The transmission of the bacteria to humans occurs through direct contact with the excrement of infected animals or through ingesting living bacteria via food, in particular unpasteurised milk products (butter, cheese).
There are sporadic incidences of food infections with B. melitensis in Austria, where the infection has taken place abroad (holidays in Mediterranean countries).
Up to 90 % of all infections are subclinical. They can only be recognised by detecting specific antibodies in the patient and are evidence of a successful immune defence. “Malta Fever” shows rather unspecific symptoms in its first stages, such tiredness, slight fever, headaches and muscular pains. Following a brief, symptom free period, influenza-like symptoms may occur together with a rise in body temperature to up to 40 °C in the evenings, often accompanied by massive sweats, low blood pressure and the swelling of the liver, spleen and lymph nodes. The infection may heal spontaneously without taking antibiotics, but could also become chronic with recurring bouts of fever without treatment.
In animals, the infection often leads to miscarriages and inflammatory changes, especially in the genital tract. In male sheep, brucellosis occurs as infectious epididymitis caused by Brucella ovis.
It is required by law to report any cases of brucellosis in cattle, pigs, sheep and goats. Combating methods focus on the identification, isolation and elimination of infected animals, as well as on the monitoring and controlling of animal transportation to prevent spreading. The disease-free status is monitored using serological examinations.
Austria is officially free from Brucella melitensis and Brucella abortus. This status must be confirmed by representative sample tests that are carried out annually. A total of 20,611 blood samples from sheep and goats from 1,528 farms were tested for B. melitensis antibodies in 2013. There were no positive Brucella melitensis samples.
Austrian cattle livestock were also officially free of bovine brucellosis in 2013 (10,367 blood samples and 1,266 milk samples).