  Context: The INTEGRAL mission has led to the discovery of a new type of
supergiant X-ray binaries (SGXBs), whose physical properties differ from those
of previously known SGXBs. Those sources are in the course of being unveiled by
means of multi-wavelength X-rays, optical, near- and mid-infrared observations,
and two classes are appearing. The first class consists of obscured persistent
SGXBs and the second is populated by the so-called supergiant fast X-ray
transients (SFXTs). Aims: We report here mid-infrared (MIR) observations of the
companion stars of twelve SGXBs from these two classes in order to assess the
contribution of the star and the material enshrouding the system to the total
emission.} Methods: We used data from observations we carried out at ESO/VLT
with VISIR, as well as archival and published data, to perform broad-band
spectral energy distributions of the companion stars and fitted them with a
combination of two black bodies representing the star and a MIR excess due to
the absorbing material enshrouding the star, if there was any. Results: We
detect a MIR excess in the emission of IGR J16318-4848, IGR J16358-4726, and
perhaps IGR J16195-4945. The other sources do not exhibit any MIR excess even
when the intrinsic absorption is very high. (abridged)
