Brucella

Question 1

General characteristics

Answer 1

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

Question 2

Infections localized to the ______

Answer 2

Reticuloendothelial system and genital tract

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

Question 3

Is brucella eradicated in the US?

Answer 3

Yes

- also B. suis and abortus

Question 4

B. abortus

Answer 4

Prefers cattle

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

Question 5

S. suis

Answer 5

Prefers swine, some strains have other hosts

Question 6

B. melitensis

Answer 6

Goats and sheep

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

Question 7

B. ovis

Answer 7

Sheep only

Question 8

B. canis

Answer 8

Dogs only

Question 9

Transmission

Answer 9

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

Question 10

Source of exposure to B. abortus and B. melitensis

Answer 10

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

Question 11

Genital infections in cows

Answer 11

Clear within 30 days after calving

- cows are not considered infectious after that time

Question 12

Vertical transmission of ____ and ____ through infected milk can occur

Answer 12

B. melitensis and B. abortus

Question 13

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

Answer 13

• B. suis
• B. ovis
• B. canis

Question 14

____ and _____ transmitted thru urine or milk

Answer 14

B. canis, B. suis

Question 15

Dogs shed B. canis ____ in vaginal discharge after abortion

Answer 15

4-6 weeks

Question 16

What is an important reservoir for B. suis?

Answer 16

Feral swine

- B. suis has been eradicated from domestic swine

Question 17

Pathogenesis

Answer 17

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

Question 18

Respiratory burst in phagocytic cells

Answer 18

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

Question 19

Spread through reticuloendothelial system

Answer 19

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

Question 20

Disease

Answer 20

No systemic illness

- females abort once, due to acquired immunity

Question 21

Abortion times

Answer 21

• 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

Question 22

Males

Answer 22

Epididymitis, orchitis, usually unilateral

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

Question 23

Extragenital infections

Answer 23

• swine: B. suis = arthritis or lumbar spondylitis

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

Question 24

Effects on herd health

Answer 24

• 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

Question 25

What are 2 accidental hosts?

Answer 25

Horses, humans

Question 26

Horses

Answer 26

B. abortus causes fistulous withers, or poll evil | - removal of infected bursa is most effective

Question 27

Human infection

Answer 27

B. melitensis is most virulent - followed by B. suis, B. abortus, and B. canis - usually an occupational risk - undulant fever

Question 28

Diagnosis

Answer 28

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

Question 29

Treatment

Answer 29

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!

Question 30

Control

Answer 30

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

Question 31

B. abortus treatment

Answer 31

Vaccination, testing, slaughter

Question 32

B. suis treatment

Answer 32

Test and slaughter

Question 33

B. ovis treatment

Answer 33

Remove infected rams and prevent new infections | - serology and palpation of epididymis

Question 34

B. canis treatment

Answer 34

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