ABIDJAN, 20 December (IRIN) - Ebola haemorrhagic fever that broke out in Gabon last week, spread to neighbouring Democratic Republic of Congo (DRC), the World Health Organization confirmed on Thursday. As of Wednesday, 27 suspected cases had been reported, of whom 11 were found to be in DRC. The UN agency said 25 out of the 27 reported cases, were confirmed for Ebola. A further 227 people believed to have had direct contact with blood or other fluids of confirmed cases, were being followed up. Of these, 133 were in Gabon and 94 in DRC. WHO is part of an international team working alongside Gabon health officials to track the disease and isolate patients. The team is also conducting community sensitisation activities to prevent further spread of the disease. "The team is operational on both sides of the border and is [also] working closely the Congolese Ministry of Health," WHO said. The disease spread despite tightening of border controls between the two countries. A preventive sanitary belt had also been enforced around a 200-km zone between Mbomo in Cuvette-West, Ouesso and Sangha - where a surveillance team was conducting investigations. Mbomo and Sangha lie within a national park, PANA reported on Wednesday. This is the fourth outbreak in Gabon since 1994, when the disease killed more than 20. Ebola is one of the deadliest viral diseases known to mankind, causing death in 50-90 percent of cases. The virus is transmitted by direct contact with the blood or body fluids of infected persons or primates, WHO said.