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# Typhoid fever: Peyer patch ulcers and typhoid nodules

- Lesion

A Salmonella that only infects humans enters through the small bowel, spreads through the body, and ulcerates the lymphoid patches of the ileum.

Updated Nov 12, 2026

## Key points

- Terminal ileum: Peyer patches enlarge into sharply outlined plateau-like elevations; ulcers are oval and run along the long axis of the ileum and can perforate.
- Mesenteric lymph nodes enlarge; the spleen is large and soft with phagocyte hyperplasia.
- Typhoid nodules: small foci of liver necrosis replaced by macrophage aggregates; also in marrow and nodes.
- Clinical: fever after a brief gut phase, abdominal pain, rose spots on the trunk; blood cultures positive in the febrile phase.
- Gallbladder carriage, especially with gallstones, sustains transmission.
- Endemic in South Asia and parts of Latin America; linked to unsafe water and sanitation.

## What it is

Typhoid (enteric) fever is caused by Salmonella enterica serovars Typhi and Paratyphi. Unlike food-poisoning Salmonella, these organisms enter M cells of the ileum, are carried by macrophages to lymph nodes, spleen, liver and marrow, and produce a systemic illness with reactive hyperplasia of phagocytes and lymphoid tissue. Humans are the only reservoir, and the gallbladder can harbour a chronic carrier state.

## Structure

- Peyer patches: plateau-like swellings, then longitudinal oval ulcers.
- Lamina propria: macrophages containing bacteria, red cells and nuclear debris, with lymphocytes and plasma cells; neutrophils superficially.
- Liver: typhoid nodules (macrophage aggregates replacing necrotic hepatocytes).

## Step by step

- Acid-resistant S. Typhi is swallowed in contaminated food or water.
- It crosses the ileal epithelium through M cells over Peyer patches.
- Macrophages carry it to mesenteric nodes, then the bloodstream.
- It multiplies in liver, spleen, marrow and gallbladder: fever and bacteraemia.
- Re-entry into the gut from bile inflames Peyer patches: ulcers and possible perforation.

## Clinical notes

- Complications: intestinal bleeding and perforation, encephalopathy, myocarditis, cholecystitis, Salmonella osteomyelitis in sickle cell disease.
- Vaccines and antibiotics exist, but drug resistance is spreading.

## Memory aid

Typhoid ulcers run lengthwise, along the ileum; tuberculous ulcers run around it.

## Test yourself

Think of the answer, then tap the question to see it.

## How are typhoid ulcers of the ileum oriented?

Oval and along the long axis of the bowel, over Peyer patches.

## What is a typhoid nodule?

A small focus of hepatocyte necrosis replaced by an aggregate of macrophages, seen in liver, marrow and nodes.

## Where does the chronic carrier of S. Typhi usually harbour the organism?

In the gallbladder, often in association with gallstones.

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## Elsewhere in DurgiPedia

- [Mucosa-associated lymphoid tissue (tonsils, Peyer patches)](https://durgical.com/en/immunology/mucosa-associated-lymphoid-tissue/)

## Connections

## Related 4

- [Infectious enterocolitis](https://durgical.com/en/general-pathology/infectious-enterocolitis/)
- [Invasive bacterial enterocolitis](https://durgical.com/en/general-pathology/invasive-bacterial-enterocolitis/)
- [Cholecystitis: acute, acalculous and chronic](https://durgical.com/en/general-pathology/cholecystitis-acute-acalculous-and-chronic/)
- [Granulomatous inflammation: caseating vs non-caseating, the causes to know](https://durgical.com/en/general-pathology/granulomatous-inflammation-caseating-vs-non-caseating-the-causes-to-know/)

## Related conditions 3

- [Typhoid (enteric) fever](https://durgical.com/en/conditions/typhoid-fever/)
- [Peritonitis](https://durgical.com/en/conditions/peritonitis/)
- [Gallstones (cholelithiasis)](https://durgical.com/en/conditions/gallstones/)

## Microorganisms 1

- [Salmonella Typhi](https://durgical.com/en/microbiology/salmonella-typhi/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Typhoid](https://www.who.int/news-room/fact-sheets/detail/typhoid) (World Health Organization, 2023).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/general-pathology/typhoid-fever-peyer-patch-ulcers-and-typhoid-nodules/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/typhoid-fever-peyer-patch-ulcers-and-typhoid-nodules/