EESA10H3 Lecture 7: LECTURE #7
5 Jul 2018
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LECTURE #7 BIOLOGICAL HAZARDS AND HUMAN HEALTH
Infectious disease
-Infectious disease: host centered
Human body is a habitat and host to many org.
-Associations that harm or bother us are infectious diseases; agents are pathogens (2-
3kg of microorganisms in us)
-Zoonosis: infectious disease transmissible to humans from other animals
-Can be transmitted human-human, can also be from animal-human
Types of pathogens
-Worms: multicellular; parasitic
-Protozoa: unicellular, largest of
microorg; parasitic (can also invade
bacteria)
-Bacteria: unicellular; most not parasitic
(most don’t cause illness, comprise most of
the 2-3kg)
Aerobic/anaerobic or tolerate both
Some form spores
If under conditions not optimal for their
growth (eg. Boil water, alcohol) some will die, some will form spores (dormant
state); is not a living org., but wake up from spores and start to go
oSpores are more resistant to treatment
-Viruses: strand of DNA/RNA; parasitic
Aren’t really alive
No cell
Can only survive within a host
Will die outside
Invade humans, can also invade bacteria
-Virus are really small
Body’s defense
-Immune system: distinguishes “self” from foreign
foreign protein is the antigen and our body produces antibodies active immunity
-vaccination
antigen preparation active immunity (inject person weak, antiquated antigens
prepares body for the antigen)
antibody preparation passive immunity (inject person with the antibodies
against the type of antigen) is faster than active
-herd immunity practical protection
if everyone is immune, it is hard to have a chain of infection
Evolution of strategies for managing transmission of disease
-use population health
-segregation of sick/exposed people
1. Isolate: separate people who are sick
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2. Quarantine: sep. everyone including the sick person, who came into contact w/
that sick person
-sanitation: misguided but beneficial
originally they just said to take a bath
then we started using alcohol, detergents etc.
-Vaccination: to prevent illness
-Antibiotics to treat illness (80 years)
Populations of pathogens become resistant over time
Methicillin-resistant Staph aureus (MRSA)
oHigh reproductive rate allows them to become genetically resistant divide
very fast
Overuse of antibiotics (eg. Resistance from too much use, antibiotics mostly in food
additives; given to livestock to prevent them from becoming sick and these
accumulate in the muscles/meat and then end up on our plate) some doctors give
people antibiotics even for those with viral disease to reduce complications from a
possible bacterial infection
oForced to create new types of Anti-b to cure that illness after it has become
resistant
-Pesticides to control vectors (vector control)
Eg. Mosquitos
Transmission of infectious disease
-Transmission through closeness/contact
Droplet transmission: coughing, sneezing
oDiphtheria, TB, pertussis, influenz, measles, mumps, rubells
Direct oral contact (eg. Kiss)
oStrep, herpes simplex 1, inflect mononucleosis
Transmission by fomite (objected/substance capable of carrying infectious
organisms)
oSkin cells, hair, clothing, bedding
oEg. Viola vera (virus) flute acted as a fomite (b/c people went to middle
east and then went back to
-Airborne transmission in aerosol droplets enter air currents and then are transmitted
over long distances
Eg. Air ducts can increase transmission
-Fecal-oral transmission of diarrheal disease
Fecal-oral pathway: one perons’s infectious D. disease becomes next persons’ disease
of fecal origin
Sewage not well controlled waterborne transmission dominates
Fecal-oral transmission also done by soil and hand-to-mouth- transmission
Cholera, typoid fever, giardiasis, zoonese, hep A, Norworlk virus, polio
-Non-fecal org. also transmitted in water or soi
Guinea worm disease
Tetanus
-And through food (foodborne transmission)
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Housefly as mechanical vector
Global patterns
-Fast global spreading (travelling, b/c can move really fast from continent to continent)
-12.3 m deaths in 2008
respiratory infections (29%), dirrheal disease (20%), and HIV/AIDS (14%) are
leading causes of infectious death
-Worldwide, 22% of all deaths in 2008
Highest in Africa (53%), SE Asia (27%), and Eastern Mediterranean (25%)
Cancer causing infections
-Infections can cause cancer risk
Chronic irritation swelling = cell proliferation = uncontrolled growth of cells
-18% are caused by
Liver (hep A/B)
Cervic (HPV)
Stomach (heliobacter pylori)
-Higher % in lower-income countries
Important types of pathogens
-Bacteria
TB/Anthrax, Plague
-Viruses
Yellow
fever/HIV/bird
flu/West nile virus
-Protozoa
Malaria
BACTERIAL DISEASE
a) TUBERCULOSIS
One of deadliest
1/3rd of human pop.
Have TB (but not
everyone becomes sick
TB is asleep in the
body; becomes
activated when
immune system becomes weaker)
in 2011, 9m people became sick with TB
1.4m TB deaths worldwide
leading killer of people with HIV
also caused by health care systems
-attacks the lungs
-symptoms: chest pain, bough blood, prolonged cough, weight loss, paleness
-transmission: cough, sneeze, speak, kiss, spit of infected person
-most active in Africa and in south Asia and in Russia as well
b) ANTHRAX
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Human body is a habitat and host to many org. Associations that harm or bother us are infectious diseases; agents are pathogens (2- Zoonosis: infectious disease transmissible to humans from other animals. Can be transmitted human-human, can also be from animal-human. Protozoa: unicellular, largest of microorg; parasitic (can also invade bacteria) Bacteria: unicellular; most not parasitic (most don"t cause illness, comprise most of the 2-3kg) Foreign protein is the antigen and our body produces antibodies active immunity vaccination. Antigen preparation active immunity (inject person weak, antiquated antigens prepares body for the antigen) Antibody preparation passive immunity (inject person with the antibodies against the type of antigen) is faster than active herd immunity practical protection. If everyone is immune, it is hard to have a chain of infection. Evolution of strategies for managing transmission of disease use population health segregation of sick/exposed people.
