lecture 25 brucella

GENUS: BRUCELLAProf. Khalifa Sifaw Ghenghesh

بسم الله الرحمن الرحيم

Aerobic, Gram-negative bacilli Appear as cocci, coccobacilli and short

bacilli Non-motile, non-capsulate Optimum temp. >> 37oC Facultative intracellular parasites Essentially pathogens of goats,

Cattle, sheep and pigs Causative agents of Brucellosis (typical zoonosis) worldwide

Also known as Malta, Mediterranean or undulant fever

Important species B. melitensis >> goats & sheep B. abortus >> cattle B. suis >> pigs

Important: All 3 species can infect man and domestic animals

Brucella speciesgram-negative bacilli

Brucella abortus

PATHOGENESIS Incubation period: 10-30 days Symptoms may be delayed for months Enter the body through:

Skin abrasions, mucous membranes of the alimentary or respiratory tracts and sometimes the conjunctivae>> reach the blood through regional lymphatics.

Symptoms may vary without the fluctuating temperature to act as guide.

Bacteria localize in various parts of the reticulo-endothelial system resulting in complications in any part of the body.

Symptoms include: malaise, low-grade fever, lassitude, insomnia, irritability and swelling around the joints.

LABORATORY DIAGNOSIS

1. Blood Culture Specimen

Blood (10 ml volumes) Inoculate

Blood culture tubes or bottles (glucose-serum broth)

Incubate in 10% CO2

Cultures should be retained for at least 6-8 weeks before being discarded as negative

Brucella melitensis colonies

2. Serological Tests Standard agglutination test Mercaptoethanol test Complement fixation test Coobs’ test

3. Brucellin Skin Test

TREATMENT AND CONTROL

Combination of streptomycin and tetracycline or rifampicin and doxycycline

Vaccination of young cattle (6-8 months)

Pasteurization of milk or milk products

Eradication by compulsory testing animals and slaughtering positive reactors.