Transcript Influenza virus

H1N1新型流感流行期間
之因應
衛生署 疾病管制局
中區傳染病防治醫療網
王任賢 指揮官
Influenza virus
History of influenza
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430-427 BC: Plague in Athens
epidemic influenza complicated by
toxigenic staphylococcal diseases
1901: first isolate from chicken
1918: pandemic, 20 million death
1931: first isolate from swine
1933: first isolate from human
Influenza virus
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Family Orthomyxoviridae
(segmented negative strand RNA virus)
Influenza A: 8 segments
Influenza B: 8 segments
Influenza C: 7 segments
Typing: CF antibody against core proteins
M1: matrix protein
NP: nucleoprotein
Influenza Surface Proteins
Neuraminidase
M1 protein
Hemagglutinin
RNA + nucleoprotein
M2 protein
(ion channel, only on type A)
Influenza A virus RNA
segment and protein
RNA segment
1
2
3
Protein
PB2
PB1
PA
Function/Activity
Cap-binding, endonuclease
RNA polymerase
Proteolysis
4
5
6
7
8
HA
NP
NA
M1, M2
NS1, 2
Attachment to sialic acid, fusion
Structural protein
Sialidase, release of virus
Structural protein, Ion channel
RNA transport, splicing, translate
Antigenic change of
influenza virus
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Antigenic drift: epidemic
point mutation in gene of HA or NA
result from increase immunity pressure
rate: 0.5-1% per year
epidemic: > 2 sites change
Antigenic shift: pandemic
acquire of new gene segment
Origin of pandemic strain
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Dormancy in a frozen state
Mutation of animal influenza virus
Gene reassortment between animal ＆ human
Avian: virus in respiratory ＆ GI tract
little antigenic variation
rarely transmit to human
Swine:mixing vessel
Antigenic Shift
Swine cell
Host range of influenza
virus
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Influenza A: broad host range
human, swine, horse, duck, bird, ruminant,
marine mammal, reindeer, mink
Influenza B: primarily pathogens of humans
human, (dog, cat, swine)
Influenza C: primarily pathogens of humans
human
流感病毒之分類
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上呼吸道流感病毒
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H1N1, H3N2, B
高傳染率,低死亡率
以社區傳染為主
Immune protection：治療以抗病毒藥為主
下呼吸道流感病毒
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H5N1
低傳染率,高死亡率
以院內傳染為主
Immune destruction ：治療以類固醇為主
Influenza Pandemics in the
20th Century
Years
Flu
Virus
Mortality
1918-1919
“Spanish”
Type A (H1N1)
20 million
worldwide
550,000 US
1957-1958
“Asian”
Type A (H2N2)
70,000 US
1968-1969
“Hong Kong”
Type A (H3N2)
34,000 US
1977-1978
“Russian”
Type A (H1N1)
negligable
Glezen WP. Epidemiol Rev. 1996;18:65.
Centers for Disease Control and Prevention. Influenza Prevention and Control. Influenza. Available at:
http://www.cdc.gov/ncidod/diseases/flu/fluinfo.htm.
Three types of influenza
viruses
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Seasonal influenza virus
 A contagious respiratory illness caused by influenza viruses
 Viruses circulating in the human population-Influenza A
(H3N2, H1N1 and B strains)
Avian influenza virus
 Animal influenza viruses infectious for humans under
special circumstances.
 Current H5N1 infections
Pandemic influenza virus
 Flu that causes a global outbreaks and spread easily from
human to human
3 pre-requisites for a Pandemic
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The emergence of a new virus strain with no
circulating immunity within the human
population
The ability of this strain to infect humans
The potential for the new virus to be easily
transmitted from person to person
WHO疫情分級
大流行警示狀況
人類風險狀況
疫情分級
大流行間期
(Inter-pandemic)
出現動物新病毒
但無人類個案
人類低風險期
Phase 1
人類高風險期
Phase 2
尚未出現人傳人或
已出現有限性人傳人的新病毒
Phase 3
證據顯示新病毒可人傳人機會增加
Phase 4
證據顯示新病毒已可以有效人傳人
Phase 5
已證實出現有效性人傳人
Phase 6
大流行警示期
(Pandemic alert)
新病毒引發人類個案
大流行期
(Pandemic)
Pandemic phases and
transmission patterns
Geographic
spread 5-6
Phases
Predominantly animal
Infections;
Limited
transmissibility
among people
5-6
4
Sustained
H-2-H
transmission
1-3
Time
Post
Peak
Post
Pandemic
流感病毒之季節性
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夏季流感
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Semi-closed population
冬季流感
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Northern hemisphere：Oct to April
Southern hemisphere：April to Sept
馬其諾防線該設在何處？
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防止感染發生，切斷感染源
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僅適用於極早期
防止重症病患死亡
衛生局之因應作為
指揮中心之因應作為: I
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加強人口密集機構之通報及查核
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社區推動呼吸道衛生及咳嗽禮節
訂定區域內停止上班上課之規定
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由衛生局於短期內對轄區內之人口密集機構實施硬
體、防疫物資、篩檢、通報、人員訓練進行查核
要求推動呼吸道衛生及咳嗽禮節
區域內出現有效人傳人之證據時即可逕行執行
加強定點醫師類流感實驗室通報
指揮中心之因應作為: II
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全面掌控克流感，只允許使用於鑑定成立之重症
病例
區域成立重症病例鑑定委員會，每日開會執行區
域內重症通報病例之鑑定
召開區域內醫療院所之教育訓練，就流感重症病
例通報、重症病例鑑定、克流感政策、感控措施
進行說明
由縣市衛生局就現有之志工進行組訓，協助執行
輕症病例之居家隔離及居家治療政策
指揮中心之因應作為: III
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衛生局、醫療院所 、人口密集機構 均須備足
口罩及消毒劑等防疫物資
鼓勵老百姓自備可換洗之布口罩
醫院之因應作為
醫院之因應作為
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前提
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醫療作為並不會增加感染風險
感染並不一定成為重症，而且輕症較多
因應作為
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執行呼吸道衛生及咳嗽禮節
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有病的人不要來上班
員工體溫監測發燒的人自行戴上口罩上班或回家
有呼吸道症狀的人自行戴上外科口罩
盡量保持人與人之生物安全距離1公尺
持續第一線傳染病篩檢及員工體溫監測
口罩政策
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直接執行照顧H1N1新型流感病人者，由醫院
配發N95口罩每日一個
其他人員醫院不主動提供口罩
有病的人應自行戴上外科口罩等級之口罩（外
科口罩、紙口罩、布口罩），建議員工每人自
備二個可換洗之布口罩，以備不時之需
照顧非H1N1新型流感病人之其他呼吸道病患，
由醫院配發外科口罩每日一個
醫院應廣設平價外科口罩販賣機及免費乾洗手
液
Droplet Precautions
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Private room
Wear a surgical mask for close patient
contact
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For SARS and Avian influenza, wear N-95
respirator and also wear eye protection
Limit patient transport
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Instruct patient to wear a surgical mask and follow
respiratory hygiene/cough etiquette. Notify
receivers of precautions
Role of Surgical Masks?
A surgical mask is NOT respiratory
protection
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1º intent: preventing wound
contamination by infectious droplets
from HCW’s respiratory tract
 2º use: barrier protecting HCW’s
nose and mouth from large droplet
splashes, sprays of infectious
material
Particles can enter at edges of mask
Some not constructed using particulate
filter media
Source: Rosie Sokas, MD MOH UIL at Chicago
Assumptions for Respirator Use
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2.
Need to protect HCWs from possible secondary
transmission from ill patients (not 1º release)
Respirators will be used in the context of a
complete respiratory protection program
N-95 Filtering Facepiece
Respirators
Benefits of fit testing
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Study: 25 volunteers, 21 models of N-95
respirators
Without fit testing, 95% of the tests had up to
33% leakage
With fit testing, 95% of the tests had no more
than 4% leakage
H1N1新型流感病患收治政策
疫情初期之政策
 輕症病患在負壓隔離房內或戶外通風良好處採
檢完後，原則上以居家治療合併自我健康管理
為處理原則
 重症病患仿效SARS收治在負壓病房或單人房，
同一感染源者可收治於同一間
 病患在病房內不需戴口罩，出外應配戴外科口
罩
克流感政策
大流行時之政策
 只限於經臨床或實驗室鑑定之流感重症使用
 接觸者、輕症、預防性投藥均不建議
 防疫的馬其諾防線設在減少重症死亡，而非減
少感染，克流感鎖碼勢在必行
疫情初期之政策
 比照H5N1流感之政策
Sensitivity of Influenza Virus
Isolates to Oseltamivir
Virus
Oseltamivir IC50
H1N1 (H274): wild type
0.69
H1N1 (Y274): resistant mutant
85.92
H3N2 (R292): wild type
1.99
H3N2 (K292): resistant mutant
1,600.00
Hong Kong/483/97
4.86
Hong Kong/213/03
5.07
Vietnam/1194/04
2.49
Vietnam/1203/04
7.68
Chicken/VN/NCVD1/04
5.87
Chicken/VN/NCVD8/03
9.90
EID 11:10;1515-21, 2005
其他
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門禁管制：不必要
發燒篩檢門診：不必要
員工體溫監測：持續進行
流感疫苗施打：不鼓勵不禁止
增加防疫物資之儲備：不必要，只需依疾病管
制局之規定辦理，但須及時遞補消耗
防護衣：依現行規定辦理
因應政策之起跑點
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除克流感政策自即日起開始實施外，其他政策
之起跑點均為國內出現第一起確認案例之後
H1N1新型流感防疫戰之思維
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馬拉松戰役
大格局的戰役之防疫主軸
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人口密集機構，防止出現“和平社區”
重症醫療
執行方法：呼吸道衛生及咳嗽禮節
懇請賜教