Lusaka :Health authorities in Zambia said on Friday that surveillance measures have been heightened in border areas following an outbreak of yellow fever in Angola and the Democratic Republic of Congo (DRC). Yellow fever has been raging since last December in Angola, especially in the capital Luanda, killing 293 people to date and infecting another 2,267. Cases have also been imported to Kinshasa in DRC, Xinhua reported. Deputy Minister of Health Chitalu Chilufya said the ministry was currently monitoring the situation on the two neighbouring countries and has since heightened activities that will prevent the spread of the disease into the country. The official, however, said so far no yellow fever has been reported in the country, local HOT FM radio reported.