Brucellosis is a disease that occurs all over the world. The Brucella bacterium can infect different animal species and it can be transmitted to humans (zoonosis). The main symptom in animals is abortion or premature birth and in that, the risk of infection for humans and animals is high. The Netherlands has been officially free of brucellosis since 1999. Wageningen Bioveterinary Research (WBVR) carries out research into this disease.

Brucellosis often goes unnoticed. As a result, the disease can spread in an animal population through the excretion of bacteria via milk. People can also become infected. This usually occurs through consumption of raw milk products from abroad. The disease cannot be transmitted from person to person.

Brucellosis is a notifiable disease in the Netherlands. Wageningen Bioveterinary Research is the national reference laboratory for Brucella in animals, advises the government on brucellosis. We conduct research regarding diagnostic test development and have various bacteriological, molecular and serologic testing methods at our disposal.

Brucellosis infection

Brucellosis is caused by a bacterium of the Brucella genus. Brucella abortus causes brucellosis in ruminants, primarily cattle, and is also called Bang's disease. B. melitensis and B. ovis cause brucellosis in sheep and goats, while B. suis and B. canis cause brucellosis in pigs and dogs respectively. B. microti and B. neotomae may occur in rodents, and B. ceti and B. pinnipedialis in sea mammals. So-called biovars are further distinguished within the species B. abortus, B. melitensis and B. suis.

A number of Brucella species are able to infect several animal species, because they are not 100% species-specific. Humans are susceptible to different Brucella species as well, although there are differences in pathogenicity (capacity to cause disease) between the species and even between the biovars within a Brucella species. B. melitensis is the most pathogenic for humans, whereas B. ovis is not.

Clinical signs brucellosis

The main symptom of brucellosis in female animals is abortion or premature birth. The placenta shows typical sources of infection, and if the placenta is not expelled in a timely way, an infection of the uterus occurs that may be fatal to the mother. There are usually few other symptoms, apart from abortion. Following infection, male animals may become infertile as a result of infection of the testicles.

Spread of brucellosis

In a number of countries, including the Netherlands, brucellosis has effectively been eradicated in the farm animal population, with the result that this population has officially been brucellosis-free in the Netherlands since 1999. Brucellosis is a notifiable disease in the Netherlands in both humans and domestic animals.

The main symptom is abortion or premature birth. In the event of abortion, large quantities of bacteria emerge with the offspring, the amniotic fluid and the placenta, resulting in a high risk of infection in humans and animals.

Apart from the secretion of bacteria via the placenta, bacteria are also secreted in the milk. Secretion in the milk may be of lengthy duration.

Brucellosis often progresses unnoticed, because there are usually few other symptoms, apart from abortion. As a result, the bacterium may be transmitted throughout a herd without being noticed.