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Diseases
Unit 5
By Definition
o Infectious disease
o Caused by an agent that has invaded the body.
o Communicable disease
o Can be spread or passed
o Non-infectious disease
o Occurring from within the body, heredity, lifestyle
o Non-communicable disease
o Cannot be passed on
o Pathogen
o Any agent that causes disease
Types of Pathogens
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Bacteria (including toxins)
Rickettsia
Viruses
Fungi
Protozoans
Parasites
Bacteria
• A single-celled microbe or organism
• One of the widest spread of all living things
• Three Basic Types (Identified by Shape)
– Bacilli = rod shaped
– Cocci = spherical shaped. Long chains are
streptococcus and clusters(grapes) are
staphylococcus.
– Spirillia = twisted or spiral shaped
Bacteria continued…
o Resident Bacteria – live on the human body to
help protect you from infection
o Mouth, skin, intestines
o More than 300 in your mouth
o Some bacteria give off poisons while others
enter and damage cells.
o Examples: Tuberculosis, tetanus, sinus infections
Toxins
• Bacteria that produces poisons
– Food Poisoning: effect depends on type and
amount ingested leads to upset stomach, loss of
respiration, and death.
– Tetanus: a toxin found in the ground that enters
through a wound or injury.
Bacteria cells split at such a rate that one cell not
attacked in 15 ½ hours turns into 4.3 billion
Rickettsia
• Pathogens that grow inside living cells
• Cause typhus, Rocky Mountain Spotted Fever
Viruses
• Smallest pathogen known to man
• Made of genetic material and a protein coat
• Takes over the living cell by release of nucleic
acid, force cells to make new viruses
• Spread rapidly and attack specific
cells(Rabies=brain cells; HIV=T cells)
• Examples: colds, mumps, flu, measles, HIV,
AIDS, and severe acute respiratory
disease(SARS)
Fungi
• Single or multi-celled organisms that absorbs
and uses nutrients of living or dead organisms.
• Feeds off of plant, animal, human tissue
• Live on skin, in lungs
• Cause ringworm, jock itch, thrush, athlete’s
foot
Protozoans
• Single-celled organisms that produce toxins
that cause a disease.
• Larger and more complex internally than
bacteria
• Cause: Malaria, African Sleeping Sickness, and
Amebic Dysentery
Parasites
• Animal parasites get their energy and nutrients
by feeding on other living things
– Helminth
– Tapeworms
– Flatworms
– Pinworms
– Hookworms
– Flukes
– Head lice
Found in undercooked meat. Infect digestive tract,
muscle tissue and blood. Poor hygiene.
Immunity
• Active Immunity: when you have had the
disease, you build antibodies.
• Passive Immunity: Is passed from mother to
baby during development or from transplants
• Vaccines: Lead to active immunity by injecting
a weakened or dead form of the disease.
• Antibiotic Resistance: a condition in which
bacteria can no longer be killed by a particular
antibiotic.
Spreading Disease
• Close contact
– Sneeze, cough
• Direct contact
– touching
• Contact with a vector(animal, insect)
– Mosquito, dog
• Contact with a fomite(object)
– Food, water
D, D, D, Defense
• Major Defenses
– Mechanical: dead cells, skins, mucous
membranes
– Chemical: resident bacteria, tears, gastric juices
– Biological: the release of chemicals by the
immune system.
• White blood cells called neutrophils eat bacteria
• Monocytes from the bone marrow eat bacteria also.
More Defense
• Affected body cells release INTERFERON, a
protective protein.
• Fever is formed when the body can’t rid itself
of internal heat. Fever weakens and kills some
pathogens.
• Some bacteria carry pyrogens(poison) that
cause fever.
Common Bacterial Diseases
• Meningitis
– Inflammation of the membranes covering the brain and
spinal chord.
– May also be caused by viruses or sometimes by fungi or
parasites
– Spread my contact with saliva or mucus from infected person
– Severe headache, fever, stiff neck sensitive to light, nausea
– Can be treated by antibiotics if bacterial and caught early.
• Tetanus
– Lockjaw, affects the nervous system and causes painful,
uncontrolled muscle spasms
– Clostridium tetani, spores found in soil, enters body through
wounds/cuts.
– Treated with antibiotics, tetanus shot(every 10yrs)
Bacterial Diseases
• Salmonellosis
– Infection of the digestive system from eating
contaminated foods.
– Headache, cramps, diarrhea, nausea, vomiting
– OTC meds for symptoms, sometimes antibiotics
– Cook foods thoroughly, wash hands
• Strep Throat
– Sore throat, fever, yellow or white specks on tonsils
– Spread through contact with infected person
– Take antibiotics
Bacterial Diseases
• Sinus Infections
– Headache, tenderness of the sinuses, thick and
greenish mucus, feeling of pressure in the head
– Spread through contact with infected persons,
allergens such as cigarette smoke or air pollutants
– Treat with antibiotics
• Influenza Virus
Viral Infections
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Flu
Headache, sore muscles, sore throat, fever, fatigue, cough
Spread by contact with infected person
Vaccinations; however, new ones developed each season b/c of new
strains developed
– Get plenty of rest and fluids
• Cold
– Scratchy, sore throat; sneezing and runny nose; cough
– Spread by contact with infected person
– Wash hands, avoid infected people, get rest and fluids, treat
symptoms
• Mumps
– Pain and swelling of glands in throat, fever, headache
– Spread by contact with infected airborne droplets and personal
contact
– Vaccinations
– Rest and plenty of fluids
Viral Infections
• Measles
– Rash covering body, fatigue, runny nose, cough, slight
fever, small white dots in mouth
– Spread by contact with infected person
– Vaccination
• Mononucleosis
– Fever, swollen lymph nodes, sore throat, weakness
– Spread by contact with infected person
– Avoid drinking or eating after others
Viral Infections
• Hepatitis
– Inflammation of the liver, jaundice, fever,
darkening of the urine
– Spread by contact with bodily fluids of infected
person and by eating/drinking infected food or
water
– Types A, B, C
• A- vaccine, washing hands regularly
• B- vaccine to prevent, but cannot once infected
• B & C- life threatening, no cure
Fungal Infections
• Athlete’s foot
• Jock itch
• Ringworm
– Skin becomes itchy and red and lesions may
appear.
– Keep clothing dry and practice good hygiene
– OTC meds will kill the fungus
Protozoan Infections
• Often found in water and soil
• About 20,000 kinds of protozoa, but only small number
cause disease
• Amebic dysentery: inflammation of intestine caused by
an ameba causing nausea, diarrhea.
• Malaria
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Plasmodium
Passed by mosquitoes
Approx one million people die each year
Fever, chills, headache, fatigue, nausea
Can be prevented and treated with antimalarial drugs.
Parasitic Infections
• Inside body
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Hookworms
Flukes
Pinworms
Tapeworms
• On the body
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Lice
Leeches
Ticks
Fleas
Lifestyle Diseases
• Lifestyle Disease
– Diseases that are caused partly by unhealthy behaviors and
partly by other factors.
• Controllable Risk Factors
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Diet and body weight
Daily levels of physical activity
Level of sun exposure
Smoking and alcohol abuse
• Uncontrollable Risk Factors
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Age
Gender
Ethnicity
Heredity
Cardiovascular Disease
• A disease or disorder that results from
progressive damage to the heart and blood
vessels
• The leading cause of death in the US
– Stroke
– High Blood Pressure
– Heart Attack
– Atherosclerosis
Stroke
• Sudden attacks of weakness or paralysis that occur
when blood flow to an area of the brain is interrupted.
• Blood clot lodges in artery and cells begin to die due to
loss of circulation or hole forms in a blood vessel and
blood leaks into the brain
• 160,000 deaths each year
• Warning Signs
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Numbness or weakness in face, arm or leg
Trouble seeing in one or both eyes
Sudden dizziness or loss of coordination
Sudden, severe headache with no known cause
High Blood Pressure
• Hypertension, the silent killer
• Blood pressure is the force that blood exerts
against the inside walls of a blood vessel. Too
high=extra strain on the walls and the heart.
• Will cause the heart to weaken or fail
Heart Attack
• The damage and loss of function of an area of the
heart muscle.
• About 1/3 are fatal
• Blood clot gets stuck in one of the coronary
arteries and stops blood flow to the heart. Heart
cells die from lack of oxygen.
• Warning Signs
– Pressure, squeezing, or pain in center of chest
– Pain spreading to shoulders, neck, arms
– Chest discomfort with lightheadedness, fainting,
sweating, nausea, shortness of breath
Atherosclerosis
• The disease characterized by the buildup of
fatty materials on the inside walls of the
arteries.
• Reduces or stops blood flow to parts of the
body
• Deposits break free and release clots into the
bloodstream
– May result in heart attack or stroke
Detection
• Check blood pressure
– Normal falls between 80/50 and 130/85
– 140/90 is considered high
• Electrocardiogram
– EKG, measures electrical activity of heart to detect
damage or irregular heart beat
• Ultrasound
• Angiography
– Inject dye into coronary arteries to look for blockages
Treatment and Prevention
• Treatment
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Diet and exercise
Medicine
Surgery
Angioplasty
Pacemakers
Transplants
• Prevention
– Cut down on fat and salt
intake
– Maintain healthy weight
– Don’t smoke
– Exercise
– Check BP and cholesterol
– Relax