[Genetic, molecular, and immunologic aspects of Vibrio cholerae infection]

The deterioration of the economical and social conditions of the majority of the population in the Americas the last 20 years has generated several epidemics of enteric infections in the region, dramatically manifested by the current massive and widespread cholera outbreak. The absence of cholera from the continent for more than 100 years, the worsening environmental conditions, the biological peculiarities of Vibrio cholerae El Tor such as decreased virulence, which generates increased number of carriers, and its improved ability to thrive in the environment are probably responsible for the rapid dissemination of the disease through out the continent. Genetic and molecular studies of the biology of V cholerae have permitted identification of a variety of new virulence factors besides the enterotoxin, and are also helping to unravel the exquisite mechanisms that regulate the expression of these virulence factors in response to different stimuli. Molecular studies of V cholerae chromosomal and plasmid DNA, and of chromosomal and plasmid gene products, with techniques such as DNA hybridization and multilocus enzyme analysis are improving the characterization of V cholerae strains, resulting in progress in understanding their epidemiology in different communities. The non-invasive character of V cholerae infections, epidemiological and immunological studies suggest that the disease and current vaccines fail in providing an effective and long lasting immunity, and that the control of the disease in endemic areas by the use of vaccines may therefore be unfeasible. Similar studies indicate that the provision of safe drinking water, adequate sewage disposal, sufficient nutrition, and education remain the most effective measures for controlling the disease.