Typhoid fever or enteric fever is caused by serious bacterial infection by the bacterium Salmonella enterica serotype Typhi. Typhoid fever is transmitted in humans through contaminated food or water, when a person drinks or eats any contaminated food which is having bacteria, they are infected by typhoid fever.
Areas that have poor sanitation and poor hygiene practices have high chance to develop the Salmonella enterica serotype Typhi bacteria. People infected with typhoid fever can easily spread bacteria around them and can affect other humans. This typically happens when an infected person uses public places such as bathrooms, restaurants, railway stations, etc.