1. Infectious disease

2. What are infectious diseases
Tiny microbes such as bacteria and viruses which get into your body and multiply in large numbers
Forces of nature or evil deeds
Discovered around 1680 – Antoni van leeuwehoek
Bacteria, fungi, protozoa, viruses, and prions (referred to them as animal-cules)
Not a microorganism

3. Mechanisms of infection
Factor one
Virulence – the organisms ability to cause disease
Factor two
The number of organisms which invade the body
Factor three
Resistance – ability to fight off infection

4. invasion Invasion Inflammation – swelling and redness Toxins
microorganisms invade tissue and release toxins
As blood passes through infected tissues the toxins are picked up and distributed throughout the body
Mo travels to a specific area of body (cns)……ZIKA virus

5. Resistance to infection
Immune system
White blood cells
Macrophages
Lymphoid tissue
Two functions
Engulfing and destroying agents
Producing antibodies

6. resistance Neutrophils – type of wbc
Mobile units formed in bone marrow
Provide rapid and potent defense
Surround and kill mo

7. resistance Macrophages Large slow moving
Reside in bone marrow, liver, spleen, and blood
Kill organisms surviving the neutrophils

8. resistance Macrophages Inflammation
Macrophages with the wbc will kill off invading mo
Pus – result of the dead macrophages and wbc

9. lymphocytes T cell B cell
Form antibodies that attach to the surface of MO marking it for destruction
Attack organisms directly
T cell
B cell

10. Types of infectious agents
Bacteria
viruses
Simple, one-celled organisms
Most are harmless
Pass body defenses or normal defenses are weakened
Pathogenic almost always cause infection
Most numerous life form – not a mo
Need a host to survive
Either dna or rna
Take over host control centers in the nucleus
Make special proteins causing symptoms & replicate themselves

11. viruses
1930’s – electron microscope helped to better understand shape and complexity
Spread through
Direct contact
Indirect contact
Insect or animal bite
Influenza virus

12. Types of infectious agents
fungi
parasites
Non-green plantlike
Cause about 30 diseases – mycoses
Evolve slowly
Skin, hair, fingernails
Live and feed on another organism
endoparasites – protozoans that live within the body (tapeworm)
Ectoparasites – live on body’s surface (ticks, fleas, lice, worms)

13. Disease classification
Type of organism causing the disease
Organ system they infect
Setting in which they occur
Most common encountered involve
Skin
Respiratory system
Gastrointestinal
urogenital

14. Prevention & treatment
Reduce exposure to infectious organisms
Maintaining body’s natural defense system
Using immunizations
Better nutrition and sanitation