[Characteristics of 273 strains of Brucella abortus of African origin].
273 Brucella strains from Africa have been examined for identification and typing in our laboratory, since 1976. Of these, 213 were isolated from Senegal, 30 from Togo, 12 from Morocco, 10 from Rwanda, 7 from Guinea Bissau and 1 from Niger. 272 strains were from cattle. Most of them (260) were from native animals that showed hygromas. 12 strains from Morocco were isolated from aborted calves of the "Pie Noire" dairy breed. One strain was from a human case of Brucellosis in Rwanda. All the strains were classified as members of B. abortus species by the recommended methods of the Subcommittee on Taxonomy of the genus. Of them, 269--including the human strain--were biotype 3/6. The others--2 from Morocco, 1 from Senegal and 1 from Rwanda--were biotype 1. Comment is needless about the 12 strains isolated from imported "Pie Noire" cattle. Their characteristics are identical with those of the B. abortus same biotypes isolated out of Africa. On the other hand, three unusual characteristics distinguish the 260 strains from native cattle and the human one from the main group of B. abortus: their growth characteristics, their mean oxidative profile and--for 219 of them--a negative oxidase test. The unusual behaviour of native B. abortus strains is discussed from an epidemiological and taxonomical point of view.