In pictures: The Ebola crisis

A man washes his hands in an attempt to stop the spread of the deadly Ebola virus in the city of Monrovia, Liberia. Abbas Dulleh / AP Photo

A Nigerian port health official uses a thermometer on a passenger at the arrivals hall of Murtala Muhammed International Airport in Lagos. On Wednesday, the death toll rose to at least 932 people in four West African countries. Sunday Alamba / AP Photo

A Nigerian port health official wears protective gear at the arrivals hall of Murtala Muhammed International Airport in Lagos. Sunday Alamba / AP Photo

A woman washes her hands before she is allowed to enter a building as part of a Ebola prevention campaign in Sierra Leone. Michael Duff / AP Photo

The Gulf Stream III that was used to transport Ebola victims. Dr Kent Brantly and Nancy Writebol and an Airborne Biological Containment System (ABCS) similar to the one used on both flights sit in a hanger in Cartersville, Georgia. Phoenix Air, the company that transported Ebola victims Dr. Kent Brantly and Nancy Writebol, held a press conference to discuss the two flights that carried the victims from Liberia to Marietta, Georgia. Branden Camp / EPA

Several paramedics, wearing protective suits, move Spanish missionary Miguel Pajares, who is infected with Ebola, into an ambulance upon his arrival at Spanish Air Force base in Torrejon de Ardoz, outside Madrid. Spanish Defence Military / EPA

The Ebola Virus. CDC / AP Photo

A South Korean quarantine officer, left, checks body temperature of a passenger against possible infections of Ebola virus at the Incheon International Airport in Incheon, South Korea. South Korea has been stepping up monitoring of its citizens returning from trips to West Africa and other areas affected by the deadly Ebola virus. Choe Jae-koo / Yonhap / AP Photo

Authorities in West African are battling to contain the spread of Ebola but will have to wait for months until a potentially life-saving experimental drug known as ZMapp, which was used on two Americans infected with the dreaded disease, could be produced for use in Africa. Sunday Alamba / AP Photo

Director General of the World Health Organization, WHO, China’s Margaret Chan and Assistant Director General for Health Security Keiji Fukuda of the US, right, share a word during a press conference after an emergency meeting at the headquarters of the WHO in Geneva, Switzerland. Salvatore Di Nolfi / AP Photo / Keystone

People walk past a billboard encouraging people suffering from symptoms linked to Ebola to present themselves at a health facility for treatment in Freetown. The outbreak that emerged in March has claimed at least 932 lives. Michael Duff / AP Photo

A trader wearing rubber gloves to avoid transmission of Ebola passes money to a client at the shop in Freetown. Michael Duff / AP Photo

Jeremy Writebol is one of two Americans working for a missionary group in Liberia that have been diagnosed with Ebola. Courtesy Jeremy Writebol / AP Photo

West Africa’s raging epidemic of Ebola virus is an “extraordinary event” and now constitutes an international health risk, the World Health Organisation (WHO) said on Friday.