In endemic areas, control of brucellosis is the first challenge. The only way to control human brucellosis is to control the animal disease and stop passage to man. Brucellosis has been controlled or even eradicated in a small number of wealthy countries, by long and costly programs of animal vaccination followed culling of infected animals at later stages. Food hygiene, especially pasteurization of milk is of great importance to prevent human infections. Excellent reviews by JM Blasco [1, 2] discus this in detail.
Control of a disease such as brucellosis requires a ‘One Health’ approach. Animal and human health must work together with the livestock holders and programs established inform and educate the population at risk. Strong implication of political decision makers is essential. If not yet established, surveillance of human and animal populations should be implemented.
Vaccination programs need good vaccines. Two live vaccines, B. melitensis Rev. 1 and B. abortus S19 have been used over past decades with great success for, respectively, small ruminant and bovine brucellosis control programs throughout the world. B. abortus RB51 is also proposed as a vaccine for bovine brucellosis to be used in the final stages of control programs in conjunction with test and slaughter. None of the available vaccines are perfect; they cause abortion in target and non-target animals, can be shed by immunized animals and all can cause brucellosis in humans. RB51 is also resistant to rifampicin, one of the drugs of choice to treat human brucellosis. We need new effective vaccines that are safe for both animals and humans. There are many projects aiming to improve the efficiency and safety of existing vaccines and to develop new vaccines. There is currently an international call for development of a new brucellosis vaccine with a substantial prize for the first new vaccine licensed (https://brucellosisvaccine.org/). Here, the focus is on a vaccine that will be beneficial in endemic regions. In past years, work has been strongly oriented to vaccines, and diagnostic tools to solve problems in countries with low levels of incidence (generally rich countries in the later stages of control programs). This has led to the DIVA concept (distinguishing between infected and vaccinated animals). While not relevant in a country with high prevalence and no infrastructure to test animals , DIVA compliance would make a vaccine more attractive in rich countries and therefore more commercially viable for the manufacturer. The general methods to create a DIVA vaccine have been to remove an immunogenic antigen from the vaccine (such as the loss of O-antigen in RB51). This may reduce efficiency of the vaccine (hence the attempts to restore O-antigen production to RB51 ) and mean that accidental human infections are not detected . A more efficient method could be to express an unrelated immunogenic protein in the vaccine strain that would induce a detectable serological response not seen in infected animals. This approach has used for viral vaccines for some time  and has recently been used with S19 by the Moreno group in Costa Rica .