Image copyright EPA Image caption Liberia is now officially Ebola-free, but health authorities are urging vigilance 
 
 The World Health Organization (WHO) has declared Liberia free of the Ebola virus, confirming that the country has had no new cases in 42 days. 
 
 President Ellen Johnson Sirleaf told the BBC that Liberia had "crossed the Rubicon" and would be celebrating a concerted effort to stem the disease. 
 
 More than 4,700 deaths from Ebola have been recorded in Liberia, more than in any other affected country. 
 
 Neighbouring Guinea and Sierra Leone continue to fight the outbreak. 
 
 It has claimed over 11,000 lives across the region since last year. 
 
 The WHO regards a country Ebola-free after a 42-day period without a new case - twice the maximum incubation period. 
 
 The last confirmed death in Liberia was on 27 March. On Saturday the World Health Organization said in a statement: "The outbreak of Ebola virus disease in Liberia is over." 
 
 President Sirleaf told the BBC: "We will celebrate our communities which have taken responsibility and participated in fighting this unknown enemy and finally we've crossed the Rubicon. Liberia indeed is a happy nation." 
 
 Image copyright EPA Image caption A poster in Paynesville, outside the capital Monrovia - part of the Liberian campaign against Ebola 
 
 Image copyright EPA Image caption Chlorinated water has been placed outside public buildings 
 
 Traumatised nation 
 
 Officials say Ebola was eventually conquered in Liberia through a collective effort. Care centres and hand-washing stations were set up to try to halt the disease, which spreads through contact with sick people. 
 
 Billboards went up with slogans such as "Ebola is real", "Wash your hands and don't touch" and "Don't be the next victim". 
 
 "It has been a terrible time in the history of our country," Monrovia resident Emmanuel Tokao wrote on a BBC Facebook page. "I'm firstly grateful to God, who I believe brought us back to normality." 
 
 At the height of the outbreak, he said, "ambulances would either come for a dead body or sick person. It reminded me of the war days". 
 
 Liberia lost around 250,000 lives in a civil war ending in 2005. 
 
 The BBC's Jonathan Paye-Layleh in Monrovia says the president gave a sense of how traumatised the outbreak remains after the outbreak. 
 
 In an address to the nation on Saturday, she said: "Even today if you hear an ambulance siren you shake a little bit." 
 
 Although Liberia has now been declared Ebola-free, correspondents say the outbreak will have a long-term impact on Liberia's fragile economy. 
 
 The current outbreak is the deadliest in history. It initially centred on Guinea's remote south-eastern region of Nzerekore in early 2014, and later spread to Liberia and Sierra Leone. 
 
 The WHO is warning against complacency. Its statement warns that there is "a high risk that infected people may cross into Liberia over the region's exceptionally porous borders". ||||| Health 
 
 As Ebola Leaves Liberia, Measles Makes A Forceful Comeback 
 
 i itoggle caption Jason Beaubien/NPR Jason Beaubien/NPR 
 
 On the northern side of Monrovia, a team of nurses is vaccinating children on the veranda of the AfroMed clinic. Tables with boxes of rubber gloves and vaccine coolers are arranged in the shade out of the intense, tropical sun. 
 
 A mother rocks her crying baby, who has just been jabbed with a measles shot. Martina Seyah, who brought her 2-year-old daughter, Irena, to get the shot, says parents in the neighborhood are very worried their children could get measles or other diseases. 
 
 Just as Liberia is getting ready to declare itself Ebola-free, another disease has cropped up. This January a measles outbreak erupted. So far this year, there have been 562 cases; seven were fatal. 
 
 "To have this number in just the first quarter of the year is definitely a huge outbreak," says Dr. Zakari Wambai, head of the World Health Organization's immunization program in Liberia. He says in the eight years he has been in the country, there has never been a measles outbreak anywhere near this scale. Now cases are being reported all across the country. 
 
 The eruption of measles, he says, is a direct result of the Ebola outbreak. 
 
 That's because when Ebola hit, it caused an almost complete collapse of health care in Liberia, including routine childhood immunization programs. Once clinics did start to reopen, parents didn't want to bring their kids anywhere near health care centers, which had been hotbeds of Ebola transmission. 
 
 "Because of Ebola there was the suspension of routine immunization services in many parts of the country," Wambai says. "Also we couldn't conduct the follow-up campaign scheduled for last quarter of 2014." 
 
 And it's not just measles that's making a comeback after the collapse of Liberia's vaccination programs. 
 
 Whooping cough has again reared its head in two parts of the country and sickened more than 500 children. Liberians had almost forgotten about this disease because of the high immunization coverage. In 2013, the World Health Organization reported that Liberia vaccinated 89 percent of all 1-year-olds against whooping cough. 
 
 But that high coverage was in the years after Liberia's brutal civil wars and before the arrival of Ebola. 
 
 The Ebola outbreak in Liberia killed more than 4,600 people, including 189 health care workers. The unabated spread of the virus forced hospitals and clinics to close, and it undermined Liberians' confidence in what was already a weak public health care system. 
 
 Now as Liberia moves on from Ebola, rebuilding the health care system and restoring its immunization programs are two of the government's top priorities. As part of that effort, the country launched a nationwide measles vaccination campaign on Friday. Health officials hope to reach almost 700,000 children in a country of 4 million people. 
 
 Liberian officials hope to vaccinate 95 percent of children under 5 years old against measles. They tried a similar campaign in February when the measles outbreak was just gaining steam. That effort failed, and again Ebola was to blame. 
 
 That February immunization drive coincided with the launch of an experimental Ebola vaccine for adults. Parents confused the two and refused to bring their children to the health clinics. 
 
 Officials say they've sent out Red Cross and other volunteers to assure parents that this immunization drive is only about protecting their kids from measles.
– The World Health Organization announced a welcome milestone in Liberia today: With no new cases in 42 days—twice the incubation period—the nation has been declared free of Ebola, reports the BBC. Last fall, Liberia saw 400 new cases every week. The disease remains active in neighboring Sierra Leone and Guinea, however. The three nations were at the epicenter of the recent outbreak that has killed 11,000 people, with Liberia seeing the worst of it. Liberian health officials can hardly rest, though: NPR reports that measles cases are surging, with more than 500 cases this year alone. It's seen as a "direct result" of the Ebola epidemic, which caused a collapse in the nation's health care system. People stopped going to overwhelmed clinics, and childhood immunizations fell by the wayside. Whooping cough also is on the rise, for the same reason. (One Ebola survivor saw his blue eyes turn green.)