Diarrheal disease is the third leading cause of death in children 1–59 months of age. It is both preventable and treatable. Each year diarrhea kills around 440,000 children under 5 and an additional 50,000 children aged 5 to 9 years. Globally, there are nearly 1.7 billion cases of childhood diarrheal disease every year. Diarrhea is a leading cause of malnutrition in children under 5 years old. The two leading bacterial causes of diarrhea in the developing world are Shigella sp. (shigellosis) and enterotoxigenic Escherichia coli (ETEC). There are no licensed vaccines for these bacterial pathogen causes of diarrheal disease associated morbidity and mortality.
Most approaches to developing vaccines for diarrheal diseases have focused on parenteral (intramuscular, intradermal, subcutaneous) injection of subunit protein-based vaccines with adjuvants. There has been only modest success, and no licensed product. In contrast the only vaccine licensed in the US for prevention of cholera, another bacterial cause of diarrheal diseases, is an orally administered, live bacterial vaccine, Vivotif. Thus, another approach to developing vaccines against shigellosis and diarrheal disease is to use a live, oral vaccine, which can be taken in the form of capsule or as a liquid. This could be a weakened form of the bacteria, as in the cholera vaccine, or it could be another bacteria that is engineered to express antigens from Shigella sp. or ETEC.
Because of the enormous unmet medical need for vaccines to prevent shigellosis and diarrheal disease caused by ETEC, SIGHTM is focused on supporting development of vaccines for these diseases.