Typhoid and Paratyphoid Fever: What They Are and Who Is at Risk

The main points

• Typhoid fever and paratyphoid fever are life-threatening illnesses, each caused by a kind of Salmonella bacteria.
• Most people in the United States who get them were infected while traveling abroad.
• Check whether you need a typhoid vaccine before you travel, at cdc.gov/travel.

Symptoms and causes

The two illnesses have similar symptoms, including fever. Anyone with symptoms should get medical help right away.

• Typhoid fever is caused by Salmonella serotype Typhi.
• Paratyphoid fever is caused by Salmonella serotype Paratyphi.

How common they are

They are most common where food and water may be unsafe and sanitation is poor, including parts of Asia (especially Pakistan, India and Bangladesh), Africa and Latin America.

Who is at risk

The chance of catching either in the United States is very low. It rises for people who:

• travel to countries in Africa, Asia or Latin America where they are common;
• visit rural areas there;
• visit family and friends there;
• are not vaccinated against typhoid.

Almost everyone in the United States with these diseases has traveled abroad — most often to South Asia.

How they spread

The bacteria leave the body in feces, shed both by people who are sick and by people who have recovered but still carry the bacteria. You get infected by swallowing them, for example in:

• food, drinks or water contaminated by sewage;
• food rinsed in contaminated water and then eaten;
• food handled by someone who didn't wash their hands after using the bathroom or changing a diaper.

You can take steps to protect yourself: see CDC's Preventing Typhoid Fever and Paratyphoid Fever.

Sources

Based on "About Typhoid Fever and Paratyphoid Fever," Centers for Disease Control and Prevention; a work of the United States government in the public domain. The source's stock photograph is not reproduced.