Ebola: Mapping the outbreak
The Ebola outbreak in West Africa was first reported in March, and has rapidly become the deadliest occurrence of the disease since its discovery in 1976.
In fact, the current epidemic that has swept across West Africa is not only the worst single Ebola outbreak in history, it has now killed more than all the others combined.
Up to 13 September, 2,461 people had been reported as having died from the disease in four countries; Liberia, Guinea, Sierra Leone and Nigeria. The total number of reported cases was in excess of 4,950.
The World Health Organisation (WHO) admits the figures are underestimates, warning that there could be as many as 20,000 cases in the region before the outbreak is brought under control.Continue reading the main story
In August, the United Nations health agency declared an "international public health emergency", saying that a co-ordinated response was essential to halt the spread of the virus.
However, WHO director general Margaret Chan said this week that the "number of patients is moving far faster than the capacity to manage them".
The concern is that there appears no indication of a reversal in the three countries worst affected, Guinea, Sierra Leone and Liberia.
According to a WHO update released on 12 September, transmission is continuing in urban areas, with the surge in Liberia driven mainly by a sharp increase in the number of cases reported in the capital, Monrovia.Current outbreak
Researchers from the New England Journal of Medicine have traced the outbreak to a two-year-old girl, who died on 6 December 2013 in Meliandou, a small village in south-eastern Guinea.
In March, hospital staff alerted Guinea's Ministry of Health and then the charity Medecins Sans Frontieres (MSF). They reported a mysterious disease in the south-eastern regions of Gueckedou, Macenta, Nzerekore, and Kissidougou.
It caused fever, diarrhoea and vomiting. It also had a high death rate. Of the first 86 cases, 59 people died.
The WHO later confirmed the disease as Ebola.Disease spreads
Gueckedou is a major regional trading centre and, by the end of March, Ebola had crossed the border into Liberia and it was confirmed in Sierra Leone in May.
In June, MSF described the Ebola outbreak as out of control.
Nigeria had its first case of the disease in July and in the same month two leading doctors died from Ebola in Liberia and Sierra Leone. Senegal reported its first case of Ebola on 29 August. A young man from Guinea, who has now been quarantined, had travelled to Senegal despite having been infected with the virus, officials said.Cumulative deaths - up to 13 September
The WHO has published updates on the spread of the virus in each of the countries affected.
The figures given are for "confirmed, probable and suspected" cases and deaths. They have occasionally been revised down to take account of changes in the countries' reporting methods, for example by excluding the "suspected" cases.2014 outbreak in context
Ebola occurs in regions of sub-Saharan Africa, though normally fewer than 500 cases occur each year.
No cases at all were reported between 1979 and 1994, however, the 2014 outbreak dwarfs all previous outbreaks.Past epidemics