The number of cases and the numbers of deaths in the Ebola outbreak in West Africa already exceed the totals for all previous outbreaks combined. The first known Ebola outbreaks took place in 1976.
The current outbreak, thought to have started in December 2013, "is a huge and urgent global problem that demands a huge and urgent global response," UN Secretary General Ban Ki-moon said in an Oct. 17 speech.
"Liberia remains the country worst affected by the epidemic," according to the WHO.
The number of new confirmed cases in Liberia's capital, Monrovia, has dropped sharply over the past four weeks. However, the latest WHO report says there are "reports from laboratory staff and first responders of large numbers of new cases."
A separate outbreak began in the Democratic Republic of Congo in August, 2014.
Here's a look at Ebola by the numbers.
Ebola outbreak in West Africa spreading rapidly
Number of countries with cases: 7 (Guinea, Liberia, Sierra Leone, Nigeria, Senegal, United States, Spain)
The WHO says these figures from the Oct. 22 report, may be underestimates:
Number of cases as of Oct. 17: 9,936
The U.S. Centres for Disease Control estimates the actual number of cases is 2.5 times the number of cases reported to the WHO.
About 22 per cent of the confirmed cases are 17 years old or younger, according to UNICEF.
Number of deaths as of Oct. 17: 4,877
Number of deaths as a share of the number of total cases, West Africa: 49 per cent
Number of deaths as a share of the number of case patients with definitive outcomes: 71 per cent
Percentage of cases that were reported in the 21 days up to Oct. 11 in Guinea and Sierra Leone, Oct. 12 in Liberia: 31 (That number clearly indicates the disease had been spreading rapidly, according to WHO.)
Number of new cases in the week ending Oct 19: 976
Number of deaths in the week ending Oct. 19: 384
In their Oct. 15 report, WHO describes the situation as deteriorating, "with widespread and persistent transmission."
On a positive note, five districts in Guinea and one in Sierra Leone reported no new cases during the 21 days ending Oct. 12. However, two areas in Guinea that had been Ebola-free recently reported their first cases.
Ebola takes down health-care workers
Number of cases involving health-care workers in West Africa, as of Oct 19: 443
Number of deaths. among those cases: 244 (55 per cent)
Doctors Without Border staff members account for at least 16 of those cases and 9 of the deaths.
Number of doctors and nurses needed for a 70- to 80-bed Ebola treatment centre: 200
Number of beds available to treat an Ebola patient anywhere in Liberia: 0 (The humanitarian response to the epidemic is running short on almost everything from body bags to mobile laboratories.)
Total bed capacity for Ebola cases in Guinea, Liberia and Sierra Leone: 1,126
Number of additional beds needed: 3,262
Percentage of health-care workers that the WHO wants to be from foreign countries: 20
Number of health care workers China has sent to Sierra Leone for Ebola response: 115 (it is also sending a mobile lab and a staff of 59 to help test for infections).
Number of health professionals Cuba has sent to Sierra Leone for Ebola response: 165
The East African Community – Burundi, Kenya, Rwanda, Tanzania and Uganda – is sending 600 health care workers, including 41 doctors, to Guinea, Liberia and Sierra Leone.
How one person spread the Ebola virus in Nigeria
The Ebola numbers for Nigeria show how the virus spreads, because all 21 cases, which include eight deaths, are believed to have followed a transmission chain that began when Liberian government official Patrick Sawyer travelled from Liberia to Lagos, Nigeria on July 20.
Number of people monitored in Lagos: 362
One man who evaded the monitoring travelled to Port Harcourt. That man later recovered but the doctor who treated him died of Ebola.
Number of people monitored in Port Harcourt: 529
The WHO declare an end to the Ebola outbreak in Nigeria on Oct. 20. The last confirmed case of Ebola in Nigeria was reported on Sept. 5.
Senegal reported one case of Ebola, a person who travelled there from Guinea on Aug. 20. That led to the monitoring of 74 people, with no one testing positive. The initial case has now fully recovered and the WHO declared an end to the Ebola outbreak in Senegal on Oct. 17.
In the U.S., 172 people are being monitored as of Oct. 12.
In Spain, monitoring is underway for 83 people, including 13 high-risk contacts.
The other Ebola outbreak: Democratic Republic of Congo
Number of cases in DRC, as of Oct 20: 66
Number of deaths, as of Oct. 9: 49 (Includes 8 health-care workers)
The WHO says all the cases are linked to an initial case reported to the WHO on Aug. 26. There has not been a confirmed case reported since Oct. 4. This outbreak is not connected to the one in West Africa.
Total number of cases predicted by the WHO: over 20,000 by Nov. 2, assuming no changes in control efforts (WHO hopes to control the outbreak within nine months.)
Total number of cases predicted by the U.S. CDC: approximately 550,000 Ebola cases in Liberia and Sierra Leone or 1.4 million if corrections for under-reporting are made, by Jan. 20, 2015, assuming no additional interventions or changes in community behaviour.
Eurosurveillance projection: 77,181 to 277,124 additional cases by the end of 2014 (This projection, from a report in the peer-reviewed journal's Sept. 11 edition, assumes continued exponential growth, which the authors say is unlikely.)
Ebola: background numbers
Incubation period for Ebola from the time of infection to symptoms: 2 to 21 days
Mean incubation period, current outbreak: 11.4 days
Number of days without a new case in a country for WHO to consider the outbreak ended: 42 (twice the maximum incubation period)
Worst previous Ebola outbreak, by number of deaths: 280 deaths out of 318 cases, in Zaire, 1976 (That was also the first recognition of the disease.)
Worst previous Ebola outbreak, by number of cases: 425 cases in Uganda 2000-01 (The death toll was 224.)
Number of Ebola vaccines getting fast-tracked through the approval process: 2 (One designed by scientists at the U.S. National Institutes of Health and licensed to GlaxoSmithKline, began human trials earlier in September. The second vaccine, identified by many scientists as more promising, was developed by scientists at the National Microbiology Laboratory in Winnipeg. The federal government has licensed the vaccine to NewLink Genetics, a small biotech company in Ames, Iowa.)
The U. S. response (as of Sept 16)
Amount the U.S. government spent prior to Obama's Sept. 16 announcement: more than $100 million US (Ned Price, National Security Council).
Amount the U.S. Agency for International Development announced it would spend to provide 1,000 treatment beds in Liberia and 130,000 protective suits for health workers: up to $75 million US
Additional amount the Obama administration is asking Congress to provide for sending additional supplies and public health experts, and to develop potential Ebola medications and vaccines: $88 million US
Number of CDC staffers in West Africa working on outbreak control: 103 (The CDC plans to send about 50 more.)
Number of Americans evacuated to U.S. hospitals from West Africa during this outbreak: 4 (Three at Emory University Hospital in Atlanta and one at the Nebraska Medical Centre in Omaha.)