Poor sanitation and the consumption of food or water that is contaminated with virulent bacteria called Salmonella typhi are the most common causes of typhoid fever in developing nations, according to Mayo Clinic. In industrial nations, typhoid fever usually develops when a traveller acquires the bacteria and then spreads it through the fecal-oral route. Direct contact with someone who is infected with typhoid fever can also spread the disease.
The bacteria that causes typhoid fever, Salmonella typhi, spreads through fecal matter or urine, notes Mayo Clinic. If an infected person does not wash his hands after using the bathroom, the bacteria can spread to other people if they eat food that he prepared.
Although they may not show the signs and symptoms of typhoid fever, some people who recover from typhoid fever, called chronic carriers, may carry the bacteria for years in their gallbladders or intestinal tracts even after antibiotic treatment, states Mayo Clinic. Chronic carriers can still infect people through the bacteria in their feces if they are not cautious.
There are two different vaccines available for typhoid fever as of 2015, according to Mayo Clinic. Because they wear off eventually, repeat vaccinations are necessary, and they are not completely effective. When traveling in areas where typhoid fever is a risk, experts recommend avoiding untreated water, washing hands regularly and eating cooked foods instead of raw fruits or vegetables.