This disease is only present if the individual is homozygous recessive for the mutant b chain allele. In the heterozygous form, the mutation provides protection against malaria. The disease typically affects individuals who have a weakened immune system, such as AIDS patients, malnourished children, and individuals whose immune system has been suppressed for organ transplantation. P. carinii attaches to the epithelial cells of lung alveoli, causing an inflammation. The combination of proliferating parasites, inflamed tissue, and secretions of plasma and red and white blood cells fills alveoli so that gas exchange is no longer occurring at a normal rate.
Many people also develop fevers and coughs.
The infection can spread throughout the lung, and, if untreated, is usually fatal. Achlorhydria Achlorhydria is a disease of the digestive system, and, more specifically, the stomach. It results from gastric atrophy, a condition where the mucous cells lining the stomach waste away. Gastric cells in the stomach's mucous membrane secrete hydrochloric acid and pepsinogen. Pepsin is involved in the initial digestion of all proteins and thus is a vital enzyme in this system.