This document summarizes the field of veterinary epidemiology and techniques used. It discusses the goals of field epidemiology to quickly inform and implement interventions to prevent illness. Emerging diseases require rapid response. The document also discusses strategies to control endemic diseases, including reducing spread and losses. Epidemiological studies explore risk factors and associations to evaluate impacts on production, economics, and societies. A variety of epidemiological techniques are used, including multivariable analysis, simulation modeling, spatial-temporal analysis, and network analysis.

1. Chaidate Inchaisri
Department of veterinary Medicine
Faculty of Veterinary Science
Chulalongkorn university
E-mail address: Chaidate@hotmail.com

2. Field epidemiology
• “A primary goal of field epidemiology is to
inform, as quickly as possible, the processes of
selecting and implementing interventions to
lessen or prevent illness or death when such
problems arise” (Goodman and Buehler, 2008)
• An emergic diseases
– Require quick response diagnosis and
managements

3. Disease control in endemic areas
• How to reduce and prevent the spread of infection?
• How to reduce disease loss?
• Do we need to eradicate or to live with disease?
• In long term, is it possible to eradicate that disease in
some areas?
• If yes, How to do it?
– Epidemiological study
• Host, agent, environment and transmission
– Difference locations, farms
– Difference strategies

4. Epidemiological procedure
• Identify problems
• Study designs
• Explore for visualization
• Find risk factors, associations between factors,
causes
• Evaluate the effect on production (animal
performance)
• Evaluate the effect on economics and social
• Give priority and make decision

5. The epidemiological techniques
Multivariable
analysis
Veterinary Tempo-spatial
Simulation
and network
model epidemiology analysis
Economics

7. 32.96 18 16.08
36 14.74
Percent of positive farms
(n=91) (n=286)
Percent of positive farms
32 16 (n=217)
28 14 10.76
24 12 (n=223)
20 13.08 13.79 10
6.11
16 11.11 (n=107) (n=116) 8
(n=117) (n=229)
12 6
8 2.24 4 1.18
0.49
0 (n=89) (n=253)
4 (n=38) 2 (n=204)
0 0
2549 2550 2551 2552 2553 2554 2549 2550 2551 2552 2553 2554
18 18
Percent of positive farms Percent of positive farms
Percent of positive farms Percent of positive farms
16 สุพรรณบุรี 16 ราชบุรี
14 14
12 12 8.73
10 10 (n=206) 7.14
6.45 (n=224)
8 (n=341)
8
6 3.1 6
1.67 (n=483) 1.76 4 1.38 0.89
4 (n=452) 0.31 0.3 (n=217)
0.47 0.35
2
(n=179) 2 (n=209) (n=280) (n=224)
(n=314) (n=329)
0 0
18 2549 2550 2551 2552 2553 2554 18 2549 2550 2551 2552 2553 2554
16 16
14 กาญจนบุรี 14 11.68 เพชรบุรี
(n=77)
12 12
10 10 6.28 6.53
6.04
8 8 (n=175) (n=149) (n=152)
6 2.23
6
1.81 1.85
4 0.36 (n=760) 0.98
0.32 0.13 (n=827)
4 (n=103)
1.28
(n=813) (n=156)
2 (n=548) (n=913) (n=760) 2
0 0
2549 2550 2551 2552 2553 2554 2549 2550 2551 2552 2553 2554
ประจวบคีรีขนธ์
ั นครปฐม (Panumas et al., 2554)

8. Percent of serum positive per flock
30
n=2-8
25
Percent of positive goats
20
15
n=7-9
n=52-87
10 n=7-12 n=25-32 n=13-17
n=16-19 n=28-39
5
n =40-46
0
A B C D E F G H I J K L M N O P
Farm (n=2-112 per farm)
เมษายน ิ
สงหาคม ธันวาคม
(Panumas et al., 2554)

9. DLD strategy
• Test and slaughter
– A serum positive goat by a serial test of ELISA and
complement fixation test (CFT) is eradicated.
– For a positive farm, all goats are retested until no
more positive results in the herd (a negative farm
at level B).
– After 6 months, a goat farm is declared to be free
from brucellosis at the level A when all goats in
flocks level B are negative for the sequence tests.

10. The structure of model for one time step
Kid death
Kidding
Sales • Closed flock
 Service per • Constant flock size
pregnancy
• Contact transmission rate???
 Abortion
Flock size •Population structure
Negative
•Prevalence
serum test
Test •Sensitivity
•Specificity
•Positive serum test
Culling •Old goat, death
•Sales
Monte Carlo Stochastic-dynamics Approach

11. Parameters Default
Input data used for Flock size Lognorm(27,32)
the simulation model Prevalence RiskUniform(0.01,0.5)
Sensitivity
ELISA RiskUniform(0.87,0.89)
CFT RiskUniform(0.79,0.82)
Specificity
ELISA RiskUniform(0.84,0.99)
CFT RiskUniform(0.87,1)
Contact number per month RiskPoisson(10,
RiskTruncate(1,30))
Transmission per contact RiskUniform(0.0005,0.001)
Transmission per service RiskUniform(0.4,1)
Ratio female per male RiskTriang(1,1,38.2)
Number services per pregnancy RiskNormal(1.7, 0.9),
RiskTruncate(1,3)
Litter size RiskNormal(1.2,0.4),
RiskTruncate(1,4)
Kidding per year RiskNormal(1.34,10),
RiskTruncate(1,2)
Abortion rate RiskNormal(0.03,0.03),
RiskTruncate(0,0.5)
Kid death rate RiskNormal(0.13,0.03),
RiskTruncate(0.07,0.2)
Program interval 1-12 months Adult death rate RiskUniform(0.05,0.15)

12. No strategy to control disease
Stochastic default values (10,000 flocks)
60
50
Percent of 100% positive flocks
40
30
20
10
0
0 12 24 36 48 60 72 84 96 108 120 132 144 156 168 180 192 204 216 228 240
Months

13. Percent of successive flocks in eradication
program with uncertain inputs
Stochastic default values (10,000 flocks)
70
60
Percent of successive flocks
in eradication program
50
40
30
20
10
0
0 12 24 36 48 60 72 84 96 108 120 132 144 156 168 180 192 204 216 228 240
Months

15. 99 99 98 98
100 95 95
Percent of successive flocks in eradiation program
90
80
within one year 70
60
50
40
30
20
10
0
1 3 6
Eradication Program Interval (months)
Perfect specificity Average specificity Poor specificity

16. Increase transmission per contact
Within 1 year
Eradication program interval = 3 months

20. Network between flocks with the size of node represents the value of degree centrality with positive
flock (red circle) and negative flock (blue circle). The box node represents the flocks without knowing
disease status.

21. Conclusions
• The important of animal movements on spreading of
disease and the specificity of diagnostic test in
eradication program
• Add other strategies
– Add other methods or technologies to control animal
movement
– Simultaneous test and slaughter program with animal
movement control
– Establish the goat farmer community to reduce
uncontrollable movements between provinces
– Quarantine farms
– Improve the specificity of diagnostic test
– When the prevalence at flock level is very low and the
specificity of diagnostic test is poor, consider culling
positive flocks.

22. Further studies
• Do more research in other areas
• Production structure, production chain, value
chain
• Evaluate the success of other strategis
• Evaluate the economical benefit of other
programs

24. GISTA (Geo-Informatics and Space Technology Development Agency)
สำนักงำนพัฒนำเทคโนโลยีอวกำศและภูมิสำรสนเทศ (องค์ กำรมหำชน)

28. 90
เปอร์เซ๊นต์ของพืนทีทได้ร ับผลกระทบจากปัญหาอุทกภ ัย
80 อ.ชุมแสง
อ.เก ้าเลียว
้
70
อ.ท่าตะโก
60 อ.โกรกพระ
อ.เมืองนครสวรรค์
50
ั
อ.บรรพตพิสย
40 อ.พยุหะคีรี
อ.ตาคลี
30
อ.หนองบัว
้ ่ ี่
20 อ.ลาดยาว
อ.แม่วงก์
10 อ.ไพศาลี
กิงอ.แม่เปิ น
่
0
กิงอ.ชุมตาบง
่
-10 อ.ตากฟ้ า

29. 65%
38%
82%
51%
30%
40%
53%
78%
49%
69%
73%
71%

31. Representation of location and size of significant clustered areas for poultry farming loss per square
kilometer. The degree of loss is indicated by the intensity of color (high intensity 0 high color)

32. Representation of location and size of significant clustered areas for swine farming loss per square kilometer. The degree
of loss is indicated by the intensity of color (high intensity 0 high color)

33. Conclusions
• Cluster mapping reveals the area with high
risk in farming loss due to the flooding
• This helps planners to assess spatial risk
factors, and to ascertain what would be the
most suitable types of livestock farming and
which period should be avoided for the
livestock farming

34. Farm DLD
University Vet
Society

35. ปั ญหำ???
วำงแผน ออกแบบกำรศึกษำและกำรวิเครำะห์ ปัญหำ

36. ร่ วมมือ ร่ วมใจ

37. บริกำรสังคม

38. เรี ยนรู้ ชุมชน

39. ศึกษำ วิจัยภำคสนำม

40. รวบรวมข้ อมูล

41. วิเครำะห์ ข้อมูล
นำเสนอรูปแบบกำรแก้ ปัญหำ
ถ่ ำยทอดควำมรู้ส่ ูชุมชน

42. Thank you