The bacterium Salmonella typhi causes typhoid fever, a disease characterized by sustained fever, headaches, loss of appetite, abdominal pain, dry cough, fatigue and constipation. On occasion, diarrhea may follow constipation. The spleen may also become enlarged. Some infected people remain asymptomatic. If antibiotics are not administered to combat the infection, complications can occur around the third week. Five to 20 percent of patients suffer a relapse within 2 weeks. Globally, the mortality rate from typhoid fever is 2 to 3 percent. Death usually results from intestinal hemorrhage or perforation.
Salmonella typhi bacteria are transmitted through foods or beverages that have become contaminated after contact with the feces, urine, vomit, or sputum of a healthy carrier or of a patient with the active disease. There have been reports of transmission by oysters cultivated in contaminated water and flies transporting fecal matter on their feet. The risk of transmission is highest in the developing parts of the world such as India, Asia, Africa, and Latin America. The incubation period lasts 1 to 3 weeks, and rarely up to 8 weeks. Individuals can transmit the disease as early as 1 week after infection and until the end of their convalescence, sometimes up to 3 months after the appearance of the first symptoms. Some people will become lifelong chronic carriers.
Take the following measures to prevent typhoid fever:
- wash hands before handling food;
- wash hands before eating and after using the toilet;
- avoid potentially contaminated foods and beverages.
The risk of getting typhoid fever is relatively low; only about 3 out of 100,000 travellers acquire it each month.
There are two types of typhoid vaccines, one is administered as an injection while the other is administered orally. The efficacy of the vaccines is approximately 50%. Vaccines are recommended for most people 2 years and older traveling to countries where the risk of transmission is considered high. It may also be considered for those traveling to countries where there is a risk of transmission based on individual risk factors (e.g., children, close contact with the local population, travel to areas that are "off the beaten path" where sanitation is poor, extended stay). Re-immunization is recommended for those at repeated or continuous risk of exposure to typhoid fever every 3 or 7 years, depending on the type of vaccine.