Download Chapter Seventeen

Immunity and Infection
Chapter 17
The Chain of Infection
• Links in the Chain
– Transmitted through a chain (six links)
• Pathogen - disease causing microorganism
• Reservoir - natural environment of the pathogen: Person, animal, or
environmental component
• Portal of Exit
• Means of transmission
– Direct transmission
– Indirect transmission
• Vectors – carrier of the pathogen
from one host to another
• Portal of entry
– Penetration of the skin
– Inhalation through mouth or nose
– Ingestion
• New host
– Breaking the Chain
Immunity and infection
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Body’s Defense System
• Physical and Chemical barriers
– Skin, mucous membranes, respiratory tract
• The Immune System
– Immunological Defenders
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Neutrophils
Macrophages – “big eaters”
Natural killer cells
Dendritic cells – eat pathogens and activate lymphocytes
Lymphocytes
– T-cells
• Helper, Killer, and Suppressor
– B-cells
• Antibodies
– Memory T and B cells
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Identify Body Defenses
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The Inflammatory Response
• Histamine.
• Dilation of blood vessels, heat, redness, and swelling.
• The immune response
– Phase 1 – Dendritic cells are drawn to the site
– Phase 2 – Helper T cells multiply
• Production of Killer T and B cells
• Cytokines – chemical messengers
– Phase 3 – Killer T cells strike
• Cell-mediated immune
• Antibody-mediated immune response
– Phase 4 – Last Phase –
• Suppressor T-cells
• Slow down activity
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Immunity
• An infected person will never get the same illness again.
• Lymphocytes create amplification of the immune
response are reserved by memory T and B cells
• Symptoms and contagion
– Incubation – viruses are multiplying in the body or when
bacteria are actively multiplying
• Will not feel symptoms until the second or third phase of the
immune response cycle
– Prodromal period – the infected host has acquired immunity
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Immunization
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The process of ‘priming’ the body to remember an
encounter with a specific antigen.
Types of vaccines
– VACCINE- Introduction of a killed or weakened
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pathogen to stimulate the body to produce antibodies.
ACTIVE IMMUNITY - person produces his or her
own antibodies to the microorganism.
PASSIVE IMMUNITY- Injection of antibodies
produced by other human beings or animals.
ACQUIRED IMMUNITY-The ability of a memory
lymphocytes to remember a previous infection. (chicken
pox).
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Immunization Issues
• Vaccine shortages in the U.S.
• Vaccine safety
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Allergy: The Body’s Defense
System Gone Haywire
• The Body’s Defense System Gone Haywire
– Allergies
– Allergens
• Pollen, Animal Dander, Dust mites and cockroaches,
Molds, Food, Insects
– The Allergic response
• Immunoglobulin (IgE)
• Anaphylaxis
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Dealing With Allergies
• Avoidance
• Medication
• Immunotherapy “allergy shots
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Pathogens and Disease
• Bacterium – Microscopic single celled organism
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Pneumonia
Meningitis
Strep Throat and other streptococcal infections
Toxic shock and other staphylococcal
Tuberculosis
Tickborne infections
Ulcers
Other Bacterial infections
• Tetanus
• Pertussis
• Urinary tract infections
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Antibiotic Treatment
• Actions of Antibiotics
• Antibiotic resistance
• Proper antibiotics usage
– Don’t take an antibiotic every time you are sick
– Use antibiotics as directed
– Never take an antibiotic without an prescription
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Type of Pathogens
• Viruses – (parasites – take what they need)
• Most common contagious disease
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Common Cold
Influenza
Measles, Mumps and Rubella
Chickenpox, Cold Sores, and other herpes-virus infections
• Varicella-zoster virus
• Herpes simplex virus (HSV) types 1 and 2
• Epstein-Barr virus (EBV)
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Viral encephalitis
Viral hepatitis
Poliomyelitis
Rabies
Human papillomavirus (HPV)
• Treatment
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Types of Pathogens
• Fungi –
– Primitive plant – Yeast infections, athletes foot, jock itch, and ringworm
– Candida albicans
• Protozoan –
– Microscopic single-celled animal – Malaria, African sleeping sickness, Giardiasis,
Tricomonias, Trypanosomiasis, and Amoebic dysentary.
• Parasitic worm –
– Largest organism that can enter the body – Tapeworm, Hookworm, and
Pinworm.
• Prions –
– Fetal degeneration disorders of the CNS, linked to “proteinaceous infectious
particles.
– Lack DNA and RNA
– Transmissible spongiform encephalopathies (TSEs)
• Spongelike holes in the brain
• Creutzfeldt-Jakob disease – Human
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Bovine spongiform encephalopathy (BSE) or mad cow disease
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Emerging Infectious Diseases
• Selected Infections of concern
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West Nile virus
Severe acute respiratory syndrome (SARS)
Rotavirus
Escherichia coli 0157:H7
Hantavirus
Ebola
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Factors Contributing to Emerging
Infections
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Drug Resistance
Poverty
Breakdown of public health measures
Environmental changes
Travel and Commerce
Mass food production and distribution
Human behaviors
Bioterrorism
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Other Immune Disorders: Cancer
and Autoimmune Diseases
• If the immune system breaks down
• Getting older
• HIV infection
• Chemotherapy
• Autoimmune diseases
– Rheumatoid arthritis
– Systemic lupus erythmatosus
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Support Your Immune System
How to support your immune system
General guidelines
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Balanced diet
Enough sleep
Exercise
Don’t smoke
Moderation of alcohol
Wash your hands
Avoid contact with
contagious people
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Plenty of clean water
Avoid contact with vermin
Practice safe sex
Do not use Injectable
drugs
• Vaccinations
• Controlling Stress
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