Typhoid fever is an illness caused by the bacterium Salmonella Typhi (S. Typhi). It infects your small intestines (gut) and causes high fever, stomach pain, and other symptoms. Typhoid fever is also called enteric fever.

You’ll commonly hear paratyphoid fever mentioned along with typhoid. Paratyphoid fever is similar to typhoid with more mild symptoms. It’s caused by Salmonella Paratyphi (S. Paratyphi).

S. Typhi and S. Paratyphi are different than the Salmonella bacteria that cause salmonellosis, a common type of food poisoning.

Food and water with bacteria in it cause typhoid fever. Close contact with a person who is carrying the salmonella bacteria also can cause typhoid fever

Most people who have typhoid fever feel better about a week after they start treatment to kill bacteria, called antibiotics. But without treatment, there is a small chance of death from typhoid fever complications. Vaccines against typhoid fever can provide some protection. But they can’t protect against all cases of illness caused by other strains of salmonella. Vaccines can help lower the risk of getting typhoid fever.

Symptoms of Typhoid Fever

Symptoms are likely to start slowly, often showing up 1 to 3 weeks after exposure to the bacteria.

Early illness

Early symptoms include:

• Fever that starts low and increases throughout the day, possibly reaching as high as 104 degrees Fahrenheit (40 degrees Celsius).
• Chills.
• Headache.
• Weakness and fatigue.
• Muscle aches.
• Stomach pain.
• Diarrhea or constipation.
• Rash.

People also may have a cough, loss of appetite, and sweating.

Later illness

A few weeks after symptoms start, the illness can cause problems in the intestines. People may have:

• Stomach pain.
• Very swollen stomach.
• An infection caused by gut bacteria spreading throughout the body is called sepsis.

In very serious cases, people may:

• Become confused.
• Not be able to pay attention to anything around them.
• Not be able to react to the world around them.

These are life-threatening complications.

In some people, symptoms may return up to a few weeks after the fever has gone away.