Atlas of foodborne infections
transmitted by contaminated food and water

Atlas of Patogens Contents Information sources Glossary Administration

Brucella

CZ: brucela
EN: brucella

Occurrence:
Milk and Milk Products
Soft Cheeses
Hard Cheeses


Category:
Bacteria


Foodborne Disease:
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brucellosis - acute undulating fever, headache, night sweats, fatigue and anorexia

Brucellosis in humans is known as Undulant fever and symptoms include recurring fever, headache, muscle aches, constipation, secondary anemia, nervous system signs, sweating and orchitis. The disease may last for three months and mortality is low.


Description:
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The principal route of infection for humans is via ingestion of infected milk products. Other routes of infection are contact with contaminated secretions and the excretement of infected animals (from respiratory tract, genital tract, conjunctiva, and skin). Contaminated secretions include blood, urine, feces, and milk of infected animals. Animals that have aborted will shed large amounts of bacteria and contaminate their environment.

Brucellosis is a disease that can cause an economic loss of up to 20% to a country’s beef industry.  A brucella-positive status severely limits a country’s ability to export its beef related products to other countries.

Although transmission of B. abortus via natural breeding does not occur very often, artificial insemination with contaminated semen can transmit the infection. Embryo transfer poses a potential risk if the embryoes are stored in bovine serum albumin that is harboring B. abortus.

The Brucella abortus organism can be isolated from fetal lymph nodes, placenta, milk, vaginal mucus, uterine exudate or semen. A nucleic acid probe assay is being developed for easier identification of Brucella abortus.

Brucella is extremely dangerous, especially if utilized as a biological agent, as there is currently no human vaccine.  The areas listed as "High Risk" for the contraction of naturally-occurring brucella are those countries in the Mediterranean locale, Eastern Europe, South America, the Middle East, Africa and the Caribbean.

 The most common way to be infected with brucella is through the ingestion of contaminated milk products.  Thus, a particular risk to tourists are "village cheeses" - or unpasteurized cheeses - from the high-risk locations mentioned above.  In addition to ingestion, brucella can also be contracted thorough inhalation or skin wounds.  Although rare, documented cases of person-to-person transmission have been reported. 

Serological tests detect antibodies present in serum, milk, whey, vaginal mucus and seminal plasma.  The serological diagnosis is considered unreliable when performed during the period of 2 to 3 weeks before and after abortion or calving (e.g. ELISA, quick test etc.)

Milk Ring Test (antibody detection in milk) is a satisfactory and inexpensive test used for surveillance of dairy herds for brucellosis.

Prevention: All susceptible, breeding age cattle should be tested before they are brought into the breeding herd. All positive cows should be culled. Newly introduced breeding animals should be tested and quarantine considered if not tested.


Pictures:

Brucella
Source: A magnified view of Brucella abortus - scan microscopy
Brucella
Source: Detail of Brucella colonies on agar
Brucella
Source: Diagnostic ELISA kit against Brucella abortus
Brucella
Source: Patogens under the light microscope (colored)
Brucella
Source: Quick test for detection of Brucella agents
Brucella
Source: Ring test - specific for detection of Brucella agents in milk

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