In the week ending on 15 February, 128 new cases were confirmed in the three countries – 74 of them in Sierra Leone, 52 in Guinea and two in Liberia.
And these conditions are exemplified by what the UN has identified as the poorest city in the world, Monrovia, the capital of Liberia.
She was one of the first suspected Ebola victims in the capital which, at the time, believed Ebola would remain confined to the east of the country on the border of Liberia.
Charity Hope 2 Liberia, have been installing the filters in schools and distributing smaller filters to families in their homes.
Related: World Health Organisation 'intentionally delayed declaring Ebola emergency' As of 18 March, the death toll from Ebola in west Africa was 10,251, with one new case on Friday in Liberia breaking the country's 42-day countdown to Ebola-free status.
The WHO confirmed on Wednesday that Liberia had gone a full week without reporting any new cases of the disease.
Related: Media and communications: the first line of defence against Ebola That all changed last August, by which time the virus had killed more than 1,000 people, and MSF doctors in Liberia were being forced to turn away dying patients as treatment centres were full.
A paper in the Lancet Infectious Diseases medical journal models the response in Montserrado, Liberia, against the spread of the virus and warns that current efforts will not bring the outbreak under control.
The Yale scientists find that if nothing more is done, there will be more than 170,000 Ebola cases – including those that are unreported – and more than 90,000 deaths by 15 December in Montserrado, a densely populated county containing the capital, Monrovia, and which has one of the highest case rates in Liberia.
So far, the bank has given $230m to Guinea, Liberia and Sierra Leone, he says.
The treatment centres that were constructed and opened, sometimes with a big fanfare, in Sierra Leone in recent months are not full because the numbers of people becoming ill are dropping, albeit less quickly than happened in Liberia.
