Tests on the suspected cases of deadly Ebola virus in Guinea's capital Conakry are negative, health officials say.
On Sunday, United Nations officials said that the virus had spread to the capital, a port city of up to two million, from remote forests in the south, where some 61 people have died.
The government has sent out text messages, urging people to stay calm and wash their hands with soap.
Ebola is spread by close contact and kills between 25% and 90% of victims.
There is no known cure or vaccine.
Symptoms include internal and external bleeding, diarrhoea and vomiting.
Neighbouring countries such as Liberia, Senegal and Sierra Leone are said to be on high alert in case the disease spreads.
Five people are already reported to have died in Liberia after crossing from southern Guinea for treatment, Liberia's Health Minister Walter Gwenigale told journalists.
However, it is not clear whether they had Ebola.
The BBC's Jonathan Jonathan Paye-Layleh in Liberia says the country's health facilities are closer and more accessible to Guineans living on the border than those in big Guinean cities.
Cross-border trade is huge between the two countries, which share some cultural and linguistic ties, he adds.
Mr Gwenigale confirmed tests were being carried out on those who had died.
He also urged people to avoid close contact with people, such as shaking hands and kissing.
Guinea is also currently grappling with epidemics of measles, cholera and meningitis.
It is said to be the first time Ebola has struck Guinea, with recent outbreaks thousands of miles away, in Uganda and Democratic Republic of Congo.
There have been 87 cases so far, with 61 deaths, according to Guinea's health ministry.
After two people died from a haemorrhagic fever in Conakry, samples were sent to the Pasteur Institute in neighbouring Senegal for testing.
WHO spokesman Collins Boakye-Agyemang told the BBC these had shown that the victims had not been infected with Ebola. It is not known what killed them.
Outbreaks of Ebola occur primarily in remote villages in Central and West Africa, near tropical rainforests, the World Health Organization says.