Typhoid fever is caused by Salmonella enterica serotype Typhi bacteria. Typhoid fever is contracted by the ingestion of contaminated food or water. Diagnosis of typhoid fever is made when Salmonella bacteria are detected with stool, urine, or blood cultures.

Typhoid fever is caused by Salmonella bacteria.

Salmonella is a genus of gram-negative bacteria that can cause various diseases in humans and animals. The specific strain of Salmonella that causes typhoid fever is called Salmonella Typhi. It is transmitted through the ingestion of contaminated food or water, or through direct contact with an infected individual.

Here is a detailed explanation of how Salmonella bacteria causes typhoid fever:

1. Transmission:
- The primary mode of transmission is through the ingestion of food or water contaminated with the feces or urine of an infected person.
- Contaminated shellfish, fruits, vegetables, and dairy products are common sources of infection.
- Poor sanitation and hygiene practices contribute to the spread of the bacteria.

2. Entry and colonization:
- After ingestion, Salmonella Typhi bacteria pass through the stomach and reach the small intestine.
- The bacteria penetrate the intestinal lining and enter the bloodstream.
- From the bloodstream, they can spread to various organs, including the liver, spleen, gallbladder, and lymph nodes.

3. Symptoms:
- Typhoid fever typically presents with symptoms such as high fever, headache, weakness, abdominal pain, and loss of appetite.
- Patients may also experience gastrointestinal symptoms like diarrhea or constipation.
- Without treatment, the infection can lead to severe complications, such as intestinal bleeding, perforation, or the formation of abscesses.

4. Diagnosis:
- Diagnosis of typhoid fever is based on clinical symptoms and confirmed through laboratory tests, such as blood cultures or stool cultures.
- These tests help identify the presence of Salmonella Typhi bacteria or their genetic material.

5. Treatment:
- Antibiotics, such as fluoroquinolones or cephalosporins, are typically prescribed to treat typhoid fever.
- Adequate rest, hydration, and a nutritious diet are also important for recovery.

6. Prevention:
- Preventive measures include practicing good hygiene, such as regular handwashing with soap and water.
- Proper sanitation and safe food handling practices are crucial in preventing the spread of the bacteria.
- Vaccination is available to provide immunity against typhoid fever and is recommended for individuals at high risk of exposure.

In conclusion, typhoid fever is caused by the Salmonella Typhi bacteria, which is transmitted through contaminated food, water, or direct contact with an infected individual. Understanding the transmission, symptoms, diagnosis, treatment, and prevention of this disease is essential in controlling its spread and reducing its impact on public health.