I read a book back in the 80's about an alien virus that jumps from person to person on a cruise ship (or may have been a luxury space ship). The book was really well written up until the last two chapters when it seems that the author either was replaced or lost their mind or something because the last two chapters completely STUNK.
If I remember the ending correctly, the alien was tricked into jumping into a goat or some other animal and sent into space. This was a teen novel (I got it from my high school library). Is there anyone that possibly would remember this book? Thanks!