Brucellosis is a zoonotic disease caused by bacteria that primarily infects domestic animals and can be transmitted to humans. It is a global disease with high prevalence in parts of the Mediterranean, Middle East, Africa, and South America. Humans typically get infected by consuming raw dairy products or through contact with infected animal tissues and fluids. Symptoms are non-specific but include undulating fever, sweats, joint pain and swelling. Diagnosis involves serological tests or culture of blood and tissues. Treatment requires a combination of doxycycline and streptomycin or rifampin for several weeks. Prevention focuses on animal vaccination, safe food handling, and protective equipment for high risk workers.

1. Brucellosis

2. Brucellosis
o Brucellosis is a zoonosis primarily of
domestic animals, causing a chronic
debilitating septicemic disease leading to
abortion.
o The disease is prevalent worldwide and is
particularly common in the Mediterranean
and Middle Eastern countries, and in parts of
Africa and South America.
Definition:-

3. Brucellosis tends to be an occupational disease, with
farmers, animal handlers, abattoir workers,
veterinarians, and laboratory personnel at greatest risk.
In humans, disease is mainly caused by B melitensis, B
abortus, B suis, and occasionally by B canis. B
melitensis has been associated with more aggressive
and acute presentations, and worldwide is the most
common species to infect humans. B abortus is usually
associated with mild to moderate disease, and rarely
causes complications outside the musculoskeletal
system. B suis has been associated with focal abscesses.

4. Epidemiology
Brucellosis occurs worldwide; major endemic areas include
countries of the Mediterranean basin, Arabian Gulf, the
Indian subcontinent, and parts of Mexico, Central and South
America
Human Infection. melitensis is the species that infects
humans most frequently.
The incubation period ranges from a few days to a few
months.
The disease is manifested as fever accompanied by a wide
array of other symptoms.

5. Pathogenesis

6. Pathogenesis
o Ingestion:
• Raw milk & unpasteurized dairy products.
• Rarely through undercooked meat.
o Inhalation:
o Inoculation:
o Person-to-person transmission is very rare.
of placental or uterine discharges, blood
and urine.

7. Pathogenesis
o Animal tissues and products, such as
placenta, uterus and milk, that are rich in
erythritol (a growth factor for brucellae) can
be heavily contaminated and highly
infectious.
o Spread in the body occurs via lymphatics,
replication within lymph nodes, and then wide
hematogenous spread to organs and tissues.

8. Pathogenesis
o Intracellular parasitism: brucellae have a
particular tendency to persist intracellularly,
notably in the reticuloendothelial system.

9. Clinical features

10. Clinical features
o Incubation period: 1-3 weeks,
occasionally several months.
o Can affect any organ or organ system.
o Fever may be intermittent or undulant.
Fever, often persists for months or
years. Undulant fever
39.5
37.0

11. Clinical features
o Non specific symptoms: sweating,
anorexia, constipation, rigor and
weakness.
o Depression.
o Osteoarticular complications e.g. arthritis,
osteomyelitis.

12. Clinical features
o Splenomegaly, lymphadenopathy and
hepatomegaly.
o Orchitis and epididymitis.
o A septicemic disease, abortion can occur.

13. Clinical features
o Classification: Acute (< 1 year) and Chronic
(>1 year).
o Low case fatality rate mostly due to
infective endocarditis.

14. Diagnosis

15. Diagnosis
1- Clinical features.
2- Serology: brucella agglutinins in the blood.
3- Blood or tissue culture.
4- Polymerase Chain Reaction (PCR).

16. Diagnosis in Humans
o Serology: brucella agglutination test.
• Four-fold or greater rise in titer.
• Samples 2 weeks apart.
o BAT detects antibody to B. abortus, B.
melitensis and B. suis but NOT to B. canis.
o Therefore, specific serologic tests for B.
Canis must be requested.
o Rose Bengal Test is useful for screening.

17. Positive
agglutination
Negative
agglutination

18. Diagnosis in Humans
o False positive: cross reactivity with
antibodies of F. tularensis,, E. coli and V.
cholerae.
o False negative: in prozone phenomenon.

19. Diagnosis in Humans
o Prozone phenomenon may occur secondarily
to hyperantigenemia, which might result in a
false-negative results.
o High levels of antigen may prevent the
formation of antigen-antibody complexes.
o To solve this problem, routine dilution of the
serum beyond 1:320 would help to prevent
such a problem.

20. o 2-ME-test (mercaptoethanol): more specific,
positive in chronic Brucellosis.
o ELISA test:
• High IgM in acute infection.
• High IgG in chronic infection.
Diagnosis in Humans

21. Diagnosis in Humans
o Culture of blood, bone marrow and tissue fluids.
• Blood culture: +ve in about 50 -70% of
cases.
• Bone marrow culture is the standard criterion,
since the reticuloendothelial system holds a
high concentration of the organism.
Sensitivity 80-90%.
• Blood or bone cultures should be incubated
for at least 6 weeks.

22. o PCR is a rapid and accurate method for
diagnosis of Brucella species.
o CBC: Non specific, (leucopenia, lymphocytosis,
anemia). Moderate elevation of ESR.
Diagnosis in Humans

23. Treatment, Prognosis and
Prevention & Control

24. Treatment of Choice
o Combination therapy has the best efficacy.
• Doxycycline for six weeks in
combination with streptomycin for 2-3
weeks or rifampicin for 6 weeks.
o CNS cases treat 6-9 months.
• Same for endocarditis cases plus
surgical replacement of valves.

25. Prognosis
o This disease is easily curable with a low
risk of relapse or chronicity.
o About 5% of treated cases relapse
• Failure to complete the treatment
regimen

26. Prevention and Control
o Education about risk of transmission.
• Farmer, veterinarian, abattoir worker,
butcher, etc.
o Wear proper attire if dealing with infected
animals/tissues.
• Gloves, masks, goggles.
o Avoid consumption of raw dairy products.

27. Prevention and Control
o Immunize animals in areas of high
prevalence.
• Effective attenuated live bacterial vaccines
exist against B. abortus (strain 19) and B.
melitesis (Rev-I), but as yet none exists
for B. suis or B. canis.
o No human vaccine.