Week 4

• Brucella


  facultative intracellular (infect, persist, and multiple in macrophages)

  obligate pathogens

  tropism of placenta, testes, fetal fluids (excreted in milk)

  transmission to humans - direct contact, consumption of animals products (no tropism to reproductive tract)

  environmental resistane
• Brucella spp.

  gram negative, rods

  aerobic + capnophilic

  non-motile

  non-spore forming

  non-encapsulated

  survival in envrionment temperature and moisture dependent (survive <30 days under most environmental conditions)
• 4 main pathogenic Brucella spp.

  Brucella abortus

  Brucella melitensis

  Brucella suis

  Brucella canis
• Brucella spp in humans

  undulant fever - B. abortus, B. suis. B. canis

  malta fever - B. melitensis
• All pathogenic Brucella spp. are reportable
• Brucella spp. mechanism of transmission


  horizontal (contact with infected reproductive tissues)

  vertical (mother to fetus, milk)

  veneral (B. ovis, suis, canis)
• Brucella spp. infection outcomes

  females - abortions (B. abortus, B. melitensis, B. canis), weak calves persistently infected (source of infection to the farm), mastitis

  males - epididymitis, sterility
• Brucella infection & pathogensis

  1. infection (mucosa, oral, wounds)
  2. regional lymph nodes (intracellular - no symptoms)
  3. spread to other lymph nodes
  4. disseminate in blood stream (B. abortus in cattle - short bactermia = 10 days)
  5. target tissues
• Brucella spp intracellular niche

  ER serves as replication sheltered from detection by immune system
• Brucella replicated in macrophages, dendritic cells, monocytes, tropblasts, bone cells, granulocyte progenitors, adipocytes
• Granulomas contain Brucella infection once an adaptive immune response is achieved. Brucella develops chronicity and persists at low replication rates
• Brucella spp. virulence factors

  LPS display reduced PAMP for recognition by innate immunity

  fails to induce robust innate immune response

  lipid A has reduced toxicity

  type IV secretion system
• Brucellosis

  disease of sexually mature animal

  predilection sites being reproductive tracts of males and females (especially pregnant uterus)

  allantoic fluid factors stimulate growth (erythritol)
• Brucellosis in humans

  highly susceptibly to infection

  Undulant or Malta fever

  clinical symptons are not pathognomic

  manifestations - undulating pyrexia, malaise, fatigue, night sweats, muscle and joint paint

  osteomyelitis is most common complication
• Brucella abortus

  incubation period: 2-8 weeks

  strong tropism for pregnant uterus and placenta

  aborted fetuses - pleuropneumonia is most common lesion

  most important source of infection - aborted fetuses and uterine secretions during delivery or abortion

  venereal transmission is not major route of infection
• Brucella abortus susceptibility 


  heifers and pregnant animals most susceptible

  older animals relatively more resistant

  increased resistance with vaccination
• Brucella abortus clinical manifestation

  abortion (3rd trimester, especially for first calf heifers)

  retained placenta (zoonotic infection)

  birth weak calves (respiratory disterss and lung infections) or stillbirth

  low milk yield

  bulls - epididymitis, seminal vesiculitis, orchitis, abscess in testes
• Brucella melitensis 


  goats are more susceptible than sheep

  abortion (later gestation) and infertility are predominant clinical signs

  no retention of fetal membranes

  mastitis (watery exudate, clotted milk)

  males - infects epididymis, testicles, seminal vesicles, and deferent ducts resulting in decreased fertility

  may infect cattle and camels - occassional abortion and excretion in milk
• Brucella suis (swine burcellosis)


  marked tropism for male reproductive system

  predominantly transmitted via venereal route

  rams - epididymitis and testicular atrophy (infertility)

  bacterium can be recovered from semen 5-14 weeks post-infection

  relatively avirulent in non-pregnant uterus; abortions in ewes secondary to veneral transmission

  not considered zoonotic
• Brucella in horses (B. abortus or B. melitensis)


  can cause abortion, infection of sexual organs in stallions, and infertility

  suppurative bursitis (fistulous withers or poll evil)
• Brucella canis 


  tropism for reproductive system

  clinical signs non specific

  can remain bacteremic for years

  cause of vertebral osteomyelitis and intervertebral disc infeciton

  uveitis with or without concomitant reproductive disease

  transmission - mainly oronasal and venereal

  zoonotic
• Brucella canis clinical manifestations 


  female dogs - mid to late term abortion followed by vaginal dicharge that can persist for weeks; embryonic death with resorption

  males dogs - epididymitis, prostatitis, orchitis, resulting in testicular atrophy, azoospermia, and infertility

  healthy pups - may be infected in utero or be asymptomatic, can serve as source of infection
• Brucella ceti


  brucellosis in some dolphins and porpoises

  fetal abortions, male infertility, neurobrucellosis, cardiopathies, bone and skin lesions, strand events, death

  zoonotic
• Brucella spp. diagnosis 


  serology tests - low accuracy (cross reactivity with other pathogens)

  skin test

  culture from milk or other tissues

  interferon test

  modified Zeil-Neelson

  catalase +, oxidase +, urease +
• Brucella diagnosis 


  Rose Bengal test

  indirect ELISA performed on sheep milk samples (IgG)

  CFT detects anti-Brucella antibodies that can activate complement
• Brucella spp. control & prevention

  vaccination (not for canine brucellosis)

  test cattle and domestic bison

  culling of infected farm animals

  isolate newly introduced cattle for 30 days

  test before birth - control transmission

  antibiotic therapy - inability to ensure total clearance due to intracellular niche
• Brucella management to decreased infective dose

  calving management

  removal of contaminated material

  cleaning and disinfecting
• Bordetella spp.

  gram negative rods

  strict aerobes

  oxidase +

  slow growing

  non-carbohydrate fermenters

  affinity for cilitated respiratory epithelium
• Bordetella spp. of veterinary importance

  B. bronchiseptica, B. avium, B. parapertusis
• Bordetella have poor survival in the environment


  normal inhabitants of upper respiratory tract

  transmission - mainly by aerosols

  high morbidity, low mortality
• Bordetella spp. respiratory disease

  rhinitis, tracheitis, bronchitis, bronchiolitis

  clinical signs - coughing with or without dyspnea, ocular or nasal discharge and weight loss
• Bordetella virulence factors

  promote adherence and colonization - fimbriae, filamentous hemagglutinin, pertactin, type III secretion system

  alter host tissues and promote lesion formation - DTX, ACT, TCT, PTX, osteotoxin (B. avium), type III secretion system, LPS
• Bordetella virulence gene (bvg) locus

  controls expression of >500 genes

  on at 37C

  off at 27C
• Bordetella bronchiseptica

  in pigs - atrophic rhinitis

  in dogs - kennel cough

  in rabbits - snuffles, otitis media
• Atrophic rhinitis

  dermonecrotic toxin - damages osteoblasts, preventing bone formation

  leads to turbinate atrophy without distortion of the snout

  causes bronchopneumonia in young pigs

  colonized nasopharynx

  infection must occur during first weeks of life
• 'Progressive' atrophic rhinitis

  B. bronchiseptica + Pasteurella multocida

  turbinate bone atrophy is permanent and progressive
• 'Non-progressive' atrophic rhinitis

  B. bronchiseptica only

  atrophy with resolve (if not complications)

  bronchopneumonia (with fibrinous pleuritis in chronic cases)
• Kennel cough

  canine infectious tracheobronchitis

  canine infectious respiratory disease

  highly contagious acute respiratory disease

  all ages affects

  most cases involve a primary viral infection or secondary bacterial involvement
• Bordetella bronchiseptica in dogs 


  kennel cough

  clinical signs - honking cough, sneezing, lethargy, runny nose, loss of appetite, low fever
• Bordetella bronchiseptica in rabbits 


  snuffles-like: rhinitis mainly P. multocida

  otitis media: mainly produced by P. multocida; an accumulation of pus or fluid in the middle or inner ear causes rabbit to twist its head

  eye localization: blindness

  bronchopneumonia or septicemia