A review of the use of reduced dose vaccine of B.melitensis Rev1 strain in adult sheep

Brucellosis is one of the most widespread zoonoses in the world caused by several species of the genus Brucella. The only feasible alternative to control B. melitensis infection in small ruminants is whole-flock vaccination under an extensive management. The live Brucella melitensis Rev 1 strain is considered as the best vaccine available for prevention of animal brucellosis. The classically recommended exclusive vaccination of young replacement animals has failed to control brucellosis in some developed countries and is frequently inapplicable in the developing countries. The vaccination of pregnant animals with full standard doses of Rev 1 administered subcutaneously is followed by abortion in most vaccinated animals. Reducing the dose of vaccine has been suggested as a method of avoiding this problem and, accordingly, a reduced-dose vaccination strategy has been widely used and reported as a safe and effective method of controlling small ruminant brucellosis. Moreover, we reviewed field and experimental results supporting the reduction of abortion in pregnant animals and fewer reports of human brucellosis as results of this strategy. The aim of this study was to review the results obtained from the use of reduced doses of Rev.1 vaccine in adult animals to overcome the problem of abortion and control the disease.