PREVENTIONAND

TREATMENT

Infectious Diseases

For teacher’s reference

Curriculum Links:

Course: SBI 3CUnit: (C) MicrobiologyExpectation: 3.5 - describe how different viruses,

bacteria, and fungi can affect host organisms, and how those effects are normally treated or prevented (e.g., hepatitis viruses can damage the liver, but vaccinations can prevent infections; streptococcus bacteria can cause respiratory infections, which are treated with antibiotics; ringworm is a fungal infection of the skin, treated with fungicides

Misconceptions

Antibiotics can cure all types of infectious diseases

Antibiotics can be taken to prevent infections

Colds and Flu are caused by bacteria (or general confusion over which illnesses are caused by viruses vs. bacteria)

You can get the flu from the flu shot

Viruses are living organisms

Agenda

Infectious DiseasesBacteria, Viruses, Fungi, and Protists that

cause Infectious DiseasesTransmission of DiseasesPrevention of DiseasesTreatment of Diseases

Infectious disease

Defined as:- A disease caused by a microscopic pathogen

such as bacteria, viruses, fungi, and parasites

- These diseases can be transmitted from person to person

Bacteria and Disease

Bacteria cause disease when they build up in large numbers in an affected area of the body.

The toxins from the bacteria “overload” a person’s immune system and it’s ability to remove these poisons

This can have varying effects on the host (depending on bacteria/disease) decrease function of cells and tissues destroying cells and tissues

Examples

Bacteria DiseaseClostridium Botulism, tetanus, gangreneStreptococcus Strep throat, scarlet fever,

pneumoniaStaphylococcus Boils, food poisoning, skin

infections, pneumonia

Neisseria meningitidis Meningococcal Meningitis Vibrio cholerae Cholera

Adapted from Nelson Biology 11 College Preparation

Viruses and Disease

Viruses depend on host cells to survive and reproduce

Through the process of reproduction, viruses attack host cells This is what causes the symptoms of the disease

Viral Infections are often difficult to treatWhy do you think this is?

Examples

How do Viruses compare to Bacteria size wise?

Virus Diseaseorthomyxoviruses Influenza (flu)rhinoviruses Common Coldretroviruses (HIV) AIDSflaviviruses West NileParamyxoviruses Measles, mumpsvaricella-zoster Chicken Poxrhabdoviruses rabies

Protists and Disease

Protists which are single celled eukaryotes (examples include amoeba, paramecium)

Protists can be parasitic, causing harm to the host organism What is meant by parasitic?

Examples

Protist Disease Plasmodium MalariaTrypanosoma African Sleeping SicknessGiardia lamblia Giardiasis

Fungi and Disease

Fungi are responsible for many human diseases.

These diseases are referred to asmycoses

Most are simply bothersomeSome can be life threatening

Examples

Fungus DiseaseMicrosporum RingwormEpidermophyton floccosum Athlete’s footBlastomyces dermatidis Blastomycosis

• Amanita phalloides (a.k.a Dead cap) world’s most dangerous mushroom. Eating one or two can be fatal

Disease Transmission

Infectious diseases can spread easily from person to person in five different ways

1._______________________________2._______________________________3._______________________________4._______________________________5._______________________________

Disease Transmission

Infectious diseases can spread easily from person to person in five different ways

1. Air2. Food3. Water4. Person to Person contact (direct or

indirect)5. Animal bites

Examples of Transmission Methods

Disease Pathogen Transmission Method

AIDS HIV Person to Person (e.g. sexual intercourse)

Common Cold rhinovirus Air, person to person

Malaria Plasmodium (protist) Mosquito bites

Measles paramyxovirus Air, person to person

Botulism Clostridium botulinum (bacteria)

Food

Adapted from Modern Biology (2002)

Prevention

Vaccinations

Immune System Specific Non-Specific – Body’s “first line of defense” for

preventing pathogens from entering the body

Non-Specific Immunity

Skin – keratin shield acts as a barrier Sweat, oils, and waxes released by skin – toxic to many

bacteria and fungi Mucus membranes – Barrier secretes mucus which

traps pathogens Stomach Acid – destroys most swallowed pathogens Inflammatory Response – Injured cells send a chemical

signal as pathogens enter (through a cut for example). Chemical signal attracts phagocytes to destroy foreign pathogen

Fever – Body’s response to infection

Specific Immunity – The Immune System

Include several organs within the body working together to identify pathogens and kill them Bone marrow Thymus Lymph Nodes Tonsils Adenoids Spleen

A great animated video to describe the immune system

Vaccinations

Vaccines contain pathogens or toxins that have been modified so they can no longer cause disease

They contain antigens that stimulate an immune response this produces memory cells

Some diseases that have been controlled through vaccines: Polio, Measles, Mumps, Tetanus, Diphtheria,

Treatment

Different depending on the pathogen causing the disease

Pathogen causing Disease

Treatment How it works

Bacteria Antibiotics Kill or inhibit growth of Bacteria.

Virus Some Antivirals (often fluid and rest)

Reduce ability of the virus to reproduce

Fungi Fungicide Destroys or inhibits growth of fungus

Protists Deworming agents

(Specific to individual pathogen)

Paralyze or kill parasite

Case Study Activity

Jessica’s Case Measles

Suzie’s Case Malaria

Tim’s Case Giardiasis

Jack’s Case Cholera

Teaching Strategies/Ideas

Graphic organizers (to divide Bacteria, Virus, Protist, and Fungi)

Diagnostic activitiesHIV simulation lab activityUse current/recent events (e.g. H1N1,

cholera outbreak in Haiti, SARS) in lessonsIncorporate Social Justice (e.g. AIDS

awareness, “buy a net” malaria prevention charity)

References

http://emedicine.medscape.com/infectious_diseases

http://www.microbiologyprocedure.com/infection-and-diseases/diseases-caused-by-bacteria.htm

http://www.ehow.com/about_5139239_diseases-do-protists-cause.html

http://science.education.nih.gov/supplements/nih1/diseases/guide/understanding1.htm

http://www.fungi4schools.org/Documentation/03World-of-Fungi/WF05_Fungi_and_Disease.pdf

http://www.phac-aspc.gc.ca/media/nr-rp/2005/2005_3bk1-eng.php