Transcript What is the difference between an infection and a disease?

What is a disease?
Definition:
A condition that impairs normal functioning of a human,
plant or animal body and has distinguishing signs and
symptoms.
Do you know the name of some diseases????
Chronic Disease —A disease or health condition that
lasts longer than three months, sometimes for the
remainder of one's life.
Acute Disease —A disease or health condition that
occurs and subsides within three months, usually
within days or weeks.
Infection
or
Disease?
(not in notes)
What is the difference between an infection and a disease?
Infection, often the first step, occurs when bacteria, viruses or other
microbes that cause disease enter your body and begin to multiply.
For instance, a person gets the disease malaria if he/she
carries an infection caused in his/her body by the bit of the
female Anopheles mosquito.
Communicable vs non-communicable
What is the difference?
COMMUNICABLE
A disease that can be
passed from one person to
another person, animal, or
object.
Sometimes called infectious
or contagious diseases.
NON-COMMUNICABLE
Diseases that are not
transmitted from one
person to another.
Communicable Disease
Communicable diseases are caused by several kinds of tiny life forms.
These microorganisms that cause diseases are called pathogens.
Sometimes you will hear pathogens called “germs”.
They are specialized to infect body tissues where they reproduce and
cause damage that gives rise to the symptoms of the infection.
An infection is a condition that occurs when pathogens enter the body,
multiply, and damage cells.
Types of Pathogens
The two most common kinds of pathogens are:
• bacteria
• viruses
Others include:
• fungi
• parasites
• prions
Let’s look at each type in more detail.
Bacteria
Bacteria are one-celled microorganisms too small to see with the naked
eye. They exist in virtually all environments in the world.
They are possibly the most numerous types of organisms on the planet.
They can live EVERYWHERE! They can live in sub freezing cold
temperatures and boiling hot temperatures. They can live high in the sky
and deep below the ocean.
Some bacteria are harmful, but most are harmless or even helpful.
In general, a bacterial infection can be treated with antibiotics, but viral
infections cannot.
Escheria coli
Bacteria were the first organisms to appear
on earth, about 4 billion years ago. Our oldest
known fossils are of bacteria-like organisms.
Streptococcus
bacteria
(e. coli) bacterium
Diseases spread by bacteria
Caused by Bacteria
o Streptococcus pyogenes – (AKA strep throat) The throat gets irritated and inflamed, causing a
sudden, severe sore throat
o Pneumonia - lung inflammation caused by bacterial or viral infection, in which the air sacs fill
with pus and may become solid
o Meningitis - an infection of the membranes covering the brain and/or spinal cord
o Salmonella – bacterium that occurs mainly in the intestine, especially a serotype causing food
poisoning
o Whooping cough - most affecting children, characterized by convulsive coughs followed by a
whoop
More Diseases from Bacteria
Some of the most deadly diseases and devastating epidemics in human
history have been caused by bacteria.
In the year 1900 pneumonia, tuberculosis and diarrhea were the three
biggest killers in the USA.
As water purification improved, vaccines and immunization programs
evolved, and antibiotic treatment became more advanced - the human
death toll in the USA from bacterial diseases has dropped significantly (as
well as in the rest of the developed world).
In developing countries, success rates have depended on several factors,
such as the strategies implemented by local health authorities, and
whether countries enjoyed periods of peacetime (no wars).
Strep Throat
Typhoid fever
Plague – aka “Black Death”
Viruses
Viruses are the smallest disease-causing organism. They are even smaller than a
bacteria.
They depend upon a host to survive, grow and reproduce. They can’t live outside
of other living cells.
The host is who/what they live in or on.
Once they are inside the body, viruses can spread and make people sick. They
reproduce by injecting their genes into a cell to produce thousands of new
viruses.
Different viruses attack specific cells – so the flu virus attacks the cells of the
respiratory system while the virus which causes meningitis attacks the cells of
the membranes which cover your brain.
Diseases spread by viruses
Caused by Viruses
o common cold -causes inflammation in the mucous membranes lining the nose and throat.
o influenza -the flu - a viral infection of the respiratory tract.
o chicken pox
o cold sores
oHand-Foot-and-Mouth Disease - viral illness that usually
affects infants and children younger than 5 years old. Symptoms
include fever, blister-like sores in the mouth and a skin rash.
Chicken pox
Shingles
Mononucleosis
Cold sore
Warts
Hand-Foot-and-Mouth Disease
Fungi
Fungal diseases are often caused by fungi that are common in the environment.
Most fungi are not dangerous, but some types can be harmful to health.
There are approximately 1.5 million different species of fungi on Earth, but only about
300 of those are known to make people sick.
Some fungal diseases may be more common than previously realized, and rare but
newly-emerging fungi are becoming increasingly problematic.
Antibiotic penicillin is made from the fungus Penicillium notatum.
Brewers' and bakers' yeast are types of fungi that grow as individual cells. They have
been used for many centuries in the production of beer, wine and bread.
Diseases such as athlete's foot, ringworm, oral and vaginal thrush are examples of
fungal infections.
ringworm
Athletes foot
Thrush caused by candida yeast
Parasites
A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of
its host (who/what it is in or on) .
Parasites can cause anything from mild disease to death to the host. Parasites can also spread diseases
from one organism to another.
Protozoa are one-celled organisms that can be free-living or parasitic in nature.
Malaria is a disease caused by a protozoa that live in certain kinds of mosquitoes. If an affected
mosquito bites a human, the person will be infected. Out of all the parasitic diseases, malaria causes the
most deaths globally. It kills approximately 627,000 people each year.
People living in the poorest countries are the most vulnerable to malaria. In 2012, 90% of all malaria
deaths occurred in the WHO African Region, mostly among children under 5 years of age.
Parasitic organisms which affect the health of people include fleas and head lice which live on the outside
of the body and tapeworms which live inside the body.
Elephantiasis is the result of
a parasitic infection caused by
three specific kinds of round
worms.
Rocky Mountain Spotted Fever
Guinea worm disease
Lyme Disease is
caused by a bacteria
carried primarily by deer
ticks
Prions
During the past two decades, evidence has linked some degenerative
disorders of the central nervous system to infectious particles that
consist only of protein. All known prion diseases frequently result in
brain tissue that is riddled with holes.
The known prion diseases include Creutzfeldt-Jakob disease (in
humans), scrapie (in sheep), and bovine spongiform encephalopathy ("mad
cow disease" in cattle).
While some prion diseases are inherited, others are apparently due to
infection by eating infected tissue or inadvertently through medical
procedures such as tissue transplants.
How are pathogens spread?
When pathogens enter in to your body you get sick.
Pathogens enter the body in the following ways:







Airborne or droplet infection (colds, flu).
Animal borne or insect borne infection (rabies, malaria, Lyme Disease).
Blood borne infection (HIV, hepatitis).
Food borne or water borne infection (salmonella, giardia).
Sexually transmitted (chlamydia, gonorrhea, syphilis).
Other direct contact (some kinds of warts, scabies).
Indirect contact (colds and flu carried from person to person on dirty
tissues, money, door knobs, phones, computer keyboards).
Preventing Disease
1. Good hygiene – wash hands often
2. Clean utensils before using
3. Cough & sneeze into your sleeve
4.
5.
6.
7.
8.
9.
Avoid touching your eyes, nose, and mouth. Especially when sick.
Do NOT share personal items – water bottles, toothbrushes etc.
Use insect repellent
Stay home when sick
Clean and disinfect commonly used surfaces
Get vaccinated
10.Avoid touching wild animals
Your Body’s Defenses
Three Lines of Defense
1. Eyes, Skin, Stomach, Saliva and Mucus
2. Immune System
a. Nonspecific Response – inflammation and increased blood flow
b. Specific Response – targets the pathogen in a specialized way
3. Lymphatic System – carries fluid known as lymph and produces white
blood cells known as lymphocytes.
There are 2 kinds of lymphocytes:
1. B-cells
2. T-cells
Kinds of
Lymphocytes
B-Cell
T-Cells
• Formed in the bone marrow
• Produced in the thymus gland
• Release antibodies
• Attack pathogens directly
• Produce specific antibodies
• Killer T-cells attack directly
• These antibodies remain in the body
• Helper T-cells activate B-cells
Immunity
Natural Immunity:
- present at birth
- includes the skin, mucus, and white blood cells
Acquired
-
Immunity
develops over time
includes passive and specific immunity
Passive Immunity is when mom passes antibodies to her child.
Active Immunity is when you body makes specific antibodies for a pathogen
Vaccines
- dead or weakened pathogens
- will not cause illness
- triggers body to make antibodies