July 30, 2014 9:08 AM EDT

More than 670 people have died from the latest outbreak of Ebola, a highly contagious virus that is also one of the deadliest human diseases.

Though it’s been almost 40 years since Ebola was first discovered in 1976, there are currently no cures or effective treatments.

Here’s what you need to know about the unprecedented outbreak.

Write to Diane Tsai at diane.tsai@time.com.

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