18 - Oral Vaccines against Cholera and Enterotoxigenic Escherichia coli Diarrhea

Abstract

This chapter describes the development and testing of oral-inactivated vaccines against cholera and enterotoxigenic Escherichia coli (ETEC) diarrhea, respectively. The development of these vaccines has been based on new insights into the mechanisms of disease and immunity in enterotoxin-induced diarrheas achieved during the last decades. ETEC together with rotavirus is the most common cause of diarrhea in children in most of the developing countries. The chapter discusees in detail the mechanisms of the disease and immunity including antitoxic immunity, colonization factors, and antibacterial immunity, The disease caused by the enterotoxin-producing bacteria is characterized by watery stools without blood and mucus. ETEC disease varies from mild diarrhea to a severe cholera-like disease and is often accompanied by nausea, vomiting, abdominal cramps, anorexia, and fever. Most cases are relatively mild, in other cases the diarrhea result in moderate to severe dehydration that is sometimes fatal. A live oral cholera vaccine, CVD 103 - HgR, has also been developed and found to be safe and immunogenic and is able to give significant protection against challenge with Vibriocholerae O1 in human volunteers. During the last decade there has been rapid progress in the development of new, much improved vaccines against cholera. The most extensively tested of these new vaccines, the oral B-WC cholera vaccine, has proved to be completely safe. It's an excellent immunogen with high-level short-term protective efficacy, and providesgood long-term protection against cholera.