The National Brucellosis Eradication Program for livestock began in 1934 and the program's intent was to prevent transmission of the disease to people. Also, exposure to the drainage from fistulous withers in horses can cause brucellosis in humans. It is not normally transferred from an infected human to others. The disease is also transmitted from an infected host to humans by direct contact with mucus membranes such as the eye or the respiratory tract. The incubation period varies from five days to several months, the average being two weeks.
Brucellosis can be a long standing disease.
An infected individual may show symptoms for weeks, months, or years, especially if it has not been diagnosed early in the course of the illness. In many patients the symptoms of brucellosis are mild and therefore brucellosis diagnosis may not even be considered. A simple uncomplicated case initially resembles one of influenza with headache, fever, chills, profuse sweating, abdominal pain and joint pain. There is also accompanying pain in the back, arms and legs, and a feeling of extreme tiredness that begins slowly with weakness and exhaustion upon activity. Other frequent signs include weakness, malaise, headache, muscle or joint pains, backache, anorexia and loss of weight.