This document discusses strategies for controlling PRRS (Porcine Reproductive and Respiratory Syndrome) and Aujesky's disease in swine. It emphasizes that biosecurity, control measures, and eradication efforts are needed to manage these prevalent and costly diseases. Specifically, it highlights that biosecurity is critical to prevent virus transmission between farms, control aims to minimize damage from the virus, and eradication seeks to ultimately remove the virus. It also contrasts key differences between PRRS and Aujesky's viruses and discusses vaccination and testing strategies used for eradication of Aujesky's disease.

1. Biosecurity, Control and
Eradication Strategies for
PRRS and Aujesky’s
Disease
AMVEC XXXVII Congreso Nacional
July 18, 2002
Puerto Vallarta, Mexico
Steve Henry, DVM, Dipl ABVP
Abilene Animal Hospital, P.A.
Abilene, KS

2. PRRS and Aujesky’s infections
► Are prevalent and costly diseases of swine
► Can be successfully managed only with
systematic plans and coordinated veterinary
strategies

3. PRRS and Aujesky’s infections
► Are prevalent and costly diseases of swine
► Can be successfully managed only with
systematic plans and coordinated veterinary
strategies
 Biosecurity – to prevent any movement of virus
between groups or farms

4. PRRS and Aujesky’s infections
► Are prevalent and costly diseases of swine
► Can be successfully managed only with
systematic plans and coordinated veterinary
strategies
 Biosecurity – to prevent any movement of virus
between groups or farms
 Control – to minimize the damage done by the
virus in infected farms

5. PRRS and Aujesky’s infections
► Are prevalent and costly diseases of swine
► Can be successfully managed only with
systematic plans and coordinated veterinary
strategies
 Biosecurity – to prevent any movement of virus
between groups or farms
 Control – to minimize the damage done by the
virus in infected farms
 Eradication – to ultimately remove the virus from
farms and regions

6. Biosecurity – the primary strategy
► The security system which prevents the
entry of new virus infections into unaffected
herds (or new strains into infected PRRS
herds)

7. Biosecurity – the primary strategy
► The security system which prevents the
entry of new virus infections into unaffected
herds (or new strains into infected PRRS
herds)
► Transmission of virus from one premise to
another is primarily by way of live animals or
transported body fluids

8. Biosecurity – the primary strategy
► The security system which prevents the
entry of new virus infections into unaffected
herds (or new strains into infected PRRS
herds)
► Transmission of virus from one premise to
another is primarily by way of live animals or
transported body fluids
► Hygiene failures have repeatedly been
shown as the reason virus is introduced

9. The many questions - How “good”
must biosecurity be if we are
confident it is adequate?

10. The many questions - How “good”
must biosecurity be if we are
confident it is adequate?
► Shower in and out of facilities?

11. The many questions - How “good”
must biosecurity be if we are
confident it is adequate?
► Shower in and out of facilities?
► Personnel or veterinary down-times
between groups or farms?

12. The many questions - How “good”
must biosecurity be if we are
confident it is adequate?
► Shower in and out of facilities?
► Personnel or veterinary down-times
between groups or farms?
► What amount of cleaning for facilities
between groups or repopulation?

13. The many questions - How “good”
must biosecurity be if we are
confident it is adequate?
► Shower in and out of facilities?
► Personnel or veterinary down-times
between groups or farms?
► What amount of cleaning for facilities
between groups or repopulation?
► How long must facilities be empty between
groups?

14. Biosecurity – key veterinary
considerations for PRRS and PRV

15. Biosecurity – key veterinary
considerations for PRRS and PRV
► Potential vectors that must be systematically
controlled for both diseases include:

16. Biosecurity – key veterinary
considerations for PRRS and PRV
► Potential vectors that must be systematically
controlled for both diseases include:
 Animal movement and knowledge of disease status

17. Biosecurity – key veterinary
considerations for PRRS and PRV
► Potential vectors that must be systematically
controlled for both diseases include:
 Animal movement and knowledge of disease status
 Transportation personnel and equipment

18. Biosecurity – key veterinary
considerations for PRRS and PRV
► Potential vectors that must be systematically
controlled for both diseases include:



Animal movement and knowledge of disease status
Transportation personnel and equipment
Caretaker and service personnel hygiene

19. Biosecurity – key veterinary
considerations for PRRS and PRV
► Potential vectors that must be systematically
controlled for both diseases include:




Animal movement and knowledge of disease status
Transportation personnel and equipment
Caretaker and service personnel hygiene
Animal care equipment

20. Biosecurity – key veterinary
considerations for PRRS and PRV
► Potential vectors that must be systematically
controlled for both diseases include:




Animal movement and knowledge of disease status
Transportation personnel and equipment
Caretaker and service personnel hygiene
Animal care equipment
► Facility cleanliness and disinfection system

21. Biosecurity – key veterinary
considerations for PRRS and PRV
► Potential vectors that must be systematically
controlled for both diseases include:




Animal movement and knowledge of disease status
Transportation personnel and equipment
Caretaker and service personnel hygiene
Animal care equipment
► Facility cleanliness and disinfection system
► Pig flow management – all out

22. Biosecurity – key veterinary
considerations for PRRS and PRV
► Potential vectors that must be systematically
controlled for both diseases include:




Animal movement and knowledge of disease status
Transportation personnel and equipment
Caretaker and service personnel hygiene
Animal care equipment
► Facility cleanliness and disinfection system
► Pig flow management – all out
► “Managing the behavior of people at all times”

23. Control of PRRS and Aujesky’s
disease requires a clear
understanding of each virus, the
behavior of the virus in herds and
the immunology of these
infections.

24. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Depends on long-term
viremia and copious
virus excretion in body
fluids
Aujesky’s

25. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Depends on long-term
viremia and copious
virus excretion in body
fluids
Aujesky’s
► Short-term viremia but
individuals are latently
infected, infections
recrudesce and
animals again shed
virus

26. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Depends on long-term
viremia and copious
virus excretion in body
fluids
► Post-infection
immunity develops
slowly (weeks) but is
long-lasting and
“sterilizing” immunity
for homologous strains
Aujesky’s
► Short-term viremia but
individuals are latently
infected, infections
recrudesce and
animals again shed
virus

27. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Depends on long-term
viremia and copious
virus excretion in body
fluids
► Post-infection
immunity develops
slowly (weeks) but is
long-lasting and
“sterilizing” immunity
for homologous strains
Aujesky’s
► Short-term viremia but
individuals are latently
infected, infections
recrudesce and
animals again shed
virus
► Post-infection
immunity is short-lived
and is not “sterilizing”
immunity

28. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Virus mutates rapidly
with diverse genetic
variants
Aujesky’s

29. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Virus mutates rapidly
with diverse genetic
variants
Aujesky’s
► Virus is very stable
and strain variation is
not important

30. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Virus mutates rapidly
with diverse genetic
variants
► Herds may become
infected with multiple
variants
Aujesky’s
► Virus is very stable
and strain variation is
not important

31. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Virus mutates rapidly
with diverse genetic
variants
► Herds may become
infected with multiple
variants
Aujesky’s
► Virus is very stable
and strain variation is
not important
► Immunity can
effectively prevent
recrudescence

32. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Virus mutates rapidly
with diverse genetic
variants
► Herds may become
infected with multiple
variants
► Immunity is not
predictably cross
protective
Aujesky’s
► Virus is very stable
and strain variation is
not important
► Immunity can
effectively prevent
recrudescence

33. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Virus mutates rapidly
with diverse genetic
variants
► Herds may become
infected with multiple
variants
► Immunity is not
predictably cross
protective
Aujesky’s
► Virus is very stable
and strain variation is
not important
► Immunity can
effectively prevent
recrudescence
► Immunity from
vaccination is
predictable

34. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Vaccines are not
predictable, safe or
effective tools in PRRS
control programs
Aujesky’s

35. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Vaccines are not
predictable, safe or
effective tools in PRRS
control programs
Aujesky’s
► Vaccine is safe,
effective and essential
to successful control
and eradication
programs

36. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Vaccines are not
predictable, safe or
effective tools in PRRS
control programs
► Lack of “marker”
vaccine technology
makes it impossible to
differentiate immune
response of field vs
vaccine infections
Aujesky’s
► Vaccine is safe,
effective and essential
to successful control
and eradication
programs

37. Contrasting the PRRS and Aujesky’s viruses
PRRS
► Vaccines are not
predictable, safe or
effective tools in PRRS
control programs
► Lack of “marker”
vaccine technology
makes it impossible to
differentiate immune
response of field vs
vaccine infections
Aujesky’s
► Vaccine is safe,
effective and essential
to successful control
and eradication
programs
► Vaccine “markers” and
differential serologic
tests differentiate field
infection from vaccinal
immune response

38. PRRS virus transmission

39. PRRS virus transmission
► Highly infectious virus, requiring few
particles to initiate infection

40. PRRS virus transmission
► Highly infectious virus, requiring few
particles to initiate infection
► Large quantities of virus are shed in most
body fluids and excretions during viremia

41. PRRS virus transmission
► Highly infectious virus, requiring few
particles to initiate infection
► Large quantities of virus are shed in most
body fluids and excretions during viremia
► Virus is NOT hardy outside the pig, does not
persist in the environment

42. PRRS virus transmission
► Highly infectious virus, requiring few
particles to initiate infection
► Large quantities of virus are shed in most
body fluids and excretions during viremia
► Virus is NOT hardy outside the pig, does not
persist in the environment
► Virus dies rapidly in decomposing tissue,
thus autolyzed carcasses pose little risk

43. PRRS virus transmission – bad news

44. PRRS virus transmission – bad news
► Semen contaminated with virus easily transmits
virus

45. PRRS virus transmission – bad news
► Semen contaminated with virus easily transmits
virus
► Injecting multiple pigs with the same needle
efficiently transmits PRRS

46. PRRS virus transmission – bad news
► Semen contaminated with virus easily transmits
virus
► Injecting multiple pigs with the same needle
efficiently transmits PRRS
► Mosquitoes and house flies have been shown to
be potential vectors (other insect candidates?)

47. PRRS virus transmission – bad news
► Semen contaminated with virus easily transmits
virus
► Injecting multiple pigs with the same needle
efficiently transmits PRRS
► Mosquitoes and house flies have been shown to
be potential vectors (other insect candidates?)
► While generally fragile in the environment, special
circumstances (snowball survival) reinforce the
need for clean, dry, disinfected facilities and
equipment

48. PRRS virus transmission – good news

49. PRRS virus transmission – good news
► Aerosol transmission is very hard to
document; distance between farms seems
effective as a barrier

50. PRRS virus transmission – good news
► Aerosol transmission is very hard to
document; distance between farms seems
effective as a barrier
► Standard caretaker and worker hygiene,
clean clothes and washing hands, prevents
transmission

51. PRRS virus transmission – good news
► Aerosol transmission is very hard to
document; distance between farms seems
effective as a barrier
► Standard caretaker and worker hygiene,
clean clothes and washing hands, prevents
transmission
► Drying and disinfection are predictably
effective in decontaminating facilities

52. PRRS virus transmission – good news
► Aerosol transmission is very hard to
document; distance between farms seems
effective as a barrier
► Standard caretaker and worker hygiene,
clean clothes and washing hands, prevents
transmission
► Drying and disinfection are predictably
effective in decontaminating facilities
► Other species are not infected with the virus

53. Aujesky’s transmission contrasted to PRRS

54. Aujesky’s transmission contrasted to PRRS
► The potential for insect vectors is NOT an
issue with Aujesky’s

55. Aujesky’s transmission contrasted to PRRS
► The potential for insect vectors is NOT and
issue with Aujesky’s
► Aerosol or area spread IS an issue as
infected premises are a high risk to any
others within 3km

56. Aujesky’s transmission contrasted to PRRS
► The potential for insect vectors is NOT and
issue with Aujesky’s
► Aerosol or area spread IS an issue as
infected premises are a high risk to any
others within 3km
► Other species are infected with infected
carcasses and meat meal posing a risk

57. Aujesky’s transmission contrasted to PRRS
► The potential for insect vectors is NOT and
issue with Aujesky’s
► Aerosol or area spread IS an issue as
infected premises are a high risk to any
others within 3km
► Other species are infected with infected
carcasses and meat meal posing a risk
► Hygiene steps to prevent PRRS
transmission are effective against Aujesky’s

58. Eradication strategies have been accepted
and shown effective with Aujesky’s.
PRRS eradication efforts are limited, much
is yet to learn but there is success. Given
the limited effectiveness of control
measures, veterinarians will be heavily
involved in PRRS eradication in the future.

59. Elimination of Aujesky’s infection

60. Elimination of Aujesky’s infection
► Modified live, “marker” vaccines are the critical tool
in herd and regional elimination

61. Elimination of Aujesky’s infection
► Modified live, “marker” vaccines are the critical tool
in herd and regional elimination
► Strict movement control procedures must be
clearly understood and enforced

62. Elimination of Aujesky’s infection
► Modified live, “marker” vaccines are the critical tool
in herd and regional elimination
► Strict movement control procedures must be
clearly understood and enforced
► A systematic vaccination strategy, implemented
and accomplished by all producers in the region, is
mandatory

63. Elimination of Aujesky’s infection
► Modified live, “marker” vaccines are the critical tool
in herd and regional elimination
► Strict movement control procedures must be
clearly understood and enforced
► A systematic vaccination strategy, implemented
and accomplished by all producers in the region, is
mandatory
► Systematic serology testing during and after the
elimination strategy, using differential testing,
determines progress of the elimination effort.

64. Example of an Aujesky’s vaccination
strategy using G1 deleted marker vaccine

65. Example of an Aujesky’s vaccination
strategy using G1 deleted marker vaccine
► Breeding herd animals



Entire herd vaccinated every 90 days
“Blanket” vaccination at one time
Repetition is critically important, being careful not to miss
any animals, as immunity is short-lived

66. Example of an Aujesky’s vaccination
strategy using G1 deleted marker vaccine
► Breeding herd animals



Entire herd vaccinated every 90 days
“Blanket” vaccination at one time
Repetition is critically important, being careful not to miss
any animals, as immunity is short-lived
► Growing animals (maternal passive immunity issue)



All animals are vaccinated at 9 weeks of age
A second dose is given at 13 weeks of age
Intranasal vaccine alternative for nursing piglets can
replace the 9 week vaccination

67. PRRS Eradication Processes

68. PRRS Eradication Processes
► Dependant on naturally acquired, sterilizing
immunity in the breeding herd

69. PRRS Eradication Processes
► Dependant on naturally acquired, sterilizing
immunity in the breeding herd
► From this immune sow herd the weaned pigs are
free of virus

70. PRRS Eradication Processes
► Dependant on naturally acquired, sterilizing
immunity in the breeding herd
► From this immune sow herd the weaned pigs are
free of virus
► Pigs are segregated from the sows at weaning and
are reared in a multi-site system

71. PRRS Eradication Processes
► Dependant on naturally acquired, sterilizing
immunity in the breeding herd
► From this immune sow herd the weaned pigs are
free of virus
► Pigs are segregated from the sows at weaning and
are reared in a multi-site system
► Successfully done by breeding stock companies,
this approach is still being explored in commercial
herds and production systems

72. PRRS eradication considerations

73. PRRS eradication considerations
► No vaccine is effective as is the case with
Aujesky’s; serologically mimics infection

74. PRRS eradication considerations
► No vaccine is effective as is the case with
Aujesky’s; serologically mimics infection
► There is no serologic test to differentiate between
vaccine and field infection responses

75. PRRS eradication considerations
► No vaccine is effective as is the case with
Aujesky’s; serologically mimics infection
► There is no serologic test to differentiate between
vaccine and field infection responses
► The testing tools, ELISA, IFA, SN, PCR all require
careful coordination and interpretation

76. PRRS eradication considerations
► No vaccine is effective as is the case with
Aujesky’s; serologically mimics infection
► There is no serologic test to differentiate between
vaccine and field infection responses
► The testing tools, ELISA, IFA, SN, PCR all require
careful coordination and interpretation
► Negative “sentinel animals”, introduced to detect
presence of virus, are a key component of the
diagnostic sequence – this requires careful
management and control

77. Conclusions

78. Conclusions
► Ultimately both PRRS and Aujesky’s diseases
must be eradicated if herds are to be successful
economically

79. Conclusions
► Ultimately both PRRS and Aujesky’s diseases
must be eradicated if herds are to be successful
economically
► The processes for eradication are technically
challenging, and require consistent effort and a
great deal of sampling with careful interpretation

80. Conclusions
► Ultimately both PRRS and Aujesky’s diseases
must be eradicated if herds are to be successful
economically
► The processes for eradication are technically
challenging, and require consistent effort and a
great deal of sampling with careful interpretation
► Veterinarians have a huge responsibility. A large
commitment of time and energy will be required of
us if eradication measures are to be effective.

81. AMVEC is an excellent Conference
thank you for this opportunity to
attend and to present this paper to
you, my colleagues
and for the wonderful hospitality in
beautiful Puerto Vallarta