During the Civil War, physicians categorized malaria into a number of different categories based on the extension of the chill/fever episodes:

Intermittent fever
remittent fever
Congestion of the brain: considered the deadliest form of malaria, which usually killed in a couple of days.

There were also categories called Typho-malaria because the men exhibited symptoms of both diseases. More than likely, the men suffered from both diseases simultaneously.

I wrote an article about health at Helena for Civil War History, entitled "This God-Forsaken Town: Death and Disease at Helena, Arkansas 1862-63." I think it was published in 2004, and should be available through Jstor to download. It explains all these diseases, and how they were treated.

Rhonda