Diagnosis of the pathogens in the intestine has been limited by the inability of gastroenterologists to distinguish normal intestinal bacteria from pathogenic bacteria, and the failure of medical providers to examine material flushed from the intestine before an endoscopic examination. Pathogens in the intestine can migrate or metastasize in the body to cause chronic disease, and even normal intestinal bacteria can cause chronic disease when the bacteria migrates or metastasizes to distant or aberrant locations.