Medicine: public health officials file suit to force HIV-positive prostitute to seek treatment

I've always been under the impression that it was illegal for an HIV-positive person to knowingly expose someone else to the virus, something akin to an attempted manslaughter charge. But I guess not, since Amarillo officials are filing suit against a woman who's been doing that to get her to stop and seek treatment. Necessary evil? We've never felt bad pulling TB or typhoid fever patients out of the community, and I don't suppose this is all that different. Just feels kinda screwed up to me. If not necessary.