What causes Tim's father's death on the prison ship in My Brother Sam Is Dead?

My Brother Sam is Dead is a work of historical fiction by James Lincoln Collier and Christopher Collier that targets young adult readers. The book traces the life of Tim Meeker, a boy living in Connecticut just before the dawn of the American Revolution, who must deal with the wildly different political views of his father, Eliphalet "Life" Meeker, (who is loyal to Great Britain) and his brother Sam (a member of the Continental Army). Tim watches as the conflict between these two--and between the countries they believe in--continues to escalate to the point of senseless violence. 

Eventually, Tim's father, is captured by Rebels who believe that he has been selling beef to New York loyalists. He later dies on a prison ship after an outbreak of cholera. 

In My Brother Sam Is Dead, what causes the father's death?

My brother Sam Is Dead is a young adult historical fiction novel that is set during the time of the American Revolution. The main character—Tim Meeker—is a 14-year-old young man who is caught between two other characters with strong opinions about the war.

Tim's brother, Sam, has decided to join the Continental Army in support of secession from the British. Tim's father, Eliphalet, is loyal to Britain. Because of this loyalty, he is accused by the rebels of selling beef to the British and forced onto a prison ship. While on the prison ship, he contracts Cholera and dies from the disease.

As can be assumed from the book title, Sam also dies after he is executed by his own army when he is falsely accused of stealing cattle from his family.