Download Milestones in the discovery of virus

Trial Version
Case Study: Are we prepared for the health consequences of an outbreak of
pandemic influenza?
Key Concepts:
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
Overview of Virus
 What is a virus?
 The discovery of virus
 How does it look like?
 The lifecycle of virus
 Examples of viral diseases: AIDS and SARS
Overview of Influenza
 What is influenza?
 The three types of viruses
 Influenza pandemics in the 20th Century
 Naming of influenza
 Seasonal pattern in Hong Kong
 Cold verses Flu: what is the difference?
 Symptoms and Treatment
Overview of H5N1 (Bird flu)
 What is H5N1?
 Why does H5N1 infectious?
 The possible ways for H5N1 transmission
 Bird flu in human
 Consequence and concern of the outbreaks
 Prevention and treatments
Role of WHO/CDC/CHP in public health control measures
 Influenza surveillance
Materials Preparation:

Prior to this class, students are asked to search “news article” relating to Influenza
(flu/bird flu).
港聞 A08
星島日報
2005-06-04
禽流爆發風險高 成半港人恐染疫
衛生署衛生防護中心估計，一旦禽流感或流感大爆發，本港將會有百分之十五人口受到感染，可
能出現多個爆發高峰。衛生防護中心總監梁柏賢表示，本港爆發禽流感的風險不斷增加，但市民
危機意識較年初時下降，當局會加強宣傳教育市民。梁柏賢指出，東南亞地區禽流感疫情持續，
禽流感在全球大爆發的風險一直未有減退，相比年初，爆發風險更有增無減。他表示，禽流感一
旦在全球爆發，估計本港將會有百分之十五人口受感染而發病。 備製錦囊教導市民 梁柏賢表
示，禽流感與沙士不同，很難做到完全接觸不到病毒，只有盡量拖慢病毒擴散的時間和減少感染
個案。署方指，根據過去的流感大爆發經驗，大爆發期間可能出現多個感染高峰，因此要預備足
夠的藥物應付。另為提高市民危機意識， 生防護中心製備了一批「防備流感大流行錦囊」，內
有一本小冊子，教導市民如何佩戴口罩、處理發燒和防範受感染。梁柏賢表示，市民可準備口
罩、探熱針和退燒藥放進錦囊，以備不時之需。他表示，市民近期對禽流感的風險意識明顯較幾
個月前降低， 生防護中心稍後會舉辦講座，講解當局的大爆發應變措施。記者謝文
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港聞
A04
蘋果日報
2005-03-23
病毒或變種： 可人傳人 無病徵
越南自去年底爆發新一輪禽流感，迄今已有十四人死亡，而疫情未受控制，反而愈來愈多人受感
染，令人擔心當地的禽流感已經變種，會人傳人，患者可以沒有病徵，病毒甚至可上腦或攻擊全
身任何部份。
在過去兩個月，越南至少有數人因為照顧感染禽流感的親人而中招，令人憂慮當地已爆發可以人
傳人的禽流感。最令人防不勝防的是，病毒可能變成令患者沒有明顯病徵如發高燒、呼吸困難
等。本月初，當局證實有老翁和寡婦感染禽流感，但沒有任何病徵。
可襲全身任何部位
科學家一直認為禽流感病毒只會攻擊人體肺部，但英國牛津大學科學家上月發表報告，指越南一
對去年死於禽流感的姊弟，發病前只呈現腸胃炎和腦膜炎的症狀，凸顯 H5N1 禽流感病毒可攻擊
人體全身任何部位，且有不同病症，病毒的致病能力似被低估了。

Find out relevant statistics that support your discussion.
Virus:
Centers for disease control and prevention – AIDS
http://www.cdc.gov/hiv/dhap.htm
Centers for disease control and prevention – SARS http://www.cdc.gov/ncidod/sars/
Influenza:
 Department of Health: (http://www.info.gov.hk/dh/diseases/index.htm)
 Centre for Health Protection - Flu Express
(http://www.chp.gov.hk/files/pdf/grp-flu_express_wk_18_en_20050510.pdf)
 Weekly Influenza Activity Summary - 27 Jun to 3 Jul 2004 (http://www.info.gov.hk/dh/diseases/influenza/summary27jun-3jul.htm)

Influenza Case Study
 (http://cme.ufl.edu/media/flu/flucase1.html)
 (http://cme.ufl.edu/media/flu/flucase2.html)
H5N1
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
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Prevention on Avian Influenza: (http://www.info.gov.hk/info/flu/eng/)
Q&A: Avian flu - (http://news.bbc.co.uk/1/hi/health/3422839.stm)
Questions and answers about bird flu –
(http://www.smh.com.au/articles/2004/01/27/1075088028617.html?oneclick=
true)
How dangerous is the Bird Flu? –
(http://yaleglobal.yale.edu/display.article?id=3278)
Global statistics of avian influenza
Human Cases of Avian Influenza A (H5N1) confirmed in 2004 and 2005
(as of 11 August 2005)
Viet Nam
Thailand
Cambodia
Indonesia
Month of
confirmation Confirmed Death Confirmed Death Confirmed Death Confirmed Death
1st
wave
2nd
wave
Jan 2004
7
6
3
3
0
0
0
0
Feb 2004
15
9
7
4
0
0
0
0
Mar 2004
1
1
2
1
0
0
0
0
Aug 2004
3
3
0
0
0
0
0
0
Sep 2004
1
1
3
2
0
0
0
0
Oct 2004
0
0
2
2
0
0
0
0
63
20
0
0
4
4
1
1
90
40
17
12
4
4
1
1
3rd
Dec 2004 –
wave Jun 2005
Total
The most recently detected cases of human avian influenza were reported in Vietnam on 5 August 2005
(Source: WHO - http://www.who.int)

Introduce the topic by starting a discussion about the flu. Ask the students if they've
ever had the flu or if they know anyone who's had it. Then ask what causes the flu.
What do they know about different types of flu? What is an epidemic? What is a
pandemic?
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Prepare notes and questions to be discussed before the session:
Level of Difficulties:
[1] Prior concepts.
[2] Essential concepts.
[3] Big and global concepts.
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Trial Version
Notes on Virus
1.
What is a virus? [1]
Viruses, before the discovery of prions, were the smallest - and some of the
deadliest - infectious agents known to human. A virus is made up of two things, a
protective coat made of protein or lipid, and a strand of nucleic acid as the genetic
materials. This nucleic acid is like a recipe, it allows the virus to make more
viruses, which in turn make you sick. There are two different kinds of nucleic acid,
DNA and RNA. They can be single or double stranded.
2.
The discovery of virus [1]
One of the earliest written records of virus infection was drawn by ancient Egyptian
at 3700 B.C. (approximately 5,700 years ago). However, people know nothing
about virus although there were numerous outbreaks of viral diseases in the
following thousands of years. Until the end of the 19th Century, scientists
successfully identifying several viruses and it was the starting point of virology.
With the discovery of new viral species and related diseases, virology becomes an
important subject that related to public health.
Milestones in the discovery of virus
Event
Related Scientists
One of the earliest written records of Ancient Egyptian
virus infection
1000 B.C.
Outbreak of smallpox in China
/
1796 A.D.
Discovery of cowpox vaccination to
Edward Jenner
prevent smallpox
1880’s
Establishment of the 'germ theory'
Robert Koch & Louis
A.D.
Pasteur
1892 A.D.
The first submission of scientific
Dmitri Iwanowski
journal about the transmission of a
plant viral disease
1898 A.D.
Establishment of model idea of virus Martinus Beijerinick
1898 A.D.
Discovery of relationship between
Freidrich Loeffler & Paul
virus and human disease
Frosch
1909 A.D.
Discovery of the first viral disease Landsteiner & Popper
poliomyelitis
1915 to
Discovery of bacteria infecting virus
Frederick Twort & Felix
1917 A.D.
d'Herelle
3. How does a virus look like? [2]
Year
3700 B.C.
Size:
Virus is one of the smallest infectious agent with the size vary from 10 to 50nm
(nanometer or 10-9 m).
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Structure:
Viruses are macromolecular complexes, composed of a nucleic acid genome
enclosed in a protein coat (or capsid) and sometimes a lipid membrane. The genome
may be RNA or DNA and can be single or double stranded. Viral genomes are
usually very small and may be composed of as few as three genes.
Shapes:
Some of the most common shapes of virus are the rod shape and the crown shape.
The shape of some virus such as bacteriophage (a special kind of virus that lives in a
bacterium) can be very complicated.
Illustrated diagram for different
kind of viruses
(Adopted from
http://duke.usask.ca/~misra/virolog
y/stud2004/frdc/viruses.html)
Illustrated diagram of bactieophage
(Adopted from
http://www.ucmp.berkeley.edu/alllife/
virus.html)
Rod-shape virus under electronic microscope
(Adopted form http://www.ucmp.berkeley.edu/alllife/virus.html)
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4.
The life-cycle of virus [2]
The life-cycle of virus includes the stages of attachment, penetration, uncoating,
replication and release. At the stage of attachment, the virus will attach to its host
cell’s surface. After the attachment, the virus will enter the host at the stage
“penetration”. In the host, the virus will release its genetic materials (uncoating).
And then, the virus replicates itself by using the metabolic system in the host. At
last, the virus will reassemble and then getting out from their host (release). The
host cell is lysed eventually. Sometimes, the original virus stays inside the host cell
and does not do anything and no syndromes will be seen. This stage is known as
latent stage.
The life-cycle of a HIV virus
(adopted from http://prosetta.com/science.html)
5.
How does a virus mutate? [2]
Some viruses like cold viruses have nucleic acid made of RNA. This allows the
virus to change faster. It does this because an RNA virus must convert its RNA into
DNA as genetic materials and many mistakes will be introduced in this step. These
mistakes are called mutations, and when the virus has made enough mistakes it
becomes different, or a new serotype. A serotype means a type of virus that our
body can recognize it as different, and thus generates a new response. That’s why
sometimes we hear in the newspaper that an animal virus can infect human.
*What is a serotype?
A serotype means a type that the body can recognize as different, and thus generate
a new response.
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6.
Examples of viral diseases: AIDS and SARS [3]
Many diseases are caused by viruses; some of the common ones are. AIDS, SARS,
influenza, rabies, polio, smallpox, German measles, etc.
i.
Acquired Immunodeficiency Syndrome (AIDS) – (See AIDS section)
HIV (human immunodeficiency virus) is the virus that causes AIDS. This virus may
be passed from one person to another when infected blood, semen, or vaginal
secretions come in contact with an uninfected person’s broken skin or mucous
membranes. In addition, infected pregnant women can pass HIV to their baby during
pregnancy or delivery. People with HIV have what is called HIV infection. Some of
these people will develop AIDS as a result of their HIV infection. Since HIV can
multiply in the human lymphocytes and kill many lymphocytes after replication, the
immune system of AIDS patients will be destroyed. Therefore, AIDS patients do
not have the capability to fight infections and cancer. Every year, an estimated 3
million people died of AIDS of whom 500,000 are children under the age of 15
years. Besides the number of deaths, the whole world has to pay billions of US
dollars in the prevention, education and treatment for this disease. Unfortunately,
there is still no promising treatment that can cure this disease.
ii.
Severe Acute Respiratory Syndrome (SARS) – (See SARS section)
Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by a
coronavirus, called SARS-associated coronavirus (SARS-CoV). SARS was first
reported in Asia in February 2003. Over the next few months, the illness spread to
more than two dozen countries in North America, South America, Europe, and Asia
before the SARS global outbreak of 2003 was contained. According to the World
Health Organization (WHO), a total of 8,098 people worldwide became sick with
SARS during the 2003 outbreak. Of these, 774 died. Clinically, SARS is a
syndrome characterized by fever, lower respiratory symptoms and radiographic
evidence of pneumonia. Around 10% of infected people die from it.
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Notes on Influenza
1. What is Influenza? [1]
Influenza is one of the most common viral infections in Hong Kong. According to the
Centers for Health Promotion (CHP) in Hong Kong, Influenza (also called “the flu”) is
a highly contagious respiratory* illness caused by influenza viruses. The infection
usually lasts for about a week and recovery from the flu occurs in one to two weeks
without requiring any medical treatments. Influenza can be deadly, especially for the
elderly people, young children, and people with certain health conditions like lung
diseases, diabetes, cancer, kidney or heart problems, are at high risk for serious
complications from the flu. However, similar symptoms could also be due to infection
caused by viruses other than the influenza virus, and such illnesses are referred as
influenza-like illness (ILI). Some flu pandemics have killed millions of people (see
Influenza Pandemics in the 20th Century).
(*The virus attacks the upper respiratory tracks – the nose, the throat, the bronchi and
rarely also the lungs.)
2.
What are the three types of influenza virus? [1]
 Influenza A (found in human and animals)
 Two subtypes: H1N1 and H3N2 (most
common in Hong Kong)
 Classification of subtypes of virus is
based on the presence of two surface
structures: haemagglutinin (H) and
neuraminidase (N).
 There are 15 different “H” subtypes and
9 different “N” subtypes. A
combination of different “H” and “N”
proteins on the surface of the influenza
virus describes different types of
influenza A viruses.
 Influenza B (found in human alone)
 Influenza C (found in human and pigs)
Of these, type A virus has highest antigenic shift
and antigenic drift. Antigenic shift is a sudden
change in antigenicity of a virus resulting from
the recombination of genes of two influenza
virus strains. Antigenic drift is a change in viral
proteins or antigens due to gene mutation. These
changes are major problems for defense and
developing vaccine against this virus. Type C
virus is antigenically most stable.
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Influenza virus is an extremely variable disease and hence difficult to control since its
spread/infection is not limited to human populations. Various strains of the virus can
infect animals like pigs, horses, and birds ((including fowls). Sometimes, more than
one strain of influenza may develop as the viruses may "share/swap" genetic
information, creating a whole new influenza strain. These new strains of influenza can
be very dangerous and contagious if conditions are right for a widespread, worldwide
epidemic (also called a “pandemic”).
3.
Overview of the influenza pandemics in the 20th Century [2]
Years
1918-1919
Flu
“Spanish”
Virus
Type A (H1N1)
1957-1958
1968-1969
1976
“Asian”
“Hong Kong”
“Swine Flu Scare” - related to the
Spanish flu virus of 1918
Type A (H2N2)
Type A (H3N2)
Type A (H1N1)
1977
Type A (H1N1)
1997
“Russian Flu Scare” - similar to
other A/H1N1 viruses that had
circulated prior to 1957. (In 1957,
the A/H1N1 virus was replaced by
the new A/H2N2 viruses).
“Avian Flu Scare”
1999
“Bird Flu”
2003
“Bird Flu”
Avian A/H5N1
- similar to
illnesses caused
by the 1918
Spanish flu
virus.
Avian flu virus
A/H9N2
Avian A/H5N1
Avian A/H9N2
Avian A/H7N7
Mortality
20 million
worldwide
550000 US
70,000 US
34,000 US
6 Hong Kong
15 Vietnam
7 Thailand
1 Hong Kong
1 Netherlands
Source:
 HHS - National Vaccine Program Office (NVPO) –
(http://www.hhs.gov/nvpo/pandemics/flu3.htm#8)
 Glezen WP. Epidemiol Rev. 1996; 18:65
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4.
Different naming systems for influenza virus [2]
The full designation of a given isolate of influenza virus would include:
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
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
Its subtype (A, B or C)
Geographical origin (e.g. Moscow, Sydney, etc)
Strain number
Year of isolation
H & N subtypes.
For example, A/Moscow/10/99 (H3N2); Fujian, etc
5.
How do I know if I have influenza? [1]
Some common symptoms of influenza:
 Fever (usually high)
 Headache
 Tiredness and weakness (can be extreme)
 Cough
 Sneezing
 Sore throat
 Runny or stuffy nose
 Muscle aches
 Diarrhea and vomiting (more common in children)
6.
How do we get influenza? [1]
Both influenza and the influenza-like illness (ILI) are transmitted through the air by
respiratory droplets and particles excreted by infected patients when they cough or
sneeze. The virus enters the body via nose or throat. Influenza patients can be
infectious one or two days before they develop symptoms to 7 days
afterwards. Influenza spreads very quickly among in crowded community. Cold and
dry weather enables the virus to survive longer outside the body.
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7.
What is the seasonal pattern for influenza in Hong Kong? [1]
The incubation period is short, usually around 1-3 days and its peak season in Hong
Kong is February, March and July.
A.
Graphical presentation of the consultation rate of Influenza-like illness and
number of influenza isolates* (*Type A: H3N2, H1N1 and Type B) in Hong
Kong (2004-2005)
Year 2004
Year 2005
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B.
Influenza activity in Hong Kong 2003-2005
Source:
 Department of Health: (http://www.info.gov.hk/dh/diseases/index.htm)
 Centre for Health Protection - Flu Express (http://www.chp.gov.hk/files/pdf/grpflu_express_wk_18_en_20050510.pdf)
6.
Cold verse influenza: What is the difference? [3]
Both the cold and the flu are caused by viruses. The common cold is caused by a wide
variety of them. Many people think cold is the same as influenza, but they are not,
and some of differences are given below:
Causative agent
Cold
Rhinoviruses are responsible
for 30-35% of all adult colds,
but most other adult cold
cases are caused by
coronaviruses, especially
those that occur in winter or
early spring.
Influenza
Influenza, on the other hand, is
caused by three types of influenza
viruses: influenza type A, B and C.
The Type A virus tends to cause
more severe illness than the other
two and it has been reported that a
new strain of Type A influenza
virus emerges every ten years or so
to replace the pre-existing strain.
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Headache
Symptoms
Rare in adults and older
children, but can be as high as
102°F in infants and
small children
Rare
Muscle aches
Tiredness and weakness
Extreme exhaustion
Mild
Mild
Never
Runny or stuffy nose
Sneezing
Sore throat
Cough
Often
Often
Often
Mild, hacking cough
Complication
Vaccination
Blocked nose
None
Treatment
Only temporary relief of
symptoms
Fever
Usually 102°F, but can go
up to 104°F and usually
lasts 3 to 4 days
Sudden onset and can be
severe
Usually, and often severe
Can last 2 or more weeks
Sudden onset and can be
severe
Sometimes
Sometimes
Sometimes
Usually, and can become
severe
Bronchitis, pneumonia
Annual vaccination and
anti-viral medicines
Anti-viral medicines
Source:
National Institute of Allergy and Infectious Diseases. Is it a cold or the flu?
(http://www.niaid.nih.gov/publications/cold/sick.pdf)
7.
What are the treatments of influenza? [1]
For most people, influenza is an upper respiratory tract infection that lasts several days
and requires symptomatic treatments only, that is, patients should have adequate rest
and sleep and drink plenty of fluid. Anti-fever medicine and cough syrup are also
useful in relieving symptoms.
Aspirin should not be used in children or teenagers with symptoms of the flu because
it may cause Reye’s syndrome, which is a rare complication, but acute and extremely
serious childhood disease affecting all organs of the body but is most harmful to the
brain and the liver that usually appears one to three days following a viral illness such
as an upper respiratory infection or chickenpox.
Contrary to popular belief, antibiotics have no effect on a virus. Most antibiotics
interfere with the reproduction of bacteria, hindering their creation of new genetic
instructions or new cell walls. Because viruses do not carry out their own biochemical
reactions, antibiotics do not affect them.
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8.
Recommendation Influenza Vaccine Composition for 2004-6 [3]
Influenza vaccine is prepared according to the prevalence of strains in the community
each year, as recommended by the World Health Organisation. The viral-strain
composition recommended for the vaccination programme in Hong Kong in the
following year is as follows:
2004-2005
*A/New Caledonia/20/99(H1N1)-like virus
*A/Fujian/411/2002(H3N2)-like virus
*B/Shanghai/361/2002-like virus
2005-2006
*A/New Caledonia/20/99(H1N1)-like virus
* A/California/7/2004(H3N2)-like virus
*B/Shanghai/361/2002-like virus
9.
What are the preventive measures for influenza attacks? [1]





Maintain good personal hygiene, and wash hands after sneezing, coughing or
cleaning the nose;
Cover nose and mouth while sneezing or coughing and dispose of nasal and mouth
discharge properly;
Good body resistance helps to prevent influenza infection. This can be achieved
through a balanced diet, regular exercise, adequate rest, avoid too much stress and
smoking;
To maintain good ventilation and during the "flu" season, it is better to avoid
crowded public places with poor ventilation;
Influenza vaccine is prepared according to the prevalence of strains in the
community each year, as recommended by the World Health Organisation.
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Notes on BIRD flu (H5N1)
1. What is H5N1? [1]
H5N1 also known as Avian Influenza A (H5N1) Virus. Avian influenza is an
infectious disease of birds caused by type A strains of the influenza virus. The
disease, which was first identified in Italy more than 100 years ago, occurs
worldwide.
2.
Why is H5N1 infectious? [1]
The causative agent is the Avian Influenza (AI) virus. They are negative-stranded,
segmented RNA viruses. The incubation period is 3 to 5 days. Symptoms in
animals vary, but virulent strains can cause death within a few days.
3.
What are negative-stranded segmented RNA viruses? [3]
RNA virus uses RNA as its genetic material or whose genetic material passes
through RNA intermediate during replication (as RNA would not exist during
typical DNA replication). This allows the RNA virus to have an exceptionally
high mutation rates. The reason of their high mutation rates is due to lack of DNA
polymerases which can find out and edit mistakes. DNA viruses have
considerably lower mutation rates. The high mutation rate allows the RNA virus
to lead a more adaptable life to face the environmental challenge and make them
higher chance to survive.
4.
How does H5N1 spread? [1]
Avian influenza spreads in the air and in bird’s manure. Wild fowl often act as
resistant carriers, spreading it to more susceptible domestic stocks. It can also be
transmitted by contaminated feed, water, equipment and clothing; however, there
is no evidence that the virus can survive in well cooked meat. Cats are also
thought to be possible infection vectors for H5N1 strains of avian flu.
Bird flu in humans
5.
Can H5N1 infect human also?
There are many subtypes of bird flu, while of the 15 known subtypes, only H5, H7
and H9 are known to be capable of crossing the species barrier from birds to
humans.
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6.
Why H5N1 is dangerous to human?
Not all Avian Influenzas can affect people, but influenzas are constantly mutating.
Each year, influenzas mutate through “antigenic drift”. This results in a new strain
of influenza that infects the same species. For example, Human influenzas
constantly mutate to become slightly different. This is why people are not immune
to the flu year after year, and this is why vaccine manufacturers must produce new
vaccines annually.
Another way influenzas mutate is through “antigenic shift”. This changes the
virus’ genome so much that it is suddenly able to infect other species. This is how
an Avian Influenza virus like H5N1 became zoonotic. Antigenic shift in influenza
viruses leads to pandemics similar to the Spanish Flu that killed over 20 million
people in 1918 (though a variety of sources quote average figures even higher, up
to 100 million in some cases). Right now, Avian Influenza H5N1 would not cause
a pandemic, because it is only transmissible from birds to humans. Currently, it is
not transmissible between humans; however, it has jumped from birds to humans
on two separate occasions (Hong Kong 1997 and 2003). This shows that the virus
can readily mutate, and may gain the ability to be transmissible between people.
7.
What are the consequences of the outbreaks in poultry? [3]
Avian influenza is a potentially devastating disease which can affect a wide range
of farmed and wild birds. The possibility of cross-infections between humans and
animals, particularly with the influenza virus is very high. In 1997 the H5N1 virus
was found to have crossed to humans, although the exact transmission route is still
not confirmed. This resulted in the slaughter of 1.5 million chickens and the
introduction of compulsory health certificates for all poultry. Economic
consequences can be especially devastating in developing countries where poultry
raising is an important source of income - and of food. Since viruses cannot be
eradicated, there is a need for better surveillance to reduce the risk of the
recurrence of the spread of H5N1.
8. Why so much concern about the current outbreaks? [3]
Public health officials are alarmed by the unprecedented outbreaks in poultry for
several reasons. First, most - but not all - of the major outbreaks recently reported
in Asia have been caused by the highly pathogenic H5N1 strain, that is, extremely
contagious in birds and rapidly fatal, with a mortality approaching 100%. Birds
can die on the same day that symptoms first appear. There is evidence that this
strain has a unique capacity to jump the species barrier and cause severe disease,
with high mortality, in humans. A second and even greater concern is the
possibility that the present situation could give rise to another influenza pandemic
in humans. Scientists know that avian and human influenza viruses can exchange
genes when a person is simultaneously infected with viruses from both species.
This process of gene swapping inside the human body can give rise to a
completely new subtype of the influenza virus to which few, if any, humans
would have natural immunity. Moreover, existing vaccines, which are developed
each year to match presently circulating strains and protect humans during
seasonal epidemics, would not be effective against a completely new influenza
virus.
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If the new virus contains sufficient human genes, transmission directly from one
person to another (instead of from birds to humans only) can occur. When this
happens, the conditions for the start of a new influenza pandemic will have been
met. Most alarming would be a situation in which person-to-person transmission
resulted in successive generations of severe disease with high mortality.
This was the situation during the great influenza pandemic of 1918-1919, when a
completely new influenza virus subtype emerged and spread around the globe, in
around 4 to 6 months. Several waves of infection occurred over 2 years, killing an
estimated 40-50 million persons.
9.
What is the prevention and treatments of H5N1? [1,2]
Avian influenza in humans can be detected with standard influenza tests**.
However, these tests have not always proved reliable. Besides, antiviral drugs are
sometimes effective in both preventing and treating the disease, but no virus has
ever been really cured in medical history. Furthermore, vaccines take at least four
months to produce and must be prepared for each subtype. As mentioned above,
H5N1 has a high mutation rate together with the re-assortment effect with any
other types of viruses and production of vaccine is possible but may not be
probable.
**Diagnostic tests available for influenza include:
1. Detection of viral protein and antigen
2. Viral isolation
3. Serology
4. Polymerase chain reaction (PCR)
5. Immunofluorescence assays
6. Examination of the symptoms alone by doctors during an influenza outbreak
in the community
Different diagnostic tests can detect:
1) Only influenza A viruses;
2) Both influenza A and B viruses, but not distinguish between the two types; or
3) Both influenza A and B and distinguish between the two.
Information on “Laboratory Diagnostic Procedures for Influenza” can be found at
Center for Disease Control and Prevention –
(http://www.cdc.gov/flu/professionals/labdiagnosis.htm#lab)
Reference: Prevention of Avian Influenza –
(http://www.info.gov.hk/info/flu/eng/news.htm)
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Notes on WHO/CDC/CHP
1.
Global and Hong Kong Influenza Surveillance [3]
Global Influenza Surveillance:
The “WHO Global Influenza Surveillance Network” was established in 1957 to
serve as global alert mechanism for the emergence of influenza viruses with
pandemic potential. This network comprises 4 WHO collaborating Centers
(WHO CCs) and 112 WHO National Influenza Centers (NICs) in 83 countries.
These NICs are responsible to collect specimens in their country and perform
virus isolation and preliminary antigenic characterization. If newly isolated
strains were found, they will ship them to WHOCCs for high level antigenic and
genetic analysis. The result will form the basis for WHO recommendations on the
composition of influenza vaccine for the Northern and Southern hemisphere each
year.
Hong Kong Influenza Surveillance:
The Surveillance & Epidemiology Branch (SEB), established in June 2004 as a
branch under the Centre for Health Protection, is responsible for formulating
strategies and implementing measures in the surveillance, prevention, and control
of communicable diseases and non-communicable diseases.
Their spectrum of work includes:
Epidemiology section



Maintain a comprehensive network of communicable disease notifications;
Conduct detailed epidemiological investigations on disease outbreaks; and
Institute appropriate control measures and health advice to stop disease
propagation.
Communicable disease surveillance section




Collect, collate, analyse and disseminate surveillance data on communicable
diseases;
Establish a central communicable disease information system and generate
regular reports;
Develop and coordinate a communicable disease surveillance system for the
Pearl River Delta Region; and
Develop specialized expertise in the surveillance of targeted infections of
public health importance.
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In accordance with the Quarantine and Prevention of Diseases Ordinance
(Cap.141), there are 30 notifiable infectious* diseases specified
(*Case definitions on “Statutorily notifiable diseases” https://ceno.chp.gov.hk/Case%20definition%2020050301.pdf).
All registered medical practitioners are required by law to notify all suspected or
confirmed notifiable diseases to the Centre for Health Protection. They may also
choose to report through the secure and convenient web-based notification system
available in the Central Notification Office (CENO) On-line website at
http://www.chp.gov.hk/ceno. The Centre for Health Protection will conduct
surveillance and control of these diseases.
Adapted from:
1. Global Influenza Surveillance (http://www.who.int/csr/disease/influenza/influenzanetwork/en/index.html)
2. Department of Health – Public health and disease surveillance
(http://www.info.gov.hk/dh/diseases/)
Local news [3]
Keywords
Title
流行性感冒 吸取沙士教訓 避免迫爆一醫院 禽流感 倘爆發 港
三階段收症
醫管局定禽流化驗應變 三小時內知道是否中招
亞洲流感殺 400 萬人
20 世紀 3 大流感疫情
殺人流感病毒寄 18 國 世 不排除已經蔓延
籲全球撥款製流感疫苗
病毒或變種： 可人傳人 無病徵
申請撥 2.5 億購流感疫苗
加州流感 將威脅北半球 港府戒備 加強檢驗 年底
輸入疫苗
Newspaper
Page number
Date
蘋果日報
健康與醫療 A30
2005-05-10
蘋果日報
蘋果日報
蘋果日報
蘋果日報
蘋果日報
蘋果日報
蘋果日報
蘋果日報
港聞 A12
國際頭條 A26
國際頭條 A26
國際頭條 A26
健康與醫療 A19
港聞 A04
港聞 A08
健康與醫療 A20
2005-04-25
2005-04-14
2005-04-14
2005-04-14
2005-04-06
2005-03-23
2005-03-15
2005-03-10
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References:
Video presentation:
1.
2.
Microbe Hunters: Tracking Infectious Agents by Donald E. Ganem, M.D. –
(http://www.hhmi.org/lectures/webcast/ondemand/99webcast1/index.html)
Emerging Infections: How Epidemics Arise –
(http://www.hhmi.org/lectures/webcast/ondemand/99webcast4/index.html)
Virus
1.
2.
3.
CDC (AIDS) - http://www.cdc.gov/hiv/dhap.htm
CDC (SARS) - http://www.cdc.gov/ncidod/sars/
Centre for Health Protection (AIDS) http://www.chp.gov.hk/view_content.asp?lang=tc&info_id=3127
4. World Health Organization - http://w3.whosea.org/EN/Section10/Section18.htm
5. Centre for Health Protection (SARS) http://www.chp.gov.hk/content.asp?lang=tc&id=24&info_id=47&pid=9
6. Discovery of Viruses - http://www-micro.msb.le.ac.uk/109/Introduction.html
http://www.tulane.edu/~dmsander/WWW/224/Classification224.html
7. Examples of viruses http://www.accessexcellence.org/RC/VL/GG/examples_of_viruses.html
8. Introduction to virus - http://pathmicro.med.sc.edu/mhunt/intro-vir.htm
9. Lifecycle of virus - http://www.web-books.com/MoBio/Free/Ch1E3.htm
10. Virus structure - http://www.vir.gla.ac.uk/staff/bhellad/virusstructureoverview.htm
Influenza
1.
2.
3.
4.
5.
6.
7.
8.
CDC – (http://www.cdc.gov/flu/)
Centre for Health Protection –
(http://www.chp.gov.hk/content.asp?lang=en&info_id=29&id=24&pid=9)
CUHK – (http://www.cuhk.hk/sars_and_flu/influenza.htm)
Department of Health - (http://www.info.gov.hk/dh/do_you_k/eng/influenza.htm)
HKSAR - (www.info.gov.hk/aids/english/itc/pdf/itcp_e02.pdf)
WHO – (http://www.who.int/mediacentre/factsheets/fs211/en/index.html)
香港十大傳染病 - 流行性感冒 (Influenza) –
(http://www.healthno1.com/articles/special/infection/03influenza.html)
Healthzone -認識流行性感冒
(http://www.cheu.gov.hk/b5/resources/exhibition_details.asp?id=2241&HTMLorText=0)
FluNet - (http://www.who.int/GlobalAtlas/InteractiveMap/MainFrame2.asp)
9.
10. Influenza 1918 - (http://www.pbs.org/wgbh/amex/influenza/index.html)
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H5N1
1.
2.
3.
4.
Prevention of Influenza in Schools - (http://www.info.gov.hk/info/flu/eng/school.htm)
Wikipedia – (http://en.wikipedia.org/wiki/Negative-sense_ssRNA_virus)
Estate Doctors Associate – (http://www.eda.org.hk/h5n1.htm#TOP)
BUPA UK private health insurance –
(http://www.bupa.co.uk/health_information/html/health_news/270104avianflu.html)
5. 禽流感在亞洲斷續爆發 –
(http://www.healthno1.com/articles/special/infection/03influenza.html)
6. 世界各地禽流感的統計數字 – (http://www.info.gov.hk/info/flu/chi/global.htm)
7. 「自然」雜誌刊載最新禽流感病毒發現 H5N1 病 毒 力 足 威 脅 全 球 (http://web.hku.hk/facmed/press/2004-07-08/press-release-tc.pdf)
8. 預防流行性感冒的健康指引 (http://www.info.gov.hk/dh/diseases/influenza/Letter20040127c.htm)
9. H5N1 禽流感 - (http://www.hkma.com.hk/chinese/newsroom/news/h5n1-s.htm)
10. Selected Resources on H5N1 Avian Influenza –
(http://www.lib.cuhk.edu.hk/Common/Reader/Channel/ShowPage.jsp?Cid=309&Pid=10&V
ersion=0&Charset=iso-8859-1&page=0)
11. 《鏗鏘集》
香港大學微生物學系副教授管軼博士表示一直在樣本中找到 H5N1 病毒 (http://www.rthk.org.hk/press/chi/20050724_66_120557.html)
12. [港聞焦點] - 禽流感問題 – (http://hk.news.yahoo.com/fc/news_fc_hk1chicken-5.html)
WHO/CDC/CHP
1.
2.
3.
Roles of WHO – (http://www.who.int/ith/en/)
Center for health and prevention in HK
 http://www.healthyhk.gov.hk/phisweb/en/links/
 http://www.info.gov.hk/dh/diseases/ph&eb/v11n3.htm
 http://www.chp.gov.hk/vision.asp?lang=en&id=22&pid=8&ppid=
 http://www.info.gov.hk/dh/
CDC of US – (http://www.cdc.gov/irmo/ea/fdefr3.pdf)
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Trial Version
Glossary
English
Acquired Immunodeficiency Syndrome
Antigen
Bacteriophage
Chickenpox
Cowpox
Deoxyribonucleic acid (DNA)
Diaherra
Epidemic
Genome
German measles
Immunofluorescence
Influenza
Mutation
Nanometer
Nucleic acid
Pandemic
Poliomyelitis
Polymerase chain reaction
Prion
Protein
Rabies
Replication
Reye’s syndrome
Ribonucleic acid (RNA)
Serology
Severe Acute Respiratory Syndrome
Small pox
Surveillance
Vaccination
Virology
Virus
Chinese
愛滋病
抗原
噬菌體
水痘
牛痘
去氧核糖核酸
腹瀉
(流行病的)傳播
基因組
德國麻疹
抗體螢光染色
流行性感冒
變種
奈米 (即十億分之一米)
核酸
全國流行的
小兒麻痺症
聚合鏈反應
傳染性蛋白質
蛋白質
狂犬病
複製
雷氏症候群
核糖核酸
血清學
嚴重急性呼吸道綜合症
天花
監視
種痘
病毒學
病毒
22