Essential role of vaccines in brucellosis control and eradication programs for livestock

Abstract

Brucellosis, in particular infections with Brucella abortus, Brucella melitensis or Brucella suis, remains a significant human health threat in many areas of the world. The persistence of pathogenic Brucella spp. in domestic livestock or free-ranging wildlife remains unresolved, despite decades of regulatory efforts worldwide. Although vaccination is probably the most economic control measure, administration of currently available vaccines alone is not sufficient for elimination of brucellosis in any host species. Complacency in brucellosis control programs usually results in failure, or at best, limited reductions in disease prevalence or incidence of human infections. New brucellosis vaccines with high efficacy and safety are needed that address the diversity in host species and can be more widely applied under field conditions. Development of safer and more efficacious vaccines alone, or combined with enhancements or increased emphasis on other regulatory program components, could have tremendous impact on reducing the worldwide prevalence of brucellosis and the associated zoonotic infections.

Immunization with Recombinant Brucella Species Outer Membrane Protein Omp16 or Omp19 in Adjuvant Induces Specific CD4 + and CD8 + T Cells as Well as Systemic and Oral Protection against Brucella abortus Infection

“…In fact, attenuated Brucella vaccines have many disadvantages (26,33). For these reasons, different strategies are being sought that provide safe, nonreplicating vaccines that are easy to reproduce for quality assurance (10,22).…”

Advancement of Knowledge ofBrucellaOver the Past 50 Years

“…91 A the present time, use of the killed 45/ 20 vaccine has ceased. Except for the introduction of B. abortus strain RB51 in the United States in 1996 91 and the implementation of the use of B. abortus strain 82 in the Russian Federation in 1974, 69 there has been a paucity of vaccines developed over the past 50 years that have progressed to significant use under field conditions in natural hosts. Similarly, a brucellosis vaccine with acceptable safety and efficacy in humans remains elusive.…”

Innocuousness of conjunctival vaccination with Brucella melitensis strain Rev.1 in pregnant Iranian fat-tailed ewes

“…1,2 Vaccination of the host animals with B. melitensis strain Rev.1 is used worldwide for disease control which has been proved to be the most effective vaccine. 3,4 It is recommended to immunize replacement animals from 3 to 6 months of age with standard doses of vaccine containing at least 10 9 live cells. 5 However, there is evidence that effective control of the disease in countries with high prevalence requires immunization of all susceptible young and adult animals in a mass vaccination campaign which is considered as the most practical measure.…”

“…[6][7][8] One problem with vaccination of adult animals is antibody responses induced by the vaccine which may last for a long time and cause sero-positivity of vaccinated animals in routine serological tests interfering with detection of infected ones. 4,9,10 This makes simultaneous implementation of vaccination and testand-slaughter impossible since vaccinated animals are falsely diagnosed as infected. 4 Moreover, vaccine-induced abortion and vaccine strain excretion in milk and vaginal discharges may occur.…”