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