The parasite mentioned in the article is Toxoplasma gondii. Tests in mice infected with Toxoplasma have shown that the infection causes changes in motor skills, and also causes behaviour changes (the mice become more reckless). I have seen a couple of articles that talk about behaviour changes in infected humans (such as this article, which mentions that infected people are more likely to be involved in car accidents). So I guess that the changes in sexual behaviour are related to the more reckless behaviour pattern.