Multi-drug resistant strains of S typhi have been reported from Asia, the Middle East and Latin America. Typhoid can be carried without causing harm People who get typhoid carry the bacteria in their bloodstream and intestinal tract while they are ill. People can transmit the disease as long as the bacteria remain in their system. Most people are infectious just before and during the first week of convalescence. These people are called carriers.
Polluted water is the most common source.
This explains why typhoid is a worrying problem in disaster areas, where water supply and sewage disposal is disrupted and controls on food lost. But immunisation against typhoid is not a compulsory requirement for entry into any country. Neither is it routinely recommended for travel to industrialised countries. In recent years new typhoid vaccines have been introduced which are more effective and much less likely to cause side effects. You can choose between a four-dose oral vaccine and a single dose injection.