  Systems of particles interacting through a screened Coulomb potential of the
Debye-Yukawa form are considered. The pressure is obtained from the stress
tensor of the field corresponding to the Yukawa interaction, by a suitable
statistical average. This approach is especially appropriate for systems living
in a curved space. In a curved space, a self contribution to the pressure
appears, and it is essential to take it into account for retrieving a correct
pressure when the Yukawa interaction tends to the Coulomb interaction.
