Fleas in dreams symbolize little problems that irritate you, your will to deal with old issues that have remained unsolved. Fleas may mirror a wide range of problems - by making an association between the things and places favored by fleas and problems they may stand for, we will find that fleas 'attack' mattresses, therefore they may represent sexual problems; fleas attack our skin, therefore there may be a personal problem etc. Fleas may also represent sickness.
But most of the times fleas seen in dreams stand for false friends who plan treachery on you and who are going to stab you in the back unless you are more cautious. However, if you succeed in chasing away or killing these annoying insects, you will also manage to unmask and expose those who betrayed you.
If a young woman sees fleas in her dream, this means that she is fooled by people who claim to be her friends, but who will eventually turn out to be her enemies. If the fleas she sees in her dream lie on her lover, this means that they do not have a constant relationship and she will have to face her partner's infidelity soon.