Diseases and the Immune/Lymphatic System

Can you define these terms?• Infectious: • Capable of spreading disease. Also known as

communicable.• Virus:• A tiny organism that multiplies within cells and

causes disease such as chickenpox, measles, mumps, rubella, pertussis and hepatitis. Viruses are not affected by antibiotics, the drugs used to kill bacteria.

• Quarantine: • The isolation of a person or animal who has a disease

(or is suspected of having a disease) in order to prevent further spread of the disease.

• Vaccine: • A product that produces immunity therefore

protecting the body from the disease. Vaccines are administered through needle injections, by mouth and by aerosol.

• Immunity: • Protection against a disease. There are two

types of immunity, passive and active. Immunity is indicated by the presence of antibodies in the blood and can usually be determined with a laboratory test.

Is contagion real?

• Have your answers out for discussion on “how real is Contagion?”

• Side Bar: Vomiting Larry• http://www.youtube.com/watch?v=pmy8x2L

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• Epidemic: A widespread occurrence of an infectious disease in a community at a particular time: "a flu epidemic"

• Outbreak: describe an occurrence of disease greater than would otherwise be expected at a particular time and place. It may affect a small and localized group or impact upon thousands of people across an entire continent.

• Pandemic: Prevalent over a whole country or the world

How Does Seasonal Flu Differ From Pandemic Flu?

U.S. Department of Health and Human Services

Contagion introduces the importance Contagion introduces the importance of zoonosis)of zoonosis)

Definition:“A zoonosis is any disease Definition:“A zoonosis is any disease and/or infection which is naturally and/or infection which is naturally transmissible from animals to man."transmissible from animals to man."

Can you think of any other zoonotic Can you think of any other zoonotic diseases in the news these days?diseases in the news these days?

(Mad Cow, Influenza, West Nile Virus, (Mad Cow, Influenza, West Nile Virus, Lyme Disease, SARS)Lyme Disease, SARS)

Let’s look at Bird Flu, birds Let’s look at Bird Flu, birds aren’t the only animals aren’t the only animals affected by that epidemic.affected by that epidemic.

Because various bird flu strains are Because various bird flu strains are spreading and reproducing in spreading and reproducing in millions of wild and domestic birds, millions of wild and domestic birds, they are also mutating … in they are also mutating … in potentially dangerous ways.potentially dangerous ways.

When we hear about Bird flu or swine When we hear about Bird flu or swine flu or SARS It isn’t obvious what the flu or SARS It isn’t obvious what the

fuss is about.fuss is about.

For example: we hear only a handful of For example: we hear only a handful of humans have been infected (so far).humans have been infected (so far).

Or the illness is far away (like in China)Or the illness is far away (like in China)

And who cares about birds & pigs And who cares about birds & pigs getting sick?getting sick?

Zoonosis type outbreaks are dangerous Zoonosis type outbreaks are dangerous because the virus is evolving!because the virus is evolving!

Usually, changes in viral antigens (the Usually, changes in viral antigens (the “bad guys”) are small. “bad guys”) are small.

The illness these “antigenic drift” The illness these “antigenic drift” variants (changes in the flu as it variants (changes in the flu as it travels the globe) produce is annoying travels the globe) produce is annoying (because you can then get the flu (because you can then get the flu every year), but not usually life-every year), but not usually life-threatening (because your body can threatening (because your body can somewhat recognize it).somewhat recognize it).

• But now and then a major change in But now and then a major change in antigens occurs. These “antigenic antigens occurs. These “antigenic shifts” can produce devastating shifts” can produce devastating results -- lethal, global epidemicsresults -- lethal, global epidemics

• The most serious occurred at the end The most serious occurred at the end of World War I (“Spanish Flu”); It of World War I (“Spanish Flu”); It killed 675,00 Americans and between killed 675,00 Americans and between 20 and 50 million people worldwide. 20 and 50 million people worldwide. That’s more than all the wars of the That’s more than all the wars of the 20th century put together. 20th century put together.

What happened?What happened?

Can it happen again?Can it happen again?

The answers relate to the nature The answers relate to the nature of influenza as an evolving of influenza as an evolving

zoonosis -- and a phenomenon we zoonosis -- and a phenomenon we could call “viral sex.”could call “viral sex.”

What’s the quick summary so far?The 1918 flu virus appears to have jumped, directly, from birds to humans.

That jump and the ability to be spread from human to human appear to be dependent on a relatively small number of changes in the avian flu genome.

What do the HIV epidemic and What do the HIV epidemic and major flu outbreaks have in major flu outbreaks have in

common?common?Human activity alters the ecology of a Human activity alters the ecology of a zoonosis in ways that encourage the zoonosis in ways that encourage the

spread of pathogens between species, spread of pathogens between species, across human populations, within across human populations, within

populations of other species, or some populations of other species, or some combination of the above. combination of the above.

Meanwhile, the pathogens evolve in Meanwhile, the pathogens evolve in ways that increase their fitness ways that increase their fitness

under new conditions.under new conditions.

These and other changes in “human These and other changes in “human ecology” are driving the emergence ecology” are driving the emergence

and spread of an entire crop of and spread of an entire crop of diseases unknown just a few years diseases unknown just a few years

ago.ago.

• Epidemiology= disease tracker• Patient Zero: Patient Zero–or the index case

as it’s clinically known–refers to the first person who shows documented symptoms of the disease.

• So, why do the infectious disease experts trip over themselves to find Patient Zero? Why don’t they just deal with the cases at hand?

2 reasons

• 1. better their chances of controlling and dampening the outbreak. By determining exactly where Patient Zero travelled and who they came into contact with. Also can isolate and treat the people who might be carriers.

• If this is done early enough, the outbreak can be artificially “shutdown”.

• 2. locating the exact place where the first infection happened which can often lead to the identification of the source of the virus, which then might for preventative steps to be taken to stop future epidemics.

TED talk…virus hunter

• http://www.ted.com/talks/nathan_wolfe_hunts_for_the_next_aids.html