The World Health Organization has released a statement saying that the Ebola outbreak in West Africa is raising major concerns that the virus could have an international spread.

The WHO said they are “gravely concerned” about the outbreak that has now killed over 400 people in the deadliest outbreak in world history.  The outbreak, which began in Guinea earlier this year, has now spread into Sierra Leone and Liberia.  Officials now say that the virus could begin to appear in other nations.

“There is an urgent need to intensify response efforts…this is the only way that the outbreak will be effectively addressed,” WHO officials stated.

The statement from the WHO comes just days after Doctors Without Borders said the outbreak was “out of control.”

Doctors said the only positive in the current outbreak is that unlike previous Ebola outbreaks with had 95 percent death rate, the current outbreak’s rate is 60 percent.