Are stations used in Ticket to Ride: The Heart of Africa?
No, the rules explicitly state what pieces are required from an earlier set:


  This game is an expansion and requires that you use the following game
  parts from one of the previous versions of Ticket to Ride:
  
  A reserve of 45 Trains per player and matching Scoring Markers taken
  from any of the following:
  - Ticket to Ride / Ticket to Ride Europe  110 Train Car Cards taken from:
  - Ticket to Ride / Ticket to Ride Europe / USA 1910 expansion


Anything not mentioned in the above list should be considered surplus to official requirements.  Though you could always try playing with stations as an interesting variant!

EDIT: yes, without stations Heart of Africa is a very claustrophobic Ticket to Ride game.  But this does seem to have been the intention of the designers, as they've admitted as much in a footnote in the rules booklet:


  In 5 player games, the Heart of Africa (center of the map) area can
  get crowded very quickly. Players beware! - and if you like your games
  to be less competitive, stick with 4 players or less.