Eradication of bovine brucellosis in Canada

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Eradication of bovine brucellosis in Canada

• Opportunity for similar success in China
• The Animal Health Policy Conference
• Beijing, China
• February 25-26, 2009
• Dr. Gordon Dittberner
• Agriteam Canada

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Outline

• Introduction
• Brucellosis in animal and human populations
• The arguments for control/eradication
• The Canadian approach to eradication
• Challenges and obstacles during the eradication
  campaign
• Lessons learned by Canada that could help China
• Conclusions

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Introduction

• Brucellosis is a zoonotic disease. The disease is
  serious in humans but it is usually not fatal.
  The disease does not spread from human to human.
  Humans contract brucellosis from close contact
  with infected animals, from ingesting milk or
  cheese, or in laboratories from infected
  specimens submitted for diagnosis.
• The predominant strain causing human brucellosis
  worldwide is B. melitensis while in North America
  it is B. abortus.
• The OIE lists brucellosis as a notifiable disease
  in animals. In Canada brucellosis in humans and
  in animals are notifiable diseases.

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Introduction (continued)

• Susceptible animal species include
• cattle, bison, buffalo, and yak
• sheep and goats
• pigs
• elk, reindeer, and caribou
• camels, llamas, and alpacas
• dogs
• seals, otters, and whales (belugas)

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Introduction (continued)

• Humans B. abortus, B. melitensis, and B. suis
• Cattle, bison, buffalo, and yak B. abortus
  (biovars 1-6, and 9) (rarely also B. melitensis
  B. suis)
• Sheep and goats B. melitensis and B. ovis
• Pigs B. suis (Biovars 1 and 2)
• Elk, reindeer, and caribou B. suis (biovar 4)
• Camels, llamas, and alpacas B. abortus
• Dogs canis
• Seals, otters, whales (belugas) B. pinnipedias
  
• Low - not zoonotic/ non-reportable

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Introduction (continued)

• In animals there are significant general
  reproductive and economic losses.
• The clinical signs seen are
• abortions, retained placentas, orchitis,
  epididymitis, and sometimes arthritis
• In female animals the infective bacteria can be
  excreted in the milk, in uterine discharges, or
  in aborted tissues. In male animals the bacteria
  can be excreted in the semen.

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Introduction (continued)

• Methods for screening for brucellosis or for
  confirming the diagnosis of brucellosis include
• demonstrating the bacteria from a smear of
  infected material - using an acid-fast stain or
  - by culturing
• using serology for tests or assays
• - buffered B. antigen tests (rose bengal,
  BAPT)- complement fixation tests (CFT)-
  enzyme-linked immunosorbent assays (ELISA) or -
  fluorescence polarisation assay (FPA)
• the brucellosis milk ring test (BMRT) on milk or
  cream
• the immunological brucellin skin test

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Brucellosis in animal and human populations

• In many countries there was a significant
  occurrence of brucellosis in both animal and
  human populations in the 1920 - 1930 period.
• In Canada it was estimated that 20 of cattle
  herds were infected.
• Human cases of brucellosis were mainly associated
  with livestock production.

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Current rates of brucellosis reported in human
populations

• Globally 500,000 cases per year (source WHO)
• USA 150 cases per year
• Canada 10 cases per year
• China 17,644 cases in 2006
• China 18,116 cases in 2007
• (Source - Shuangyashan News, December 5, 2007,
  quoting Ministry of Health, China)

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The arguments for control/ eradication of
brucellosis

• Brucellosis is a serious disease in humans and
  causes significant economic and production losses
  in livestock.
• The cause of the disease and how it is spread
  from animals to people is known.
• Reducing the prevalence of the disease in animals
  has been shown to reduce the rates of infection
  in people.
• Cost effective control measures in animals have
  demonstrated that the rate of infections in
  animals can be reduced.

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The arguments for control/ eradication of
brucellosis (continued)

• Many countries have successfully eradicated
  bovine brucellosis over the past 30 years.
• Cost benefit studies consistently conclude that
  the benefits to eradicate this disease outweigh
  the costs.
• Even studies in Inner Mongolia have supported the
  cost advantages to eradication.
• Public pressure may force governments to take
  actions on social and public health concerns
  (such as brucellosis).

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The arguments for control/ eradication of
brucellosis (continued)

• Shuangyashan News, December 4, 2007, reported
• Statistics from the Ministry of Health show that
  Chinas prevention and control of human
  brucellosis is in serious circumstances, and
  occurrence in cow and sheep producing regions is
  a grave concern.
• . ten provinces and autonomous regions
  ....account for 98.15 per cent of reported cases
  nationally.

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The Canadian approach

• Brucellosis-free listed herds started as a
  voluntary control program in 1930.
• Reactor animals were removed from the herds.
• In 1940 Canada began voluntary calfhood
  vaccination with the strain 19 vaccine.
• In the 1950s the rate of infection was 9 so
  Canada decided to proceed to Phase 1 of the
  eradication program.
• Phase 1 consisted of mass calfhood vaccination
  (free of charge to farmers).

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The Canadian approach (continued)

• By the 1960s the infection rate was down to 4.
• Phase 2 consisted of- mandatory testing and
  slaughter of reactors- farm quarantines-
  farm-to-farm area testing- BMRT- testing of all
  animals sent to cattle markets and abattoirs -
  movement control measures before cattle could
  be moved, Canada required the cattle to have
  negative tests as well as permits to be moved

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The Canadian approach (continued)

• In Phase 2 diagnosis was achieved through-
  screening tests - card agglutination, plate and
  tube agglutination, and BMRT and-
  confirmation tests complement fixation tests
  (CFT) or by culturing of the organism.
• By 1966 the infection rate was down to 0.2.
• Phase 3 began and free vaccination was stopped so
  that any hidden/latent brucellosis infection
  would be exposed.

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The Canadian approach (continued)

• In 1975 an increase in the rate of brucellosis
  infection resulted in- another review of the
  eradication program and
• - the establishment of a consultative
  committee of representatives from the federal
  and provincial governments, the cattle and meat
  industries, and veterinary associations to
  develop the next steps of the eradication
  program.

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The Canadian approach (continued)

• The consultations and reviews resulted in
• an enhanced eradication program with- more
  inspection staff- a better ear-tag
  identification system- stricter interpretation
  of test results- specialized education for
  veterinarians and epidemiologists- education
  of veterinary technicians in cattle testing
  procedures- education programs for farmers
• the introduction of movement controls within the
  provinces
• whole herd depopulation replacing the test and
  slaughter policy

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The Canadian approach (continued)

• The 1980s saw significant decreases in the number
  of infected herds.
• By 1985 no brucellosis infections were uncovered
  despite very intense and extensive surveillance.
• Canada declared it was free from bovine
  brucellosis it continued to maintain high
  levels of surveillanceand extended the program
  to other livestock farming sectors (elk, bison,
  and deer).
• Since 1985 there have been five outbreaks - well
  within OIE requirements for brucellosis-free
  status.

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OIE requirements for freedom from bovine
brucellosis

• The disease must be notifiable.
• The rate of infection in the country must not
  exceed 0.2 of the cattle herds.
• Periodic serological or BMRT of the herds must be
  conducted.
• Vaccination of animals against bovine brucellosis
  must have stopped for at least the past 3 years.
• All reactors must be slaughtered.
• Any additions to the herds must come only from
  officially declared brucellosis-free herds.

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The Canadian approach (continued)

• Five confirmed outbreaks in Canada from 1985 to
  2009
• 1986 - one beef cow reactor found in Alberta
  herd was depopulated.
• 1987 - one beef cow reactor found in Manitoba
  herd was depopulated.
• 1987 - one outbreak four herds - in Alberta
  all four herds were depopulated.
• 1988 - one bison herd infected in Alberta herd
  was depopulated.
• 1989 - one beef cow reactor found in
  Saskatchewan herd was depopulated.

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Wood Buffalo National Park

• Canada has one geographically isolated
  reservoir of brucellosis in wildlife in Wood
  Buffalo National Park. To this time there has
  been no spread to livestock, a containment plan
  is in place, and there is enhanced livestock
  surveillance south of the park.

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The Canadian approach (continued)

• After 1990, with bovine brucellosis-free status
  achieved, Canada was able to reduce its levels of
  surveillance
• stopped testing at cattle markets (except in
  Northern Alberta to address the potential risks
  from Wood Buffalo National Park)
• focused on testing samples from abattoirs
• BMRT reduced from every 2 months to every 4
  months
• added brucellosis to the national serological
  survey
• maintained strict import requirements especially
  for cattle from the U.S.

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The Canadian approach (continued)

• Since 2000 Canada has
• developed a national cattle identification
  program
• prohibited vaccination for brucellosis
• initiated regular surveillance of farmed bison,
  elk, and deer herds
• eliminated the BMRT program and
• set up a regular national serological survey
  (randomized but weighted to account for higher
  provincial animal densities and higher risk
  areas).

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Initial challenges Canada faced

• Insufficient knowledge of the epidemiology of the
  disease
• Skepticism and limited cooperation among some
  cattle farmers
• An inability to distinguish between vaccinated
  and infected reactors
• An inadequate animal identification system for
  tracking movements and trace-back investigations
• Insufficient compensation paid to farmers for
  animals ordered destroyed

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Initial challenges Canada faced (contd)

• Insufficient veterinary and technical staff to
  conduct all the field work and laboratory testing
• Federal and provincial governments were reluctant
  to spend money on the eradication program as it
  required long term (multi-year) commitments
• Inadequate federal (national) government policies
  to recognize the risks of latent infections in
  herds
• Refusal of the Department of the Environment to
  allow the eradication of the infected bison herd
  in Wood Buffalo National Park (Alberta/North West
  Territories)

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Lessons learned

• The importance of
• applying the best veterinary science to solve the
  epidemiological problems and to establish optimal
  eradication policies
• seeking independent veterinary advice and
  opinions
• conducting cost-benefit studies to get political
  and financial support by demonstrating - the
  economic advantages to the government and to
  the cattle producers - the public benefits of
  reducing human disease and the associated costs

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Lessons learned (continued)

• The importance of
• having extensive and reliable surveillance data
  for designing the eradication program
• involving the cattle farmers to help with the
  development of the eradication plan
• ensuring that farmers received 100 of the fair
  market value for all animals ordered destroyed
• having independent evaluation teams establish
  fair market compensation for farmers

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Lessons learned (continued)

• Vaccination is an important tool to get high
  infection rates down quickly.
• Once the infection rates have been lowered
  vaccination is a hindrance to eradication
  efforts.
• Training veterinarians and technicians to use an
  inexpensive screening test (Brewers Card Test)
  at cattle markets played a significant role in
  preventing the disease from spreading to other
  herds.

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Lessons learned (continued)

• Having a more reliable and effective
  identification system would have reduced the time
  taken to eradicate the disease.
• More attention should have been given to the
  infection risks associated with elk, deer, and
  bison farming.
• Accept that some battles cannot be won for
  example, the failure to persuade the Department
  of Environment to allow an eradication program in
  Wood Buffalo National Park.

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Conclusions

• The Canadian approach to eradicating bovine
  brucellosis has proven successful.
• Eradicating bovine brucellosis is not unique to
  Canada several other countries have succeeded -
  before and after Canada.
• China has the potential to eradicate brucellosis.
• However, China will face broader challenges
  because of other Brucella species in the
  livestock.

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Conclusions (continued)

• Brucellosis is an eradicable disease eradication
  can be achieved at various levels township,
  prefecture,province, and country.
• There are better tools available today to assist
  in an eradication program including- more
  effective vaccines- much better, faster, and
  cheaper diagnostic tests- more advanced
  epidemiological knowledge and expertise and-
  advanced computer technology.
• There are also better animal identification
  systems available.

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Conclusions (continued)

• There are also many resources available to assist
  China with an eradication program. These include
  the OIE, OIE members, and scientists within
  China.
• For example, see Veterinary Microbiology,
  December 2002, for Epidemiology and control of
  brucellosis in China by Shang Deqiu, Xiao
  Donglou, and Yin Jiming, Institute of
  Epidemiology and Microbiology, Chinese Academy of
  Preventive Medicine, Beijing.

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Conclusions (continued)

• The challenge for the Chinese animal health
  authorities is to make a commitment to eradicate
  bovine brucellosis now and to quickly implement
  an action plan.
• Thank you and good luck!