Re-emergence of Brucellosis in Cattle in France and Risk for Human Health

Researchers report on the investigation into a single case of human brucellosis diagnosed in France in January 2012. The source of infection was identified as unpasteurised cheese from a neighbouring farm but the source of the bacteria is still under investigation.
calendar icon 28 August 2012
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In a paper published in Eurosurveillance, A. Mailles of the French Institute for Public Health Surveillance and a number of co-authors from other agencies report that a case of human brucellosis was diagnosed in France in January 2012.

The investigation demonstrated that the case had been contaminated by raw milk cheese from a neighbouring dairy farm.

As France has been officially free of bovine brucellosis since 2005, veterinary investigations are being conducted to determine the origin of the infection and avoid its spread among other herds.

A number of hypotheses about the source of this infection are discussed, including contact with an infected cattle or small ruminant or contamination of cattle by wildlife.

The authors report that veterinary investigations are still ongoing to determine the origin of the contamination of the herd, to investigate the possible spread of the infection to other herds and to take control measures to avoid the infection of new herds and consequently the occurrence of additional human cases.

However, the absence of infected animals in the herds that are epidemiologically linked with the infected herd, and the absence of other autochthonous human cases argue in favour of a single outbreak and a limited episode, according to Mailles and co-authors. The index animal on the farm was born from a dam that itself was born in 1999 before the last outbreak in the area and died in 2006. The lifetime of the mother of the index infected animal is therefore consistent with the hypothesis of a congenital case of bovine brucellosis.

The researchers add that surveillance of human brucellosis in non-endemic countries is complicated by the lack of specificity of serological tests. In their experience, all available tests still may cross-react with other bacteria (mainly but not only with Yersinia enterocolitica), and can also give false positive results in patients presenting with immune disorders. In countries with low prevalence and incidence of the disease, this low specificity contributes to the low positive predictive value of serology, which can have important implications, both for patient therapy and for the dairy animals involved (culling).

Reference

Mailles A., Rautureau S., Le Horgne J.M., Poignet-Leroux B., d’Arnoux C., Dennetière G., Faure M., Lavigne J.P., Bru J.P. and Garin-Bastuji B. 2012. Re-emergence of brucellosis in cattle in France and risk for human health. Euro Surveill. 17(30):pii=20227.

Further Reading

You can view the full report by clicking here.

Further Reading

Find out more information on brucellosis by clicking here.


August 2012
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