The World Health Organisation, WHO, said on Wednesday in Geneva that it may declare Nigeria and Senegal Ebola-free within days if they complete a 42-day period with no new cases.
A statement from WHO indicated that the completion date for Nigeria would be next Monday, October 20.
“If the active surveillance for new cases that is currently in place continues, and no new cases are detected, WHO will declare the end of the outbreak of Ebola virus disease in Nigeria next Monday, October 20 and Senegal on Friday 17 October, it said.
WHO said this had become imperative because 42 days from the time when the last person with high risk exposure tests negative for the virus, gives sufficient confidence to declare an outbreak over.
“The 42-day period is twice the generally accepted maximum incubation period of the virus,” it said.
However, it said that some incubation periods were longer, but in 95 per cent of cases, the incubation period was between one and 21 days.
It said in 98 per cent cases it was no longer than 42 days.
WHO said that the virus could survive even longer, remaining for as much as 90 days in the semen of an infected person.
It noted that outside West Africa, the spread of the disease had been confirmed in Spain and the United States.
Possible cases have been investigated in several other countries, but none has yet turned out to be Ebola.
The WHO said it was concerned by media reports that some countries facing a possible first Ebola case had declared the cases to be negative within hours.
“Such rapid determination of infection status is impossible, casting grave doubts on some of the official information that is being communicated to the public and the media,” it said.
WHO called on countries without recognised laboratories specialising in viral haemorrhagic fever testing to send their first 50 negative specimens to a WHO collaborating centre.
It cautioned that all countries should have their first 25 positive tests double-checked.