Yes there are sex vampires who draw away energy from others, especially by attracting the victims towards themselves. But this is fortunately not common. There are lot of people who even otherwise draw energy and in whose atmosphere one may fall sick. The best thing to do when you come in contact with such people is to remain inwardly detached, communicate very little with them and call the Mother inwardly. If you feel they are drawing the energies, then put the Mother between you and them. Invoke Her White Light and surround yourself with Her Presence. What is needed is wideness and strength in the lower vital parts, especially freedom from excess of anger, ambition, fear and sex which often open the door. The more one is able to get rid of desires, the more one has faith and the more one is able to establish a settled peace in these parts, the more one is able to grow strong in these parts and shield oneself against such forces.
Affectionately,
Alok Da