Typhoid Fever

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Typhoid Fever is a life-threatening illness caused by the Typhi serotype of the bacteria Salmonella, referred to as Salmonella Typhi.

Typhoid Fever is transmitted by eating food or drinking beverages improperly handled by an infected person with Salmonella Typhi or if contaminated water containing the bacteria is used to for washing food or drinking.

Unlike other Salmonella-related infections, where a range of animals can become infected and act as reservoirs for the bacteria, humans are the sole source of infection for Typhoid Fever. Of those infected, 10% of untreated cases can shed the bacteria in their feces or urine for up to 3 months and a smaller percentage can become asymptomatic carriers for a year or longer. Both ill and asymptomatic people can carry the bacteria in their blood or gastrointestinal tract and act as a source of infection to others by shedding the bacteria in their feces and sometimes in urine.

Contaminated drinking water is more common in countries without adequate sewage and sanitation treatment. Most cases of Typhoid Fever reported in the United States are travel-related.  Countries where travelers from the United States have been most at risk of acquiring Typhoid Fever include those throughout Asia, Latin America and Africa.

Common sources of infection in areas of the world at risk include:

  • Drinking water and beverages contaminated with human waste – untreated tap water ingested directly, used to make ice or roadside drinks, or swallowed during teeth brushing or showering
  • Raw fruits and vegetables – rinsed or washed with untreated water sources or handled by an infected food handler
  • Shellfish, such as oysters, clams, scallops and mussels – contamination can occur when harvest beds are exposed to human waste in untreated water runoff

Once Salmonella Typhi bacteria are ingested they multiply and spread from the intestines into the bloodstream. Symptoms onset generally develops 1-3 weeks after exposure, but may take as long as 2 months. Unlike salmonellosis, Typhoid Fever does not commonly cause gastrointestinal illness.

Common symptoms of infection can last 2-4 weeks and include:

  • Sustained continuous fever (which can persist for weeks or until treatment is initiated)
  • Weakness and fatigue
  • Stomach pains
  • Loss of appetite
  • Headache
  • Body aches
  • Some cases develop a rash of flat, rose-colored spots
  • Constipation or diarrhea

General recommendations for avoiding Typhoid Fever:

  • Avoid risky foods and beverages when traveling to high risk countries – ‘Boil it, Cook it, Peel it, or Forget it.’
    • Buy bottled water or boil water for at least 1 minute prior to drinking. Bottled carbonated water and beverages are safer than non carbonated water.
    • Unless ice is made from a bottled source, ask for drinks to not contain ice. Also avoid any locally made popsicles, flavored ices, gelatos or sorbets that may have been made with contaminated water.
    • Only eat foods that have been thoroughly cooked and are still visibly steaming hot.
    • Avoid raw fruits and vegetables – components of salads, such as lettuce and leafy greens are easily contaminated and difficult to wash well.
    • Fruits or vegetables that can be peeled prior to eating – wash hands prior to handling, peel them yourself and do not eat any of the peelings.
    • Avoid eating any raw or uncooked shellfish or seafood, especially oysters, clams, mussels, scallops and shrimp.
    • Avoid any food or beverages from street vendors or roadside stands – many ill travelers report eating food from street vendors. Keeping food clean on the street is difficult.
  • When overseas to an area of the world that is known to be at risk for Typhoid Fever, vaccination prior to travel date is a consideration. However, because the vaccine is not fully protective, avoiding risky food and beverage exposures will not only reduce the risk of acquiring Typhoid Fever, but other illnesses such as hepatitis A, cholera and other causes of gastrointestinal infection, including parasitic infections, traveler’s diarrhea and dysentery.


  • Discuss vaccination options with a doctor or at a travel clinic.
  • Vaccination will need to be completed at least 1-2 weeks prior to your travel date.
  • Typhoid Fever vaccination loses effectiveness over time – check with a doctor to identify whether a booster is required.
  • Do not take antibiotics as a preventative measure – antibiotics will not prevent Typhoid Fever.

Recent Texas Trends
Over the last ten years, 2010-2019, the average number of cases of typhoid fever reported in Texas has been 27 cases per year (ranging from 13 to 37). The majority of cases reported in Texas are acquired while traveling internationally.