An Ebola epidemic which has killed dozens of people in Guinea's southern forests has spread to the capital Conakry, health sources said on Thursday, confirming four new cases. The patients were immediately put in isolation centres to avoid the highly contagious virus getting into the population, the sources told AFP. Between 1.5 and two million people are estimated to be living in Conakry, a vast, sprawling port city on Guinea's Atlantic coast. The tropical virus leads to haemorrhagic fever, causing muscle pain, weakness, vomiting and diarrhoea and -- in the most severe cases -- organs failure and unstoppable bleeding. Authorities in the city identified three cases of haemorrhagic fever -- two of them fatal -- on Sunday but samples taken from the victims tested negative for Ebola.