The prevalence of brucellosis in cattle, sheep and goats in Maputo Province, Moçambique

Abstract

Brucellosis is a constraint to livestock production in Moçambique. Reproductive failure due to brucellosis has been reported in the country and abortions occur in cattle, sheep and goats on many of the farms in Maputo Province of Moçambique. Brucellosis is an infectious disease affecting mainly sexually mature animals and is caused by organisms of the genus Brucella. Brucella abortus is the species that mainly affects cattle throughout the world, while Brucella melitensis affects mainly goats and sheep. Control of bovine brucellosis using B. abortus S19 vaccine was undertaken before the civil war in Moçambique which started in 1978 and ended in 1992. During this period the vaccination status of animals was not known. The diagnosis of brucellosis is mainly based on serological surveys and conflicting results obtained previously emphasized the need for additional studies. The aims of this research were to determine the prevalence of brucellosis in cattle, goats and sheep due to B. abortus and B. melitensis in five districts of Maputo Province based on serology, and to assess the relationship between abortions and reproductive failure occurring in the study area by isolation of Brucella organisms or nucleic acid detection. A total of 971 adult beef and dairy cattle, 752 goats and 260 sheep from the study area were tested for Brucella antibodies using the Rose Bengal test (RBT), indirect ELISA and complement fixation test (CFT). Milk from 85 dairy cows and tissue samples from 32 cows and bulls from Gaza and Inhambane provinces slaughtered in Maputo municipal abattoir and Machava abattoir, and an aborted foetus were also examined. All serological test results for small stock were negative. An overall apparent prevalence of 14.0% (n=971) was found in beef and dairy cattle in the study area based on a 95% confidence interval. The highest prevalence was observed in Manhiça District (27.4% (n=180)) with a significant difference compared to other districts (p<0.05). The lowest prevalence was observed in Magude District (7.1% (n=241)). The prevalence in the remaining districts were 14.5% (n=138) in Matutuine, 8.7% (n=173) in Moamba and 14.6% (n=239) in Boane. Apparent prevalences of 15.5% (n=161) in small, 14.0% (n=578) in medium and 12.9% (n=232) in large livestock production sectors where found in the study area with no significant differences (p>0.05) between them. B. abortus was isolated from the spleen of an aborted foetus. A PCR amplification product of 600bp was generated from this isolate 584/05 and from the organs of five slaughtered cows using primers ISP1 and ISP2 for Brucella genus-specific sequences. The isolate 584/05 was confirmed as a B. abortus field strain when fragments of 498bp and 178bp were generated using a PCR assay for differentiation of B. abortus field strains and vaccine strains 19 and RB51. A correlation was made between the 584/05 isolate and serum from the cow that aborted. The results confirmed that the isolate was not a vaccine strain. The results from this study will supplement existing epidemiological data and aid brucellosis control programmes in Moçambique. Copyright