RESUMEN
We made vibriocidal antibody titration in the serum of some populations in Algeria and in Mali either during or between cholera epidemics. The seropositivity rate was 43.3% in healthy contacts in Alger in 1990 during an epidemic of cholera. For 12/16 healthy contacts examined two times in a 25-day interval, the seropositivity rate increased during the epidemic and the mean of antibody titres rose 8.88 folds. In Constantine, 53% of 195 blood donors had significant titres of vibriocidal antibodies in 1992, 6 years after an epidemic of cholera. The seropositivity rate in population seemed decreasing during this year. In Bamako, 46% of selected patients had significant vibriocidal antibody titres 8 years after the last epidemic of cholera in Mali. Seven of 10 children born after the epidemic had vibriocidal antibodies. These data confirm the persistence of vibriocidal antibodies in population during many years. The importance of the seropositivity rate in healthy contacts and in children born during a non epidemic period shows that asymptomatic infection is frequent and that Vibrio cholerae O:1 may be circulating in population between epidemics. As part of surveillance of cholera outbreaks in endemic areas, it might be of interest to study on a regular basis the vibriocidal antibody seropositivity rate in populations.