Vaccine development for the control of cholera and related toxin-induced diarrhoeal diseases

The toxin-induced diarrhoeal diseases in greatest need of effective vaccines for use in control programmes are cholera and diarrhoea due to enterotoxigenic Escherichia coli. Such vaccines, whether consisting of inactivated immunogens or live attenuated organisms, should be administered by the oral route to stimulate the gut mucosal immune system to a maximal extent. For optimal efficacy they should probably contain or produce immunogens evoking both antibacterial and antitoxic immunity that can interfere in a synergistically cooperative manner with colonization as well as toxin action (binding) events in the pathogenesis. The actual or predicted advantages and limitations of oral vaccines based on protective antigen cocktails and different approaches to live, attenuated organisms are discussed. A conclusion is that effective vaccines could play an important role in the control of diarrhoeal disease by reducing mortality and morbidity, and ideally also the transmission of disease.