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1. Brucellosis Epidemiological
Surveillance System in Animal
Health Sector
By
Prof. Dr. Mohamed Refai
Faculty of Veterinary Medicine,
Cairo University, Giza, Egypt
Tel:33806554, 0105187590, E-mail mohrefai@yahoo.com

2. Points to be discussed in this
lecture:
 Definition of surveillence system
 Objectives of surveillence system
 Means and tools for the control of
brucellosis
 Evaluation and monitoring of the
surveillence system

3. Epidemiological Surveillance
* Epidemiological Surveillance is the
ongoing and systematic collection,
analysis and interpretation of health-
related data
* It involves describing and monitoring
health events in populations of animals
and humans

4. Surveillance System
A surveillance System is a set of activities,
institutions, facilities and procedures
• to conduct, analyze, transfer, and diffuse
information
• for planning, management, and evaluation of
activities in a given field, sector, services, etc.
*i.e. a surveillance system is designed for
decision-making

5. Surveillance System
 activities : herd-visits, serological tests,
vaccination, etc
 institutions : local vet. units, laboratories, data
processing centers, etc
 facilities : vehicles, computers, faxes etc.
 procedures : filling of forms, data storage, data
processing, analysis and transfer

6. Epidemiological Surveillance System
provides answers to the following questions
 When infection occurred?
 Where infection occurred?
 What is the source of infection?
 What is the mode of transmission?
 How extensive is the infection?
 Is the prevalence and incidence increasing,
decreasing or static?
 Which animal species is/are involved?
 What species of Brucella are involved?, etc.

7. Challenges in designing surveillance
programme for brucellosis
 The infection is chronic
 Symptoms and I.p. are variable
 Laboratory confirmation is essential
 Lack of animal identification
 Poor movement control, etc.

8. Designing and operating
brucellosis surveillance system
The following points should be considered:
1. Identifying indicators of human and animal
health events
2. Establishing clearly defined objectives
3. Developing specific case definition
4. Identifying existing data sources or develop new
data collection systems, including a flow chart
5. Defining role of laboratories
6. Analysing and interpreting data
7. Developing dissemination methods
8. Evaluating the surveillance system

9. Designing and operating
brucellosis surveillance system
1. Identify indicators of human and animal
health events
 Numerical: e.g. number of known infected herds
 Ratios: e.g. number of newly identified herds in
a year compared with that of previous year
 Rates (percentages): number of infected herds
divided by number of herds at risk
Incidence (new cases) rate is preferred than
prevalence (all cases) rates because it reflects
better the dynamics of the disease

10. Designing and operating
brucellosis surveillance system
2. Establish clearly defined objectives
 Determination of the incidence and prevalence
of infected humans, animals, herds, or group of
animals, villages, regions, etc
 Detection of epidemics and sporadic or endemic
cases
 Identification of modes and means of
transmission to humans, or between animals
 Monitoring of short- and long term trends by
location and over time

11. Designing and operating
brucellosis surveillance system
3. Develop specific case definition
 In animals: using isolation and serology to
place every herd or animal in one of 3
categories: positive, negative or uncertain
 In man: using symptoms and signes + lab.
Test to describe possible, probable or
confirmed cases

12. Designing and operating
brucellosis surveillance system
4. Identify existing data sources or develop
new data collection systems, including a
flow chart
 Passive Surveillance System (monitoring)
the routine mandated reports received by health
or veterinary departments
 Active Surveillance System
the specific efforts made to supplement the
passive data by use of directed investigations,
surveys and epidemiological studies

13. Passive Surveillance System
Data passively acquired from :
 Abortion submissions to diagnostic lab.
 Routine testing of on-farm animals, such
as milk or blood
 Notification from field veterinarians
 Off-farm sampling from markets or
slauhgterhouses
All these data may be biased

14. Passive Surveillance System
 Advantages:
* Generally less costly than active surveillance
* Huge amounts of data are collected
 Disadvantages:
* Its specificity and sensitivity are generally
unknown
* Data may be biased
* Periodic evaluation of the system is needed

15. Active Surveillance System
3 approaches
 1. Total (census) testing
efficient but costly
 2. Random (probability-based) sampling,
provides statistically reliable estimates
 3. Non-random (purposive) sampling of
suspected high-risk group
likely to be biased

16. Random (probability-based)
sampling
 Simple Random Sampling, using tables or
computer-generated numbers
 Systematic Random Sampling, by
selecting every nth animal, herd, village, etc
 Stratified Random Sampling, by dividing
population into sections e.g. owners, breeds, etc
 Multistage Random Sampling, e.g.
randomly selected herds, then randomly
selected animals within a herd

17. Active Surveillance System
 Advantages:
* The performance of the system is
measurable and prederterminable
 Disadvantages:
* Increased expenses involved
* Limitation of only selected data

18. Which type of Surveillance
System to be applied?
Due to advantages in both ways
 Passive collection is the main source of data
 Active collection is suitable for ad hoc surveys,
which are carried out to:
* evaluate the performance of passive data
collection
* evaluate the need for implementation of a
routine system for data collection

19. Sources of passive data
collection
 Peripheral public health services
 Peripheral veterinary services
 Hospitals
 Veterinary laboratories and clinics
 Physicians and veterinary practioners
 Universities
 International organizations

20. Sources of active data collection
 Surveys for the presence or absence of
the disease
 Surveys to prove that the disease is not
present
 Surveys to establish the level of
occurrence of the disease (prevalence)

21. Factors influencing Brucellosis
Surveillance
 Political and legal factors
 Financial and administration factors
 Culture, motivation and education factors
 Veterinary Services infrastrucure factors
 Intersectoral collaboration and cooperation

22. Factors to be considered in
Designing a Surveillance System
 The major species of Brucella infecting man and
animals in the country
 The current or baseline levels of infection in the
primary animal reservoirs (prevalence)
 The units of observation (herd, village, etc.)
 Test eligibale animals
 Type of livestock production, marketing and
slaughter systems
 Information on animal numbers and
identification
 Laboratory support and testing strategies

23. Data recording systems for
surveillance
 Herd, flock or village form
 Individual animal sample form
 Laboratory investigations form
 Abortion outbreak/incidence form
 Records of on-farm testing
 Records of off-farm testing
 Epidemiological investigation of reactor herd
form

24. Control of brucellosis in
animals
 1. Prevention of exposure of
animals to infection
 2. Rapid recognition of infected
animals
 3. Measures to be taken in infected
herds
 4. Vaccination

25. 2. Rapid recognition of infected
animals
*Abortion, if it occurs
*Presence of the organism in the body by
bacteriological examination of
each abortion or premature birth
*Presence of antibodies in diagnostic
titres by regular serological testing
of animals

26. Diagnosis of brucellosis
*Accordingly, diagnosis depends on:
1. Isolation of Brucella which is
conclusive if +, but not when -
2. Detection of antibodies which is
conclusive if - , but it is not 100%
conclusive when +(false +, false -)

27. Isolation of brucellae
 Isolation is the most definitive
diagnosis when it is positive.
 Failure to isolate the organism
does not mean negative result.

28. Isolation failure may be due to:
 the viability and numbers of
organisms in the sample
 the nature of the sample, which
is commonly contaminated.

29. Serological Diagnosis of
brucellosis
 Although the serological diagnosis
is not 100% reliable when positive
 It is the main tool for the rapid
recognition of infected herd and
individual animals

30. A positive serology means:
 field strain infection
 vaccination infection
 residual vaccination titre
 cross-reactivity with other
organisms, like Yersinia,
Salmonella, Pasteurella etc
 human errors.

31. Polymerase chain reaction (PCR)
 PCR is particularly useful in case of
tissues and fluids contaminated with non-
viable or low numbers of Brucella
organisms in diagnosis,
 It can detect Brucella DNA.
 A good sensitivity of PCR was reported by
Fekete et al. (1990 a and 1990b), Baily et
al. (1992) and Da Costa et al. (1996).

32. Vaccination

33. Natural infection gives life-long
immunity
This means the best immunity is
achieved by using live vaccines
Bang, 190

34. ATTENUATED BRUCELLA VACCINES
 Brucella abortus Strain 19
Spontaneous loss of virulence
 Brucella suis 2
by in-vitro transfer
 Brucella melitensis Rev 1
Selective mutagenesis
 Brucella abortus RB51
through antibiotics

35. Brucella abortus Strain 19 (S19)
vaccine
 1. It is Brucella abortus biovar 1
 2. Can be smooth or rough
 3. Does not revert to virulence
 4. Rarely persists in the body for
long
 5. Is not excreted

36. Brucella melitensis Rev 1
vaccine (Elberg,1955)
 Streptomycin independent variant of
streptomycin-dependent mutant of B.
melitensis biovar 1
 Genetically stable
 Low virulence , good immunogenicity
 Effective protection in small ruminants

37. Vaccines through genetic
engineering
 aim : to produce alternative
vaccines that are:
* safe and
* do not induce antibodies,
which interfere with the
serodiagnosis of field infection.

38. Brucella cell components acting as
antigens
 1. Purified extracts
 2. Cell wall fractions
 3. Lipopolysaccharide (LPS)
 4. O-polysaccharides (OPS)
 5. Outer membrane proteins (OMPs)
 * conserved in all Brucella species
 6. Ribosomal fractions
 7. DNA

39. Conclusion about Vaccines
through genetic engineering
 Subunit vaccines proved to be not
effective in protecting animals
from subsequent infection
(Confer et al., 1987 and Winter et al., 1988).

40. The failure to obtain an effective subunit or
recombinant monovalent Brucella vaccine
 This problem is in great extent
related to the antigen processing
and presentation events which are
rather complex
(Schurig, 1994).

41. The failure to obtain an effective subunit or
recombinant monovalent Brucella vaccine
 Moreover, microorganisms do not
express the same antigens at all times
(Yura et al., 1993).
 This is why, the best immunity is
commonly achieved by live
microorganism.

42. A good, strong and long-lasting
immunity against Brucella requires
that:
1. the vaccinal strain persists a time
longe enough in lymphoid organs
to produce the desired immunity
2. the vaccinal strain has a low but real
residual virulence linked to ability to
multiply and resist

44. Brucella abortus RB51
* It is a laboratory-derived rough mutant
of the virulent strain 2308 of Brucella
abortus
* Rifampin and penicillin resistant
* It contains the same OMP as S19 and
S2308

45. The genome sequence of Brucella
melitensis strain 16M
 contains 3,294,935 bp on 2
chromosomes:
 2,117,144 bp and 1,177,787 bp
encoding 3,197 ORFs.
 2,487 (78%) ORFs were assigned
functions

46. Surveillance techniques /Stage of
brucellosis control programm
 No or minimal efforts to control brucellosis
 Intensive vaccination phase of herds and
flocks
 Test and removal, segregation or
slaughter phase
 Freedom phase: herds, regions and
countries

47. No or minimal efforts to control
brucellosis
 Voluntary investigation of abortion
(passive)
 Sero-surveillance (active)
 Bacteriological and serological
examination of tissues and blood from
cattle of breeding age at markets or
slaughter (active)

48. Intensive vaccination phase of
herds and flocks
 Evaluate vaccination coverage, over 80%
should be seropositive within 2-3 w after
vaccination
 Monitor abortion rate
 Monitor randomly selected herds by tests that
distinguish between infected and vaccinated
animals such as competitive ELISA
 Culture blood and tissue samples of randomly
selected slaughtered animals

49. Test and removal, segregation or
slaughter phase
 Use screening test for identifying infected herds
 Use confirmatory test for confirmation of cases
 Once infected herd has been identified, all test-
eligible animals should be tested:
animals of 18-20 m at 3-6 m intervals
 Once incidence or prevalence rates decreased,
start market and/or slaughterhouse testing with
trace-back efforts

50. Freedom phase: herds, regions
and countries
 Periodical sero-surveillance
 No vaccination for at least the past 3 years
 All reactors are slaughtered
 Newly introduced animals officially free
 MRT and indirect ELISA are primary
methods of surveillance for dairy herds
 Test prior and after movement
 Test adjacent herds

51. Evaluation of Brucellosis
Surveillance System
 Evaluate the brucellosis surveillance indicators
 Evaluate the overall system for simplicity,
flexibility, acceptability, sensitivity, predictive
value, representativeness and timeliness
 Evaluate the usefulness of information obtained
by surveillance for actions taken by decision-
makers
 Evaluate the out-come in relation to objectives
 Evaluate conclusions and recommendations

52. Brucellosis Surveillance Indicators
 Performance indicators
incidence rates based on groups of animals is
the most sensitive indicator for success or failure
of a programme
 Resource indicators
cost per test (serology, Bacteriology)
cost for epidedmiological investigation
cost per animal for vaccination
 Diagnostic indicators

53. Brucellosis Surveillance Indicators
Diagnostic indicators
 Number of complete herd test at monthly
intervals needed to clear herds of infection
 Efficiency of trace-back procedures
 Number of culture-positive animals in
relation to number of seropositive ones
 Number of serological tests in a herd
 Number of animals or herds vaccinated
 Mean quarantined period of a herd

54. ‫استماعكم‬ ‫حسن‬ ‫علي‬ ‫شكرا‬
Thank you for your
attention