152. General characterisation and epidemiology of brucellae (Zoon.). Swine brucellosis (Zoon.).

Question 1

Brucellosis?

Answer 1

BRUCELLOSIS

• Chronic, Female: abortion in the last trimester,
• Male: epididymitis and orchitis
• The main impact is economic,
• deaths are rare (except in the fetus and neonates)
• Zoonosis and notifiable disease! (Except.: B. ovis!)

Question 2

General features of brucella?

Answer 2

GENERAL FEATURES OF BRUCELLA

• Small (0.5-1.5µm) coccoid rod, no capsule/flagella/spore, Gram ʹ, obl. aerobe, capnoph.
• B. ovis, B. abortus
• Köster-staining (MZN-staining) +
• 3% diluted safranin: 3-5 minutes, 1 x heating till steaming
• 0.5% H2SO4 for several seconds, then rinsing in water
• Counterstain with methylene blue for 2 minutes
• Results: Brucella ʹ red (exc. B. ovis, B. canis), others are blue
• Fastidious: blood agar, 0.5% yeast extract, vit. B ʹ 2 days
• Facultative intracellular pathogen
• Antigenic structure : Cell wall ʹ A and M polysaccharide
• B. melitensis : A predominates, B. abortus ʹ M predominates, B. suis => both at same proportion
• Cross reaction: B.melitensis ʹ B abortus ʹ B. suis, B. ovis ʹ B. canis
• Yersinia enterocolitica ʹ O:9 cross reaction in agglutination (can give false positive results!)
• Resistance is average ʹ above 60°C and under pH 4 (pasteurized/cured milk, matured meat) = die quickly
• Lymph nodes and parenchymal organs ʹ 3 weeks
• In cooled raw milk, cream, cottage cheese, soft cheese ʹ 1 month
• Fetal membranes in shady, cool environment ʹ 1-2 months
• Cannot tolerate disinfection ʹ 2% NaOH, 3% formalin

Question 3

Species of brucella?

Answer 3

Question 4

Occurence ethiology and epidemiology swine brucellosis?

Answer 4

SWINE BRUCELLOSIS

OCCURRENCE, ETIOLOGY AND EPIDEMIOLOGY

• Worldwide in swine-raising regions, has been eradicated from domestic pigs in US, Canada, Europe and Australia,
• but persist in wild swine population
• Biotype 1-2-3: worldwide,
• 2 ʹ wild boars and hares in Europe,
• 4 ʹ arctic reagions of North America and
• Russia, 5 ʹ in the former USSR (rodents)
• Caused by B. suis biotype 1-2-3
• Intro. into a herd with infected, asymptomatic breeding animals, vehicles, instruments, dogs, wild boars

Question 5

Pathogenesis and clinical signs of swine brucellosis?

Answer 5

PATHOGENESIS

• Infection acquired by ingestion or by mating
• Orchitis, vertebral osteomyelitis can be seen more frequently (compared to bovine brucellosis)

CLINICAL SIGNS

• Bacteremia (gen. asympt.)
• Sows ʹ abortion (any gestational period), stillbirth, neonatal mortality increase, non-viable or poorly developed piglets,
• vaginal discharge for several days, temporary infertility
• Boars ʹ excreting brucellae in semen (with or w/o clinical signs) ʹ orchitis, sterility
• Lameness, incoordination, posterior paralysis ʹ vertebral abscess, fractures

Question 6

Pathology of swine brucellosis?

Answer 6

• Fetus :
• edema of fetus and fetal membranes,
• small hemorrhages,
• maceration, mumification
• Sows:
• necrotic foci in the uterine wall,
• Boars
• enlarged testicle, inflammatory necrotic foci
• Lesions in bones and joints
• vertebral body deformities

Question 7

Diagnosis of swine brucellosis?

Answer 7

DIAGNOSIS

• Isolation of B. suis, serology
• slide agglutination, tube agglutination
• Herd replacement for eradication program
• CFT or ELISA (low susceptibility & specificity,
• only for livestock diagnosis)- No treatment!

Question 8

Maintaining disease free status of swine brucellosis?

Answer 8

MAINTAINING DISEASE-FREE STATUS

• Control of import of susceptible animals,
• examination of abortion cases,
• serological survey of breeding boars in each 6 months,
• serological examination of sows in each year
• Keeping wild boars away from swine herds!