Disease Pathogens

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Disease Pathogens
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Infectious (Communicable) Disease

• Any disease caused by several types of small,
  microscopic organisms (pathogens) that enter and
  multiply within the human body and can be passed
  from person to person or animal/insect to person,
  or through the environment.

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Bacteria

• A single-celled microorganism that lives almost
  everywhere on earth.
• Most are harmless and many are essential for
  life.
• Examples include
• Lactobacilli
• Coliform Bacilli
• Both are found in the intestine.

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Bacteria

• Some bacteria produce a toxin (a substance that
  kills cells or interferes with cell function)
• In healthy individuals, these bacteria are
  usually destroyed by the immune system.
• If a persons immune system is weakened or
  overwhelmed, disease occurs.

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Bacteria

• Under perfect conditions (right temperature and
  sufficient nourishment), bacteria can multiply by
  cell division.
• Cell division can occur every 20 minutes and
  after 15 ½ hours a single bacterium can have
  multiplied into more than 4 billion bacteria.

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Bacteria

• Most bacterial diseases can be treated with
  antibiotics, but some bacteria have become
  resistant to the medicines that we currently have
  to kill them.
• Examples
• Tuberculosis
• Gonorrhea
• MRSA

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Viruses

• Pieces of genetic material surrounded by a
  protein coat.
• They are the smallest known type of infectious
  agent (one half to one hundredth the size of the
  smallest bacterium.
• They invade all known forms of life.

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Viruses

• By themselves they are inactive (not living) and
  are dependent on living cells for survival and
  reproduction.
• After a virus penetrates a cell (host cell), the
  viruses take control of the cell to manufacture
  more viruses.
• The new viruses burst from the cell, killing it,
  and take over other cells.

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Viruses

• Viruses usually run their course and are
  eventually killed by the immune system.
• Antibiotics are not effective in destroying
  viruses, but can sometimes treat some symptoms of
  a virus.

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Viruses

• Examples include
• The Common Cold
• Influenza
• Viral pneumonia
• Viral hepatitis
• Polio
• Mononucleosis
• Measles
• HIV/AIDS
• Chicken Pox

• Viral meningitis
• Herpes
• Rabies
• Smallpox
• West Nile Virus

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Rickettsias

• Organisms that resemble small bacteria, but like
  viruses are able to multiply only by invading the
  cells of living organisms.
• They are found in the intestinal tract of insects
  and small rodents and are passed to humans
  through bites or through feces deposited on the
  skin.

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Rickettsias

• Examples include
• Typhus
• Rocky Mountain Spotted Fever
• Hunta Virus

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Protozoan's

• Single-celled organisms which are larger and more
  complex than bacteria.
• Most are harmless, but some can cause disease in
  people with a weakened immune systems.

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Protozoan's

• Examples include
• Malaria
• Amoebic dysentery
• Sleeping sickness

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Fungi

• Simple plant-like organisms (mold yeasts) that
  cannot make their own food and feed off dead
  animals, insects, and leaves.
• They prefer dark, damp environments and usually
  invade the deep layers of hair, nails and skin,
  or the mucous membranes of the lungs.

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Fungi

• Examples include
• Ringworm
• Athletes foot
• jock itch
• Vaginal yeast infections

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Disease Transmission

• Transmission can occur through direct or indirect
  contact and through breathing contaminated air.
• Some diseases can be spread in more than one way.
• If you know how a disease is spread, you can take
  precautions and avoid infection.

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Disease Transmission

• Direct Contact
• Includes touching, biting (animal or human),
  kissing, and sexual contact.
• Pregnant women can transmit an infection to her
  unborn child through the placenta.
• Animal bites and scratches can also transmit
  disease.

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Disease Transmission

• Indirect Contact
• Contaminated Objects
• Objects can become contaminated with infectious
  discharges or secretions and can be transmitted
  if you come into contact with the contaminated
  object and then touch your nose or mouth.
• Frequent hand washing and disinfecting objects
  can prevent transmission.

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Disease Transmission

• Indirect Contact
• Vectors
• Organisms that carry and transmit pathogens to
  humans and other animals.
• Examples include dogs, cats and other animals, or
  insects such as the mosquito, tick or flea

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Disease Transmission

• Indirect Contact
• 3. Water and Food
• Careless handling and storage of food are major
  sources of contamination and illness.
• Water supplies can also be contaminated with
  human or animal feces and cause illness.

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Disease Transmission

• Airborne Transmission
• Sneezing coughing can spray infectious droplets
  of saliva or mucus into a nearby persons eyes,
  nose or mouth.
• Even when the droplets evaporate, the pathogens
  may float on dust particles for a long time and
  travel long distances.
• You dont have to be close to an infected person
  to inhale the pathogen.