Brucella spp

From Cow
Autolysed aborted 6-month-old fetus as a result of Brucella spp infection

Brucella spp are a genus of facultative intracellular Gram-negative bacteria which parasitise the reproductive tract of cattle worldwide[1].

Species of Brucella which have been reported in cattle include:

  • B. abortus
  • B. suis (non-pathogenic)[2][3][4]
  • B. melitensis[5]

Transmission of the bacterium amongst cows occurs via grass contaminated with vaginal discharge as well as cows licking each other.

Venereal transmission by infected bulls is rare.

Clinical signs

Infection by Brucella spp causes infertility, retained placenta, abortion, pyometra, post-partum anoestrus and reduced milk yields.

Few clinical signs are apparent in infected bulls, although inflammatory changes to the seminal vesicles, ampullae, testicles, and epididymides may occur.

Diagnosis

Diagnosis is based on clinical signs of reproductive disorders accompanied by confirmation of isolated Brucella spp in aborted material via bacteriology or serology. ELISA[6] and PCR[7] testing of milk can be done for monitoring Brucella spp infections in the herd situation.

A differential diagnosis must include excluding other causes of infertility such as bovine viral diarrhoea, infectious bovine rhinotracheitis, Mycoplasma spp, Tritrichomonas spp and Neospora caninum[8].

Treatment

Medical treatment of individual animals may minimise infectivity.

Preventative vaccination remains the forestay of preventing this disease in cattle. Brucella abortus Strain 19 or RB51 increases resistance to infection[9][10].


References

  1. Baek BK et al (2012) The first detection of brucella canis in cattle in the Republic of Korea. Zoonoses Public Health 59(2):77-82
  2. Tae H et al (2012) Complete genome sequence of Brucella suis VBI22, isolated from bovine milk. J Bacteriol 194(4):910
  3. Cook DR & Noble JW (1984) Isolation of Brucella suis from cattle. Aust Vet J 61(8):263–264
  4. Norton JH & Thomas AD (1979) Brucella suis infection in pregnant cattle. Aust Vet J 55(11):525-527
  5. Wang F et al (2011) Deep-sequencing analysis of the mouse transcriptome response to infection with Brucella melitensis strains of differing virulence. PLoS One 6(12):e28485
  6. Tan W et al (2012) Recombinant VirB5 protein as a potential serological marker for the diagnosis of bovine brucellosis. Mol Cell Probes 26(3):127-131
  7. Fekete A et al (1990) Preliminary development of a diagnostic test for Brucella using polymerase chain reaction. J Appl Bacteriol 69(2):216–227
  8. Njiro SM et al (2011) A study of some infectious causes of reproductive disorders in cattle owned by resource-poor farmers in Gauteng Province, South Africa. J S Afr Vet Assoc 82(4):213-218
  9. Pajuaba AC et al (2012) Immunoproteomics of Brucella abortus reveals differential antibody profiles between S19-vaccinated and naturally infected cattle. Proteomics 12(6):820-831
  10. Singh R et al (2012) Safety and immunogenicity of Brucella abortus strain RB51 vaccine in cross bred cattle calves in India. Indian J Exp Biol 50(3):239-242