If one knows one has a deadly communicable disease and is willfully negligent knowing that your actions are likely to cause particular harm then it would be assault.
Rarely people with HIV have _chosen_ to spread it through intercourse, if someone purposefully chose to give you HIV would you say you had fully consented to that sexual act, given you were entirely ignorant to their infection and their choice?
How would you protect people from active malicious infection? Or, have you done reason that we shouldn't consider these things to be assault?