Influenza
Influenza
• 1.What is Influenza? • 2.How Influenza Spreads • 3.Symptoms • 4.Diagnosis • 5. Treatment • 6.How to Prevent
1.What is Influenza?
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Influenza (the flu)
Influenza (the flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The best way to prevent seasonal flu is by getting a seasonal flu vaccination each year.
made when people with flu cough, sneeze or talk ▪ These droplets can land in the mouths or noses of people who are
nearby or possibly be inhaled into the lungs. ▪ Less often, a person might also get flu by touching a surface or
Whether a person has typical seasonal flu or swine flu, the symptoms seem to be quite similar. Flu symptoms are usually more severe than cold symptoms and come on quickly. Symptoms of swine flu and seasonal flu include sore throat, fever, headache, muscle aches and soreness, congestion, and cough. Swine flu in particular is also associated with vomiting and diarrhea.
20th century
World War I ：8 to 10 million
1918 1957 1968
H1N1 H2N3 H2N3
Spanish flu Far east flu Hong Kong flu
40 million 2 million 700000
Key Influenza A Viral Features
▪ Influenza (the flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death.
Antigenic shift: ▪ Is an abrupt, major change
▪ Results in a new influenza A subtype or a virus
2.How Influenza Spreads
▪ People with flu can spread it to others up to about 6 feet away ▪ Most experts think that flu viruses are spread mainly by droplets
血凝素 （H）
神经氨酸酶 （N）
Influenza: An Ever-Changing Virus
Antigenic drift: ▪ Small change ,happen continually over time
▪ Is one of the main reasons why people can get the flu more than one time
Cold symptoms usually begin with a sore throat, which usually goes away after a day or two. Nasal symptoms, runny nose, and congestion follow, along with a cough by the fourth and fifth days. Fever is uncommon in adults, but a slight fever is possible. Children are more likely to have a fever with a cold. With cold symptoms, your nose teems with watery nasal secretions for the first few days. Later, these become thicker and darker.
History：2,400 years
Difference Between Cold or FLU
A cold is a milder respiratory illness than the flu. While cold symptoms can make you feel bad for a few days. Flu symptoms can make you feel quite ill for a few days to weeks.
•In virus classification influenza viruses are RNA viruses that make up three of the five genera of the family Orthomyxoviridae.
Influenzavirus A Influenzavirus B Influenzavirus C