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Environmental Hazards and Human Health, Part 2

Environmental Hazards and Human Health, Part 2. Causes of global deaths. Infectious diseases. Some definitions. Disease Chronic Acute Epidemic Pandemic. Transmissible (infectious) disease: one that is caused by a living organism. Pathways for infectious disease in humans. Figure 18-4.

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Environmental Hazards and Human Health, Part 2

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  1. Environmental Hazards and Human Health, Part 2

  2. Causes of global deaths

  3. Infectious diseases

  4. Some definitions • Disease • Chronic • Acute • Epidemic • Pandemic

  5. Transmissible (infectious) disease: one that is caused by a living organism • Pathways for infectious disease in humans. Figure 18-4

  6. Common Vectors That Transmit Disease Mosquito Tick Mouse Deer

  7. Examples of Vector-Borne Diseases Characteristic bull rash caused by Lyme disease • Mosquito-borne • West Nile Virus • Malaria • Dengue • Yellow Fever • Tick-borne • Lyme Disease • Rocky Mountain Spotted Fever • Hanta Virus (mice droppings) • Bubonic Plague (fleas)

  8. How Weather Affects Vector-Borne Diseases • Climate Change • Larger geographic area where disease is common • Intensity and duration of outbreaks • Altered seasonal distributions Tropical and subtropical regions Temperature Humidity Surface water What might happen with future predicted climate changes?

  9. Examples • Mosquitoes develop more rapidly • Mosquitoes bite more frequently • Viral load in mosquitoes is higher • Because more people are infected, more mosquitoes become carriers that transmit disease

  10. Historic Infectious Diseases • Diseases of poor sanitation • Hepatitis • Cholera • Diarrheal • Plague • Malaria • Tuberculosis

  11. Plague • Bubonic plague, Black Death • Caused by a bacterium carried by fleas and thus their hosts

  12. Malaria – Death by Mosquito

  13. Tuberculosis • Caused by a bacterium that infects the lungs • Spread when someone coughs • Highly infectious • Bacterial cells can live in air for several hours

  14. Growing Global Threat from Tuberculosis • The highly infectious antibiotic-resistant tuberculosis (TB) kills 1.7 million people per year and could kill 25 million people by 2020. • Recent increases in TB are due to: • Lack of TB screening and control programs especially in developing countries due to expenses. • Genetic resistance to the most effective antibiotics.

  15. Growing Germ Resistance to Antibiotics

  16. Emergent infectious diseases • Previously not described, or • Have not been common for at least the previous 20 years • Examples: • HIV/AIDS • Ebola • Mad Cow • Avian flu • West Nile • SARS

  17. Emergent diseases

  18. Ebola hemorrhagic fever

  19. Bovine Spongiform Encephalopathy • Mad Cow Disease • Caused by prions

  20. Avian flu • H1N1 virus • In 1918 killed an estimated 40 million people • 2006 a closely related (H1N5) emerged from Asia, passed from domestic birds to people • 2010 a new emergence of H1N1 first found in Mexico (swine flu)

  21. SARS • Sudden Acute Respiratory Syndrome • Severe form of pneumonia first identified in 2003 • 8000 cases, 750 that year • Virus is passed from person to person through airborne and surficial means • Virus can live up to 6 hours in the open environment

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