Exam #2 F 3/30 in WCH 1.120Review Th 3/29 at 5pm in GRG 102

Homework #3 is due 4/11.Bonus #2 is due W 4/4.Bonus #3 is due F 4/27.

Immune System Overview

CB 43.14

Influenza, an ssRNA envelope virus

Spanish flu of 1918-1919

Spanish flu of 1918-1919

•Killed between 20-50 million people worldwide; 675,000 in the U.S.(2.5%-5% of world population)

•Infected 1/5 to 1/4 of world population

•Was most lethal to people 20-40 years old

http://virus.stanford.edu/uda/

Spanish flu of 1918-1919People on their way to work suddenly developing the flu and dying within hours (Henig).

One physician writes that patients with seemingly ordinary influenza would rapidly "develop the most viscous type of pneumonia that has ever been seen" and later when cyanosis appeared in the patients, "it is simply a struggle for air until they suffocate," (Grist, 1979).

Another physician recalls that the influenza patients "died struggling to clear their airways of a blood-tinged froth that sometimes gushed from their nose and mouth," (Starr, 1976).

http://virus.stanford.edu/uda/

The high fatality rate from the Spanish flu was probably due to an immune system over-reaction

Spanish flu of 1918-1919

This influenza virus was similar to avian flu

Avian flu exists in two distinct forms:High pathogenicity AI virus that produce >75% mortality (HPAI)

Low pathogenicity is everything else (LPAI)

Public Health Risk from Avian Influenza Viruses by Perdue and Swayne in AVIAN DISEASES 49:317–327, 2005

Avian flu is maintained in wild birds as low pathogenicity, and occasionally mutates to high pathogenicity in domesticated birds.

Approximately 25 outbreaks since 195915 since 1990 and 6 since 2000

Public Health Risk from Avian Influenza Viruses by Perdue and Swayne in AVIAN DISEASES 49:317–327, 2005

Influenza viruses type A, B, and C. Type A viruses are the most common and are found in swine, horses, wild birds, domestic poultry, and humans. Sporadic infections have been reported in farmed mink, wild whales and seals, dogs, andcaptive populations of big cats (tigers and leopards).

Public Health Risk from Avian Influenza Viruses by Perdue and Swayne in AVIAN DISEASES 49:317–327, 2005

Influenza, an ssRNA envelope virus

The influenza A virus genome contains 8 genes that code for 10 different proteins.

Public Health Risk from Avian Influenza Viruses by Perdue and Swayne in AVIAN DISEASES 49:317–327, 2005

CB 18.8

Influenza, an ssRNA envelope virus

The influenza A virus genome contains 8 genes that code for 10 different proteins.

Membrane protein

Viral genetic material can change allowing the virus to infect different cells.

Virus 1 Virus 2

Virus1+2

During co-infection viral genomes can be mixed resulting in a new hybrid virus.

Public Health Risk from Avian Influenza Viruses by Perdue and Swayne in AVIAN DISEASES 49:317–327, 2005

How is bird flu being spread?

Declan Butler NATURE Vol 439 pg 772 February 16, 2006

http://news.bbc.co.uk/1/shared/spl/hi/world/05/bird_flu_map/html/1.stm

Bird Flu Spread

Migratory wild birdsorPoultry trade (black market)

Prevention efforts will only be effective if the source can be defined

If the flu is being spread by migratory birds, why are some migratory routes free of flu?

In 2004 an outbreak in Tibet was traced to illegal poultry transport from China.

How should we spend resources to protect poultry and humans?

Even with today’s vaccine technology and the knowledge that vaccines will prevent severe illnessand death, only 300 million doses are produced and used worldwide.More than 95% of the world’s population remains at risk for infection.

Each year an estimated 250,000 to 500,000 people die worldwide as a result of influenza virus infections.

Public Health Risk from Avian Influenza Viruses by Perdue and Swayne in AVIAN DISEASES 49:317–327, 2005

It can be estimated that in the United States, for example, the yearly economic burden caused by influenza deaths, infections, vaccinations, loss of productivity, and attendant health care costs is equal to 0.1%–0.5% of the gross domestic product.

Public Health Risk from Avian Influenza Viruses by Perdue and Swayne in AVIAN DISEASES 49:317–327, 2005

Exam #2 F 3/30 in WCH 1.120Review Th 3/29 at 5pm in GRG 102

Homework #3 is due 4/11.Bonus #2 is due W 4/4.Bonus #3 is due F 4/27.