The Centers for Disease Control Changed Its Ebola Prevention Page on September 19, 2014. Why?

The Centers for Disease Control edited its Ebola prevention fact page on September 19. A note at the bottom of the page says as much.

So what was changed?

Here is the top of the page as it reads now, after the edit.

Here is how it read before the edit.

As you can see, the CDC edited out the following text on Sept 19:

Because we still do not know exactly how people are infected with Ebola, few primary prevention measures have been established and no vaccine exists.

When cases of the disease do appear, risk of transmission is increased within healthcare settings. Therefore, healthcare workers must be able to recognize a case of Ebola and be ready to use practical viral hemorrhagic fever isolation precautions or barrier nursing techniques. They should also have the capability to request diagnostic tests or prepare samples for shipping and testing elsewhere.

Why did the CDC edit all of that information out? Did the science change, or did the government make the edit for some other reason(s)?

h/t Morgan