What book is this?

I have been trying to find a book that I have been looking for , and I can’t seem to find any information on it.
I read it a few years ago, but I’m not sure when it was published. It’s not very old, maybe 10–20 years since first print.
I feel like the title had the word “Medusa” in it. Something like “The Medusa Strain”, although I already checked that, and there is a book called The Medusa Strain, but it’s not the same.
I believe it was written by a woman. It’s a fiction novel that I had found in the horror/mystery section of a used book store.
What I remember of the plot is that there is a woman who is a psychology researcher for some kind of big deal facility or asylum. The asylum only houses women, or maybe she only deals with women, I’m not sure. Anyways, there is some kind of weird phenomenon happening where some of the women get a terrible symptom (again, not sure exactly what it is) and then die or are taken away.
Towards the end the main character (that researcher) starts to figure out what is happening to the women. She gets scared that someone is watching her and is either mugged, or raped, or almost raped in a park in New York.
I don’t remember anything else. Not the ending, the name of the characters, the title of the book. Nothing. I hope someone on here might know. Thanks.