The World Health Organisation (WHO) says it has found evidence that sexual contact may be causing the Ebola virus to spread.
A lack of education about treatment has meant sufferers are now hiding from aid organisations, creating the potential for new outbreaks.
The United Nations has described the fight against the deadly virus is at its “most critical” moment.
The WHO’s Dr Margaret Harris, who recently toured Ebola-affected communities in West Africa, said international organisations are fighting a new front in the battle against the virus.
“There are still places where the virus is very active,” Dr Harris said.
Victims of the disease are now hiding out, believing sufferers of the disease are taken to treatment centres to die.
“We had an instance a few weeks ago in Sierra Leone where we had a cluster of cases in the fishermen’s community, on the wharves in Freetown,” she said.
“And one of the people who was infected disappeared and went off to his home village in Bombali, he sparked another 30 cases.”
New health warnings are being issued in the region.
“And we’re really saying now use condoms at all times. Use condoms at all times and with all manner of sexual contact,” Dr Harris said.
Rumours have spread within African villages that the purpose of treatment centres is to harvest organs from the dead and take blood from victims of the virus.
“It looked like there were no cases, and quite a few of the response teams believed that. So it simply went underground,” Dr Harris said.
Authorities lose control as crowds become desperate for supplies
Last week, in an effort to find new cases, Sierra Leone placed 2.5 million people under lockdown in a desperate attempt to stamp out the deadly virus.
Residents in and around Freetown, an Ebola hotspot, were told to stock up on food and water but on the second day of the campaign some families ran out of food.
In the Devil Hole neighbourhood, hundreds of people left their homes to gather at a food collection point.
Authorities lost control, however, as the crowd become more desperate for supplies.
Adam Dumbuya was among those looking for food aid.
“People are desperate for food, because of how the distribution is going. They are not satisfied and think they will not be able to get any because of the number of people present for the distribution,” Mr Dumbuya said.
The army was eventually called in.
The death toll from the disease has now risen to over 10,000 people.