The Collaborative International Dictionary of English v.0.48:

Paludal \Pa*lu"dal\, a. [L. palus, -udis, a marsh.]
   Of or pertaining to marshes or fens; marshy. [R.]
   [1913 Webster]

   Paludal fever, malarial fever; -- so called because
      generated in marshy districts.
      [1913 Webster]