Cases of diarrhoeal disease number from 1.7 to 5 billion per year worldwide. One 
of the main causes of diarrhoeal disease is typhoid fever, which is a 
potentially life-threatening multi-systemic illness. According to the most 
recent estimates, a total of 26.9 million typhoid fever episodes occurred in 
2010. The geographical distribution of the disease differs widely; in developed 
countries, the incidence rate per 100,000 per year varies from < 0.1 to 0.3, and 
the disease mainly affects people who travel to endemic areas located in low- 
and middle-income countries. Low- and middle-income countries are mainly 
affected owing to the lack of clean water and proper sanitation. In the fight 
against this plague, prevention is fundamental, and vaccination against typhoid 
is an effective measure. Vivotif® is an oral live attenuated vaccine which 
contains a mutated strain of Salmonella (Ty21a) and reproduces the natural 
infection. The vaccine was first licensed in Europe in 1983 and in the US in 
1989, and over the years it has proved efficacious and safe. It is indicated for 
adults and children from 5 years of age upwards. Specifically, in the most 
developed countries, vaccination is suggested for highrisk population groups and 
particularly for international travellers to destinations where the risk of 
contracting typhoid fever is high. It must also be borne in mind that 
international travel is increasing. Indeed, international tourist arrivals 
totalled 1,184 million in 2015 and, on the basis of current trends, 
international travel is expected to grow by 3-4% in 2017. Vivotif® appears to be 
a powerful means of disease prevention, the importance of which is highlighted 
by the spread of antibiotic-resistant strains of Salmonella typhy (S. typhi).