Ebola virus didn't mutate to become more dangerous: study

The Ebola virus that has killed over 11,000 people in West Africa is no more deadly, and may even be weaker, than the original virus that first emerged in 1976, US scientists have claimed.
Researchers from the US National Institutes of Health (NIH) found that the current strain, called Makona, may have "a decreased ability to cause disease" in an animal model than the original Mayinga strain, which first emerged in Central Africa in 1976.
In the study, scientists found that three macaques infected with the 1976 virus developed symptoms roughly two days earlier than three macaques infected with the current pathogen.

While both groups of macaques were spreading virus three days after being infected, those with the 1976 strain developed a rash on day four and became extremely ill on days five and six.
Those with the current strain did not develop a rash until six days after infection, and severe disease appeared on days seven and eight.
Further, liver damage - typical in Ebola disease - was delayed by about two days in the current-strain-infected group compared to the group with the 1976 strain, 'Xinhua' news agency reported.

In humans, the current outbreak has a case-fatality rate of 50 per cent, while the 1976 one has a case-fatality rate of 90 per cent, researchers said.

"It seems fair to conclude that virulence of the strain from West Africa in macaques is not increased compared with other EBOV (Ebola virus) strains," the researchers wrote in the journal Emerging Infectious Disease.
"The main message is it's certainly not worse and it may be less virulent. It's good news," Anthony Fauci, director of the US National Institute of Allergy Infectious Diseases told 'USA Today'.
Fauci said the findings lend credence to theories that the virus spun out of control in Liberia, Sierra Leone and Guinea because of a "perfect storm" of factors where it took root in densely populated cities and victimised poverty-stricken nations with poor health care and porous borders.