1. Part Two: Viruses and Vaccines
Notes: Microbes
Part Two: Viruses and Vaccines

2. Parasites
Parasites are organisms that live in or on another organism (the host) and benefit by deriving nutrients at the host's expense.
They don’t typically kill the host, but they make it much harder for them to go about their business.
Malaria (Plasmodium falciparum):
Transferred when the plasmodium parasite is absorbed as a mosquito draws blood.
These mosquitoes are mainly found in warmer, tropical regions.
Starts in the liver, then attacks red blood cells, which burst and cause fevers.
~1,000,000 people die from it every year.

4. There’s a FUNGUS Among Us
A fungus is a eukaryotic organism that doesn’t move under its own power and eats by absorbing nutrients.
They include mushrooms, yeasts, and molds.
They play a vital role:
They are the main decomposers in ecosystems.
Mushrooms are tasty.
Yeast is used to make bread.
Penicillin is a powerful antibiotic.
They can be not so helpful though:
Athlete’s foot is a fungal infection that causes a scaly, itchy, burny rash that in between the toes.
It can be treated with antifungals, but it often comes back.
It is also contagious.
Yeast infections are fungal infections on the skin or mucous membranes.
They are caused by the candida fungus (aka yeast).
This fungus lives in your normally, but if your immune system is suppressed, they can overgrow.

5. Viruses
In the late 1800s, it was found that something smaller than bacteria could cause disease.
A virus is a small infectious agent that replicates only inside the living cells of other organisms.
They can infect all types of life forms: from animals to plants to bacteria.
They have various shapes/designs.
Their origin is unclear, but some may have evolved from plasmids: small, circular loops of DNA that can move between cells.
Viruses can be spread many different ways:
Through food, the air, sex, water, etc.
Viral infections usually provoke an immune system response, that usually eliminates the virus.
Some, like HIV, can avoid the immune response and result in long lasting infections.
ANTIBIOTICS HAVE NO EFFECT ON VIRUSES!

6. Viruses: The Bad and The Ugly
Common Cold (Rhinovirus):
You know what a cold is.
Most people get colds in the fall and winter NOT because it’s cold out, but because rhinovirus loves low humidity.
There are 99 different types that affect humans.
They are amongst the smallest viruses.
How to avoid it: wash your hands.
It can survive up to 3 hours outside someone’s nose.
Treatment: rest and fluids.
Chicken Pox (Varicella):
Highly contagious.
When it occurs in children it’s not so bad. In adults it is much more severe.
Symptoms are a characteristic rash that gets ITCHY.
Treatment: mainly aimed at the symptoms.
Usually after you get it, you are immune for a long time.
However it can stay in your body and cause shingles later.
These are INCREDIBLY painful chicken pox rashes.
How to avoid it:
Avoid contact with infected individuals.
There is a vaccine for it.

7. Influenza – “The Flu” (Orthomyxovirus):
A respiratory infection that causes trouble breathing.
If you are having stomach distress, it’s not the influenza flu.
Symptoms last 2 weeks, then they’re gone.
They can get pretty severe though.
There are several different versions that affect humans. Some also affect animals.
Avian Flu (H5N1): a mutated version that affects birds and can pass to humans.
Swine Flu (H1N1): a mutated version that affects pigs and can pass to humans.
How to avoid it: Same way you avoid a cold. Or get vaccinated.
Treatment: Rest. If caught early enough, there is a antiviral that can be prescribed.

8. Ebola (Ebola virus):
Ebola Hemorrhagic Fever was first identified near the Ebola River in 1976.
FYI: To hemorrhage means an escape of blood from a ruptured blood vessel, especially when profuse.
It’s bad. Really bad. Symptoms:
Fever, aches, sore throat (like the flu)…
Then diarrhea, stomach pain, and vomiting…
THEN internal and external bleeding.
Your organs start to melt…then you die.
The bright side: Ebola is contained to one part of the world.
There is a VERY slight chance you’d ever get it.
It is spread by contact with infected bodily fluids.
Video: Ebola Explained

9. HIV (Human Immunodeficiency Virus):
This is a retrovirus that kills the cells that help the body fight infection.
Once the immune system has been fully compromised, it can develop into AIDS.
Acquired Immune Deficiency Syndrome (AIDS) develops once the body’s immune system can no longer fight other infections.
People don’t die of AIDS. They die from the secondary infections that their body can no longer fight.
How to get it:
Sexual contact with an infected person.
Sharing needles with an infected person.
Treatment: there’s no cure. Researchers are trying to find ways to slow the progress of the virus
HIV doesn’t necessarily cause secondary illnesses.
AIDS does.

10. HIV prevalence as a percentage of adult populations

11. Prions
Prions are proteins that replicate and cause disease similar to viruses.
They are different than all other microbes in that they don’t have any nucleic acids.
All known prion diseases in mammals affect brain tissue or nervous tissue.
All are currently untreatable and fatal.
You get it by eating infected meat or nervous tissue.
Mad Cow Disease (Bovine Spongiform Encephalopathy):
A fatal degenerative brain disease in cows.
The U.K. is the most affected country.
A variation of it in humans is called Creutzfeldt-Jakob disease.
Video: “Prions: The Real Zombie-Makers”

12. Vaccines
A vaccine is an agent that provides active acquired immunity to a particular disease.
It typically contains a weakened or dead form of a microbe.
Vaccines have been the most effective means to fight and eradicate infectious diseases.
They don’t work every time.
Your body might not develop immunity fast enough.
Alternative strands of the same virus can get around the immunity.
The effectiveness of vaccines have been widely studied and verified.
The side effects, if any, are general mild.

14. How Vaccines Work
Vaccines are made from dead or weakened strands of the microbe in question.
When your body recognizes the vaccine as a foreign agent, it attacks, destroys, and remembers it.
When your body encounters the virulent version of the microbe it knows to attack it.
Vaccines allow us to develop immunity to various infections.
This is an inherited, acquired, or induced resistance to an infection.
Vaccines have contributed to the eradication of disease like smallpox and the near eradication of diseases like measles, polio, and typhoid.
They do this by creating herd immunity: an effect in which a disease outbreak is much less likely because a majority of people are vaccinated against the disease.
Video: “Why Are There Dangerous Ingredients in Vaccines?