Brucellosis

• Bovine brucellosis is a contagious bacterial disease that impacts the health of cattle and the general public
• Also known as contagious abortion or Bang's disease
• Transmitted through direct contact with infected animals or consumption of contaminated raw animal products
• Significant economic consequences include decreased milk production, weight loss, abortion, infertility, and lameness
• Brucella abortus is a small, Gram-negative, and facultative intracellular bacterium
• Causes disease mainly in cattle
• At least nine biotypes (1-9) are recognized, as well as several variants
• Sheep, goats, and other domestic animals can also be infected
• Transmission of brucellosis in cattle occurs through ingestion of contaminated feed and drinking water
• Spread through direct or indirect interaction with diseased cattle or their discharges
• Cattle licking their fetuses and newborn calves is a major source of infection
• Can be transmitted by feeding pooled colostrum to newborn calves
• Rarely spread through sexual contact in cattle
• Humans acquire Brucella infection via ingestion of unpasteurized milk or milk products
• Work-related contact with cattle or their products is a major risk for human brucellosis
• Brucella infection in cattle is more common in sexually mature and pregnant cattle
• Erythritol sugar in fetal tissues of cattle stimulates the growth of Brucella organisms
• Mode of transmission of Brucella is through ingestion, inhalation, via conjunctiva, and through abrasions/wounds in the skin
• B. abortus multiplies in phagocytic cells and reaches trophoblasts and mammary gland in pregnant females
• Brucella reaches the placenta in females via hematogenous route and to the fetus
• Clinical signs of Brucella infection include abortion, stillbirths, retention of placenta, weak calves, and hygromas on leg joints
• Granulomatous inflammatory lesions are commonly seen in Brucella infections in animals
• Lesions often within lymphoid tissues and organs with a major involvement of the mononuclear phagocytic system
• Diagnosis based on clinical signs, serologic testing, and microbial culture
• Samples for culture include placenta, udder secretions, and tissue samples from aborted fetuses
• Agglutination tests for the detection of antibodies in serum, milk, whey, and semen are standard diagnostic methods
• Brucellosis treatment in animals is typically ineffective due to the intracellular nature of the organisms
• Immunization of calves or heifers is the most effective means of managing Brucella in an endemic area
• Brucellosis can be eradicated by quarantining infected cattle, vaccination, and test-and-slaughter methods