Is there a link between living alone and poor health?

It has been a year since my roommate has left and now lives out of town. In that same year, my health suddenly became the worst it has ever been in my life. I contracted strep throat twice, pneumonia, and swine flu (I barley survived) all in one year. This is the first time I've ever lived alone. Does anyone know of a study that links living alone and poor health?