Ebola outbreak in West Africa was first reported in March 2014, and has rapidly become the deadliest occurrence of the disease since its discovery in 1976.
In fact, the current epidemic sweeping across the region has now killed more than all other known Ebola outbreaks combined.
Up to 19 October, 4,877 people had been reported as having died from the disease in five countries; Liberia, Guinea, Sierra Leone, Nigeria and the United States. The total number of reported cases is in excess of 9,900.
The World Health Organisation (WHO) admits the figures are underestimates and warns there could be as many as 20,000 cases by November if efforts to tackle the outbreak are not stepped up.
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.
By September, WHO director general Margaret Chan said that the “number of patients is moving far faster than the capacity to manage them”.
Director of the Centers for Disease Control and Prevention (CDC) in the US, Thomas Frieden, said in October that the Ebola outbreak in West Africa is unlike anything since the emergence of HIV/Aids.
Despite attempts to deploy more health workers and open new Ebola treatment centres in the worst-affected countries, the WHO said that there was still a significant lack of beds in Sierra Leone and Liberia, with more than 3,000 needed.
The WHO has declared the outbreaks in Nigeria and Senegal officially over, as there have been no new cases reported since 5 September.
The same cannot be said for Guinea, Sierra Leone and Liberia.
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.
The situation in Sierra Leone also continues to deteriorate with a sharp increase in the number of newly-reported cases in the capital, Freetown, and its neighbouring districts of Port Loko, Bombali, and Moyamba, which were placed under quarantine on 25 September.
That means that five of Sierra Leone’s 15 districts are on lockdown, with more than a third of the population of six million no longer able to move freely.
Researchers from the New England Journal of Medicine have traced the outbreak to a two-year-old toddler, 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.
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 had travelled to Senegal despite having been infected with the virus, officials said.
The first case of the deadly virus diagnosed on US soil was announced on 1 October. Thomas Eric Duncan, 42, who contracted the virus in Liberia before travelling to the US, died on 8 October.
He had not displayed symptoms of the disease until 24 September, five days after his arrival. Other people with whom he came into contact are being monitored for symptoms.
*In all but three cases the patient was infected with Ebola while in West Africa. Infection outside Africa has been restricted to health workers in Madrid and in Dallas. DR Congo has also reported a separate outbreak of an unrelated strain of Ebola.
Two medical workers in Dallas, Texas, who treated Duncan have tested positive for Ebola since his death and are receiving treatment.
Spanish nurse Teresa Romero was the first person to contract the virus outside West Africa. She was part of a team of about 30 staff at the Carlos II hospital in Madrid looking after two missionaries who returned from Liberia and Sierra Leone after becoming infected.
Germany, Norway and France and the UK have all treated patients who contracted the virus in West Africa.
Cumulative deaths up to 19 October
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 was first identified in 1976 and occurs in regions of sub-Saharan Africa. There are normally fewer than 500 cases reported each year, and no cases were reported at all between 1979 and 1994.
In August 2014 the WHO confirmed a separate outbreak of Ebola in the Democratic Republic of Congo. By the beginning of October there had been 70 cases reported and 43 deaths.
However, the outbreak in DR Congo is a different strain of the virus and unrelated to the epidemic in West Africa, which now dwarfs all previous outbreaks.
Past epidemicsRead More