Transcript Human Health Risk

HUMAN HEALTH &
ENVIRONMENTAL RISKS
APES: Ch 17
Leading Causes of Death in the World
Categories of Human Health Risk
 Risk is a measure of the likelihood that you will suffer
harm from a hazard. Types of risk:



Physical: environmental factors like natural disasters.
 Ex: tsunamis, UV exposure, climate change
Biological: risk associated with disease.
 HIV/AIDS, malaria, TB, obesity
Chemical: risk associated with exposure to chemicals,
both natural occurring to synthetic chemicals like
pesticides.
 DDT, PCB (synthetic) & arsenic, He, Pb (Natural
occurring)
 Nicotine, caffeine, and other substances that are abused
or recreationally used are included in this category.
Biological Risk: Disease
 Cause most of the human deaths.
 A disease is any impaired function of the body with a
characteristic set of symptoms.
 Types of disease:

Infectious disease – caused by infectious agents called
pathogens (living organism). Ex: pneumonia & sexually
transmitted
 Pathogens that cause most infectious diseases are
viruses, bacteria, fungi, protists, and parasitic worms.
 Top three infectious diseases:
 respiratory infections (TB, Flu, pneumonia)
 HIV/AIDS
 Diarrheal diseases
Pathogens
Biological Risk: Disease
 Non-transmissible disease:
 Diseases not caused by living organisms cannot
spread from one person to another
 Ex. Cancer, heart disease, cystic fibrosis

~60% of deaths
 Disease is also categorized as:
 Chronic – slowly impair the body over time
(decades)


Heart disease & cancer
Acute – rapidly impair the body (days or weeks)
Chronic Disease
 Risk factors of chronic disease is different for
developing & developed countries:


Developing country risk factors are associated
with unsafe drinking water, poor sanitation,
malnutrition.
Developed country risk factors are less activity,
poor nutrition, availability of tobacco, and
overeating.
Obesity and poor air quality
Malnutrition and sanitation
Biological Risk: Infectious
Diseases
 Pathogens have evolved a wide variety of
pathways for infection:




Human to human (influenza, rhino virus)
Animals to human (plague, malaria)
Food to human (Botulism, mad cow)
Water to human (Cholera, giardia)
 Epidemic – rapid increase in disease
 Pandemic – epidemic that occurs over a large
geographic area (continent)
Biological Risk: Infectious
Disease
 Plague (Black Death, Bubonic plague):




Cause – bacterium (Yersinia pestis) carried by
fleas of rodents.
Transmitted by flea bite or handling of rodents
Killed hundreds of millions (one-fourth
European population)
Treatment – modern antibiotics
Biological Risk: Infectious
Disease
 Malaria:





Cause – protists from the genus Plasmodium.
Transmitted to humans by mosquitos.
Effect – Kills 1 million people/ year
Symptoms – re-current flu-like symptoms
Hardest hit are sub-Saharan Africa, Asia,
Middle East
Treatment – spray mosquitos with insecticides
like DDT (now banned globally)
Biological Risk: Infectious Disease
 Tuberculosis:




Highly contagious!!
Cause – Bacterium (Mycobacterium tuberculosis)
Infects lungs and spreads by coughing (bacteria
can live several hours)
Effect - One third of the world population is
infected with TB


Each year 9 million are infected & 2 million die
Treatment – antibiotics if available.

If antibiotics are stopped before all bacterium are
killed, they become drug resistant
Emergent Infectious Diseases
 Defined as infectious that were previously not described for the prior
20 years
HIV/AIDS
 In 1970’s rare types of pneumonia and cancer began
appearing.
 Cause: Human Immunodeficiency Virus (HIV)


Spread through both sexual contact & sharing needles
Source found to be chimpanzees (from the eating of flesh)
 Effect: 25 million died from HIV/AIDS
 Treatment: antiviral drugs used maintain low levels of
HIV in humans

Drug cocktails are very expensive but governments and
non-profits have greatly improved distribution in
developing countries.
Ebola Hemorrhagic Fever
 Cause: Ebola virus


First discovered in the Congo
Infected humans & primates
 Effect: Kills a large % of those infected (50 –
89% death rate) in two weeks.
 Treatment: there are no drugs available to
fight virus

Origin remains unknown
Mad Cow Disease
 Neurological disease in which pathogen slowly destroys the
hosts nervous system.
 Cause: prions (proteins in the brain of cattle that mutate and act
as a pathogen
 Discovered disease could be passed to humans
 Cow must consume nervous system of infected cow to
contract disease
 Effect: 180 k cattle infected & 166 people died
 Treatment: outlaw the practice of feeding cows dead cow
protein
Bird Flu
 1918 Spanish flu (bird flu) killed 100 million
people
 Cause: H1N1 virus & H5N1 virus



H5N1 could potentially kill 150 million
Rarely deadly to wild birds
Not easily passed among people but future
mutation could change that
West Nile Virus
 Lives in hundred of species of birds and is
transmitted among birds by mosquitos



First human to contract West Nile was in 1937
Causes inflammation of the brain
1999 virus appeared in New York