Human trafficking is a phenomenon linked to several forms of exploitation, such as sexual exploitation, forced labour, forced marriage, begging, forced criminal activity, or organ removal. There are different debates about a potential overrepresentation of some of these exploitation purposes, such as the sexual one, in the discourses underlying international regulations, news or institutional campaigns. This may have consequences on the identification of some of the population affected by this phenomenon and the assistance provided to them. The aim of this paper is to analyse the temporal evolution of the purposes of exploitation, actors and topics most represented in the activity on human trafficking and exploitation on Twitter during the 2011-2020 period. The results show that sexual exploitation is the purpose most represented in Twitter activity and the fact that international organisations and the criminal prosecution of the crime of human trafficking have progressively become more relevant. Furthermore, the networks of topics suggest that sexual exploitation seems to be linked to the notion of prostitution. This may have consequences for the displacement of other purposes of exploitation or the approaches centred on the promotion of human rights to less relevant positions, as well as for the construction of certain images of victims of human trafficking.