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Transcript of Communicable Diseases
Understanding Communicable Diseases
Common Communicable Diseases
Fighting Communicable Diseases
Physical and Chemical Barriers
The Immune System
Understanding the Causes of Communicable Diseases
Emerging Diseases and Pandemics
How Diseases Affect the World
A communicable disease is
a disease that is spread from one living organism to another or through the environment.
They are also known as contagious or infectious diseases.
Communicable diseases are caused by several kinds of microorganisms.
Communicable Diseases can occur when pathogens, microorganisms that cause disease, enter your body. If your body does not fight off the invaders you can develop an infection. An infection is
a condition that occurs when pathogens in the body multiply and damage body cells.
Diseases can be caused by 5 main pathogens. These pathogens include viruses, bacteria, fungi, protozoa, and Rickettsias.
A virus is a piece of genetic material surrounded by a protein coat.
Bacteria are single-celled microorganisms that live almost everywhere on earth. Most are harmless, but others can cause toxins.
Toxins are substances that kill cells or interfere with their functions.
Fungi are plantlike organisms that can cause diseases of the lungs, the mucous membranes, and the skin.
Protozoa are single-celled microorganisms that are larger and more complex than bacteria.
Rickettsias, which resemble bacteria, often enter the body through insect bites.
Diseases can be transmitted in a variety of ways.
Many pathogens are transmitted through direct contact with an infected person.
contact with infected animals
vectors (organisms that carry and transmit pathogens to humans or other animals)
contaminated food and water
Diseases can also be spread by airborne transmission. An example of this would be if someone sneezed or coughed. When they sneeze or cough it sends off tiny droplets that can travel up to 10 feet. They can settle on dust particles until they are inhaled or they can be taken in through pores.
You can take steps to prevent infection.
There is no guaranteed way to completely avoid communicable diseases, but you can take some steps to reduce your risk of catching them.
Wash Your Hands:
before you eat
after you use the bathroom
after handling pets
before and after inserting contact
lenses or applying makeup
after touching an object handled by an
Protect Yourself from Vectors by:
limiting the time you spend outdoors at dawn and dusk, when mosquitoes are most active
wearing pants and long-sleeved shirt to avoid insect bites
using insect repellent, and avoiding contact with dead birds
Other Prevention Strategies:
Avoid sharing personal items, such as eating utensils.
Handle food properly.
Eat well and exercise.
Avoid tobacco, alcohol, and other drugs.
Abstain from sexual contact.
Cover your mouth when you cough or sneeze, and wash your hands after using a tissue.
Many diseases begin with respiratory infections.
You can practice a few techniques to help you avoid getting sick:
Avoid close contact with sick people. If you're ill, stay home.
Wash your hands often.
Avoid touching your mouth, eyes, and nose.
Eat right and get physical activity to strengthen your immune system.
Abstain from smoking.
Colds, influenza, pneumonia, strep throat, and tuberculosis are the most common respiratory infections.
The common cold is a viral infection that causes inflammation of the mucous membrane
(the lining of various body cavities, including the nose, ears, and mouth).
Influenza, or the flu, is a viral infection of the respiratory tract.
Pneumonia is an infection of the lungs in which the air sacs fill with pus and other liquids.
Strep throat is a bacterial infection spread by direct contact with an infected person or through airborne transmission.
Tuberculosis, or TB, is a bacterial disease that usually attacks the lungs.
There are 3 common types of hepatitis; hepatitis A, hepatitis B, and hepatitis C.
Hepatitis A usually attacks the digestive system through contact with the feces of an infected person.
Hepatitis B can be spread through sexual contact or contact with an infected person's blood.
Hepatitis C is most often spread by direct contact with needles that are contaminated with infected blood.
Stay informed about communicable diseases.
Some other communicable diseases include:
Physical and chemical barriers make up your body's first line of defense against pathogens.
Physical barriers, such as the skin, block pathogens from invading your body.
Chemical barriers, such as the enzymes in tears, destroy those invaders.
Your body's immune system is your best ally in the fight against communicable diseases.
The immune system is a network of cells, tissues, organs, and chemicals that fight off pathogens.
The immune system fights pathogens using an immune response:
Pathogens invade the body.
Macrophages engulf the pathogen.
Macrophages digest the pathogen, and T cells recognize antigens of the pathogen as invaders.
T cells bind to the antigens.
B cells bind to antigens and helper T cells.
B cells divide to produce plasma cells.
Plasma cells release antibodies into the bloodstream.
Antibodies bind to antigens to help other cells identify and destroy the pathogens.
Strategies for preventing the spread of disease include practicing healthful behaviors, tracking diseases, and getting vaccinations.
Track Reportable Diseases such as: hepatitis, influenza, and yellow fever.
You should get regular vaccinations to prevent disease. Vaccinations fall into 4 categories:
New Viruses and Second-Generation Viruses
When you receive a vaccine, you are not only keeping yourself healthy, but you are also helping to protect everyone around you.
Some diseases are becoming more dangerous and widespread.
An emerging infection is a communicable disease whose occurrence in humans has increased within the past two decades or threatens to increase in the near future.
There are many emerging infections including
West Nile Virus
Salmonella and E. coli
Recreational Water Illnesses
SARS (Severe Acute Respiratory Syndrome)
Mad Cow Disease
Diseases can spread with an amazing speed.The world’s countries are connected through trade and travel, making it easy for infectious diseases to travel faster and farther than ever before.
Sometimes a disease can become a pandemic (a global outbreak of an infectious disease).
Diseases can spread through travel. For instance, when a bus travels from one country with a specific disease to a country without that disease, the country without the disease gets the disease and it will start to spread.
Pathogens can become drug-resistant in a 3-step process:
Pathogens invade the body and cause illness.
Antibiotics attack the pathogens.
The pathogens that survive the antibiotics reproduce, creating a new generation of drug-resistant pathogens.
Viruses invade the cells of living organisms. Once
inside the cell it begins to multiply and take over other cells.
Usually, the virus runs its course and is killed by the immune system. Antibiotics do not work against viruses, they can sometimes treat the symptoms.
by a virus:
Symptoms include jaundice, and some individuals may develop cirrhosis.
There is a vaccine for hepatitis A and B, however because the disease comes from a virus there is no cure.
The immune system fight pathogens
using 2 major strategies:
Inflammatory response -A reaction to tissue damage caused by injury or infection.
Specific Defenses - reaction to certain pathogens; process called immune response.
Lymphocytes = 2 types
1. T cells
Helper T cells - trigger production of B cells and killer T cells
Killer T cells - Attack and destroy infected cells. (not pathogen)
Suppressor T cells - Turn off helper T cells
2. B Cells
Produce Antibodies - A protein that acts against a specific antigen
Attach to antigens to mark them for destruction
Destroy invading pathogens
Block viruses from entering body cells.
Immunity = 2 types
Active - develops from natural or artificial processes.
1. exposed to antigens from invading pathogens
Passive - body receives antibodies from another person or animal.
1. Mother to child
2. Injection of antibodies produced by animal or human immune
Two of the most common communicable diseases—the cold and the flu—are caused by viruses.
Many communicable diseases occur in the respiratory tract, the passageway that includes the nose, throat, and lungs.
The passageway that makes breathing possible
A yellowing of the skin and eyes
Cirrhosis - Scarring of the liver
Lymphocytes are white blood cells that help the body fight pathogens.
White blood cells that attack invading pathogens
When the immune system recognizes a particular pathogen, it activates specific defenses in an attempt to prevent this type of infection from occurring again
Antigen - Substances that can trigger an immune response
Immunity - The state of being protected against a particular disease
are made from pathogens grown in laboratories
are made from dead pathogens.
are made with genetically altered cells.
are made from inactivated toxins from pathogens.
A disease outbreak that affects many people in the same place and at the same time