The disease can cause poor functioning of the lungs, intestine, kidneys, or heart. The most serious complication of the disease is pulmonary fibrosis and typically causes death in patients 40 - 50 years old. The disorder is common in Puerto Rico, where many of the clinical research studies on the disease have been conducted. Neither the full extent of the disease nor the basic cause of the disease is known. There is no known treatment for HPS.