Elsevier

Veterinary Microbiology

Volume 140, Issues 3–4, 27 January 2010, Pages 392-398
Veterinary Microbiology

Review
Brucellosis: A re-emerging zoonosis

https://doi.org/10.1016/j.vetmic.2009.06.021Get rights and content

Abstract

Brucellosis, especially caused by Brucella melitensis, remains one of the most common zoonotic diseases worldwide with more than 500,000 human cases reported annually. The bacterial pathogen is classified by the CDC as a category (B) pathogen that has potential for development as a bio-weapon. Brucella spp. are considered as the most common laboratory-acquired pathogens. The geographical distribution of brucellosis is constantly changing with new foci emerging or re-emerging. The disease occurs worldwide in both animals and humans, except in those countries where bovine brucellosis has been eradicated. The worldwide economic losses due to brucellosis are extensive not only in animal production but also in human health. Although a number of successful vaccines are being used for immunization of animals, no satisfactory vaccine against human brucellosis is available. When the incidence of brucellosis is controlled in the animal reservoirs, there is a corresponding and significant decline in the incidence in humans.

Section snippets

Introduction and historical perspective

Brucellosis is an ancient disease that can possibly be traced back to the 5th plague of Egypt around 1600 BC. Recent examination of the ancient Egyptian bones, dating to around 750 BC, showed evidence of sacroiliitis and other osteoarticular lesions, common complications of brucellosis (Pappas and Papadimitriou, 2007). David Bruce isolated Brucella melitensis (Micrococcus melitensis at that time) in 1887 from the spleen of a British soldier who died from a febrile illness (Malta fever) common

The etiologic agents

Brucella spp. are facultative intracellular gram-negative cocco-bacilli, non-spore-forming and non-capsulated. Although Brucella spp. are described as non-motile, they carry all the genes except the chemotactic system, necessary to assemble a functional flagellum (Fretin et al., 2005). They belong to the alpha-2 subdivision of the Proteobacteria, along with Ochrobactrum, Rhizobium, Rhodobacter, Agrobacterium, Bartonella, and Rickettsia (Yanagi and Yamasato, 1993). Nine Brucella species are

Global distribution and economic impact

The geographical distribution of brucellosis is constantly changing, with new foci emerging or re-emerging. The epidemiology of human brucellosis has drastically changed over the past few years because of various sanitary, socioeconomic, and political reasons, together with increased international travel. New foci of human brucellosis have emerged, particularly in central Asia, while the situation in certain countries of the Middle East is rapidly worsening (Pappas et al., 2006b). The disease

Zoonoses

Five out of the nine known Brucella species can infect humans and the most pathogenic and invasive species for human is B. melitensis, followed in descending order by B. suis, B. abortus and B. canis (Acha et al., 2003). The zoonotic nature of the marine brucellae (B. ceti) has been documented (Brew et al., 1999, McDonald et al., 2006, Sohn et al., 2003). B. melitensis, B. suis and B. abortus are listed as potential bio-weapons by the Centers for Disease Control and Prevention in the USA. This

Human brucellosis

One of the best descriptions of human brucellosis before discovery of antibiotics was “the disease rarely kills anybody, but it often makes a patient wish he were dead” (TIME magazine 1943). The incubation period of brucellosis normally is 1–3 weeks, but it can be several months before showing signs of infection. B. melitensis is associated with acute infection whereas the infections with other species are usually subacute and prolonged (Mantur et al., 2007). Most common symptoms of brucellosis

Animal brucellosis

In livestock species (cattle, sheep, goats, swine, and camel), the most frequent clinical sign following infection with Brucella is abortion (Acha et al., 2003). The principal strain that infects cattle is B. abortus, cattle can also become transiently infected by B. suis and more commonly by B. melitensis when they share pasture or facilities with infected pigs, goats and sheep. B. melitensis and B. suis can be transmitted by cow's milk and cause a serious public health threat (Acha et al.,

Diagnosis

Human brucellosis presents a great variety of clinical manifestations making it difficult to diagnose clinically. In some endemic areas every case of human fever of unknown origin is assumed to be due to brucellosis. Therefore, the diagnosis must be confirmed by laboratory tests. Accurate and fast diagnosis of human brucellosis is very important as delay or misdiagnosis usually results in treatment failures, relapses, chronic courses, focal complications, and a high case-fatality rate (Dahouk

Treatment

Due to intracellular localization of Brucella and its ability to adapt to the environmental conditions encountered in its replicative niche e.g. macrophage (Seleem et al., 2008), treatment failure and relapse rates are high and depend on the drug combination and patient compliance. The optimal treatment for brucellosis is a combination regimen using two antibiotics since monotherapies with single antibiotics have been associated with high relapse rates (Pappas et al., 2005, Pappas et al., 2006a

Vaccines

Beside the public health concern of such an important zoonosis, Brucella infections in animals have an important economic impact especially in developing countries as they cause abortion in the pregnant animals, reduce milk production and cause infertility. In regions with high prevalence of the disease, the only way of controlling and eradicating this zoonosis is by vaccination of all susceptible hosts and elimination of infected animals (Briones et al., 2001). The most commonly used vaccines

Perspective

It is somewhat paradoxical that brucellosis can be considered a re-emerging zoonosis affecting many animals and people throughout the world. The paradox lies in the fact that cost effective control measures for controlling brucellosis are known, yet there is either a lack of funds and/or political “know how” to implement the measures in many countries. Controlling animal brucellosis in developing countries requires a considerable effort to build infrastructure that educates people about the

References (64)

  • M.N. Seleem et al.

    Brucella: a pathogen without classic virulence genes

    Vet. Microbiol.

    (2008)
  • V. Taleski et al.

    An overview of the epidemiology and epizootology of brucellosis in selected countries of Central and Southeast Europe

    Vet. Microbiol.

    (2002)
  • J.M. Verger et al.

    Taxonomy of the genus Brucella

    Ann. Inst. Pasteur Microbiol.

    (1987)
  • J.C. Wallach et al.

    Human infection by Brucella melitensis: an outbreak attributed to contact with infected goats

    FEMS Immunol. Med. Microbiol.

    (1997)
  • M.M. Wanke

    Canine brucellosis

    Anim. Reprod. Sci.

    (2004)
  • M. Yanagi et al.

    Phylogenetic analysis of the family Rhizobiaceae and related bacteria by sequencing of 16S rRNA gene using PCR and DNA sequencer

    FEMS Microbiol. Lett.

    (1993)
  • N.P. Acha et al.
    (2003)
  • E. Alp et al.

    Doxycycline plus streptomycin versus ciprofloxacin plus rifampicin in spinal brucellosis [ISRCTN31053647]

    BMC Infect. Dis.

    (2006)
  • J. Ariza et al.

    Treatment of human brucellosis with doxycycline plus rifampin or doxycycline plus streptomycin. A randomized, double-blind study

    Ann. Intern. Med.

    (1992)
  • I. Arroyo Carrera et al.

    Probable transmission of brucellosis by breast milk

    J. Trop. Pediatr.

    (2006)
  • S.D. Brew et al.

    Human exposure to Brucella recovered from a sea mammal

    Vet. Rec.

    (1999)
  • G. Briones et al.

    Brucella abortus cyclic beta-1,2-glucan mutants have reduced virulence in mice and are defective in intracellular replication in HeLa cells

    Infect. Immun.

    (2001)
  • T.M. Buchanan et al.

    2-Mercaptoethanol Brucella agglutination test: usefulness for predicting recovery from brucellosis

    J. Clin. Microbiol.

    (1980)
  • P.S. Chain et al.

    Whole-genome analyses of speciation events in pathogenic Brucellae

    Infect. Immun.

    (2005)
  • W.E. Cook et al.

    Brucella abortus strain RB51 vaccination in elk. I. Efficacy of reduced dosage

    J. Wildl. Dis.

    (2002)
  • S.A. Dahouk et al.

    Changing epidemiology of human brucellosis, Germany, 1962–2005

    Emerg. Infect. Dis.

    (2007)
  • V.G. DelVecchio et al.

    The genome sequence of the facultative intracellular pathogen Brucella melitensis

    Proc. Natl. Acad. Sci. U S A

    (2002)
  • Y. Ersoy et al.

    Comparison of three different combination therapies in the treatment of human brucellosis

    Trop. Doct.

    (2005)
  • D.R. Ewalt et al.

    Brucella suis biovar 1 in naturally infected cattle: a bacteriological, serological, and histological study

    J. Vet. Diagn. Invest.

    (1997)
  • M.E. Falagas et al.

    Quinolones for treatment of human brucellosis: critical review of the evidence from microbiological and clinical studies

    Antimicrob. Agents Chemother.

    (2006)
  • G. Foster et al.

    Brucella ceti sp. nov. and Brucella pinnipedialis sp. nov. for Brucella strains with cetaceans and seals as their preferred hosts

    Int. J. Syst. Evol. Microbiol.

    (2007)
  • D. Fretin et al.

    The sheathed flagellum of Brucella melitensis is involved in persistence in a murine model of infection

    Cell Microbiol.

    (2005)

    • Cited by (0)

    View full text
    Copyright © 2009 Elsevier B.V. All rights reserved.