Brucellosis re-emerging zoonotic disease - An update on potential new Brucella strains and reservoirs

Introduction Brucellosis is considered worldwide commonest re-emerging zoonotic disease with significantly changes of global ecological map identifying new strains, hosts and reservoirs. Disease have been eradicated successfully in most of developed countries but remains endemic in Mediterranean region, Middle East, Asia, and Central and South America. Aim To present recently identified new Brucella strains, hosts and reservoirs. Material and Methods Review of most recent published data of reported and confirmed potential new Brucella strains, hosts and reservoirs. Discussion Until recently the genus Brucella was considered to represent a genetically homogeneous and clonal group of bacteria associated with: 1. Terresterial mammalian hosts (Classical strains B. melitensis, B. abortus, B. suis, B. canis, B. ovis, B. neotomae), 2. Marine mammals (B. ceti and B. pinnipedialis), and 3. „Atypical”, more recently identified (B. microti, B. inopinata, B. papionis and B. vulpis). All species are genetically highly related to each other (> 99%). Infections occur among various warm-blooded animal species, marine mammals, and humans. Recently reported brucellae from amphibians (worldwide-distributed exotic frogs) are genetically highly diverse and might represent several new Brucella species or link between free living soil saprophytes and the pathogenic Brucella. Amphibian brucellae are capable of causing disease in different frog species ranging from localized manifestations to generalized infections. Frogs represent new and ecologically significant natural host and reservoir. Conclusions New brucella strains, hosts and reservoirs makes control of Brucellosis more complicated. Identification of new, amphibian, Brucella species and new hosts and reservoirs, have significant contribution to understanding of evolution of the genus Brucella from a soil-associated motile bacterium to a host-adapted pathogen. To date, there is no evidence that frog’s isolates represent a zoonotic threat, but precaution to avoid contacts with potentially infected amphibians until the zoonotic potential is better investigate and understood is useful advice. Key words: brucellosis, new brucella, reservoirs