VIVO Infectious Diseases Bacterial Diseases of Man and Animals

Brucella species and Brucellosis: Introduction and Index

In 1886, Dr. David Bruce, a physician and microbiologist working for the British Army, along with his wife and collaborator Mary, described a disease they called Malta fever or undulant fever. That was the first recognition in the modern age of what we now call brucellosis; the genus Brucella was named in Bruce's honor. It should be acknowledged however that descriptions of what was very likely brucellosis date back to the writings of Aristotle, indicating that this infection has been causing problems in humans and animals for a very long time.

Brucellosis is one of the most, if not the most common zoonotic diseases in the world. Domestic animals, including cattle, sheep, goats, camels and swine, are the major reservoir hosts for those species of Brucella that cause human infections. The major clinical effect of infection in these animal hosts is in the reproducive system. Of great importance is that the organism causes abortions, stillbirths, and inferility. If a cow or a goat aborts due to brucellosis, the fetus and birthing fluids contain huge numbers of Brucella organisms. Also, the bacteria are excreted for long periods in the milk of infected livestock. Consequently, a large majority of human infections result from exposure to infected livestock or through consumption of contaminated milk or cheese.

Recent estimates are that there are more than 2 million new human cases of brucellosis worldwide each year, and that is likely a significant underestimate of the true burden of disease. In addition to natural infection, Brucellae are the most common bacteria responsible for laboratory-associated infections. The infectious dose of Brucella is very low, laboratory workers can readily be infected by aerosol, and in many clinical laboratories, brucellosis is not expected as a causative pathogen, leading to unsafe handing of patient samples or cultures. Brucellosis in humans is rarely lethal, but does often incapacite patients, and these bacteria are also considered a potential bioweapon.

Core concepts for Brucella and brucellosis are presented as the following topics:

Advanced and Supplemental Topics

Bacterial Diseases of Man and Animals Biology of Brucella and An Overview of Brucellosis

Last updated: February 2026. Send comments to Richard Bowen: rabowendvm@gmail.com