CHAPTER 15 Infectious Diseases (Transmitted from person to person, needs a pathogen to exist)

Microbes Microbes – Tiny organisms, such as bacteria, yeasts, and viruses, that are too small to be seen with the naked eye.   Microbes known as PATHOGENS cause infectious diseases. Infectious Disease: caused, and transmitted from person to person, by microorganisms

TYPES OF MICROBES Bacteria – beneficial functions such as protecting the digestive tract. Viruses – specialize in causing illnesses. Others such as fungi and protozoa.

Examples of Common Infectious Diseases

VIRUSES Vary in a few ways from bacteria - Smallest in size - They are invaders, invade host cells, take over, and make copies of themselves. - No Cures, just treatment for symptoms. Viruses Bacteria Small in size Large in size Are strands Are cells

VIRUSES Reproduce with astonishing speed. Harm living cells, which cause diseases such as a cold or more serious influenza or the flu. Once the cold/flu symptoms are gone the virus causing the illness is gone from the body.

VIRUSES Other viruses can occur such as: Shingles – skin condition caused by the chicken pox virus occurring over and over at a later age. Chicken pox Chronic fatigue syndrome – unexplained repeated bouts of extreme fatigue that bed rest does not cure and lasts at least 6 months.

BACTERIA Bacteria are microscopic, single-cell organisms of varying shapes and sizes Grows and multiplies best in environments like the human body. Thrives in deep puncture wounds that can be washed away with hot soapy water.

BACTERIA Tetanus: A type of bacterium especially likely to invade a puncture wound. Can be serious and fatal Produces a poison that causes uncontrollable muscle contractions If it affects the lungs and heart is can become deadly

BACTERIA Tuberculosis: (TB) an infection of the lungs

Tuberculosis Infects a person every second of everyday and kills millions each year New concerns of TB are new drug resistant strains of TB that fail to respond to medication Symptoms include: fatigue, shortness of breath, weight loss, loss of sensations, and pain in the chest, back, or kidneys

BACTERIA Lyme Disease: An infection spread by tiny deer ticks. Begins with a “bulls eye” dot on the skin Weeks to month’s flu like symptoms occur. If untreated the bacteria can spread to the lymph node system, blood, and other organs eventually damaging the heart.

HOW DOES DISEASE SPREAD? An infected person (the host) contaminates the air, food, or objects around another person. They breath the air in and consume food and pass the pathogen into the body. The chances are once inside the body, the pathogens will grow and multiply causing illnesses

THE COURSE OF A DISEASE 1. Incubation PERIOD EVENTS 1. Incubation After invasion of pathogens when they multiply in the body 2. Prodrome Start of symptoms 3. Clinical Symptoms known to be caused by the disease 4. Decline Symptoms decrease, your body is winning 5. Convalescence Body repairs damage and returns to normal

Chain of Infection

Ways to break the link of Infection Kill the Pathogen (Medicine) Prevent contact (quarantine) Prevent Escape (Cover your mouth when you cough) Prevent Transmission (control disease) Block the Ports (Band-Aids, Kleenex, cover mouth) Resistant Host: stay immune

BODY’S DEFENSE Barriers to Diseases: The body controls pathogens by stopping the entry of pathogens into tissue, skin, and membranes. How come everyone Is not getting sick?

Protective Outer Layer SKIN: Produced salty and acidic secretions One way pores (nothing gets in) Makes a natural antibiotic protein that has a unique killing action

Membranes BODY’S MEMBRANES: Line the body chambers which are barriers to pathogens Layer of mucus that traps microbes Cilia that sweeps microbes away Cells and chemicals that destroy microbes Mucus keeps us healthy

PUBLIC DEFENSE AGAINST DISEASE   Public Services People’s own Barriers Immune Systems

PUBLIC PROGRAMS AGAINST PATHOGENS Government agencies provide public sanitation and protection from infections. Government chlorinates public water supply to kill pathogens. People can get an illness called cholera from contaminated water. Public pools use disinfectants, that are chemicals that kill microbes.

IMMUNIZATION Public health programs control diseases by: Destroying insects Immunize household pets Spraying for insects Rabies- A viral disease of the CNS caused by bites and scratches from animals. Vaccines- Used to prevent people from becoming ill, A drug made from poison that recognizes the active agent. Vaccines importance

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