The World Health Organization has joined the government of Sierra Leone in marking the end of the recent flare-up of Ebola virus disease in the country, but warned that the country, Liberia and Guinea are still at risk.

“As of today, March 17, 42 days have passed, two incubation cycles of the virus, since the last person confirmed to have Ebola virus disease in the country tested negative for a  second time,” a statement issued by the WHO and copied to the Ghana News Agency said.

“This latest flare-up of Ebola brings to 3,590 the number of lives lost in Sierra Leone to an epidemic that devastated families and communities across the country and disrupted every aspect of life. Today marks another milestone in the country’s effort to defeat Ebola,” it said.

A fourth person has died of Ebola in Guinea in the latest flare up of an epidemic that has killed more than 11,300 people in that country, Sierra Leone and Liberia since 2013 but now claims few victims.

"The young girl who was hospitalized at the Ebola treatment centre in Nzerekore is dead," said Fode Tass Sylla, spokesman for the centre that coordinates Guinea's fight against the virus.

When the Ebola outbreak was confirmed in Guinea two years ago, one of the reasons the virus spread so quickly was due to the high amount of people traffic across the borders of Guinea, Liberia, and Sierra Leone. To mitigate the introduction of new Ebola cases or other diseases by cross border travellers, the Red Cross has introduced a community event-based surveillance system. It is successful, in large part, due to the engagement of community members.

A comprehensive new study of measles and pertussis outbreaks in the United States suggests that adults’ reluctance or refusal to vaccinate themselves and their children has played a key role in the resurgence of diseases that had been largely eradicated in this country.

In an analysis published Tuesday in the Journal of the American Medical Assn., epidemiologists scoured reports of measles and pertussis outbreaks to glean what role vaccination refusal and hesitance played. They also considered the effect of waning immunity among those who were vaccinated.