Typhoid fever pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aysha Aslam, M.B.B.S[2]

Overview[edit | edit source]

The sequence of events in the pathogenesis of typhoid fever include inoculation, gastrointestinal infection, systemic involvement, and chronic carrier state.^{[1][2][3][4][5][6][7][8][9][10][11]}

Pathogenesis[edit | edit source]

The pathogenesis of typhoid fever consists of the following sequence of events.^{[1][2][3][4][5][6][7][8][9][10][11]}

Innoculation[edit | edit source]

• Orofecal transmission
• Infective dose: 1000 to 1 million organisms

Gastrointestinal Infection[edit | edit source]

Stomach

• Bacterium enters stomach
• Can survive a pH as low as 1.5

Small intestine

• Bacterium enters mucosa of the small intestine via M cells or direct penetration
• Adherence to the mucosal cells via special proteins
• Invade mucosal M cells overlying peyer's patches
• Internalisation in M cells of ileum
• Translocation to underlying lymphoid tissue and draining lymph nodes

Systemic spread[edit | edit source]

• Dissemination of S.typhi to reticuloendothelial system
• Spreads via lymph and blood
• Replication within reticuloendothelial system such as spleen, liver, bone marrow
• Evades immune system by hiding intracellularly within macrophages

Chronic carrier state[edit | edit source]

• Resides and multiplies in gall bladder
• Excretion in urine and stool may infect other individuals

References[edit | edit source]

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