The three-nation Ebola outbreak in West Africa has seen a death toll of 337, the World Health Organization said Wednesday, making it the deadliest ever outbreak of the haemorrhagic fever.
Fresh data from the UN health agency showed that the number of deaths in Guinea, the hardest-hit country, has reached 264, while 49 had died in Sierra Leone and 24 in Liberia.
The new toll marks a more than 60-percent hike since the WHO's last figure on June 4, when it said 208 people had succumbed to the deadly virus.
Including the deaths, 528 people across the three countries have contracted Ebola, one of the deadliest viruses known to man, the WHO said.
Yet agency spokeswoman Fadela Chaib insisted the far higher number of cases did not mean the virus was spreading faster.
"There is no sudden rise," she said in an email to AFP, pointing out that the increase could be explained by the heightened vigilance in the region and the confirmation of previously suspected cases.
Retroactive investigations were pushing up the numbers, she said, stressing that WHO's toll should be seen as "provisional", since "new samples are being taken daily and tests are underway."
- Most cases in Guinea -
A majority of the cases, 398 of them, have surfaced in Guinea, where west Africa's first ever Ebola outbreak began in January.
That marks a hike of 70 known cases since the beginning of the month, belying Guinean authorities claims the situation was under control.
The number provided Wednesday is more than three times higher than the 121 known cases at the end of April, when Guinean President Alpha Conde insisted the outbreak was "well in hand", voicing optimism that no one else would get sick.
For Marie-Christine Ferir, emergency programmes coordinator at Doctors Without Borders (MSF), the data showed a "fresh outbreak because there have been new cases" in Guinea.
"We are facing a second peak of the epidemic," she said, adding that the fact that infected cases were not being isolated is complicating efforts at containing the outbreak.
MSF said earlier this month that the sick were often reluctant to go to hospital and family members in some cases have removed their sick loved ones from isolation facilities and taken them back to their villages.
The practice of moving the dead to be buried in other villages also poses a risk, while West African authorities have been struggling to stop mourners from touching bodies during traditional funeral rituals.
Sierra Leone, which only confirmed its first deaths from Ebola three weeks ago, has registered 97 cases in total.
In Liberia, where the outbreak appeared to have died down a few months ago, the virus has resurfaced, infecting 33 people so far.
WHO has described the epidemic as one of the most challenging since the virus was first identified in 1976 in what is now the Democratic Republic of Congo.
That outbreak, until now the deadliest, killed 280 people, according to WHO figures.
Ebola is a tropical virus that can fell its victims within days, causing severe fever and muscle pain, weakness, vomiting and diarrhoea -- in some cases shutting down organs and causing unstoppable bleeding.
No medicine or vaccine exists for Ebola, which is named after a small river in the DRC.
Aid organisations have said the current outbreak has been especially challenging since people in many affected areas have been reluctant to cooperate with aid workers.
Chaib pointed to the difficulty of containing the outbreak in a region that until now had been unfamiliar with the disease and stressed the importance of communicating better to affected populations the dangers of the virus and how to contain it.