Why is travel not banned from those locations?

The Marburg virus — a lethal pathogen similar to Ebola — is spreading rapidly in both Equatorial Guinea and Tanzania, and could soon expand beyond Africa, The Daily Beast reports. Marburg, which is described as a "hemorrhagic fever," according to The New York Times, is capable of killing up to "90 percent of the people it infects," and although a "rare" condition, the "steady uptick in occurrences in Africa in recent years is raising alarm."

https://www.alternet.org/amp/viral-hemorrhagic-matter-time-2659863938

Sounds too deadly to spread far. Ebola has the same problem, outbreaks burn out fast because infected people die before they can spread it around much.