Typhoid Fever

Symptoms and Causative Agent

Typhoid fever is a bacterial disease caused by Salmonella typhi. While rare in industrialized countries, typhoid fever is a significant threat in some low-income countries.

Symptoms of typhoid fever range from mild to serious, and usually develop one to three weeks after exposure to the bacteria. Symptoms include fever, headache, nausea, constipation or diarrhea, loss of appetite, and a rose-colored rash on the body.  

Typhoid fever symptoms are similar to other common gastrointestinal illnesses. The only way to know that a person is ill with typhoid is to test their blood or feces for Salmonella typhi.

Transmission

Typhoid fever spreads from person to person via contaminated food and water. Transmission is via the fecal-oral route, meaning that contaminated feces (and sometimes urine) may enter water supplies or food supplies, which may then be consumed by and infect others.  Salmonella typhi lives only in humans; there is no animal reservoir for the bacteria.

About 21 million cases of typhoid fever and 220,000 deaths occur annually worldwide.

Treatment and Care

Typhoid fever is more commonly found in densely populated areas where water supplies are vulnerable to contamination. Good water sanitation methods and proper storage and handling of food and water can help prevent spread of S. typhi.

Antibiotics are the only effective treatment for typhoid fever. Most patients improve after beginning antibiotic treatment, especially if the disease is detected early.

Complications

Typhoid fever may lead to intestinal bleeding and perforation. This in turn can cause severe abdominal pain, nausea, vomiting, and sepsis. Surgery may be needed to repair the intestinal damage.

Less common complications that can occur are inflammation of the heart muscle, inflammation of the lining of the heart and valves, pneumonia, inflammation of the pancreas, meningitis, kidney or bladder infections, and delirium.

Available Vaccines and Vaccination Campaigns

Two typhoid vaccines are licensed for use in the United States. These are typically reserved for people traveling to areas where typhoid fever is common, or for people who may come into direct contact with the disease.

Ty21a is a live, attenuated vaccine given in oral capsule form. Within the first two years of vaccination, the vaccine is moderately effective at preventing disease. Three years after initial vaccination, the vaccine offers no protection. The minimum age for this vaccine is six years.

Vi capsular polysaccharide (ViCPS) is an injected subunit vaccine. In clinical trials, it reduced disease rates by nearly 66%, though effectiveness wanes after several years. The minimum age for this vaccine is two years.

Typhoid conjugate vaccine (TCV), not available in the United States, was approved for use in India in 2013 and was pre-qualified by the World Health Organization (WHO) in 2017. This new vaccine may be given to infants six months of age and older. It offers protection for up to five years after immunization.

Sources

• Anwar, E., Goldberg, E., Fraser, A., Acosta, C.J., Paul, M., Leibovici, L. . The Cochrane Database of Systematic Reviews 1: CD001261. 2014. Accessed 01/25/2018.
• Centers for Disease Control and Prevention. National Center for Emerging and Zoonotic Diseases. . Accessed 01/25/2018.
• CDC. . Accessed 01/25/2018.
• The Mayo Clinic. . Accessed 01/25/2018.
• Szu, S.C. . Expert Review of Vaccines 12 (11): 1273–86. November 2013. Accessed 01/25/2018.
• World Health Organization. . Accessed 01/25/2018.
• World Health Organization. . Accessed 01/25/2018.
• World Health Organization. . March 2018. Accessed 4/2/2018.