GENEVA, October 20. /TASS/. Nigeria has been declared officially free of Ebola after a 42 day period with no new cases elapsed, the World Health Organization (WHO) said on Monday.

The WHO can declare an Ebola outbreak over if two incubation periods of 21 days pass with no new cases detected. Senegal was the first West African country declared free of the deadly virus on Friday.

The Ebola epidemic has killed more than 4,500 people in West Africa and infected more than twice as many this year, the vast majority of them in Liberia, Guinea and Sierra Leone, according to the WHO.

Ebola virus

The death toll of the Ebola outbreak reached 4,447 last Tuesday. and the number of probable and suspected cases stood at more than 8,900.

The World Health Organization describes Ebola virus disease (formerly known as Ebola haemorrhagic fever) as a severe, often fatal illness, with a case fatality rate of up to 90%.

Symptoms include sudden onset of fever, intense weakness, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, impaired kidney and liver function, and in some cases, both internal and external bleeding. T

he infection is transmitted by direct contact with the blood, body fluids and tissues of infected animals or people. People are infectious as long as their blood and secretions contain the virus. The incubation period is 2 to 21 days.

There is no known cure or vaccine for the disease. The only treatment offered is “supportive intensive care.” During an outbreak, those at higher risk of infection are health workers, family members and others in close contact with sick people and deceased patients.