The mechanical damage of the worms and the stimulation of secretions and metabolites cause inflammation of the bile duct epithelium, narrowing of the duct lumen, as well as proliferation of fibrous tissue around the bile duct, which can cause atrophy of the nearby liver parenchyma and even cirrhosis in severe cases.
Untreated, loss of liver function causes death and, in children, long-term malnutrition, affecting growth and development.