Some turtle scientists have noticed that the disease often shows up where the ocean water is bad. Ocean water isn't naturally bad. People make it that way by not being careful. Many people are careless and let sewage go right into the ocean. They think the ocean is big and can hold a lot of sewage.
Many countries treat the ocean like a watery garbage dump.
Animal sewage also gets into the ocean. Sometimes rain washes manure into a stream that runs into the ocean. Sometimes it runs into ditches that lead to the ocean. Most farmers use chemicals to kill bugs and grow crops. When it rains, these chemicals can wash out of the plants and soil.