Download Diseases - Ms. Alger

DISEASES
Caused by bacteria and viruses
PATHOGENS
• Disease causing agents
• Viruses reproduce by infecting living cells
and can cause harm to the host
• Bacteria requires nutrients and energy
which can interfere with the host’s ability
to function properly
BACTERIAL DISEASE IN HUMANS
• The growth of bacterial pathogens
disrupts the body’s normal functions
• Louis Pasteur (French chemist) was the
first person to show that bacteria causes
diseases
• Established the Germ Theory
BACTERIA PRODUCES DISEASE IN 2
WAYS
• directly breaking down cells for food
• Ex. Mycobacterium tuberculosis (Tuberculosis) is inhaled into the lungs where it
destroys lung tissues. It can also enter a blood vessel and travel to new sites
• releasing toxins (poison) that travel through the host
• Ex. Streptococcus (strep throat) releases toxins into the bloodstream, causing
scarlet fever
• Ex. Corynebacterium diphtheriae (Diphtheria) releases toxins in the throat and
causes breathing problems, heart failure, paralysis, and death.
PREVENTING BACTERIAL DISEASE
• Vaccine
• Many bacteria diseases can be stopped by
stimulating the body’s immune system
• Antibiotics- compounds that block the
growth and reproduction of bacteria
• Ex. Penicillin and tetracycline
BACTERIAL DISEASE IN ANIMALS
• Animals can be infected by bacterial disease as
well
• Which can transmit to ranchers and animal handlers
• Ex. Bacillus anthracis (anthrax) are often found in
sheep
• Produces tough, resistant spores that can last for years
• Was developed as a biological weapon
• Sverdlovski (Soviet Union) in 1979 hundreds of people died
when anthrax was accidently released.
CONTROLLING BACTERIA
• Although most bacteria are harmless
(many are beneficial), there are various
methods used to control the growth of
bacteria.
• Sterilization
• Destroys all bacteria through the use of
heat as most bacteria can’t survive high
temperature for a long time
CONTROLLING BACTERIA
• Disinfectants
• Chemical solutions that kill pathogenic bacteria (AKA antibacterial
products)
• Overuse of antibacterial products increases the chances that common
bacteria will evolve to become more resistant and therefore more
dangerous and difficult to kill
CONTROLLING BACTERIA
• Food storage and processing
• Refrigeration stores food at lower
temperatures which keeps it fresher
• Raising the temperature of the food to the
point where bacteria are killed
• Ex. Boiling, frying, or steaming
VIRAL DISEASES IN HUMANS
• Viruses attack and destroy certain cells
causing symptoms of the disease
• Ex. Polio virus infects and kills cells of the
nervous system producing paralysis
• Some viruses will infect cells to change
their patterns of growth and development
• Vaccines are a way to prevent viral diseases
• Many decades of childhood vaccines
against smallpox have virtually eliminated
this disease
VIRAL DISEASE IN ANIMALS
• Ex. An epidemic of foot-and-mouth disease
infected thousands of cattle in Europe in the
late 1990’s
• Some animal viruses can cause cancer
• Oncogenic – tumor-causing viruses
VIRAL DISEASE IN PLANTS
• Viruses can also infect plants
• Ex. Tobacco mosaic virus, potato virus, etc
• Many plant viruses are spread by insects
VIRAL DISEASE IN PLANTS
• Plant viruses contain a core of nucleic acid and a
protein coat, however, they have a hard time
entering plant cells due to the cell walls
• Plant viruses developed a way to take advantage of even
minor damage to plant tissues (ex. Tears in leaves, breaks
in stems and roots, or microscopic cell wall damaged
caused by human or animal contact)