1 / 28

Zoonotics and the environment

Zoonotics and the environment. Zoonotic. Jump or spillover of an animal disease to humans 60% of all human infectious diseases currently known either cross routinely or have crossed between other animals and us in the past

dahlia
Download Presentation

Zoonotics and the environment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Zoonotics and the environment

  2. Zoonotic • Jump or spillover of an animal disease to humans • 60% of all human infectious diseases currently known either cross routinely or have crossed between other animals and us in the past • Yellow fever, Lyme disease, mad cow disease, West Nile virus, Ebola virus, dengue fever, malaria, Hanta virus…

  3. How does zoonotic disease differ from non-zoonotic disease? • Not zoonotics: • Smallpox • Viral, spread by contact with pustules, and indirectly thru contact with infected materials • Poliomyletis (polio) • Viral, spread from droplets from cough or sneeze as well as contact with feces • Zoonotics • Rabies • Viral, spread by contact with fluids via breaks in skin • Seasonal influenza (flu) • Viral, spread by aerosols from cough or sneeze

  4. Variolation Innoculation VaccinationEradication

  5. Declared eradicated in 1980 • No animal host since it is not a zoonotic • Immunization of humans led to its disappearance outside of remaining laboratory stockpiles

  6. Killed (IPV) versus attenuated live virus (OPV)

  7. http://www.youtube.com/watch?v=uskccZNIxS8 http://www.youtube.com/watch?v=Rp7fo2QB9E8 Nigeria, Pakistan, Afghanistan, and Somalia

  8. Zoonotics require one or more reservoir hosts • These are organisms infected with a zoonotic pathogen but are asymptomatic • Helps zoonotic pathogens distribute themselves and reproduce • Multiple host organisms make it likely that pathogens will mutate and undergo molecular changes that may make it more or less lethal • Animal reservoirs make it difficult to eliminate zoonotic pathogens completely.

  9. Rabies virus • Bite from dogs (95% of all cases), cats, raccoons, skunks, foxes, bats • Not a cause of death in the developed world, but high public health costs ($300 million annually) in US • Where public health system has collapsed, rabies is associated with mortality • 55,000 deaths annually in Asia and Africa

  10. Preventable zoonotic disease • Rabies is a good example of a preventable zoonotic disease. Another example is African sleeping sickness carried by the tsetse fly • Public health systems that are able – financially as well as politically – to monitor and respond to human and animal disease reduce transmission, mortality, and suffering • Nature of emerging zoonoses also differs

  11. What is the difference between the types of zoonotic disease in rich and poor countries? http://www.cdc.gov/outbreaks/

  12. Influenza: an example of a zoonotic that is less preventable

  13. Types of seasonal influenza • Three basic types of influenza viruses: A, B, and C. • Influenza B and C viruses only infect humans • Only influenza A viruses infect nonhuman hosts • Epidemics of seasonal influenza occur due to influenza A or B viruses.

  14. Naming influenza A viruses (H1N1, H3N2…) • H and N refer to hemagglutinin and neuraminidase. • These are antigens, proteins that provoke the human immune system to produce antibodies • Antigens are categorized according to antibodies that respond to them. • There are 17 known hemagglutinin subtypes for influenza A (H1 to H17) and 10 known neuraminidase subtypes (N1 to N10).

  15. Naming influenza A viruses (H1N1, H3N2…) http://www.cdc.gov/flu/about/season/vaccine-selection.htm • Flu vaccination is a preventative stimulation of your body to produce antibodies to a particular combination of H and N subtypes predicted to be abundant during flu season • Antigenic shift – emergence of novel H and N proteins for which there is no immunity

  16. Center of origin for influenza • Most seasonal influenza originates in Asia where there there is a high density of poultry and humans in close proximity. Undomesticated waterfowl may also carry and transmit influenza A. • Thus far, H1, H2, and H3 of influenza A are known to cause pandemics

  17. H7N9: a new influenza A virus that emerged in 2013. 30% mortality rate. • So far, H7N9 has not spread from person to person, so no pandemic • Emergence of H7N9 virus led to closing of poultry markets and culling • Closing of markets judged successful from disease standpoint

  18. Influenza has a high potential for pandemic • H and N antigens can evolve that we do not have antibodies • 16 x 9 = 144 pairings • Multiple animal hosts • Different viral subtypes within an animal can lead to viral reassortment • Mutation of RNA segments

  19. Spanish Influenza of 1918 • One third of Earth’s population infected • 20-50 million deaths worldwide • 675,000 deaths in the United States with unusually high death rate among healthy adults 15 to 34 yrs

  20. Influenza in your future: • A global pandemic at some point seems likely • World-wide monitoring networks in place • Poverty may enhance its spread by limiting detection

More Related