What is the name of the disease caused by drinking unpasteurized milk? Why does it make us sick?

Brucellosis. Different strains of the Brucella bacteria cause the illness related to consumption of unpasteurized milk. It has a wide range of illness ranging from asymptomatic to severe/fatal disease that can affect any organ system. In pregnant women, it can lead to miscarriage, preterm birth and even intrauterine infection with fetal death.