What are the species of Brucella?
There are 6 species of Brucella, 4 of which cause human brucellosis
• Brucellosis is a zoonosis
• Brucella is a small Gram negative coccobacillus (Biosafety level 3)
• Non-motile, Non-capsulated
• Strict aerobe, Slow growing
• Intracellular pathogen
What are Brucella spp associated with human infection?
Brucella melitensis – reservoir: goats/sheep
Brucella abortus – reservoir: cattle
Brucella suis – reservoir: pigs
Brucella canis – reservoir: dogs,foxes
What is Brucellosis?
- In animals, Brucella infection leads to abortion
- Brucellosis is endemic in Britain and Ireland
- Cattle: transmission through aborted fetus, milk; May be excreted in milk for many months in animals with mammary gland involvement
What is human Infection of Brucellosis?
- Contact with an infected animal e.g., via inhalation of aerosols, conjunctiva, cuts or by consumption of an infected food product i.e., via GIT
- Occupational hazard – vets, farmers, abattoir workers, laboratory personnel
- Notifiable infection
What are the portals of entry of Human Brucellosis?
- Conjunctivitae: By aerosols or fingers
- Inhaled aerosols: Slaughterhouse procedures, Laboratory accidents, Veterinary manipulations.
- Ingestion: Diary products, contaminated fingers.
- Abraded Skin: Veterinarian, Abattoir workers
What are the characteristic features of human Brucellosis?
- Ingested by PMNs and macrophages
- Multiplies in regional lymph nodes
- Enters blood stream
- Spread to organs and reticulo-endothelial system
- Small granulomata produced in target sites
What is acute brucellosis?
• After an Incubation Period of 2-4 weeks, an Influenza-like illness occurs in 50% of infected patients
• PUO- Undulant fever, Rigors/sweating
- Dry cough/lassitude/arthralgia, myalgia/headache/weight loss
• Lymphadenopathy, hepato/splenomegaly
• Depression
What is chronic brucellosis?
- Occurs in untreated or inadequately treated patients
- Recurs over months or years
- Characterised by
- Evening depression
- Sweating episodes
- Aches/weakness
- Insomnia
What is the diagnosis of Brucellosis?
A: CLINICAL SUSPICION
B: LABORATORY INVESTIGATIONS
1. Blood cultures; 30 - 50% positive in acute infection, take more than 1 set, up to 6 weeks incubation (Biosafety level 3)
2. Bone marrow aspirate
3. SEROLOGY
1. Serum Agglutination test (SAT), Complement fixation test, Coombs test
2. Usually have titre of > 1:160
4. PCR blood, tissue ( reference laboratory)
What is the treatment of Brucellosis?
Recommended regimens:
• Doxycycline + Rifampicin for 6 weeks
• Pregnant patients, children or patients intolerant of doxycycline : cotrimoxazole + rifampicin
What are the methods of prevention of Brucellosis?
- Pasteurisation of milk
- Eradication of infected cattle
- Immunisation of healthy cattle - live attenuated strain of Brucella abortus
- Avoid soft goats or sheep cheese in geographical areas where B. melitensis is prevalent
- Notifiable infection
- Post exposure prophylaxis e.g. laboratory exposure, Vaccine accidents with vets or farmers
