Avian Influenza (AI) Outbreak Avian Influenza (AI) Outbreak among - - PowerPoint PPT Presentation

Avian Influenza (AI) Outbreak Avian Influenza (AI) Outbreak among Poultry in a High Risk Area, among Poultry in a High Risk Area, Thailand, June Thailand, June-

• December 2005

December 2005

Karoon Karoon Chanachai Chanachai, DVM

, DVM

Field Epidemiology Training Program Field Epidemiology Training Program -

• Thailand

Thailand

Tippawan Prakmawongsanon Tippawan Prakmawongsanon,

, DVM, DVM, MSc MSc

Suphanburi Suphanburi Provincial Livestock Office Provincial Livestock Office

Chuleeporn Chuleeporn Jiraphongsa Jiraphongsa, MD, PhD

, MD, PhD

Field Epidemiology Training Program Field Epidemiology Training Program -

• Thailand

Thailand

Background Background

Jan 2004: the first avian influenza-H5N1 (AI) outbreak in poultry officially reported in Thailand. 2004-2005: the AI persisted in same areas In Thailand, native chickens, broilers, layers, bantams, guinea fowl, quail, ducks, geese, sparrow, pigeons and Asian open- billed stork were found AI positive

Geographical Location of AI Confirmed Flocks Jul 2004-Dec 2005

Most affected areas were in central and lower northern parts of Thailand

50 100 150 200 250 300

3/7 - 9/7 10/7 - 16/7 17/7 - 23/7 24/7 - 30/7 31/7 - 6/8 7/8 - 13/8 14/8 - 20/8 21/8 - 27/8 28/8 - 3/9 4/9 - 10/9 11/9 - 17/9 18/9 - 24/9 25/9 - 1/10 2/10 - 8/10 9/10 - 15/10 16/10 - 22/10 23/10 - 29/10 30/10 - 5/11 6/11 - 12/11 13/11 - 19/11 20/11 - 26/11 27/11 - 3/12 4/12 - 10/12 11/12 - 17/12 18/12 - 24/12 25/12 - 31/12 1/1 - 7/1 8/1 - 14/1 15/1 - 21/1 22/1 - 28/1 29/1 - 4/2 5/2 - 11/2 12/2 - 18/2 19/2 - 25/2 26/2 - 4/3 5/3 - 11/3 12/3 - 18/3 19/3 - 25/3 26/3 - 1/4 2/4 - 8/4 9/4 - 15/4 16/4 - 22/4 23/4 - 29/4 30/4 - 6/5 7/5 - 13/5 14/5 - 20/5 21/5 - 27/5 28/5 - 3/6 4/6 - 10/6 11/6 - 17/6 18/6 - 24/6 25/6 - 1/7 2/7 - 8/7 9/7 - 15/7 16/7 - 22/7 23/7 - 29/7 30/7 - 5/8 6/8 - 12/8 13/8 - 19/8 20/8 - 26/8 27/8 - 2/9 3/9 - 9/9 10/9 - 16/9 17/9 - 23/9 24/9 - 30/9 1/10 - 7/10 8/10 - 14/10 15/10 - 21/10 22/10 - 28/10 29/10 - 4/11 5/11 - 10/11 11/11 - 17/11 18/11 - 24/11 25/11 - 1/12 2/12 - 8/12 9/12 - 15/12 16/12 - 22/12 23/12 - 29/12 2004 2005

Laboratory Confirmation of AI in Poultry Flocks, Laboratory Confirmation of AI in Poultry Flocks, Thailand Jul 2004 Thailand Jul 2004 – – Dec 2005 Dec 2005 (n = 1,724; (n = 1,724; data source Department of Livestock

data source Department of Livestock Development ,Thailand Development ,Thailand)

)

Number of confirmed flock

Date

2004 2005

active surveillance campaign active surveillance campaign active surveillance campaign active surveillance campaign

Background (2) Background (2)

2005: 848 suspect and 188 AI confirmed flocks First epizootic occurred Jan to Apr,

No flock reported positive for 2 months Epizootic recurrence in June 2005

Jun – Dec 05: 70 confirmed flocks

Suphanburi 25 flocks Kampangphet 23 flocks Kanchanaburi 6 flocks

Objectives Objectives

To characterize the AI poultry outbreak in Suphanburi province from Jun to Dec 2005 To identify the possible risk factors of the outbreak To give recommendations for outbreak investigation, control and prevention in the future

Methodology (1) Methodology (1)

Descriptive study

Reviewed the positive cases reported in Suphanburi at Department of Livestock Development Reviewed active case finding in poultry at Suphanburi Provincial Livestock Office Interviewed poultry owners of all confirmed flocks in the province about

demographic data clinical symptoms

• nset date

number of dead poultry in the first three day

• ther characteristics of the outbreak

Case Definition of AI Infected Flocks Case Definition of AI Infected Flocks

Poultry flocks in Suphanburi province*

Suspect flocks: Poultry flocks with > 10% die off within one day from unknown cause and have at least one of following clinical signs: sudden death, respiratory system illness, neurological system illness or diarrhea Confirmed flocks: Flocks with laboratory confirmation of H5 by hemagglutination test performed by National Institute of Animal Health

* Case definition of the Department of Livestock Development during Jun – Dec 2005

Methodology (3) Methodology (3)

Matched case control study

Conducted in Nov 2005 to identify potential risk factors among confirmed flocks

1 case : 2 control Cases were confirmed flocks from descriptive study Control flocks were randomly selected from houses within 20 houses around case flocks; control flocks had no abnormal death of poultry Jun – Nov 2005

Analysis was performed using Epi-Info version 3.3

Methodology (4) Methodology (4)

Environmental study

Reviewed data of poultry population and natural bird survey from provincial natural resources authority Analyzed the association of poultry population and

• ccurrence of suspect and confirmed AI at the village

level using correlation analysis

Results Results

AI Confirmed Flocks in AI Confirmed Flocks in Suphanburi Suphanburi Province, Jun Province, Jun-

• Dec 2005

Dec 2005

There were 54 suspect flocks and 25 confirmed flocks. Confirmed flocks were found in 6 of the province’s 10 districts. The flocks were located in 22 sub-districts and 24 villages.

* There are 10 districts, 110 sub-districts and 998 villages in Suphanburi province

Spatial Distribution of Suspect and AI Confirmed Flocks Jun- Dec 2005

2 4 6 8 10 12

1 6 /6 -2 2 /6 2 3 /6 - 2 9 /6 3 0 /6 - 6 /7 7 /7 - 1 3 /7 1 4 /7 - 2 0 /7 2 1 /7 - 2 7 /7 2 8 /7 - 3 /8 4 /8 - 1 0 /8 1 1 /8 -1 7 /8 1 8 /8 -2 4 /8 2 5 /8 -3 1 /8 1 /9 -7 /9 8 /9 -1 4 /9 1 5 /9 -2 1 /9 2 2 /9 - 2 8 /9 2 9 /9 -5 /1 0 6 /1 0 -1 2 /1 0 1 3 /1 0 -1 9 /1 0 2 0 /1 0 - 2 6 /1 0 2 7 /1 0 - 2 /1 1 3 /1 1 -9 /1 1 1 0 /1 1 -1 6 /1 1 1 7 /1 1 -2 3 /1 1 2 4 /1 1 -3 0 /1 1 1 /1 2 -7 /1 2

Onset Date of Suspect and Confirmed Flocks Onset Date of Suspect and Confirmed Flocks Jun Jun-

• Dec 2005 (n= 79)

Dec 2005 (n= 79)

Analytic study

Suspect Confirmed

Number of flocks Date

Flock Size by Type of AI Confirmed Flock Size by Type of AI Confirmed Flocks Flocks

Type of flock Number

Median Flock Size (range)

Proportion (% )

Backyard Chickens Free-grazing ducks Layers Broilers Quail 16 Total 64 2 100 (10-200) 3,450 (2,400-4,500) 1,010 (19-2,000) 9,400 (8,000-10,800) 3 96,000 (50,000-122,000) 12 25

• 8

2 8 2 8 100

Cumulative Mortality Rate among Backyard Chicken and Cumulative Mortality Rate among Backyard Chicken and Free Free-

• grazing Duck Flocks with Confirmed AI (n= 18)

grazing Duck Flocks with Confirmed AI (n= 18)

Percent Day after onset

a (b, c) = median (1st , 3rd quartile)

5 10 15 20 25 30 35 day1 day2 day3 4 (2,7) 10 (6,29) 19 (13,27)

Cumulative Mortality Rate among Broiler, Layer and Quail Cumulative Mortality Rate among Broiler, Layer and Quail Flocks with Confirmed AI (n= 7) Flocks with Confirmed AI (n= 7)

Percent Day after onset

a (b, c) = median (1st , 3rd quartile)

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 day1 day2 day3

0.10 (0.03-0.31) 0.31 (0.07-2.97) 0.46 (0.15-0.81)

Timeliness of Important Events Timeliness of Important Events among the Confirmed Flocks among the Confirmed Flocks

Abnormal death of poultry

• bserved by owner

Owner informed involved person Culling poultry flock

2 days (0 - 9 days) 2 days (0-18 days)

Results of Results of Match Case Control Study Match Case Control Study

Univariate Univariate Matched Analysis Results Matched Analysis Results

Case Control

Exp

Non- exp

Exp

Adjusted odds ratio (95% CI )

Abnormal die off of neighborhood poultry

15 8 17 32 4.25 (1.22-14.84)

dead poultry introduced to farm site (by dog)

3 22 50 Infinite

Shared feeding area with other domestic poultry

7 18 10 40

Non- exp

1.80 (0.48-6.75)

Risk factors

Univariate Univariate Matched Analysis Results (2) Matched Analysis Results (2)

Case Control

Exp

Non- exp

Exp

Match odd ratio (95% CI )

Contact or proximity with free-grazing ducks

2 23 7 43 0.67 (0.13-3.30)

Contact or proximity with water fowl feeding area

15 10 14 36 6.33 (1.64-24.47)

Observed illness or death among natural birds

9 16 3 47

Non- exp

8.50 (1.79-30.31)

Risk factors

Univariate Univariate Matched Analysis Results (2) Matched Analysis Results (2)

Case Control

Exp

Non- exp

Exp

Match

• dd ratio

(95% CI )

Cock fighting

3 22 12 38 0.45 (0.12-1.72)

Introduction of possible fomites (vehicle, poultry)

6 19 8 42

Non- exp

2.00 (0.71-5.66)

Risk factors

Multivariate Matched Analysis Results Multivariate Matched Analysis Results

Case Control

Exp

Non- exp

Exp

Adjusted odd ratio (95% CI )

14

10.68 (1.29-88.38)

dead poultry introduced to farm site (by dog)

3 22 50 infinite

Abnormal die offs of neighborhood poultry

15 8 17 32

1.87 (0.42-8.24)

Observed sick or dead natural birds

9 16 3 47

Contact or proximity with water fowl feeding area

Non- exp

2.42 (0.39-14.97)

10 36 15

Risk factors

I nverse Distance Weighted of Free-grazing Ducks and Point Location of AI outbreaks

• Total 736 free-

grazing duck flocks and 1,693,121 free- grazing ducks

• P-value = 0.70

(Correlation analysis)

27 27

• There are total

47,426 backyard chicken flocks and 1,392,783 backyard chickens

• P-value = 0.30

(Correlation analysis )

I nverse Distance Weighted of Backyard Chicken Population and Point Location of AI outbreaks

AI Survey Among Natural Birds AI Survey Among Natural Birds

Jun-Dec 2005, 399 natural live birds in Suphanburi were caught for AI screening and all specimens were negative. However, laboratory found confirmed AI in natural birds (sparrow, pigeon, Asian open- billed stork) during Jun-Dec 2005 in 2 neighboring provinces (Aunthong and Kanchanaburi provinces) * * Data source: personal contact

Sub Sub-

• district of Neighboring Province that

district of Neighboring Province that Found Confirmed AI in Natural bird Found Confirmed AI in Natural bird

Kanchanaburi Aunthong

Natural bird positive

Discussion Discussion

Mortality Rates Lower in Commercial Farms Mortality Rates Lower in Commercial Farms

Mortality rates post-onset were much lower in broiler, layer and quail flocks than in backyard chicken and free grazing duck

• flocks. This might be due to:

Heightened alertness of commercial poultry workers to unusual deaths/illness may lead to earlier detection and control. Increased hygiene in commercial settings may limit transmission. Case definition for AI surveillance should be considered

Risk Factors for AI Occurrence Risk Factors for AI Occurrence

Contact or proximity with water fowl feeding areas and introduction of sick poultry into farms by dogs were the strongest risk factors for AI occurrence.

Water fowl have played an important role in spreading of AI in other settings; these results support those findings. Presence of free-grazing ducks was not associated with AI in this study. Characteristics of the outbreak during our study (Jun-Dec 05) may differ from the

• utbreak in the past (Jul 2004 to Mar 2005;

Gilbert et al., 2006)

Limitations Limitations

Some suspect flocks did not have any specimens sent for testing. Routes of water fowl movement were not available to analyze other risk factors for AI. Data on the AI occurrence in the area surrounding the confirmed flocks was sometimes not available due to lack of reporting from

• wners.

Movement of free-grazing duck may effect to the data analysis

Recommendations (1) Recommendations (1)

For poultry owners:

Prevent poultry from contact with natural birds, especially water fowl Protect poultry from introduction of ill or dead poultry and natural birds Timeliness of AI notification to officials should be improved.

Recommendations (2) Recommendations (2)

Greater co-operation between staff of multiple

• rganizations for improving AI early detection,

prevention and control Risk factors for AI outbreak in poultry should be evaluated from time to time Further epidemiological study of AI needed:

Factors influencing AI notification by the poultry

• wner

Natural birds movement as the role of AI outbreak

Acknowledgements Acknowledgements

• Dr. Nirandorn Auntrakulsuk
• Dr. Sirikarn Chotiprasatinthara
• Dr. Potjaman Siriarayaporn

ESRI-Thailand

• Dr. Chris Skelly
• Dr. Augusto Pinto
• Dr. Micheal O’Reilly
• Dr. Poh-Chin Lai

Staffs of bureau of disease control and veterinary service, Department of livestock Development Staff of Suphanburi provincial livestock office FEPT staffs and trainees