Swine Flu (Influenza A H1N1) Pandemic Pr


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Swine Flu (Influenza A H1N1) Pandemic : 

Swine Flu (Influenza A H1N1) Pandemic Prepared by Nikki-Jeunelle Wilson & Mohisha Webley

Objectives : 

Objectives Explain what is swine flu Explain the swine flu pandemic Describe the pathogenesis of swine flu Transmission of swine flu Identify the symptoms Diagnosis of swine flu Treatment Precautions

Swine Influenza/H1N1 Virus : 

Swine Influenza/H1N1 Virus An electron microscope image of the reassorted H1N1 influenza virus

What is Swine Flu? : 

What is Swine Flu? Swine flu (swine influenza) is a respiratory disease caused by viruses (influenza viruses) that infect the respiratory tract of pigs. In some instances, people have developed the swine flu infection when they are closely associated with pigs (for example, farmers, pork processors), and likewise, pig populations have occasionally been infected with the human flu infection Direct transmission of a swine flu virus from pigs to humans is occasionally possible (this is called zoonotic swine flu).

What is Swine Flu Cont’d : 

What is Swine Flu Cont’d This cross-species situation with influenza viruses has had the potential to change. Investigators think the 2009 swine flu strain should be termed novel H1N1 flu since it is mainly found infecting people and exhibits two main surface antigens, H1 (hemagglutinin type 1) and N1 (neuraminidase type1). Recent investigations show the eight RNA strands from novel H1N1 flu have one strand derived from human flu strains, two from avian (bird) strains, and five from swine strains.

Structure of the Influenza A Virus : 

Structure of the Influenza A Virus

Why is swine flu (H1N1) infecting humans? : 

Why is swine flu (H1N1) infecting humans? Influenza viruses have 3 main types A, B & C. They are enveloped RNA viruses with a segmented genome; i.e. the viral RNA genetic code is not a single strand of RNA but exists as eight different RNA segments in the influenza viruses. some of the replicating RNA strands from the human virus can get enclosed inside the enveloped swine influenza virus. Various combinations of RNA segments can result in a new subtype of virus known as antigenic shift that may have the ability to preferentially infect humans but still show characteristics unique to the swine influenza virus

Why is swine flu (H1N1) infecting humans? Cont’d : 

Why is swine flu (H1N1) infecting humans? Cont’d Antigenic shift is the formation of a new viral type where as ; Antigenic drift is small changes in an individual RNA segment in flu viruses and can result in minor changes in the virus. pigs play a unique role as an intermediary host to new flu types because they can be infected with many flu viruses Therefore they function as a "mixing pot" for flu RNA segments Pigs pick up these viruses from the environment and is therefore the major way that flu virus RNA segments enter the mammalian flu virus population.

Antigenic Shift & Drift : 

Antigenic Shift & Drift Antigenic Drift Yearly Epidemics Antigenic Shift Influenza Pandemics

Is swine flu a cause of an Epidemic or Pandemic? : 

Is swine flu a cause of an Epidemic or Pandemic? An epidemic is an outbreak of a contagious disease that is rapid and widespread, affecting many individuals at the same time, (the swine flu outbreak in Mexico fit this definition). A pandemic is an epidemic that becomes so widespread that it affects a region, continent, or the world. However, WHO officials determined that swine flu (influenza A H1N1) 2009 reached their level 6 criteria (person-to-person transmission) and was therefore declared a pandemic.

Current WHO phase of Pandemic alert : 

Current WHO phase of Pandemic alert

Pathogenesis of swine flu : 

Pathogenesis of swine flu The swine flu virus, like any strain of influenza virus is a little package of inert genetic material. The virus particle attaches to a living cell and injects the genetic material into it The virus's genetic material hijacks the cell's normal RNA/DNA machinery and tells the cell to create copies of the virus. The cell then bursts, and hundreds of virus particles are released to repeat the cycle. All of the target cells in your body would get infected and burst.

Transmission of swine flu to Humans : 

Transmission of swine flu to Humans Through close contact with infected pigs Through contact with infected persons. Infected people may be able to infect others beginning 1 day before symptoms develop and up to 7 or more days after becoming sick Through contaminated droplet e.g. coughing, speaking or sneezing of infected persons that get into someone else's mouth, eyes or nose and thus become infected By contaminated surfaces

Symptoms of swine flu : 

Symptoms of swine flu Symptoms of swine flu are similar to most influenza infections: fever (100F or greater), cough, nasal secretions, fatigue, and headache, with fatigue being reported in most infected individuals. Some patients experience nausea, vomiting, and diarrhea Patients might develop severe respiratory symptoms and need respiratory support (such as a ventilator to breathe for the patient). Patients can get pneumonia (bacterial secondary infection) if the viral infection persists, and some can develop seizures. Death often occurs from secondary bacterial infection of the lungs

Diagnosis of swine flu : 

Diagnosis of swine flu Swine flu is diagnosed clinically by the patient's history of association with people known to have the disease and their symptoms A quick test e.g. nasopharyngeal swab sample is done to see if the patient is infected with influenza A or B virus. Most of the tests can distinguish between A and B types. The test can be negative (no flu infection) or positive for type A and B. If the test is positive for type B, the flu is not likely to be swine flu (H1N1). If it is positive for type A, the person could have a conventional flu strain or swine flu (H1N1). However, H1N1 is definitely diagnosed by PCR-real time where particular antigens of the virus type are identified

Treatment available for swine flu : 

Treatment available for swine flu The best treatment for influenza infections in humans is prevention by vaccination. The first vaccine released was a nasal spray vaccine and consists of a live attenuated H1N1 virus. It should not be used in anyone who is pregnant or immunocompromised and is approved for ages 2-49 The second, an injectable vaccine is made from killed H1N1. It is approved for use in ages 6 months to the elderly, including pregnant females Both of these vaccines have been approved by the CDC only after they had conducted clinical trials to prove that they were safe and effective

Treatment cont’d : 

Treatment cont’d Two antiviral agents have been reported to help prevent or reduce the effects of swine flu. They are zanamivir (Relenza) and oseltamivir (Tamiflu), both of which are also used to prevent or reduce influenza A and B symptoms. These drugs should not be used indiscriminately, because viral resistance to them can and has occurred. They are not recommended if the flu symptoms already have been present for 48 hours or more

Precautions : 

Precautions Avoid exposure to the virus; this is done by frequent hand washing, not touching your hands to your face especially the nose and mouth Avoiding any close proximity to or touching any person who may have flu symptoms. Since the virus can remain viable and infectious for about 48 hours on many surfaces, good hygiene and cleaning with soap and water or alcohol-based hand disinfectants are also recommended.

References : 

References www.virology.ws/2009/06/02/pathogenesis_of_influenza_in_humans/ www.cdc.gov/H1N1flu/qa.htm www.cdc.gov/H1N1flu/key_facts.htm www.who.int/csr/disease/swineflu/en/index.html www.deseretnews.com/article/705300204/how-stuff-works-how-swine-flu-works.html en.wikipedia.org/wiki/swine_influenza (for electron microscope image of swine flu virus) www.medicinenet.com/swine_flu/article.htm www.pediatrics.about.com/od/swineflu/a/409_symptoms.htm www.nlm.nih.gov/medlineplus/h1n1fluswineflu.html www.funonthenet/articles/swine_flu.html www.who.int/csr/disease/avian_influenza/phase/en/index.html Dr. Chong’s “Novel Influenza A H1N1” ppt Dr. Alaa Nagy’s “Swine Flu” ppt Internal medical consultant, Dr. Adil Khazindar’s “H1N1” ppt

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