Which organ in the human body is affected by Typhoid?

Typhoid fever (or enteric fever) is an illness caused by the bacterium Salmonella Typhi. Common worldwide, it is transmitted by ingestion of food or water contaminated with feces from an infected person.[1] The bacteria then multiply in the blood stream of the infected person and are absorbed into the digestive tract and eliminated with the waste.

Diagnosis is made by blood, bone marrow or stool cultures and with the Widal test (demonstration of salmonella antibodies against antigens O-somatic and H-flagellar). In epidemics and less wealthy countries, after excluding malaria, dysentery or pneumonia, a therapeutic trial with chloramphenicol is generally undertaken while awaiting the results of Widal test and blood cultures.

https://en.wikipedia.org/wiki/Typhoid

Typhoid is a multisystemic illness characterized by the classic prolonged fever, sustained bacteremia without endothelial or endocardial involvement, and bacterial invasion of and multiplication within the mononuclear phagocytic cells of the liver, spleen, lymph nodes, and Peyer patches.

http://www.emedicine.com/MED/topic2331.htm