Ebola
2013–2016 West Africa

In March 2014, the World Health Organization (WHO) reported a major Ebola outbreak in Guinea, a West African nation. Researchers traced the outbreak to a one-year-old child who died in December 2013. The disease rapidly spread to the neighbouring countries of Liberia and Sierra Leone. It was the largest Ebola outbreak ever documented, and the first recorded in the region. On 8 August 2014, the WHO declared the epidemic an international public health emergency. Urging the world to offer aid to the affected regions, its Director-General said, "Countries affected to date simply do not have the capacity to manage an outbreak of this size and complexity on their own. I urge the international community to provide this support on the most urgent basis possible." By mid-August 2014, Doctors Without Borders reported the situation in Liberia's capital, Monrovia, was "catastrophic" and "deteriorating daily". They reported that fears of Ebola among staff members and patients had shut down much of the city's health system, leaving many people without medical treatment for other conditions. In a 26 September statement, WHO said, "The Ebola epidemic ravaging parts of West Africa is the most severe acute public health emergency seen in modern times. Never before in recorded history has a biosafety level four pathogen infected so many people so quickly, over such a broad geographical area, for so long."

Intense contact tracing and strict isolation largely prevented further spread of the disease in the countries that had imported cases.

It caused significant mortality, with a considerable case fatality rate. By the end of the epidemic, 28,616 people had been infected; of these, 11,310 had died, for a case-fatality rate of 40%. As of 8 May 2016, 28,646 suspected cases and 11,323 deaths were reported; however, the WHO said that these numbers may be underestimated. Because they work closely with the body fluids of infected patients, healthcare workers were especially vulnerable to infection; in August 2014, the WHO reported that 10% of the dead were healthcare workers.

In September 2014, it was estimated that the countries' capacity for treating Ebola patients was insufficient by the equivalent of 2,122 beds; by December there were a sufficient number of beds to treat and isolate all reported Ebola cases, although the uneven distribution of cases was causing serious shortfalls in some areas. On 28 January 2015, the WHO reported that for the first time since the week ending 29 June 2014, there had been fewer than 100 new confirmed cases reported in a week in the three most-affected countries. The response to the epidemic then moved to a second phase, as the focus shifted from slowing transmission to ending the epidemic. On 8 April 2015, the WHO reported only 30 confirmed cases, the lowest weekly total since the third week of May 2014.

On 29 December 2015, 42 days after the last person tested negative for a second time, Guinea was declared free of Ebola transmission. At that time, a 90-day period of heightened surveillance was announced by that agency. "This is the first time that all three countries – Guinea, Liberia and Sierra Leone – have stopped the original chains of transmission...", the organisation stated in a news release. A new case was detected in Sierra Leone on 14 January 2016. However, the outbreak was declared no longer an emergency on 29 March 2016.
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