Question: Once Ian Crozier was infected with Ebola Virus Disease, what was his chance or survival?

Context paragraphs:
Ebola virus disease in Nigeria: Ebola virus disease in Nigeria occurred in 2014, the epidemic of Ebola virus disease (commonly known as "Ebola") in Guinea represents the first ever outbreak of Ebola in a West African country.  Previous outbreaks have been confined to countries in Central Africa.  The epidemic, which began with the death of a 2-year-old boy in December 2013, is now part of a larger Ebola virus epidemic in West Africa which has spread through Guinea and the neighboring countries of Liberia and Sierra Leone, with smaller outbreaks occurring in Senegal, Nigeria, and Mali.

Reston virus: Reston virus (RESTV) is one of five known viruses within the genus "Ebolavirus".  Reston virus causes Ebola virus disease in non-human primates; unlike the other four ebolaviruses, it is not known to cause disease in humans, but has caused asymptomatic infections.  Reston virus was first described in 1990 as a new "strain" of Ebola virus (EBOV).  It is the single member of the species "Reston ebolavirus", which is included into the genus "Ebolavirus", family "Filoviridae", order "Mononegavirales".  Reston virus is named after Reston, Virginia, US, where the virus was first discovered.

Ebola virus disease: Ebola virus disease (EVD), also known as Ebola hemorrhagic fever (EHF) or simply Ebola, is a viral hemorrhagic fever of humans and other primates caused by ebolaviruses.  Signs and symptoms typically start between two days and three weeks after contracting the virus with a fever, sore throat, muscular pain, and headaches.  Then, vomiting, diarrhea and rash usually follow, along with decreased function of the liver and kidneys.  At this time, some people begin to bleed both internally and externally.  The disease has a high risk of death, killing between 25 and 90 percent of those infected, with an average of about 50 percent.  This is often due to low blood pressure from fluid loss, and typically follows six to sixteen days after symptoms appear.

Ian Crozier: Ian Crozier is an American physician who contracted Ebola virus disease in September 2014, while working in West Africa.

Ebola virus cases in the United States: In December 2014, Ebola virus cases in the United States occurred due to four laboratory-confirmed cases of Ebola virus disease (commonly known as "Ebola") in the United States.  Eleven cases have been reported, including these four cases and seven cases medically evacuated from other countries; the first was reported in September 2014.  Nine of the people contracted the disease outside the US and traveled into the country, either as regular airline passengers or as medical evacuees; of those nine, two died.  Two people have contracted Ebola in the United States.  Both were nurses who treated an Ebola patient; both have recovered.

VP40: In molecular biology, VP40 is the name of a Viral matrix protein.  Most commonly it is found in the "Ebola virus" (EBOV), a type of non-segmented, negative-strand RNA virus.  Ebola virus causes a severe and often fatal haemorrhagic fever in humans, known as Ebola virus disease.  The virus matrix protein VP40 is a major structural protein that plays a central role in virus assembly and budding at the plasma membrane of infected cells. VP40 proteins work by associating with cellular membranes, interacting with the cytoplasmic tails of glycoproteins and binding to the ribonucleoprotein complex.

Ebola virus disease in Spain: In 2014, Ebola virus disease in Spain occurred due to two patients with cases of the disease contracted during the Ebola virus epidemic in West Africa; they were medically evacuated.  A failure in infection control in the treatment of the second patient led to an isolated infection of Ebola virus disease in a health worker in Spain itself.  The health worker survived her Ebola infection, and has since been declared infection-free.

Ebola virus: Ebola virus ( ; EBOV, formerly designated Zaire ebolavirus) is one of five known viruses within the genus "Ebolavirus".  Four of the five known ebolaviruses, including EBOV, cause a severe and often fatal hemorrhagic fever in humans and other mammals, known as Ebola virus disease (EVD).  Ebola virus has caused the majority of human deaths from EVD, and is the cause of the 2013–2015 Ebola virus epidemic in West Africa, which has resulted in at least suspected cases and confirmed deaths.

Prevention of viral hemorrhagic fever: Prevention of viral hemorrhagic fever is similar for the different viruses.  There are a number of different viral hemorrhagic fevers including Ebola virus disease, Lassa fever, Rift valley fever, Marburg virus disease, Crimean-Congo haemorrhagic fever (CCHF) and yellow fever.  Lassa, Ebola, Marburg and CCHF can be spread by direct contact with the body fluids of those infected.  Thus the content here covers the prevention of Ebola.

BCX4430: BCX4430 (Immucillin-A) is an antiviral drug, an adenosine analog (a type of nucleoside analog).  It is developed by BioCryst Pharmaceuticals with funding from NIAID, originally intended as a treatment for Hepatitis C, but subsequently developed as a potential treatment for deadly filovirus infections such as Ebola virus disease and Marburg virus disease.  It also shows broad-spectrum antiviral effectiveness against a range of other RNA virus families, including bunyaviruses, arenaviruses, paramyxoviruses, coronaviruses and flaviviruses.  BCX4430 has been demonstrated to protect against both Ebola and Marburg viruses in both rodents and monkeys, even when administered up to 48 hours after infection, and development for use in humans is being fast-tracked due to concerns about the lack of treatment options for the 2013-2016 Ebola virus epidemic in West Africa.  BCX4430 also showed efficacy against Zika virus in a mouse model, though there are no plans for human trials at this stage.

Supporting paragraphs: Ian Crozier Ebola virus disease
Answer: about 50 percent