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AVIAN INFLUENZA IN VIETNAM:SITUATION AND LESSONS LEARNED
Assoc. Prof. Nguyen Tran Hien, MD, MPH, PhD.Director, National Institute of Hygiene and Epidemiology (NIHE)
Hanoi, Vietnam
NIHE
OVERVIEW OF AVIAN INFLUENZA
SITUATION IN VIETNAM, DEC 2003 – UNTIL NOW
• From Dec. 2003 – March 2008– 5 epidemic waves of avian
influenza A/H5N1– Almost all provinces have
reported outbreaks in poultry;~ 50 million poultry culled
– 36/63 provinces have human cases; Total 106 cases, 52 deaths (CFR: 49.0%)
• No new outbreaks in humans have been reported since March 4, 2008.
2
GEOGRAPHIC DISTRIBUTION GEOGRAPHIC DISTRIBUTION
OF H5N1 CASES IN VIETNAMOF H5N1 CASES IN VIETNAM
57/64 provinces reported poultry outbreaks; 43.9 million poultry culled.
13/64 provinces reported human outbreaks: 23 cases, 16 deaths; CFR: 69.6%.
WAVE 1: FROM DEC 2003 TO MAR 2004WAVE 1: FROM DEC 2003 TO MAR 2004
17/64 provinces reported poultry outbreaks; 84,000 poultry culled)
3/64 provinces reported human outbreaks: 4 cases, 4 deaths; CFR: 100%.
GEOGRAPHIC DISTRIBUTION GEOGRAPHIC DISTRIBUTION
OF H5N1 CASES IN VIETNAMOF H5N1 CASES IN VIETNAM
WAVE 2: FROM JUL 2004 TO AUG 2004WAVE 2: FROM JUL 2004 TO AUG 2004
3
GEOGRAPHIC DISTRIBUTION GEOGRAPHIC DISTRIBUTION
OF H5N1 CASES, IN VIETNAMOF H5N1 CASES, IN VIETNAM
36/64 provinces have poultry outbreaks; 470,000 poultry killed
25/64 provinces had human outbreaks; 66 cases, 22 deaths; CFR:33.3%)
WAVE 3: FROM DEC 2004 WAVE 3: FROM DEC 2004
UNTIL NOV.2005UNTIL NOV.2005
GEOGRAPHIC GEOGRAPHIC
DISTRIBUTION DISTRIBUTION
OF H5N1 CASES OF H5N1 CASES
IN VIETNAMIN VIETNAM
18/64 provinces reported poultry outbreaks; 176.407 poultry culled (data source of Department of Aminal Health)
6/64 provinces reported human outbreaks: 8 cases, 6 deaths; CFR: 75%.
WAVE 4: FROM MAY 2007 TO DECEM 2007WAVE 4: FROM MAY 2007 TO DECEM 2007
4
GEOGRAPHIC GEOGRAPHIC
DISTRIBUTION OF DISTRIBUTION OF
H5N1 CASES IN H5N1 CASES IN
VIETNAMVIETNAM
5/64 provinces reported human outbreaks: 5 cases, 5 deaths; CFR: 100%.
WAVE 5: FROM JAN 2008 TO MAR 2008WAVE 5: FROM JAN 2008 TO MAR 2008
number of human avian influenza cases and deaths by month
0
2
4
6
8
10
12
14
16
18
20Number
12/ 03 3/ 04 6/ 04 9/ 04 12/ 04 3/ 05 6/ 05 9/ 05 12/ 05 3/ 06 6/ 06 9/ 06 12/ 06 3/ 07 6/ 07 9/ 07 12/ 07 3/ 08
Case death
5
DISTRIBUTION OF CASES AND DEATHS DISTRIBUTION OF CASES AND DEATHS BY AGE GROUPSBY AGE GROUPS
age
17
242418
85 3 3
33
19 21 19
60 2 0
05
101520253035404550
0-9 10-19 20-29 30-39 40-49 50-59 60-69 >70
%
case death
DISTRIBUTION of avian influenza cases and deaths by gender
Death by gender
52%48%
Case by gender
46.2%
53.8%
Male Female
6
Mean age of cases and deaths by epidemic waves
15.816.0
5.5 5.5
30.626.3 25.6
24.026.6 26.6
20.819.6
05
101520253035404550
Age (Year)
Wave 1 Wave 2 Wave 3 Wave 4 Wave 5 Average
Mean age of cases
Mean age of deaths
CORRELATION BETWEEN RIVER NETWORK AND LOCATIONS WITH HPAI OUTBREAKS
rivers outbreaks
7
SURVEILLANCE OF AVIAN INFLUENZA
IN VIETNAM
MOH
Central and Regional Hospitals
Central Hospitals
Provincial Hospitals
District Hospitals
NIHE
Regional Pasteur Institutes
Provincial centre for Preventive Medicine
District centre for Preventive Medicine
Commune health Centre
COMMUNICABLE DISEASE SURVEILLANCE SYSTEM
8
Severe Viral Pneumonia (SVP) Surveillance
1. Case definition:• Sudden onset of fever > 38oC, AND• Difficulty in breathing, AND • Chest radiograph findings compatible with viral
pneumonia, AND• No alternative diagnosis, such as bacterial
pneumonia 2. Method• Hospital based in all provinces• Immediate reporting required• Investigation of cases by public health authorities
within 48 hours of report• RT-PCR testing for influenza viruses by regional
public health laboratories within 48 hours of notification
54 of 64 provinces reported SVP cases
Jan.2006-April 2008
(N=418) 01 - 34 - 89 - 1516 - 4142 - 70
9
Influenza virus causes of SVP
Type/SubtypeType/Subtype Number casesNumber cases Percent PositivePercent Positive
A/H5A/H5 1313 3.13.1
A/H3A/H3 66 1.41.4
A/H1A/H1 66 1.41.4
BB 33 0.70.7
Total positiveTotal positive 2828 6.76.7
N=418N=418
National Influenza National Influenza Sentinel Sentinel Surveillance 2006Surveillance 2006--20072007
Organizational Organizational network of 4 network of 4 regional public regional public health laboratories health laboratories and 15 sentinel and 15 sentinel sitessites
NIITD
DAK LAK
THAI BINH
HCMc TDH
HCMC PH #1
BA TRIEU
MOH/CDC/WHO/NIHE
KHANH HOATAY NGUYEN
HCMC
NIHE
THUA THIEN-HUE
LANG SON
HOA BINH
NPH
THANH XUAN
DONG NAI
TIEN GIANG
DA NANGNHATRANG
10
A case-control study in Vietnam 2004 have shown the risk factors for H5N1 infection:
• Direct contact to ill/dead poultry 7 days prior to onset (OR=31.0, 95%CI: 3.4 - 1050).
• Having ill/dead poultry in household 7 days prior to onset (OR=7.4; 95%CI: 2.7 – 59.0)
• Lack of an indoor water source (matched OR 6.46, 95% CI 1.20–34.81, p = 0.03).
• Factors not significantly associated with infection:
– raising healthy poultry, – preparing healthy poultry for consumption, – exposure to persons with an acute respiratory illness.
RISK FACTORS FOR INFECTION
• Gender :– Male: 76.9% – Female: 23.1%
• Age: – Max: 40 – Min: 4– Mean: 23,2 (+/-2.6)
Epidemiological Characteristics of H5N1 cases in 2007-2008 (n=13)
• Occupation– Children: 7,6% (1/13) – Student: 15,3% (2/13) – Farmer: 61,5% (8/13)– Civil servant: 15,3%
(2/13)
11
• Occupational exposure – Cleaning cage/farm, slaughtering poultry:
3/13– Working at A/H5 influenza labs: 0/13– Working at health facilities: 0/13
Epidemiological Characteristics of H5N1 cases in 2007-2008 (n=13)
• Animal exposures – Slaughtering, direct contact: 53% (7/13), in which:
• 3/7: Healthy poultry• 3/7: sick/dead poultry• 1/7: unknown
– Involved in culling poultry: 0– Eating poultry and its products: 69% (9/13)
• 3/7: Healthy poultry• 4/7: sick/dead poultry• 2/7: unknown
No evidences that patients ate raw poultry blood or half-done products
Epidemiological Characteristics of H5N1 cases in 2007-2008 (n=13)
12
• Animal exposures– Raising poultry near house: 9/13
• 4/9: Healthy poultry• 5/9: Sick or dead poultry
– Raising pigs/exposure to pig within 1m• 3/13: yes• 10/13: no
– Visiting poultry cages within 6 weeks before onset:
• 1/13: yes• 10/13: no• 2/13: unknown
Epidemiological Characteristics of H5N1 cases in 2007-2008 (n=13)
Average Timelines
• Average time (days) from onset to: – CHC: 2,6 (Std:0,9)– District hospital: 3,5 (Std:0,5)– Provincial hospital: 4,5 (Std:0,5)– Central hospital: 5,6 (Std:0,3)– Date of testing for H5: 7,6 (Std: 0,7)– Test result releasing: 9,6 (Std:0,7)
13
PracticesProject of “Community based active surveillance model on AI”
implemented by Care International in Vietnam
Percentage of doing at least 3 behaviours to protect family from AI
54
29
0
20
40
60
Doing at least 3 behaviours to protect familyfrom AI
*p<0.05
InterventionControl
PracticesProject of “Community based active surveillance model on AI”
implemented by Care International in Vietnam
Percentage of households reporting of sudden death of poultry
72
9
0
20
40
60
80
Reporting to Volunteer or village authority
*p<0.001
InterventionControl
14
Percentage of seeking help for people in family catching a flu over the past 2 years
Project of “Community based active surveillance model on AI”implemented by Care International in Vietnam
41
45
31
63
32
5
0 20 40 60 80
Self-treating at home
Taking to commune healthcentre
Taking to district/provincialhospital
*p-value<0.05
Intervention Control
EVOLUTION OF H5N1 VIRUSES IN VIETNAM
• In 2007-2008, H5N1 clade 2.3.4 viruses replaced clade1 viruses in northern Vietnam and human isolates have high homology to contemporary poultry isolates.
• Mutations on NA protein have been recognized at position117V (clade 2.3.4 viruses, 2007-2008), which is associated with reduced susceptibility to oseltamivir and is unrelated to treatment.
• The new mutation (I117V) was also found in poultry isolates,
• No mutations in the M2 gene were found conferring amantadine resistance.
15
A/Cambodia/JP52/2005
A/chicken/VietNam/1/2004
A/VietNam/JP14/2005
A/VietNam/JP4207/2005
A/VietNam/JP178/2004
A/VietNam/JPHN/30321/2005
A/VietNam/HN1194/2004
A/VietNam/HN1203/2004
A/Thailand/SP83/2004
A/VietNam/HN3062/2004
A/VietNam/HN30408/2005
A/VietNam/HN30212/2004
Clade 1
A/chicken/Guangxi/12/2004
A/duck/Guangxi/13/2004
A/chicken/Yunnan/493/2005
Clade 2.4
A/chicken/Indonesia/11/2003
A/chicken/Indonesia/7/2003
A/VietNam/HN31203/2007
A/chicken/HongKong/YU324/2003
Clade 2.1
A/chicken/Korea/2003
A/chicken/Yamaguchi/7/2004Clade 2.5
A/barheaded goose/Qinghai/12/2005
A/chicken/India/NIV33487/2006
A/Egypt/2321NAMRU3/2007
A/turkey/Turkey/1/2005
Clade 2.2
A/duck/Vietnam/568/2005
A/goose/Guangxi/3017/2005
A/duck/China/E319.2/03
Clade 2.3.2
Clade 2.3.1 A/chicken/Hunan/999/2005
A/chicken/Guiyang/3570/2005
A/goose/Guiyang/3422/2005Clade 2.3.3
A/Anhui/1/2005
A/duck/Laos/3295/2006
A/Japanese white-eye/HongKong/1038/2006
A/VietNam/HN30850/2005
A/VietNam/HN31432/2008
A/VietNam/HN31461/2008
A/Vietnam/HN31312/2007
A/VietNam/HN31323/2007
A/chicken/NCVD74/2007
A/duck/NCVD75/2007
A/duck/NCVD79/2007
A/VietNam/HN31239/2007
A/VietNam/HN31394/2008
A/duck/NCVD92/2007
A/muscovy duck/NCVD85/2007
A/muscovy duck/NCVD87/2007
A/chicken/NCVD84/2007
A/VietNam/HN31388/2007
A/chicken/NCVD89/2007
A/duck/NCVD91/2007
A/duck/NCVD86/2007
A/VietNam/HN31413/2008
A/duck/NCVD76/2007
A/VietNam/HN31412/2008
A/VietNam/HN31242/2007
A/VietNam/HN31244/2007
Clade 2.3.4
98
10097
88
63
100
90
95
99
64
9989
99
96
64
95
99
95
81
80
97
0.005
A/duck/Vietnam/568/2005
A/goose/Guangxi/3017/2005
A/duck/China/E319.2/03
Clade 2.3.2
Clade 2.3.1 A/chicken/Hunan/999/2005
A/chicken/Guiyang/3570/2005
A/goose/Guiyang/3422/2005Clade 2.3.3
A/Anhui/1/2005
A/duck/Laos/3295/2006
A/Japanese white-eye/HongKong/1038/2006
A/VietNam/HN30850/2005
A/VietNam/HN31432/2008
A/VietNam/HN31461/2008
A/Vietnam/HN31312/2007
A/VietNam/HN31323/2007
A/chicken/NCVD74/2007
A/duck/NCVD75/2007
A/duck/NCVD79/2007
A/VietNam/HN31239/2007
A/VietNam/HN31394/2008
A/duck/NCVD92/2007
A/muscovy duck/NCVD85/2007
A/muscovy duck/NCVD87/2007
A/chicken/NCVD84/2007
A/VietNam/HN31388/2007
A/chicken/NCVD89/2007
A/duck/NCVD91/2007
A/duck/NCVD86/2007
A/VietNam/HN31413/2008
A/duck/NCVD76/2007
A/VietNam/HN31412/2008
A/VietNam/HN31242/2007
A/VietNam/HN31244/2007
Clade 2.3.4
9989
99
96
64
95
99
95
81
80
97
0.005
SUMMARY
1. Cases were reported sporadically and in scattered provinces
2. Majority of human cases have exposure history to infected poultry.
2. Epidemics occured mainly in wet and cold seasons (winter and spring)
3. Genetic factors may play a very important role in susceptibility to the virus among family-clusters.
4. Clade 1 viruses are currently being replaced by clade 2.3 viruses in poultry and humans.
5. No evidence of human to human transmission is available.
16
LESSONS LEARNED IN HPAI PREVENTION AND CONTROL
IN VIETNAM
LESSONS LEARNED
1. Highest political commitment: Strong leadership of the Government.
2. Establishment of multi-sectoral Steering Committees for control and prevention of avian and human influenza at all levels, from central to communal level.
3. Good collaboration between MARD, MOH, other ministries and mass organizations to develop and implement “Integrated Operational Program for Avian and Human Influenza (OPI)”Role of Poultry Vaccination: contributing in reducing epidemics among poultry and H5N1 human cases
17
LESSONS LEARNED
4. The well developed health care system including curative care and preventive medicine system from central to local level, which implemented prevention activities, surveillance and early detection, care and treatment
5. Timely sharing information and mobilizing support from international organizations and other Governments
CHALLENGES1. New and emerging disease: lack of knowledge about
viral behaviors, pathogenicity, transmission mechanism, treatment
2. Virus maintain among ducks as asymptomatic hosts3. Poultry raising system is not appropriate: back-yards
in household, small farms4. Poor recognition and reporting of suspected HPAI in
poultry. Human case identifications mostly occurred before reports of disease in poultry.
5. Low awareness and high risk behaviors of handling and eating sick poultry/their products
6. Collaboration between human and animal health sectors not yet strong enough, especially at local level
7. Lack of capacity and resources for active surveillance and research
18
RECOMMENDATIONS
1. Avian Influenza should be considered as a combined agricultural, major public health, economic and social threat.
2. Strengthen epidemiological, virological and clinical surveillance and researches for better assessment of AI situation with the more concrete collaboration mechanism between animal and human health sectors, at all levels.
3. Increase capability to study pathogenicity, transmissibility, and antiviral susceptibility of HPAI virus.
4. Develop and implement integrated operational program for avian and human influenza
5. Develop regional and global multi-sectoralcollaboration on surveillance, researches and responses
Thank youfor your attention
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