A key moment in the battle against the world's deadliest outbreak of Ebola will be reached on Tuesday when Guinea, the first of three west African states struck by the epidemic, is set to be declared free of the disease.

One of the poorest nations in the world, Guinea leapt to global prominence after becoming the host country for "patient zero" - an infant, Emile Ouamouno, who on December 2013 became the outbreak's first victim.

The fever spread stealthily and terrifyingly, striking two neighboring countries, Sierra Leone and Liberia, with sporadic cases also in Mali, Nigeria and Senegal.

As world health watchdogs struggled to respond, the death toll mounted at a dizzying rate, igniting fears in Europe and elsewhere of a virus that mocked borders and national controls.

Around 11,300 people died out of almost 29,000 recorded cases, according to a World Health Organization tally that many experts believe greatly understates the impact of the outbreak.

It was the deadliest epidemic of Ebola since the disease was first identified in 1976. The last known case in Guinea is a three-month-old baby named Nubia, who was born with the disease but whose recovery was confirmed on November 16.

That started the countdown to Tuesday's expected announcement, as a period of 42 days - twice the virus's incubation period - is required to declare a country Ebola-free.

"It's the best year-end present that God could give to Guinea, and the best news that Guineans could hope for," said Alama Kambou Dore, an Ebola survivor.

"From 2013 to 2015, Guineans suffered, they lived and survived, they endured, they were stigmatized, rejected, even humiliated because of this disease, which leapt out of nowhere."

The WHO officially declared Sierra Leone Ebola-free on November 7, triggering wild celebrations in the capital Freetown. On Dec 3, Liberia released its last two known Ebola cases from hospital, starting the six-week countdown.

A WHO representative is expected to make the hugely anticipated announcement in Conakry, the Guinean capital, late morning on Tuesday.

This will be followed by official ceremonies on Wednesday, where President Alpha Conde will be flanked by representatives from donor countries.