Contagious: Brucellosis

Contagion summary: Usually caught from contaminated animals or milk.

Contagion summary: Direct person-to-person spread of brucellosis is extremely rare. Mothers who are breast-feeding may transmit the infection to their infants. Sexual transmission has also been reported. For both sexual and breast-feeding transmission, if the infant or person at risk is treated for brucellosis, their risk of becoming infected will probably be eliminated within 3 days. Although uncommon, transmission may also occur via contaminated tissue transplantation.¹

Contagion discussion: Humans are generally infected in one of three ways: eating or drinking something that is contaminated with Brucella, breathing in the organism (inhalation), or having the bacteria enter the body through skin wounds. The most common way to be infected is by eating or drinking contaminated milk products. When sheep, goats, cows, or camels are infected, their milk is contaminated with the bacteria. If the milk is not pasteurized, these bacteria can be transmitted to persons who drink the milk or eat cheeses made it. Inhalation of Brucella organisms is not a common route of infection, but it can be a significant hazard for people in certain occupations, such as those working in laboratories where the organism is cultured. Inhalation is often responsible for a significant percentage of cases in abattoir employees. Contamination of skin wounds may be a problem for persons working in slaughterhouses or meat packing plants or for veterinarians. Hunters may be infected through skin wounds or by accidentally ingesting the bacteria after cleaning deer, elk, moose, or wild pigs that they have killed. ¹

Zoonotic. Commonly transmitted through abrasions of the skin from handling infected mammals. In the United States, occurs more frequently by ingesting contaminated milk and dairy products. Highly infectious in the laboratory via aerosolization; cultures are considered to warrant biosafety level-3 precautions.²

Human brucellosis can shift from an occupational disease to a foodborne disease, most frequently affecting person who consume raw milk and cheeses made with raw milk ³

Footnotes:
1. excerpt from Brucellosis General: DBMD
2. excerpt from Brucellosis: DBMD
3. excerpt from Facts About Brucellosis: CDC-OC

Last revision: April 9, 2003

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