Yellow fever outbreaks in three African countries that have claimed nearly 300 deaths in Angola constitute an emergency situation, a senior World Health Organization (WHO) official said Tuesday in Geneva, according to dpa. Since the disease broke out in the southern African country of Angola late last year, 696 people are confirmed to have caught the virus and 293 have died, according to the latest WHO data. The UN health agency has sent out letters to all its member states asking them to inform travellers of the outbreak, said Sylvie Briand, the head of WHO's department of pandemics and epidemics. "We are responding to this as an emergency," she said, while making clear that WHO did not declare a global health emergency as it has done for the Ebola and Zika outbreaks. Angola's capital Luanda and other urban centres in the country and in the Democratic Republic of Congo are among the hot spots. Disease outbreaks in urban centres are difficult to control, and cities are a possible transmission hub to other countries, Briand said. Many people do not take outbreaks such as this one seriously and do not get vaccinations before they travel to affected countries, Briand said. "It's the right time to take the disease seriously," she added. In the Democratic Republic of Congo there have been 41 confirmed cases, 90 per cent of them imported from neighbouring Angola and the rest from a local outbreak. Another separate outbreak has resulted in 7 confirmed infections in Uganda. "It is very concerning that there are three yellow fever outbreaks occurring at the same time", Briand said. The virus has also been exported from Angola to Kenya, which had recorded two cases as of last week, as well as China with 11 cases. Yellow fever is not directly transmitted among humans, but through mosquitoes. Luanda has been almost entirely vaccinated, but the vaccination campaign was conducted in a slow manner that allowed the virus to spread beyond the city, according to Briand. Vaccinations are expected to start soon in Congo's capital Kinshasa. The vaccine is highly effective in people who get it, but yellow fever has a high mortality rate if health agencies do not manage outbreaks well, Briand warned.