by Kolapo Olapoju

A nurse was recently reported to have survived the Ebola virus disease, and many have begun to wonder how she was able to get through the life threatening impact of the deadly Ebola virus.

The nurse has been discharged from the isolation centre at the Mainland Hospital in Lagos, while reports say that some more patients who are undergoing treatment at the centre may be discharged this week.

Statistics and precedence show that 60-90 per cent of people who get infected with the Ebola virus go on to die, while some people tend to recover from the infection.

Derek Gatherer, a Bioinformatics researcher at Lancaster University in the United Kingdom, who has experience in the study of viral genetics and evolution shared his opinion on what led to the survival of the infected victims.

He said, “when a person becomes infected with Ebola, the virus depletes the body’s immune cells, which defend against infection. In particular, the Ebola virus depletes immune cells called CD4 and CD8 T lymphocytes, which are crucial to the function of the immune system”, Gatherer noted, arguing that “if a person’s immune system can stand up to this initial attack — meaning their immune cells are not as depleted in the first stages of infection — then they are more likely to survive the disease.”

“The patients that survive it best are the ones who don’t get such a bad immune deficiency. But if the body is not able to fend off this attack, then the immune system becomes less able to regulate itself.”

Another determinant of surviving Ebola is when a patient has a strong immune system, which is in place of a gene called human leukocyte antigen-B, which makes a protein that is important in the immune system. A 2007 study found that people with certain versions of this gene, called B*07 and B*14, were more likely to survive Ebola, while people with other versions, called B*67 and B*15, were more likely to die.

Some people may also be resistant to Ebola infection entirely, if they have a mutation in a gene called NPC1. Studies show that, when researchers take cells from people with the NPC1 mutation and try to infect them with Ebola in a laboratory dish, these cells are resistant to the virus.

Gatherer added that in European populations, about 1 in 300 to 1 in 400 people has this mutation, He said, “But in some populations, this mutation is more common: in Nova Scotia, between 10 and 26 per cent of people have this mutation. But the frequency of this mutation in African populations is not known.”

Meanwhile, the World Health Organisation says the death toll has risen to 1,145.

Kolapo Olapoju