How was molly sick in private peaceful?

In Michael Morpurgo's novel "Private Peaceful," Molly, the protagonist Tommo's sister, dies from a rare and mysterious illness. The illness is never explicitly named, but it's described as something that makes her "thin and pale," and she suffers from "feverish fits" and "weakness."

The illness is portrayed as a symbol of the harshness of life during World War I, highlighting the vulnerability and fragility of life, especially in a time of war. It also serves as a poignant reminder of the human cost of conflict, as Molly's death deeply affects Tommo and leaves a gaping hole in his life.

The specific details of Molly's illness are left vague to allow the reader to interpret it through their own lens, making the loss even more powerful and resonating with the reader on a deeper emotional level.