Value of phage typing of Vibrio cholerae biotype eltor in West Africa.

The epidemiological value of phage typing of El Tor vibrios in West Africa was assessed by testing 211 representative strains from all outbreaks of the cholera epidemic in Togo (1970-73) with the prophage typing method of Nicolle et al. and the lytic El Tor phages of Basu & Mukerjee. Prophage typing proved to be of limited epidemiological value in Togo since 203 of the 211 strains tested belonged to the same phage type-namely, type 2 of Nicolle et al., which corresponds to the Celebes type of Takeya. Six strains belonged to type 1, 1 strain to type 4, and 1 strain was untypable.Tested by the lytic El Tor phages, 175 strains were found to belong to type 4 of Basu & Mukerjee, 35 strains to type 1, and 1 strain was untypable. All but two strains of type 1 were isolated from 3 outbreaks in which this phage type was found almost exclusively. The results are in good agreement with epidemiological data collected during the epidemic. El Tor phage V reacted with a specificity of over 99% when tested against 601 strains of El Tor and NCV vibrios from Togo and may be recommended for the rapid identification of El Tor vibrios.