Le diagnostic bactériologique du choléra

Cholera is an acute intestinal infection that is strictly limited to humans. It can cause epidemics and cholera infection has reached pandemic proportions, representing a major international public health concern. The massive loss of diarrheal fluid rich in electrolytes, due to the activity of the cholera toxin, causes dehydration leading to major shock. If left untreated, cholera has a 25-50 % mortality rate. Treatment reduces the mortality rate to less than 1 %. Cholera is caused by two serogroups (O1 and O139) of a Gram-negative bacterium, Vibrio cholerae. Bacteriology laboratories are very important for the diagnosis of isolated cases - generally imported - or for the diagnosis of the first cases of an epidemic. Bacteriological diagnosis of cholera is reasonably easy, due to the abundance of Vibrio cholerae in stool. Epidemics, however, frequently occur in areas with either limited or no laboratory facilities, while rapid and accurate diagnosis of cholera is essential to mobilize the resources needed for treatment of patients and containment of the epidemic. A rapid diagnostic test, which would be very useful to countries lacking the necessary infrastructure, is currently being validated by the WHO. Its use, however, will not remove the need to isolate the cholera-inducing Vibrio strains, essential for studying characteristics of epidemiological interest. Continued monitoring of strains and information-sharing at the international level are part of an effective cholera surveillance system.