  The mechanism of a confining medium is investigated within the
Nambu-Jona-Lasinio (NJL) approach. It is shown that a confining medium can be
realized in the bosonized phase of the NJL model due to vacuum fluctuations of
both fermion and Higgs (scalar fermion-antifermion collective excitation)
fields. In such an approach there is no need to introduce Dirac strings.
