Here's a better write up on it.
Basically, it isn't just the act of deforestation, but the increased exposure to what previously lay hidden within the forest that increases the number of infections. So even intense forest exploration would have chances of similar effect. Any time someone enters a perviously hidden space, they should expect to encounter biohazards.
When the exposure increases even to a small degree in a particularly virulent strain of disease, it can run rampant through a human population. So a few extra people bringing back illness from the forest can result in a massive outbreak. Ebola in both animals and humans is passed on only through direct contact by infected body fluid (blood, mucous, etc.). That means there's a good chance to control the spread, but the disease is particularly deadly, and so does pose a real threat should it escape Africa.