What is a Microorganism?• It is a living organism that is visible (as an individual

organism) only with the aid of a microscope. When grouped together in chains or clusters, microorganisms can be seen without a microscope.

• Most are single-celled.• As with all living organisms, microorganisms have 6

basic needs:FoodWater

AirTemperature of environment

ReproductionWaste

Infectious Disease

• An infectious disease is any disease caused by a pathogen (germ) such as a virus, bacteria, parasite, or fungus.

Pathogens

• “Pathogen” is the scientific name for germ. Infectious diseases are caused by pathogens. When your mom tells you to wash your hands she wants you to get all the pathogens off your hands so they won’t bet in your mouth and body.

Examples

• Viruses- influenza, common cold, measles, and hepatitis.

• Bacteria- Tuberculosis, cholera, typhoid fever, and tetanus.

• Parasites- Parasites are organisms that live off their hosts. Malaria, sleeping sickness, and scabies.

• Fungus- fungal meningitis, ringworm, and thrush.

MICROBE DETECTIVES THROUGH THE AGES…

HOW FAR HAVE WE COME?

Here are some beliefs of the past…

WHERE DO FROGS COME FROM?

• OBSERVATION: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times.

• CONCLUSION: It was perfectly obvious to people back then that muddy soil gave rise to the frogs.

WHERE DO MICE COME FROM?

• OBSERVATION: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around.

• CONCLUSION: It was obvious to them that the mice came from the moldy grain.

WHERE DO FLIES COME FROM?

• OBSERVATION: Since there were no refrigerators, the mandatory, daily trip to the butcher shop, especially in summer, meant battling the flies around the carcasses. Typically, carcasses were “hung by their heels,” and customers selected which chunk the butcher would carve off for them.

• CONCLUSION: Obviously, the rotting meat that had been hanging in the sun all day was the source of the flies.

For centuries, people based their beliefs on their interpretations of what they saw going on in the

world around them without testing their ideas to determine the validity of these theories.Fortunately for us, we have come a long way in scientific discoveries.

Some important people are…

ANTONY VAN LEEUWENHOEK

• The first person to peer into a microscope was a Dutch cloth merchant named Antony Van Leeuwenhoek (lay-ven-hook). A self-taught scientist, Leeuwenhoek discovered a way to make magnifying lenses more powerful than any previously made. Around 1668, he used a lens no bigger than the head of a hat pin to create the earliest know single-lens microscope. He looked at scrapings from his teeth, and saw some tiny organisms in the sample.

1860 LOUIS PASTEUR

• Louis Pasteur proves the “germ theory of disease,” stating that every infectious disease is caused by a specific microbe.

1867 JOSEPH LISTER

• Joseph Lister develops antiseptic methods of surgery- such as boiling instruments – to curb the infection of wounds.

1928 ALEXANDER FLEMING

• Alexander Fleming discovers that a mold called Penicillium kills bacteria, paving the way for the use of antibiotics.

Wanted Poster

Wanted Poster Topics• Protist Diseases•

MalariaAfrican Sleeping SicknessGiardiasisAmoebic DysenteryToxoplasmosisBacterial Diseases

•AnthraxBacterial PneumoniaBlack PlagueBotulismWhooping CoughCat Scratch DiseaseFlesh Eating Bacteria (strep throat)Lyme DiseaseGangrene (Gas Gangrene)TetanusDiphtheriaTraveler’s DiarrheaBacterial MeningitisTuberculosisRocky Mounted Spotted FeverSalmonellosisTyphoid Fever

•  •

Viral Diseases•ChickenpoxPolioMumpsMeaslesSmallpoxInfluenza (flu)EbolaMononucleosis (Mono)Plantar Wart•

Fungal Diseases•RingwormThrush