Not bad, but not the best writing out there either. I could tell within the first few pages that this could've used another proofread, especially when it comes to punctuation. The author seems not to know that questions in dialogue end with a question mark and not a comma or period.
All the characters here were pretty flat and one-dimensional, and seem driven solely by sex, even those not infected with the disease. The women were objectified the most, differentiated by breast size every time one was introduced. But the treatment of the men wasn't much better either.
All that aside, there were some redeemable qualities of the story. The pacing was good, and it was an interesting enough premise to keep me reading. The action at the climax of the story flowed pretty nicely. Also, there were some passages that had me equally aroused and disgusted at the same time, so good job on that, I guess? I mean, that's gotta take some skill.