Basics of Avian and Pandemic Influenza
description
Transcript of Basics of Avian and Pandemic Influenza
![Page 1: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/1.jpg)
Basics of Avian and Pandemic Influenza
Basics of Avian and Pandemic Influenza
![Page 2: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/2.jpg)
The Pandemic Clock is ticking…we just don’t know what time it is.
Edgar Marcus University of Washington School of Medicine
Will pandemic flu strike again?
![Page 3: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/3.jpg)
The “Forgotten Pandemic”
The influenza pandemic of 1918-19 killed more humanskilled more humans than any other disease in a period of similar duration in the history of the world.
Alfred W. Crosby, historian & author
![Page 4: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/4.jpg)
Influenza pandemics in the 20th century
1918: “Spanish Flu” 1957: “Asian Flu” 1968: “Hong Kong Flu”
50 million deaths 1-4 million deaths
1-4 million deaths
![Page 5: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/5.jpg)
An Influenza Ward during the 1918: “Spanish Flu”
Avian strain of influenza virus
Virus was similar to current bird flu virus
Spread around the globe in 4-6 months
Infected between 25-30% of the world population
Killed 40-100 million world-wide
Majority of deaths in persons 18 to 40 years old
![Page 6: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/6.jpg)
Influenza pandemics are recurring events
• Influenza pandemic is NOT a one-off event.
• They are regular events that occur a few times per century.
• As long as the influenza virus continues to mutate we will continue to have influenza pandemics.
• We cannot be sure exactly when the next one will be, but experts agree it will happen eventually.
• The H5N1 Avian Influenza virus currently circulating in birds is the
No.1 candidate for causing the next pandemic.
![Page 7: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/7.jpg)
A Pandemic WILL occur:
the question is “when and how severe will it be”?
![Page 8: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/8.jpg)
WHO Situational Assessment as at May 2006
• Risk of Pandemic is great• The risk will persist• The evolution of the threat cannot be
predicted• The early warning systems are weak• Reduction of morb/mort impeded by
inadequate medical supplies
• Preparation is the best protection
![Page 9: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/9.jpg)
H5N1 - The Basics
– Avian influenza H5N1 virus in poultry flocks
– Aggressive infection - quickly kills whole flocks
– Can infect humans - mainly only people living/working with poultry
– Over 200 people infected - more than half have died (mortality rate >50%!!!!)
– CannotCannot yet easily spread from person to person
H5N1 has similarities to 1918-19 virus
![Page 10: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/10.jpg)
THE DISEASE IN HUMANS
Influenza viruses are normallynormally highly species-specifichighly species-specific, meaning that viruses that infect an individual species (humans, certain species of birds, pigs, horses, and seals), and only rarely spill over to cause infection in other species.
Of the hundreds of strains of avian influenza A viruses, only four are known to have caused human infections: H5N1, H7N3, H7N7, and H9N2. In general, human infection with these viruses has resulted in mild symptoms and very little severe illness,
with one notable exception: the highly pathogenic H5N1 virus.
![Page 11: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/11.jpg)
H5N1--great concern for human health
First, the H5N1 virus has caused the greatest number of human deaths.
The virus has met all prerequisites for the start of a pandemic save one: an ability to spread efficiently among humans.
![Page 12: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/12.jpg)
H5N1 - The Basics
An Influenza Virus must have three attributes to become a Pandemic Virus:
1) A novel (new) virus which humans have no
immunity
2) The virus causes significant human illness and
death
3) The virus can spread easily from person to
person x
Avian Flu H5N1 has 2 out of 3 today…
![Page 13: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/13.jpg)
H5N1 - The Basics
An Influenza Virus must have three attributes to become a Pandemic Virus:
1) A novel (new) virus which humans have no
immunity
2) The virus causes significant human illness
and death
3) The virus can spread easily from person to
person xx
Avian Flu H5N1 has 2 out of 3 today…
![Page 14: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/14.jpg)
禽流感在公共衛生的重要性在 20世紀時的三次重大「世界性大流行」均與其病毒來自「禽類」有關。若張三感染了「『禽』流感病毒(紅色基因)」而他的親友李四卻感染「『人』流感病毒(藍色基因)」,那重新洗牌八段藍色基因與八段紅色基因,容易產生一種『新』型病毒是原來人的抗體無法抵擋的,卻又可在人群中傳播。
禽流感病毒 人流感病毒 新型流感病
××
![Page 15: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/15.jpg)
Genetic drift
• A change that occurs on the molecular level to effect a change in the antigenic properties of a bacteria or virus.
• Antigenic drift occurs naturally and more rapidly in certain viruses (for example HIV).
• It is antigenic drift which complicates the development of an effective HIV (AIDS) vaccine.
![Page 16: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/16.jpg)
As the human influenza strains are continually evolving
via these mutations, the virus is able to escape from the human immune response and cause epidemics.
For this reason, manufacturers must change the composition of the influenza vaccine on an annual basis in order to ensure an accurate match is achieved with the circulating viral strains
![Page 17: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/17.jpg)
Genetic shift
• Antigenic shift is the process by which different strains of a virus, (or different viruses), combine to form a new subtype
• having a mixture of the surface antigens of the two original strains.
![Page 18: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/18.jpg)
Antigenic drift is the natural mutation over time of known strains of influenza (or other things, in a more general sense) which may lead to a loss of immunity, or in vaccine mismatch. Antigenic drift occurs in all types of influenza including influenza A, B and C.
Antigenic shift, however, occurs only in influenza A because it infects more than just humans. Affected species include other mammals and birds, giving influenza A the opportunity for a major reorganization of surface antigens
What is the difference between Antigenic shift and antigenic drift?
![Page 19: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/19.jpg)
Antigenic drift is the natural mutation over time of known strains of influenza (or other things, in a more general sense) which may lead to a loss of immunity, or in vaccine mismatch. Antigenic drift occurs in all types of influenza including influenza A, B and C.
Antigenic shift, however, occurs only in influenza A because it infects more than just humans. Affected species include other mammals and birds, giving influenza A
the opportunity for a major reorganization of surface antigens.
Antigenic shift vs antigenic drift:
![Page 20: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/20.jpg)
Infectivity period: 1 day before, 14 days after
1. Contact transmission: Direct - Kissing Indirect – Sharing
2. Mainly by “droplet” spread: Coughing, sneezing and talking Mucous membranes Virus active on hard surfaces for 48
hours 3. “Aerosol” spread:
Unusual but possible in very crowded conditions
How is Influenza Spread?
![Page 21: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/21.jpg)
WHO Classification of Pandemic Phases
![Page 22: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/22.jpg)
H5N1 Avian Flu – where is it now?
• Human infections (as at 8 May 2006):
– Turkey (12 cases, 4 deaths)– Vietnam (93 cases, 42 deaths)– Indonesia (33 cases, 25 deaths)– Cambodia (6 cases, 6 deaths)– Thailand (22 cases, 14 deaths)– China (18 cases, 12 deaths)– Iraq (2 cases, 2 deaths)– Azerbaijan (8 cases, 5 deaths)– Egypt (13 cases, 5 deaths)
![Page 23: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/23.jpg)
![Page 24: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/24.jpg)
![Page 25: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/25.jpg)
Prevention and control of
Avian Flu
![Page 26: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/26.jpg)
Annual influenza vaccination is now recommended for the following groups
• persons at high risk for influenza-related complications
• persons who live with or care for persons at high risk
• health-care workers.
Vaccines: the first line of defence
![Page 27: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/27.jpg)
Depopulation of farms and markets
![Page 28: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/28.jpg)
PILLARS OF THE STRATEGY
• Preparedness and
Communication
• Surveillance and Detection
• Response and Containment
![Page 29: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/29.jpg)
Influenza A(H7N9) is one of a subgroup of influenza viruses that normally circulate among birds. Until recently, this virus had not been seen in people. However, human infections have now been detected.
The disease is of concern because most patients have been severely ill. There is no indication thus far that it can be transmitted between people, but both animal-to-human and human-to-human routes of transmission are being actively investigated.
H7N9
Courtesy of WHO Collaborating Centre for Reference and Research on Influenza, National Institute of Infectious Diseases, Japan
Dr Margaret Chan Director-General of WHO
![Page 30: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/30.jpg)
Hong Kong Quarantines 19 People After Second Case of H7N9
Hong Kong health officials have quarantined 19 people who had contact with an 80-year-old man confirmed to have the city’s second case of H7N9 influenza, which has killed 45 people in China this year.
Bloomberg news Dec 8, 2013
Disease Outbreak News
![Page 31: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/31.jpg)
SARS
![Page 32: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/32.jpg)
Pandemic Influenza is different to SARS
SARS Pandemic Flu
One off unexpected event Recurring event
Difficult to catch Easy to catch
People only infectious when they are symptomatic
People are infectious before they are symptomatic
Several thousand cases, epidemic lasted several months
Potentially millions of cases, pandemic could last more than a year
Easy to contain an outbreak Almost impossible to contain an outbreak
• Many institutions are using their SARS plan as the basis for their pandemic influenza plan.
• But SARS is different to pandemic influenza:
![Page 33: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/33.jpg)
咳嗽禮節
![Page 34: Basics of Avian and Pandemic Influenza](https://reader035.fdocuments.in/reader035/viewer/2022062409/56814a7d550346895db7922f/html5/thumbnails/34.jpg)
Thank You