Flu

Made by : Kristína Čopová, Barbora Tóthová, Štefan Páll, Adam Mihalov, Matúš Dobrovolský, Mária LisikováII.B

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Types of influenza virus

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Virus characteristics

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How To Provide

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The

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the Influenza

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Pandemics Caused By One Of The Types Of Flu

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Symptoms

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Types of influenza virus

Influenzavirus A This genus has one species, influenza A virus. Wild aquatic birds are the

natural hosts for a large variety of influenza A. Occasionally, viruses are transmitted to other species and may then cause devastating outbreaks in domestic poultry or give rise to human influenza pandemics. The type A viruses are the most virulent human pathogens among the three influenza types and cause the most severe disease. The influenza A virus can be subdivided into different serotypes based on the antibody response to these viruses. The serotypes that have been confirmed in humans, ordered by the number of known human pandemic deaths, are:

H1N1, which caused Spanish flu in 1918, and the 2009 flu pandemic H2N2, which caused Asian Flu in 1957 H3N2, which caused Hong Kong Flu in 1968 H5N1, a current pandemic threat H7N7, which has unusual zoonotic potential H1N2, endemic in humans and pigs

Influenzavirus B This genus has one species, influenza B virus. Influenza B almost exclusively

infects humans and is less common than influenza A. The only other animals known to be susceptible to influenza B infection are the seal and the ferret. This type of influenza mutates at a rate 2–3 times lower than type A and consequently is less genetically diverse, with only one influenza B serotype. As a result of this lack of antigenic diversity, a degree of immunity to influenza B is usually acquired at an early age. However, influenza B mutates enough that lasting immunity is not possible. This reduced rate of antigenic change, combined with its limited host range (inhibiting cross species antigenic shift), ensures that pandemics of influenza B do not occur.

Influenzavirus C This genus has one species, influenza C virus, which infects humans, dogs

and pigs, sometimes causing both severe illness and local epidemics. However, influenza C is less common than the other types and usually only causes mild disease in children.

Pandemics Caused By One Of The Types Of Flu

Most of the major pandemics have been caused by various types of flu that fall into the Type A category.  These are the most contagious of the three, and also the easiest to mutate, making them even harder to treat since doctors have to adjust treatments and vaccines.  Here are some of the larger pandemics.

1918- The Spanish Flu Pandemic- This was caused by the H1N1 virus, which is a Type A virus.  Type A influenza is the only one with subcategories, mainly to accommodate the rapid mutation of the virus.  This pandemic killed over 500,000 people in the U.S., and had a worldwide death toll of between 20 and 50 million.  This by far the deadliest pandemic of the 20th century.

1957- Asian Flu Pandemic- This was caused by the H2N2 virus, but was not as severe as the outbreak of Spanish Flu.  This strain luckily died in 1968, and hasn't been seen since.  The drawback, no one under the age of 35 has a natural immunity to it, making it possible for the virus to come back without warning.  The type of flu caused roughly 70,000 deaths in the U.S.

1968- Hong Kong Flu- H3N2 was a closely related to the Asian Flu, which illustrate how the virus can change and mutate into another type.  While it was less severe than its predecessor, it still caused around 35,000 deaths in the U.S.

1997- Avian Flu- This is still considered a threat by many, especially since it mutated and spread so quickly.  It has a number of names, including H5N1, H9N2, H7N2, and H5N1.  It was first found to be transmitted from birds to people mainly through poultry, with some types of this flu killing 50 percent of those infected.  This type of flu has caused the culling of several types of poultry due fear of the disease spreading.

2009- Swine Flu- The H1N1 virus, which we've heard about in past pandemics, has caused mass media hysteria since the initial report of cases in Mexico City.  While this flu hasn't killed many people, the world is currently taking a very cautious approach to it, since past similar strains have seen mutations that have killed hundreds of thousands of people.

Virus characteristics

The virus is a novel strain of influenza. Existing vaccines against seasonal flu provide no protection. A study at the U.S. Centers for Disease Control and Prevention (CDC) published in May 2009 found that children had no preexisting immunity to the new strain but that adults, particularly those over 60, had some degree of immunity. Children showed no cross-reactive antibody reaction to the new strain, adults aged 18 to 64 had 6-9%, and older adults 33%. It was also determined that the strain contained genes from five different flu viruses: North American swine influenza, North American avian influenza, human influenza, and two swine influenza viruses typically found in Asia and Europe . Further analysis showed that several of the proteins of the virus are most similar to strains that cause mild symptoms in humans, leading virologist Wendy Barclay to suggest on May 1, 2009 that the initial indications are that the virus was unlikely to cause severe symptoms for most people. The first complete genome sequence of the pandemic strain was deposited in public databases on April 27, 2009, by scientists from the U.S. Centers for Disease Control and Prevention in Atlanta . Scientists in Winnipeg later completed the full genetic sequencing of viruses from Mexico and Canada on May 6, 2009.

The history of the Influenza

The word Influenza comes from the Italian language meaning "influence“

The word influenza was first used in English in 1743 when it was adopted

Archaic terms for influenza include epidemic catarrh, grippe (from the French), sweating sickness, and Spanish fever

The most famous influenza was Spanish flu, witch was since 1918 to 1919

Symptoms Symptoms of influenza can start quite suddenly one to

two days after infection. Usually the first symptoms are chills or a chilly sensation, but fever is also common early in the infection, with body temperatures ranging from 38-39 °C (approximately 100-103 °F). Many people are so ill that they are confined to bed for several days, with aches and pains throughout their bodies, which are worse in their backs and legs. Symptoms of influenza may include:

Fever and extreme coldness (chills, shivering, shaking (rigor))

Cough Nasal congestion Body aches, especially joints and throat Fatigue Headache Irritated, watering eyes Reddened eyes, skin (especially face), mouth, throat and

nose In children, gastrointestinal symptoms such as diarrhea and

abdominal pain, (may be severe in children with influenza B)

It can be difficult to distinguish between the common cold and influenza in the early stages of these infections, but a flu can be identified by a high fever with a sudden onset and extreme fatigue. Diarrhea is not normally a symptom of influenza in adults, although it has been seen in some human cases of the H5N1 "bird flu" and can be a symptom in children.

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