Hogs are probably susceptible to a greater number of diseases than any other domestic animal. Respiratory and parasitic ailments are major problems, particularly with limited exercise and lack of sunlight. With an estimated 65% to 85% of U.S. herds exposed to swine pneumonia viruses, drugs are increasingly important to the hog industry. Some swine diseases are transmissible to humans. Among them are brucellosis, trichinosis, and cysticercosis. The last two are supposedly the basis of the first food sanitation codes.