MICR 201 Microbiology for Health Related Sciences

1. MICR 201 Microbiology for Health Related Sciences Microbiology- a clinical approach by Anthony Strelkauskas et al. 2010 Chapter 8: Emerging and re-emerging infectious diseases

2. Why is this chapter important? • The world is facing challenges from both new diseases and re-emerging ones. • Methods of management and prevention can be developed by understanding the dynamics of disease. • Understanding how once dormant diseases are now re-emerging is critical to controlling the damage such diseases can cause.

3. Map for chapter 8 Advertisement: MICR 420 Emerging and Re-Emerging Diseases offered in Spring 2013

4. Definitions • Emerging infectious diseases • Infectious diseases whose incidences have increased over the past 30 years or threaten to increase • Includes new pathogens not observed before • Mutated viruses • Includes diseases whose etiology was not established before • Re-emerging infectious diseases • Infectious diseases we once thought to have overcome bounce back

5. Girolamo Frascatoro speaking about syphilis • “There will come yet other new and unusual ailments in the course of time. And this disease will pass away, but it later will be born again and be seen by our descendants.” • This quote was written 450 years ago by GirolamoFrascatoro, an Italian physician who named the disease syphilis.

6. Historical infectious diseases • The Black Death in the Middle Ages killed millions in Europe. • Measles destroyed the South American Aztec civilization. • Smallpox destroyed indigenous peoples of North and South America. • Syphilis (“The French disease”) spread in Europe in 15th/16th century in an aggressive form.

7. Emerging infectious diseases • Legionnaire’s disease • Acquired Immune Deficiency Syndrome (AIDS) • Hepatitis C • Hemorrhagic fevers (Hanta virus, Ebola virus) • Severe Acute Respiratory Syndrome (SARS) • Avian influenza • Prion diseases (Creutzfeldt-Jacob disease) Viral diseases

8. Ebola hemorrhagic fever

9. Ebola hemorrhagic fever • Ebola virus infects endothelial cell, monocytes and macrophages, and liver cells • Leads to vascular instability, bleeding disorder, shock, fever. • Mortality 50 – 90% • Transmitted from human to human via body fluids.

10. Re-emerging infectious diseases • Some diseases are re-emerging after being dormant for more than one hundred years. • Tuberculosis • Cholera • Many of these diseases were thought to be controlled through antibiotics. • In some cases the re-emerging disease is resistant to antibiotics. • In recent years, falling living standards and decline of infrastructure in some countries has aided the re-emergence of some infectious diseases.

11. How do emerging and re-emerging infectious diseases arise and spread? • Population growth • Crowding, more elderly • Urbanization • Now contacts with infectious agents • Crossing the species barrier • Ecological disturbances including climate change • Globalization and technological advances • Microbial evolution and adaptation • Human behavior and attitudes

12. How infectious disease agents can change: influenza virus

13. Prions and prion diseases • These infectious diseases are not caused by microorganisms. • All microorganisms contain nucleic acids • Cellular: prokaryotes and eukaryotes, cell membrane, proteins, nucleic acids, polysaccharides • Acellular: viruses, protein and nucleic acids • They are caused by infectious proteins called prions. • Composed of proteins only • Prion diseases are called transmissible spongiform encephalopathies (TSE).

14. Prions • Prions are proteins normally found on nerve cells and are known as PrPc (prion protein cellular). • Infectious prions are folded improperly and are known as PrPsc (prion protein scrapie). • They are routinely found in scrapie (a neurological disease of sheep).

15. Prions • Prions are practically indestructible. • They can withstand cooking. • They can withstand autoclaving. • They are resistant to strong alkali treatment. • They are resistant to disinfectants. • They can survive in soil for years. • Inactivation requires autoclaving in an alkali solution (bleach containing 2% chlorine) for one hour.

16. Prion disease hypothesis • Abnormally folded PrPscprions. • Aggregate into fibrous structures in the brain, referred to as a plaque. • Disrupt the cell membrane, causing cell death. • Convert normal prions into abnormal prions.

17. Transmission of prions • Infective prions can be ingested with prion-containing material. • These prions can move through the intestinal wall rapidly and enter lymph nodes where they incubate • They are picked up by peripheral nerves and moved to the spinal cord and brain. • Infectious prions can be transmitted between species • Incubation time is significantly longer when they cross between species.

18. Prion disease • Prions produce transmissible spongiformencephalitis • It is a neurodegenerative disease. • It can affect cattle and humans. • There is no test for it in live organisms. • There is no treatment. • There is no cure.

19. Transmissible spongiform encephalitis Normal Spongiform encephalitis Fibrillar deposit Neurological Damage

20. Transmissible spongiform encephalitis • Biology • A long incubation time • Plaque deposits in the brain • No antibody response • No inflammatory response • Symptoms include: • Lack of coordination • Staggering • Slurred speech • Dramatic mood swings • Paralysis • Death within one year of symptom onset

21. Chapter 8 key concepts • Emerging and re-emerging diseases will provide new and challenging problems for health care professionals. • Genetic mutation, environmental changes, and travel can contribute to these types of infection. • Most emerging diseases are caused by viruses. • Re-emerging diseases are those that were thought to be under control but have returned. In many cases this is due to an increase in resistance to antibiotics. • Avian influenza has the potential to become a very dangerous problem that could cripple the health care system of the United States. • Prions are proteins that are not folded correctly and cause transmissible spongiform encephalitis in humans and mad cow disease in cattle.

22. When genes are rearranged between two different viral strains through a gene “shuffling” event, this is called _____. • Recombination • Replication • Re-assortment • Redirection • Point mutation

23. Which of the following groups is susceptible to tuberculosis (TB)? • Malnourished individuals • AIDS patients • Immunocompromised individuals living in long-term care facilities • Alcoholics • All of the above

24. Quiz 1 – Wednesday, April 17 • 11:40am – 12:10pm • Chapters 1 thru 6: Lecture, Reading, Chapter End Self Study Questions • Twenty-five Multiple Choice Questions = 50 points • Please bring: • Scantron (form No. 882-E for the Quiz – available at no cost at the Student Bookstore) • No. 2 pencil only