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Infectious Agents > Brucella > Flashcards

Brucella Flashcards

1
Q

General characteristics

A
  • small, GN coccobaciclli
  • no capsules, flagella, or spores
  • colonies not apparent until 3-5 days of incubation (up to 21 days)
  • obligate parasites
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2
Q

Infections localized to the ______

A

Reticuloendothelial system and genital tract

  • abortions in females
  • epididymitis and orchitis in males
  • zoonotic pathogen
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3
Q

Is brucella eradicated in the US?

A

Yes

- also B. suis and abortus

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4
Q

B. abortus

A

Prefers cattle

  • bison, camels, yaks infected as well
  • still present in bison in Yellowstone
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5
Q

S. suis

A

Prefers swine, some strains have other hosts

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6
Q

B. melitensis

A

Goats and sheep

  • also camels, alpacas, llamas
  • most zoonotic
  • most severe
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7
Q

B. ovis

A

Sheep only

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8
Q

B. canis

A

Dogs only

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9
Q

Transmission

A

Can survive up to 4 months in the environment

  • cold weather extends survival time
  • exists in milk, urine, water, damp soil
  • ingestion is most common
  • exposure thru conjunctival, genital mucosa, respiratory routes occurs
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10
Q

Source of exposure to B. abortus and B. melitensis

A

Through aborted fetuses, placenta, postabortion uterine fluids
- common for B. suis

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11
Q

Genital infections in cows

A

Clear within 30 days after calving

- cows are not considered infectious after that time

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12
Q

Vertical transmission of ____ and ____ through infected milk can occur

A

B. melitensis and B. abortus

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13
Q

Infection of accessory sex glands in males allows for venereal transmission of

A
  • B. suis
  • B. ovis
  • B. canis
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14
Q

____ and _____ transmitted thru urine or milk

A

B. canis, B. suis

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15
Q

Dogs shed B. canis ____ in vaginal discharge after abortion

A

4-6 weeks

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16
Q

What is an important reservoir for B. suis?

A

Feral swine

- B. suis has been eradicated from domestic swine

17
Q

Pathogenesis

A

Can penetrate intact mucosa

  • preferred site is epithelium covering Peyer’s patches
  • localizes in lymph nodes –> either proliferates or is killed
  • phagocytosed bacteria survive intracellularly –> phagosome is acidified = virulence gene expression
18
Q

Respiratory burst in phagocytic cells

A

Less effective at killing Brucella

  • suppresses production of oxygen radicals
  • expresses catalase and superoxide dismutase = increased resistant to oxygen radicals
  • inhibits apoptosis of infected macrophages to allow persistence
19
Q

Spread through reticuloendothelial system

A

Hematogenous spread to repro tract of males and females

  • preference for pregnant females
  • localized to RER of trophoblasts of the placentome
  • infection spreads to the fetus and causes abortion
20
Q

Disease

A

No systemic illness

- females abort once, due to acquired immunity

21
Q

Abortion times

A
  • B. abortus: cattle, 5th month or later
  • B. melitensis: late term abortion, acute mastitis in goats
  • B. suis: any time in gestation
  • B. canis: abortion usually around 50 days of gestation
  • B. ovis: rarely causes abortion
22
Q

Males

A

Epididymitis, orchitis, usually unilateral

  • epididymis enlarged
  • dogs have scrotal swelling and dermatitis
  • decreased fertility, sometimes sterility
23
Q

Extragenital infections

A
  • swine: B. suis = arthritis or lumbar spondylitis

- dogs: B. canis = meningoencephalitis, osteomyelitis, discospondylitis, anterior uveitis

24
Q

Effects on herd health

A
  • B. abortus: decreased fertility, reduced milk production, abortions in replacement animals, testicular degeneration in bulls
  • B. suis: abortion, stillbirths, neonatal mortalities, temporary sterility
  • B. canis: abortions, decreased fertility, reduced litter sizes, neonatal mortality
25
Q

What are 2 accidental hosts?

A

Horses, humans

26
Q

Horses

A

B. abortus causes fistulous withers, or poll evil

- removal of infected bursa is most effective

27
Q

Human infection

A

B. melitensis is most virulent

  • followed by B. suis, B. abortus, and B. canis
  • usually an occupational risk
  • undulant fever
28
Q

Diagnosis

A

Culturing from abscess, semen, or vaginal fluids

  • milk from cows or goats
  • blood cultures for B. canis
  • incubation in 10% CO2 requires 10-21 days
  • antibody can confirm isolates
  • DNA detection by PCR
  • serum antibody detection
29
Q

Treatment

A

Livestock are generally not treated due to cost, failure rate, eradication programs

  • treatment of dogs requires prolonged antibiotic therapy
  • best results from 90 day treatment
  • relapses are common
  • serological testing after treatment and 3-6 months later are recommended
  • males should be neutered!
30
Q

Control

A

Vaccines that stimulate antibody response are counterproductive! –> opsonization allows entry into phagocytes, perpetuating infection

31
Q

B. abortus treatment

A

Vaccination, testing, slaughter

32
Q

B. suis treatment

A

Test and slaughter

33
Q

B. ovis treatment

A

Remove infected rams and prevent new infections

- serology and palpation of epididymis

34
Q

B. canis treatment

A

Serologic testing of dogs prior to breeding, palpation for testicular and epididymal lesions

Infectious Agents (44 decks)

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