Typhoid: The Disease & Vaccines
Have you ever heard the term “Typhoid Mary?” Today, this phrase is sometimes used to describe a person who infected many others. But in the early 1900s, it referred to a specific person — Mary Mallon.
Mary was born in Ireland. When she came to the U.S., she was hired as a cook for wealthy families around New York City. When typhoid outbreaks occurred among people who visited homes where she was the cook, the source of their infections was traced back to her even though she was not ill. This tells us two things about typhoid. First, people can spread the disease even when they are not having symptoms. Second, people can be infected by consuming contaminated food. In Mary’s case, because she was preparing food — some of which was served without cooking — she could spread the bacteria to household members and their guests. Although Mary was quarantined at different times and instructed not to take additional jobs as a cook, she continued to work as a cook when she was not in quarantine. As a result, it’s estimated that Mary infected at least 122 people — five of whom died.
Typhoid remains an issue around the world today. Each year, about 9 million people are infected, and more than 100,000 die from this infectious disease.
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The disease
What is typhoid?
Typhoid is caused by a bacterium called Salmonella typhi. The bacteria attack the intestines and cause symptoms, such as:
- Fever that increases slightly over a period of about a week before decreasing in a similar incremental fashion
- Stomach pain, lack of appetite
- Feeling out of sorts, called malaise
- Muscle aches
- Rash in about 1 in 5 people; occurs most often on the chest, abdomen and back
Severe cases can result in shock, confusion, coma or even death. In some cases, lesions in the intestine can rupture causing internal bleeding, called hemorrhaging.
Before antibiotic treatments were available about 1or 2 of every 10 people with typhoid died from their infection.
How does typhoid spread?
The bacteria that cause typhoid only infect people. The disease is spread by bacteria present in the feces of infected people. Most often, spread occurs from contaminated food and water, especially in countries where sanitation standards are low or compromised.
While the bacteria can spread from person to person, such as demonstrated by Mary Mallon, this type of spread is less common than spread from contaminated water sources. In the U.S. rates of disease decreased rapidly once widespread water treatment procedures were instituted.
People can avoid this infection during travel by drinking only bottled water, and avoiding ice, unpeeled fruits, undercooked meats, shellfish, salads and food from street vendors.
Where can you catch typhoid?
Typhoid infections are common in developing regions of Africa, East and South Asia, Eastern Mediterranean and the Western Pacific.
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The vaccine
What is the typhoid vaccine?
The typhoid vaccine comes in two forms:
- "Ty21a" is a live, weakened form of the bacteria. This vaccine is given by mouth to people 6 years of age and older. A total of four capsules is taken one every other day. People should take the capsules with a cold or lukewarm beverage one hour before eating. The vaccine should be given at least one week before travel. People with immune-compromising conditions should not get this vaccine because it is a live, weakened vaccine.
- The "polysaccharide" vaccine is made from the sugar that coats the surface of the bacteria. This vaccine is given as a single shot to people 2 years of age and older. The vaccine should be received at least two weeks before travel.
The vaccines protect about 50 to 80 of every 100 people, so even those who are vaccinated should the heed the warning, "boil it, peel it or forget it."
Who should get the typhoid vaccine?
The typhoid vaccine is not required for international travel, and most travelers are not recommended to be vaccinated prior to travel.
People recommended for vaccination are those who will be:
- Traveling in a high-risk area for more than six weeks
- Staying in rural areas or small towns
- Eating uncooked foods or unpeeled fruits or drinking unbottled water
Who shouldn't get the typhoid vaccine?
The typhoid vaccine should not be given to anyone less than 2 years of age. People with immune-compromising conditions should not use the live, weakened version (Ty21a).
Does the typhoid vaccine have side effects?
Both typhoid vaccines can cause headache and fever. Neither causes serious side effects.
Other questions you might have
Are typhoid and typhus the same?
No. Their names are similar because they were originally thought to be the same disease, but they are not. Both typhoid and typhus are caused by bacteria, and both cause similar symptoms, like fever, muscle aches and headache. But they are caused by different bacteria, and they are spread in different ways. Typhoid is caused by Salmonella typhi, and it is spread through food and water contaminated with feces. Typhus is caused by Rickettsia and Orientia types of bacteria that are spread through fleas, mites, chiggers and lice. Of note, Anne Frank died of typhus in a German concentration camp.
Relative risks and benefits
Do the benefits of the typhoid vaccine outweigh the risks?
The risk for typhoid is similar to that of cholera. The disease can be avoided by paying attention to the foods that you eat and the water that you drink during travel to affected regions. Although the disease is highly prevalent, and occasionally deadly, in some areas, it can be prevented by avoiding non-bottled water, ice, uncooked meats, salads, unpeeled fruits, shellfish and foods from street vendors. For this reason, the typhoid vaccine is not necessary for most people.
Some people are recommended for vaccination prior to travel if they will be staying for more than six weeks in small towns, rural areas or other places without standard tourist accommodations and substandard sanitation. Likewise, if they may eat foods or drink water likely to be contaminated with the bacteria that cause typhoid, they should be vaccinated. For those in these situations, the benefits of the vaccine outweigh the risks.
Disease risks
- Fever, stomach pain and rash
- Disease can cause shock and death
Vaccine risks
- Headache and fever in some people
Reference
Orenstein WA, Offit PA, Edwards KM and Plotkin SA. Typhoid Fever Vaccines in Plotkin’s Vaccines, 8th Edition. 2024, 1177-1214.
Reviewed by Paul A. Offit, MD, on April 22, 2026