Profile of Typhoid Fever Caused by Salmonella Typhi

Carriers of Typhoid Fever May Not be Sick

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Did you know? Typhoid Mary was an actual person in the early 1900s who was an asymptomatic (without symptoms) carrier of Salmonella typhi. During her career as a cook, she unknowingly infected 47 people with typhoid fever and was eventually quarantined after she refused to heed warnings from public health officials and stop cooking.

Typhoid is still a reality for many who live and work in areas where water and sanitation do not protect them from typhoid.

This can also be a disease that travelers pick up when they are abroad. It can spread from eating food or drinking water or other drinks that have typhoid bacteria in them. The risk of being infected can be reduced with a vaccine.

Species Name: Salmonella typhi is the most common species that causes Typhoid Fever. Other species, including Salmonella enteritidis or Salmonella typhimurium, can cause gastroenteritis (diarrhea) or typhoid-like diseases.

Type of Microbe: Gram-negative bacteria

How it spreads: Salmonella typhi can be shed from people with typhoid fever, as well as from carriers, who are individuals who have recovered from the disease but continue to carry and shed the bacteria in their feces. Infection occurs through ingestion of foods or drinks contaminated with Salmonella typhi, including water used for drinking or washing foods.

Who’s at risk? Typhoid fever is more common in unindustrialized countries, especially Asia, Africa, and Latin America.

About 400 cases occur each year in the United States, the majority of which are acquired during international travel. In developing countries, 21.5 million people are affected yearly. There is a vaccine that can reduce this risk.

Symptoms: It's important to seek help if you have a fever after travel.

This diseases can result in a high fever of 103 F to 104 F, abdominal pain, headache, fatigue, loss of appetite. The disease can take a while to develop. There can be diarrhea or constipation. There can be a rash. Some can have perforation of their bowel and need surgery. The symptoms often require a trained professional to recognized.

Diagnosis: The diagnosis is often made on the basis of antibodies in countries where Typhoid is common. This requires a doctor with experience to interpret. Blood or stool culture. Bone marrow aspirate is also a sensitive more invasive method used for diagnosis.

Prognosis: With antibiotic treatment, symptoms start to ease within 2 to 3 days, and the prognosis is generally good. Without treatment, fever may last for weeks to months, and the disease is fatal in up to 20% of afflicted individuals.

Treatment: You should talk to your doctor or nurse about treatment. This can be a very dangerous disease. It should be treated with any medical help that is available.

Antibiotics (Ceftriaxone trimethoprim-sulfamethoxazole, or ciprofloxacin) are usually prescribed. These antibiotics may not work though if there is resistance where the bug was picked up. It's important to talk to a medical professional. The selection of antibiotics depends on the pattern of antibiotic-resistance in the location where the infection was acquired. It can require IV antibiotics and treatment for 2 weeks (often with treatment by oral medications for much of the treatment).

Prevention: Two vaccines available in the United States for typhoid fever: an oral vaccine (Vivotif Berna) and an injected vaccine (Typhim Vi). If you are traveling to a developing country where typhoid fever may be a problem, see your healthcare provider for a vaccination at least 1 week before you travel. Even if you’ve been vaccinated in the past, a booster may be needed. In addition, practice safe eating habits while traveling. Drink only bottled or boiled water, eat only hot, thoroughly cooked foods, and only eat raw fruits and vegetables that have been both washed and peeled.

How it causes disease: Anywhere from one week to one month after Salmonella typhi is ingested, it invades the intestines, multiplies, and spreads into the bloodstream. The bacteria can then spread to the spleen and liver, where they multiply even more, re-entering the bloodstream, causing illness and spreading to the gall bladder and back to the intestine, where severe damage to the intestines occurs.

Symptoms of typhoid fever are believed to be caused by an immune response to massive amounts of lipopolysaccharide (LPS), which is a toxic component of the bacterial surface. The immune system releases proteins called cytokines which activate a strong inflammatory response against the bacteria. Once the bacteria enter the bloodstream, the immune response circulates to all tissues and organs throughout the body and can be fatal without antibiotic treatment.

Complications: In addition to risk of death or persistent infection, other potential consequences of Salmonella typhi infection include liver damage, toxemia (bacterial toxins in blood), myocarditis (inflammation of the myocardium in the heart), and intestinal lesions may occur.

Sources:

Salmonella spp. USFDA Bad Bug Book. Center for Food Safety and Nutrition.

Typhoid Fever. Centers for Disease Control and Prevention.

Salyers, AA and Whitt, DD. Bacterial Pathogenesis. A Molecular Approach. American Society for Microbiology. Washington, D.C. 1994. pp. 229-243.

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