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Reporting Obligations

Confirmed and suspected cases shall be reported immediately to the local Health Unit.


Aetiologic Agent

Brucellosis is caused by the bacterium Brucella. Brucella species are small, nonmotile, gram-negative coccobacilli. The species that infect humans include B. suis, B. abortus, B. melitensis, and rarely B. canis.

Brucellosis is a potential bioterrorism agent.

Clinical Presentation

Acute or insidious onset of symptoms, such as intermittent fever, headache, weakness, profuse sweating, chills, arthralgia, depression, weight loss, and generalized aching. Localized infections of organs, including the liver and spleen, may be present. Physical findings include lymphadenopathy, hepatosplenomegaly and occasionally arthritis. Serious complications include meningitis, endocarditis and osteomyelitis. Disease may last days, months, or occasionally a year or more if not adequately treated.

Modes of Transmission

Transmission occurs as a result of direct contact of breaks in the skin and mucous membrane with infected animal tissue, body fluids (blood, urine, vaginal discharges), aborted fetuses and especially placentas, as well as through ingestion of undercooked meat, raw milk and unpasteurized dairy products from infected animals. Airborne inhalation in laboratories and abattoirs has also been reported.

Incubation Period

The incubation period is variable and difficult to ascertain; commonly 1–2 months, with a range of 5 days to 5 months.

Period of Communicability

Person-to-person transmission is rare, but sexual transmission and in utero transmission have been reported. Breastfeeding women may transmit infections to their infants.

Risk Factors/Susceptibility

The severity and duration of the illness varies widely and the duration of acquired immunity following infection is uncertain.

Diagnosis and Laboratory Testing

Any of the following will constitute a confirmed case of Brucellosis with clinically compatible signs and symptoms:

  • Isolation of Brucella spp. from an appropriate clinical specimen (e.g., blood, tissue) OR
  • A significant (i.e., fourfold or greater) rise in Brucella agglutination titre between acute and convalescent serum specimens obtained 2 or more weeks apart OR
  • Detection of Brucella spp. deoxyribonucleic acid (DNA) from an appropriate clinical specimen
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Treatment and Case Management

Treatment is under the direction of the attending physician and depends on clinical symptoms and age of the case; antibiotics are usually prescribed for six weeks to prevent recurring infection. For hospitalized cases, routine practices are recommended and contact precautions are indicated for people with draining wounds and or lesions.

Public Health staff will be involved to investigate cases of brucellosis to determine the source of infection.

Patient Information

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Additional Resources

Heymann, D.L. Control of Communicable Disease Manual (Twentieth Edition). Washington, American Public Health Association, 2015.


Ministry of Health and Long-Term Care, Infectious Diseases Protocol, 2022.