1 / 39

Infectious Disease

Infectious Disease. Infectious Disease. Globally, Infectious disease is still the single most common cause of death in 1993, >16 million people died from infectious diseases Many diseases, previously considered conquered, have once again re-emerged Tuberculosis pneumonia

peyton
Télécharger la présentation

Infectious Disease

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. Infectious Disease

  2. Infectious Disease • Globally, Infectious disease is still the single most common cause of death • in 1993, >16 million people died from infectious diseases • Many diseases, previously considered conquered, have once again re-emerged • Tuberculosis • pneumonia • food-borne illnesses

  3. Reemerging Infectious Disease

  4. Reemerging Infectious Disease • Why? • Human Demographics and Behavior • Technology and Industry • Economic development and Land Use • Microbial Adaptation and Change • Breakdown of Public Health Measures • and Deficiencies in Public Health • Infrastructure

  5. Communicable infection - a disease that is transmitted from person to person (NOT necessarily spread by direct contact!) influenza HIV tuberculosis chicken pox Noncommunicable infection - a disease that is not directly transmitted from person to person malaria botulism Rabies What is an Infectious disease?

  6. Cryptosporidiosis (protozoan) Diphtheria (bacterium) Malaria (protozoan) Meningitis, necrotizing fasciitis (flesh-eating disease), toxic-shock syndrome, and other diseases Group A Streptococcus (bacterium) Pertussis (whooping cough) (bacterium) Reemerging

  7. Reemerging • Rubeola (measles)(virus) • Schistosomiasis (helminth) • Rabies (virus) • Tuberculosis (bacterium) stricken) • Yellow fever (virus)

  8. What causes infectious diseases? • Microorganisms • Bacteria • Virus • Prion • Fungus • Protozoa • Helminth • Products from microorganisms • toxins

  9. Just how big are these guys anyway? Bar is 10 microns • viruses • 0.05 to 0.1 microns • bacteria • 0.5 to 1.5 microns • red blood cell • 5 microns • lymphocyte (white blood cell) • 5 to 8 microns • human sperm • 60 microns

  10. Some Definitions • Infectivity- capacity of an agent to enter & replicate within a susceptible host • Pathogenicity - capacity of an agent to cause clinical signs (disease) in a host • Virulence - refers to the severity of disease • Clinical disease - patient has noticeable symptoms of illness • Subclinical disease - no apparent symptoms; if infection persists, patient is known as a carrier

  11. Modes of Transmission

  12. Why do people get sick? • Agent Factors • new pathogens (HIV, Nile-like virus) • changes in pathogens (acquire antibiotic resistant genes) • Environmental Factors • changes in environmental conditions (el niño) • new environments (natural or man-made) • (Sweetwater wetlands)

  13. Why do people get sick?, contd. • Host Factors • age • gender • ethnicity • immune status • nutritional status • behavior • Balance is Key!

  14. Are all bacteria bad? • No! • Some bacteria perform essential functions in the body such as: • skin: prevents more harmful bacteria from colonizing • intestines: helps body break down and absorb certain nutrients; prevents more harmful bacteria from causing intestinal infections • vagina: prevents yeasts from overgrowing and causing infections • Other body areas are colonized and infections only occur in immunocompromised people • nasopharynx, oropharynx, esophagus, stomach

  15. Prevention and Treatment • Sanitation • water and waste treatment • personal hygiene • Vaccination • probably the #1 way to prevent communicable diseases • Healthy living (avoidance) • practice safe sex • avoid IV drugs • avoid hospital stays (5% of patients acquire a nosocomial infection) • Antibiotics and other drugs • use wisely and sparingly • don’t use antibiotics for viral infections

  16. Antibiotics • Penicillin • discovered in 1940s • natural product of bread mold • thought to be the miracle cure for all infections • now many organisms are resistant • Antibiotic Resistance • antibiotics do not work on viral infections • inappropriate use and overuse has resulted in many antibiotic resistant organisms (some organisms can transfer resistance between species) • research into new antibiotics has fallen behind • many multiply resistant organisms exist

  17. Your Immune System • Part of the lymphatic system • Primary lymphoid organs • bone marrow • spleen • lymph nodes • thymus • Secondary lymphoid organs • Peyer’s patches • tonsils • appendix • mucosal associated lymphoid tissues (MALT)

  18. Immunity

  19. Cells of the Immune System • Leukocytes (white blood cells) • neutrophils (PMN’s) • monocyte/macrophage • eosinophil • basophil • Specialized cells • B-cells antibodies • T-cells

  20. Innate immunity • First-line defenses • skin • low pH, low moisture, normal desquamation, antibacterial substances • vaginal epithelium • low pH, normal flora, • conjunctival epithelium • flushing effects of tears, lysozyme, lactoferrin • respiratory epithelium • secretory IgA (sIgA), lysozyme, lactoferrin, mucociliary escalator • gastrointestinal epithelium • hydrochloric acid, gastric enzymes,mucus,sIgA, normal flora • urinary epithelium • flushing effects of urine

  21. Innate immunity • Second-line defenses (occurs after organism breaches epithelial layer) • Initial environment • tissue fluids: lysozyme, lactoferrin • monocyte/macrophage: engulf & destroy • NK cells: recognize altered self cells • lymphatic fluid: drains tissues to lymph nodes

  22. Innate immunity • Second-line defenses, cont’d. • Inflammation - normal host response to a traumatic or infectious injury • heat • pain • redness • swelling • loss of function

  23. Innate immunity • Second-line defenses, cont’d. • Phagocytic defenses (by order of appearance) • PMN’s -polymorphonuclear leukocytes (neutrophils) • monocytes (in blood) • macrophages (in tissue)

  24. Adaptive Immunity • Cell-mediated • T-cells(CD4, CD8) • Humoral • B-cells • antibodies (immunoglobulins: IgM, IgG, IgA, IgE, IgD) • Both • complement cascade

  25. Autoimmune Diseases • Immune system fails to differentiate between self and non-self and generates antibodies against self proteins • lupus - immune cells attack DNA • arthritis - immune cells attack cartilage and bone • multiple sclerosis - immune cells attack central nervous system

  26. Prevention

  27. Epidemiology

  28. Initial case investigation- looking at reported cases of interest There are three questions to consider: • Who? • Where? • When?

  29. Who? • Gender • Age • Occupation • Cultural background • Signs and symptoms

  30. Where? • Physical location • Open or enclosed • High or low

  31. When? • Time of day • Time of Week • Time of month and year • Duration of event • Sequence of events

  32. Epidemiological Guidelines 1. Investigate reported cases

  33. 2. Form a Hypothesis

  34. 3. Come up with a working case definition

  35. 4. Design a questionnaire

  36. 5. Apply questionnaire to cases and controls

  37. 6. Refine case definition, refine hypothesis • Identify similarities • Assemble identified case reports • Exclude disqualified reports • Test hypothesis against identified cases

  38. Take Action

  39. 8. Communicate Findings

More Related