The UN health agency on Saturday declared Liberia Ebola-free, hailing the “monumental” achievement in the west African country where the virus has killed more than 4 700 people.

“The outbreak of Ebola virus disease in Liberia is over,” the World Health Organisation (WHO) said in a statement, adding that 42 days had passed since the last confirmed case was buried.

That period is double the number of days the virus requires to incubate, and WHO hailed its eradication as an enormous development in the long crisis.

“Interruption of transmission is a monumental achievement for a country that reported the highest number of deaths in the largest, longest, and most complex outbreak since Ebola first emerged in 1976,” it said.

The declaration was a source of both great pride to Liberians who had been stalked by the deadly virus they simultaneously sought to battle.

“We are out of the woods. We are Ebola free. Thanks to our partners for standing with us in the fight against Ebola. We are Liberians,” tweeted Liberian Information Minister Lewis Brown.

The news was also cheered by international organisations like the Red Cross, Unicef and Doctors Without Borders (MSF), as well as officials from the US and European Union.

However whailing the “important marker” White House spokesman Josh Earnest, in a statement, said: “The world must not forget that the Ebola outbreak still persists in neighbouring Sierra Leone and Guinea.

“We must not let down our guard until the entire region reaches and stays at zero Ebola cases.”

Relief and sorrow

The WHO warned that because the Ebola outbreaks were continuing in neighbouring Guinea and Sierra Leone, the risk remained high that infected people could re-enter the country.

Because of that risk, MSF also tempered its applause of the declaration with reminders that the crisis will not be over for any one nation until the virus has been eradicated everywhere.

For average Liberians, the development was a source of both relief and sorrow.

“I lost a brother in the Ebola crisis so I am happy and sad,” said 40 year-old Monrovia taxi driver Nyaningo Kollie.

During the two months of peak transmission last August and September the capital Monrovia was the setting for “some of the most tragic scenes from West Africa’s outbreak: gates locked at overflowing treatment centres, patients dying on the hospital grounds, and bodies that were sometimes not collected for day,” noted WHO official Alex Gasasira, who read the organisation’s statement Saturday.

At the height of the crisis in late September Liberia was suffering more than 400 new cases a week, with uncollected and highly infectious bodies piling up in the streets of Monrovia, a sprawling, chaotic city at the best of times.

The health system – embryonic before the crisis, with some 50 doctors and 1 000 nurses for 4.3 million people – was devastated, losing 189 health workers out of 275 infected.

“At one point, virtually no treatment beds for Ebola patients were available anywhere in the country,” Gasasira recalled.

Schools remained shut after the summer holidays, unemployment soared as the formal and black-market economies collapsed and clinics closed as staff died and non-emergency healthcare ground to a halt.

And then, as suddenly as it had spread, Ebola retreated.

‘Thank all Liberians’

Liberia, which had recorded 389 deaths in one week in October alone, saw fatality counts dropping below 100 within weeks, and into single figures by the start of 2015.

During a WHO-hosted ceremony Saturday in the Ebola crisis cell in Monrovia, Liberian President Ellen Johnson Sirleaf saluted her fellow citizens and health workers for rising to the crisis.

“I thank all Liberians for the effort. When Ebola came, we were confused. We called on our professionals. They put their best in the fight, this is the result I have sent a message to the international community to thank them,” she said.

In the coming years there will be a reckoning on the response to the greatest ever Ebola outbreak, which left 11 000 dead.

The West was initially accused of ignoring the crisis and then treating Liberia and its neighbours as pariahs, blocking flights and quarantining returning health workers after the first-ever domestic infections outside of Africa, in the US and Spain.

The WHO, at times seen as overly bureaucratic and politicised, was berated for waiting until August – almost five months after the outbreak was identified – to declare it a “public health emergency of international concern.”

“Quite simply, we were all too late. The world – including MSF – was slow to start the response from the beginning,” said MSF’s head of Ebola operations in Brussels, Henry Gray, in a statement.

Ebola is threatening the very existence of Liberia as the killer virus spreads like “wild fire”, the defence minister warned Tuesday, following a grim World Health Organisation assessment that the worst is yet to come.

After predicting an “exponential increase” in infections across West Africa, the WHO warned that Liberia, which has accounted for half of all fatalities, could initially only hope to slow the contagion, not stop it.

“Liberia is facing a serious threat to its national existence,” Defence Minister Brownie Samukai told a meeting of the UN Security Council on Tuesday.

The disease is “now spreading like wild fire, devouring everything in its path,” he said.

The WHO upped the Ebola death toll on Tuesday to 2 296 out of 4 293 cases in Liberia, Sierra Leone, Guinea and Nigeria as of September 6. Nearly half of all infections had occurred in the past 21 days, it said.

The agency also evacuated its second infected medical expert, a doctor who had been working at an Ebola treatment centre in Sierra Leone.

Emory University Hospital in the United States admitted an American on Tuesday who had contracted the disease in west Africa, but declined to confirm whether the patient was the WHO employee.

The hospital has successfully treated two other infected US nationals.

Ebola, transmitted through bodily fluids, leads to haemorrhagic fever and – in over half of cases – death. There is no specific treatment regime and no licensed vaccine.

The latest WHO figures underscore Ebola’s asymmetric spread, as it rips through densely populated communities with decrepit health facilities and poor public awareness campaigns.

Speaking on Tuesday, WHO’s epidemiology chief Sylvie Briand said the goal in Senegal and Nigeria was now “to stop transmission completely”. Senegal has announced only one infection, while Nigeria has recorded 19 infections and eight deaths.

The Democratic Republic of Congo is battling a separate outbreak which has killed 32 in a remote northwestern region.

“But in other locations, like Monrovia, where we have really wide community transmission, we are aiming at two-step strategies,” Briand said in Geneva, “first, to reduce the transmission as much as possible and, when it becomes controllable, we will also try to stop it completely.

“But at this point in time we need to be pragmatic and try to reduce it in the initial steps.”

A day earlier the WHO had warned that aid organisations trying to help Liberia to respond would “need to prepare to scale up their current efforts by three- to four-fold”.

Before the current outbreak, it noted, Liberia only had one doctor for every 100 000 patients in a population of 4.4 million.

In Montserrado county, which contains Monrovia, there are no spare beds at the few Ebola treatment sites operating, the WHO said.

It described how infected people were being driven to centres only to be turned away, return home and create “flare-ups” of deadly fever in their villages.

It said 1 000 beds are needed – far more than the 240 currently operational and 260 planned.

Guinea’s President Alpha Conde described Ebola as a “war” his nation – with 555 dead so far – needed to win.

He slammed neighbouring states including Côte d’Ivoire and Senegal for shutting their borders, and airlines for suspending flights to affected countries.

“They forget that when you close borders, people just go through the bush. It’s better to have official passages of transit,” he said.

African Union commission chief Nkosazana Dlamini-Zuma also called Monday for travel bans to be lifted “to open up economic activities”.

In Gambia, customs officials said Tuesday they had closed the borders to Guineans, Liberians, Nigerians and Sierra Leoneans – though not to neighbouring Senegal.

“We are also advising Gambians intending to travel to these countries to cancel their trips, but any Gambian who fails to heed our advice, we will not allow you in the country if you return,” Ebrima Kurumah, a health officer posted at the border with Senegal, told AFP.

There were restrictions further afield, too. China, one of the region’s main investors, announced on Tuesday it was reinforcing checks on people, goods and vehicles – and even mail – arriving from affected countries.

Meanwhile, Italy announced its first possible case of Ebola – a woman recently returned from Nigeria.