More than 500 people have now died in the Ebola outbreak gripping the Democratic Republic of Congo, World Health Organization figures showed Monday. A newly updated count issued by the UN health agency showed that there have been 1,561 confirmed cases in the DR Congo since the outbreak was declared in mid-May, including 506 confirmed deaths. Two others have also died in neighbouring Uganda, where the situation is more stable. The country has seen 16 patients recover out of 20 total confirmed cases. The WHO's figures for the DR Congo, which come from the health authorities in the vast country, show that the outbreak there has a case fatality rate of 32 percent. Watch moreAuthorities race to contain spread of Ebola in eastern DR Congo A total of 254 patients have recovered, while 354 suspected cases of the viral haemorrhagic fever are currently under investigation. The outbreak is being driven by the rare Bundibugyo species of Ebola, for which there are no approved vaccines or treatments. The trial of two potential treatments for Bundibugyo began in the DR Congo on Thursday. The trial is evaluating the safety and effectiveness of the monoclonal antibody MBP134 and the antiviral drug remdesivir, alone and in combination. Breaking point Frontline workers deployed in Ituri province, the epicentre of the outbreak, issued a 24-hour notice on Sunday threatening to strike if authorities fail to pay them and improve their working conditions. The workers include mostly health professionals who have been labouring with little rest as they battle attacks from angry residents and widespread scepticism about the virus. In the notice to the government, a copy of which was seen by the Associated Press, the workers both in and outside hospitals said they had not been paid benefits since the outbreak began and they do not have adequate supplies for their work.