Typhoid
Typhoid spreads by the fecal-oral route, most commonly by way of contaminated food or drinking water.
Signs and symptoms of the early stages of Typhoid fever include: headache, a fever that increases daily, weakness and fatigue, sweating, a dry cough, loss of appetite that can lead to weight loss, abdominal pain, constipation, rash, and an extremely swollen abdomen.
Signs and symptoms of the later stages include becoming delirious and what is known as the "typhoid state." While in the "typhoid state," one lies motionless with their eyes half closed.
Other effects include inflammation of the intestines (which can lead to intestinal bleeding and/or holes in the intestine), inflammation of the heart muscle, and inflammation of the pancreas. These effects can be chronic.
Horace's contraction of Typhoid Fever during the war was likely the cause of his chronically inflammed intestines, although it is also possible that the condition could have developed on its own or been the result of another disease. As advanced medical testing did not exst back then, we will never know.