Cholera and drinking water

Abstract

Cholera is caused by intestinal infection of Vibrio cholerae O1 or O139 through oral route by ingestion of contaminated food and water. Symptoms of cholera include acute watery diarrhea, vomiting, cramps and dehydration. If not treated in time, patient can die of dehydration and hypovolemic shock. Effective therapy is rehydration replacement of salts and electrolytes orally and/or intravenously. Once diarrhea has commenced antibiotic administration only help reduce the bacterial burden and duration of illness. Pathogenesis of cholera is characterized by entry of vibrios in small intestine, adherence to epithelial surface, colonization and release of enterotoxin followed by secretion of isotonic fluid. Mucinase, motility, adherence, multiplication, colonization and secretion of one or more types of toxin are among important factors contributing to disease process. Lipopolysaccharide and flagellar antigens, cholera lectins, haemagglutinins and major outer membrane proteins have been identified as mediating adherence and colonization. Immune response after infection is exclusively humoral. Antibodies to cholera antigens have been detected in sera of experimental cholera and convalescent patients. Antibacterial and antitoxin immunities are synergistic and contribute in protection. A vaccine providing durable immunity has remained elusive despite tremendous efforts. However, judicious application of knowledge of mucosal immunity, pathogenesis, antigen formulations and vaccine delivery will yield the right cholera vaccine.