Weepers have discolored skin and subconjunctival hemorrhages, which causes blood to drip from their eyes in a tear-like fashion, hence their name. Weepers are very gaunt, have blood on their chests and faces, vomit black sludge, and often experience hair loss. Decreased immune functioning also leaves weepers susceptible to parasites, which burrow and hatch inside their bodies. The resulting insects will sting anyone who comes too close to the afflicted. Rats will not attack weepers, even when summoned by Corvo with Devouring Swarm, due to their advanced stage of infection.
It is believed by some that weepers are not actually hostile, and their "attacks" are really attempts to seek aid from uninfected humans. However, the Heart reveals that at least some weepers have chosen to spend their last moments infecting any uninfected they encounter.