The changing Brucella ecology: novel reservoirs, new threats

Brucellosis is a zoonosis that preceded humans but continues to cause significant medical, veterinary and socioeconomic problems, mainly because its overall burden remains underestimated and neglected. Its ecology, or what we know of it, has evolved rapidly in recent years. Two novel species, Brucella ceti and B. pinnipedialis, with the potential for causing human disease have been isolated from marine mammals. Another novel species, B. microti, has been isolated from wildlife animals, whilst B. inopinata has been isolated from a human case. An active spillover of Brucella between domestic animals and wildlife is also being recognised, with elk transmitting B. abortus to cattle, and freshwater fish becoming infected with B. melitensis from waste meat. In recent years the global epidemiology of the disease has not altered drastically, apart from increased awareness of brucellosis in sub-Saharan Africa and a rapid expansion of disease endemicity in the Balkan Peninsula. Isolated stories and events underline that Brucella knows no borders. The modern world has offered the pathogen the ability to travel and manifest itself anywhere and has also offered scientists the ability to track these manifestations better than ever before. This may allow the disease to be neglected no longer, or at least to be recognised as neglected.