The cause is the bacterium Salmonella Typhi & Paratyphi A, also Known as Salmonella enterica serotype typhi (S. Typhi) and Paratyphi A, growing in the intestines and blood. The term Enteric Fever is used to describe both infections. Typhoid is spread by eating or drinking food or water contaminated with the feces of an infected person. Risk factors include poor sanitation and poor hygiene. Symptoms may vary from mild to severe and usually begin six to thirty days after exposure. Often there is gradual onset of a high fever over several days. Weakness, abdominal pain, constipation, and headaches also commonly occur. The test results are intended to help in the diagnosis of S. Typhi infection and, to monitor the effectiveness of therapeutic treatment.