better for human health and for dcotor.

1. Assignment of :
Clinic Medicine-II
Submitted To:
Dr. AlamZeb Sb.
Submitted By:
Muhammad Tayyab
Class:
DVM
Semester:
7th
Roll No:
2242
Session:
2020-24
FVAS Gomal University
Quaid-e-Azam Campus
Dera Ismail Khan

2. Brucella spp.
Brucella Infections
Physiology and structure:
Very small gram-negative coccobacilli.
Non-fermentative.
Strict aerobe.
Requires specialized media and prolonged incubation for growth in culture.
Virulence
Intracellular pathogen that is resistant to killing in serum and by phagocytes.
Epidemiology
Animal reservoirs are goats and sheep (Brucella melitensis), cattle (Brucella abortus), swine (Brucella suis), and dogs
(Brucella canis).
worldwide distribution, although vaccination of herds has controlled disease in the United States.
Most disease in the United States is reported in the Hispanic population in California and Texas.
Non-essential incidence.
Individuals at greatest risk for disease are people who consume unpasteurized dairy products, people in direct contact
with infected animals, and laboratory workers.
Disease
Brucellosis
Diagnosis
Microscopy is insensitive.
Culture is sensitive and specific if prolonged incubation is used.
Serology can be used to confirm the clinical diagnosis.
Treatment, Prevention, and Control
Treatment for 3 to 6 weeks with doxycycline either alone or with rifampin or gentamicin for patients older than 8
years; doxycycline is replaced with trimethoprim-sulfamethoxazole for children younger than 8 years or for pregnant
women.
Human disease is controlled by eradication of the disease in the animal reservoir through vaccination and serologic
monitoring of the animals for evidence of disease; pasteurization of dairy products; and use of proper safety
techniques in clinical laboratories working with this organism.
Epidemiology of Brucellosis
 Animals are natural reservoir
• Cattle, goats, sheep, swine, bison, elk, dogs, foxes, coyotes
 500,000 human cases per year worldwide
 Less than 100 annual cases in the U.S. due to successful control of the disease in livestock and the animal
reservoir
 Transmission via i) ingestion of contaminated milk or cheese, or ii) direct contact with infected animals or
animal products
 Because it can be transmitted to humans, brucellosis is one of the most regulated diseases of cattle in the
U.S.
Incidence of Brucellosis in USA

3. Brucellosis in Animals
 Brucella infect organs rich in erythritol (a sugar metabolized in preference to glucose) like breast, uterus,
placenta and epididymis (tube that connects a pair of ducts that conduct spermatozoa during ejaculation)
 Asymptomatic carriage, sterility or abortions
 Transmitted between animals in aborted tissues
Human Brucellosis & Associated Species
Species Animal Reservoir Clinical Disease
Brucella melitensis Goats, sheep Severe acute disease with
complications (common)
Brucella abortus Cattle Mild disease with suppurative
complications (common)
Brucella suis Swine Chronic, suppurative, destructive
disease
Brucella canis Dogs Mild disease with suppurative
complications (uncommon)
Brucellosis in Humans
 Reportable disease
 Human brucellosis = Bang's disease, named for Bernhard Bang & Sir David Bruce who discovered Brucella
 Facultative intracellular pathogens of mononuclear-phagocyte system (formerly reticuloendothelial system
which is involved in immune defense against microbial infection and removal of worn-out blood cells)
• Bacteria are phagocytosed by macrophage or polymorphonuclear leukocyte
• Survive intracellularly by inhibiting killing
• Carried to spleen, liver, bone marrow, lymph nodes, kidneys
 Form granulomas (mass of granulation tissue produced in response to chronic infections, inflammation, or
foreign bodies) and cause destructive tissue damage
 Consumption of contaminated unpasteurized milk or direct contact with infected animal reservoir
• Disease associated with contact with infected cattle, cattle products, or dogs is a milder form
• Disease associated with contact with goats and sheep is acute and severe with complications common
• Disease associated with contact with swine is chronic & suppurative with destructive lesions and
localization in cells of the reticuloendothelial system (RES)
 Occupational hazard of laboratory personnel, veterinarians, farm workers, and meat handlers at risk through
direct contact or inhalation
 Protective clothing for abattoir workers, avoidance of unpasteurized dairy products
 Highest numbers of cases reported in CA and TX

4. Clinical Presentation of Human Brucellosis
 Acute disease often develops with initial nonspecific symptoms of malaise, chills, fatigue, weakness,
myalgias (muscles), weight loss, arthralgias (joint), and nonproductive cough
 Mild disease with rare suppurative complications
 Chronic disease and recurrence are common because it can survive in phagocytic cells and multiply to high
concentrations
 May also take the form of destructive lesions
Diagnosis & Treatment of Human Brucellosis
 Plate agglutination test (a.k.a., Brucella ring test) diagnosing Brucella
• Drop of serum mixed with drop of Brucella antigen
• Clumping indicates infection
• If the mixture remains clear, the result is negative.
 Treated with combination of tetracycline and doxycycline
 For infants, tetracycline is toxic, so children are treated with trimethoprim-sulfamethoxazole.

5. Control & Prevention of Brucellosis
 In 1934, the U.S. Department of Agriculture (USDA) established the National Brucellosis Eradication Effort
which is managed by Animal, Plant, and Health Inspection Service (APHIS)
 APHIS certifies states as brucellosis-free, classes A, B, or C of which all states are currently classified A
 Serology & confirmatory bacterial culture to identify infected animals
 Positive animals/herds are destroyed
 Vaccination is available but is not a 100% effective and is costly to cattle ranchers