Passengers were flying high on a major airline when they discovered a surprise traveler aboard their flight: A rat.

Nearly every airline requires animals to be confined inside a carrier when they fly ... It’s not clear how the “super rat” got onboard, but the unusual passenger had far more legroom ...

The West African multimammate rat is the only known carrier of the virus. These rats are found in sub-Saharan Africa, and Lassa fever has been found in Sierra Leone, Liberia, Guinea and Nigeria ...

The low-cost carrier is now reopening talks with Frontier ... For all we know, the rat could have been a paying passenger ...