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Viruses

Viruses. Lytic Infections by viruses Lysogenic infections by viruses Treating viral infections Viral Epidemics Human Viral Diseases. What is a Virus?. Non-living particle made of proteins, nucleic acids, and sometimes lipids They can reproduce only by infecting living cells

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Viruses

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  1. Viruses Lytic Infections by viruses Lysogenic infections by viruses Treating viral infections Viral Epidemics Human Viral Diseases

  2. What is a Virus? • Non-living particle made of proteins, nucleic acids, and sometimes lipids • They can reproduce only by infecting living cells • Lytic Infections: virus enters a cell, multiplies, and causes cell to lyse, or burst, sending new viruses out to infect more cells (SARS, common cold, influenza, rabies) • Lysogenic Infections: viral DNA is inserted into host cell DNA and multiplies w/out harming host cell; causes each new cell to be infected with virus (HIV, Herpes, HPV, shingles)

  3. Prevention & Treatment • Viruses are difficult to eliminate b/c their replication pathway requires host cells; drugs are often toxic to the host cell • Also must be grown in live cells and tissues which takes time to do • Methods: vaccinations to provide immunity from infections and antiviral drugs that interfere with viral replication • ** viruses mutate rapidly so antiviral drugs must be used only when necessary • Viruses can become resistant quickly

  4. Viral Epidemics in history • Smallpox among Native Americans: 1492-1900, death toll is estimated at 80-90% of the population • Influenza: 1918-1929 worldwide, death toll approx. 75 million • HIV/AIDS: 1981-present worldwide, death toll approx. 25 million

  5. Human Viral Diseases • STD’S: HIV/AIDS, herpes • Childhood diseases: measles, mumps, chicken pox • Respiratory diseases: influenza, common cold • Skin diseases: shingles, warts • Digestive tract diseases: gastroenteritis • Nervous system diseases: polio, viral meningitis, rabies • Other diseases: smallpox, hepatitis

  6. Latest News • 7 APRIL 2013 - As of 7 April 2013 (16:30 CET), the Chinese health authorities notified WHO of an additional three laboratory-confirmed cases of human infection with influenza A(H7N9) virus. • To date, a total of 21 cases have been laboratory confirmed with influenza A(H7N9) virus in China, including six deaths, 12 severe cases and three mild cases. • The Chinese government is actively investigating this event and has heightened disease surveillance.

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