Trans-species transmission of Brucellae among ruminants hampering
brucellosis control efforts in Egypt
Abstract
For the aim of genotypic fingerprinting of Brucella melitensis bv3
isolated from different ruminant species in Kafrelsheikh governorate,
Egypt, a multilocus variable-number tandem-repeat analysis (MLVA 16) has
been approached. The MLVA 16 was performed on 41 B. melitensis bv3
isolates identified by bacteriological and molecular techniques.
Thirty-one isolates originated from the preferential host (28 sheep and
three goats), and ten isolates from atypical hosts (nine cattle and one
buffalo). Recovering the same genotype in two different animal species
suggests cross-species adaptation of B. melitensis bv3 to different
atypical ruminant species in Egypt. Furthermore, the isolation of B.
melitensis from aborted cows after the entry of a replacement cow from
an unknown brucellosis status herd in cattle farms that had never reared
small ruminants indicates that cows can be infected and spread the
infection without the presence of the original host. Our results further
showed that different genotypes of B. melitensis could be isolated from
different samples of the same animal. The local geographic distribution
of genotypes showed a very close genetic relatedness with previously
reported genotypes outside the study area. Worldwide, all genotypes and
strains identified in this study were mostly related to the Western
Mediterranean lineage and were less likely to the Americas clonal
lineage. In conclusion, uncontrolled animal movement and the ability of
B. melitensis to spread among atypical hosts in the absence of the
original hosts are potential causes for the failure of brucellosis
control programs in endemic areas. The legal importation and illegal
movement of cattle and sheep are the main factors for maintaining the
infection of B. melitensis within the country. Further investigations
are required to understand the reasons for the presence of more than one
genotype of B. melitensis in the same animal and the efficacy of the
current applied strategy for brucellosis control.