee will reconvene in the coming weeks to evaluate the situation and determine whether the yellow fever epidemic has been contained or constitutes a public health emergency of international concern.