MICROORGANISMS and INFECTIOUS

DISEASE

Microorganisms *a tiny living thing

*usually single-celled

*can be seen only with a microscope

Mold Bacteria

Yeast Algae

Germs *microorganism that causes disease

Infection *growth of disease organisms

in the body of a host

Infectious Disease

*contagious /communicable can spread from one organism to another

disease can spread in three basic ways:

direct contact water

air

Causes of Infectious Disease

Fungi

Bacteria Virus Protozoans

Viruses Cause... • Most bronchitis/chest colds

• Green/yellow nasal discharge

• Flu

• Most sore throats

• Ear aches and some sinusitis

….viruses clear up on their own - antibiotics won't

help!

Influenza Virus

“Flu”

Bacteria

• make you sick when they are parasitic (where they don’t belong) or grow more rapidly than normal

• live in your mouth, nose and throat

• are necessary for normal body functions (like digestion)

• are one of the oldest living things on Earth

• most are good guys (helpful or harmless)

“Bad” Bacteria Cause... • Strep throat

• Some ear infections

• Some sinus infections

• Pneumonia

...these can be treated with ANTIBIOTICS

Streptococcus Pneumoniae Bacteria

•Ear infections

•Meningitis

•Pneumonia

Virus or Bacteria: Who Knows?

• Let your healthcare provider decide!

• It is often hard to tell if illnesses are caused by a virus or bacteria

20

Why do young children have more illness?

Infection can result from: *sharing towels, dishes, contaminated objects. *Indirect contact or skin-to-skin contact

Sometimes an illness is passed to others by

a carrier (a person who has been infected by a germ

but does not look or feel sick)

•may carry the germ in their nose, throat, or stomach.

•can pass the germ by coughing, sneezing, or by not washing their hands properly.

• Your hands carry many germs-you can’t SEE them.

• Many people don’t wash hands (they LOOK clean)

Light patches indicate germs

carried on the hands

Evolution and Ecology of Pathogens

Martin Polz

Massachusetts Institute of Technology

Thanks to

*Centers for Disease Control and Prevention

www.cdc.gov/

*National Center for Infectious Diseases