Determinants of Health and Disease

1. Determinants of Health and Disease

2. What Determines Good Health? Good physical health Mental health – if you believe that you’re not healthy you are more susceptible to getting sick. Spiritual – people who are religious/spiritual tend to be more upbeat, positive, optimistic etc…

3. Terms Associated with Disease Pathogenic – disease causing Opportunisticpathogen – is generally harmless in its normal habitat but can become pathogenic in a host who is seriously debilitated or has a weak immune system. • Ex. – pneumocytsiscarnii– will cause pneumonia in AIDS patients Virulent – Has a very high degree to cause infection • Ex. – Ebola(80% mortality)

4. Virulent Application Which is more virulent? E. coli 0157H7 – pathogen (found in burgers at Jack- in-the-Box) or E. coli in Felix’s gut Note: E. coli in Felix’s gut is an opportunistic pathogen. Has the ability to cause an infection but it has to be in the right conditions/environment like a sterile site.

5. Portal of Entry The area in which a microorganism enters the body. They may be cuts, lesions, injection sites, or natural body orifices • Four major pathways • Skin • Mucous membranes • Placenta • Parenteral route

6. Exposure to Microbes: Contamination and Infection • Contamination – the mere presence of microbes in or on the body • Infection – results when the organism has evaded the body’s external defenses, multiplied, and become established in the body

7. Portals of Entry • Skin • Outer layer of packed, dead, skin cells usually acts as a barrier to pathogens • Some pathogens can enter through openings or cuts • Others enter by burrowing into or digesting the outer layers of skin

8. Portals of Entry • Mucous membranes • Line the body cavities that are open to the environment • Provide a moist, warm environment that is hospitable to pathogens • Respiratory tract is the most common site of entry – entry is through the nose, mouth, or eyes • Pathogens able to survive the acidic pH of the stomach may use the gastrointestinal tract as a route of entry

9. The Movement of Microbes into Hosts: Infection [INSERT TABLE 14.4]

10. Differentiate Disease and Infection Diseases • Cystic fibrosis • Cancer • Diabetes • Cardiovascular heart disease (CHD) • Mental diseases (depression) • Alcoholism • Autoimmune (Lupus) Infection • Cellulitis (pyoderma) • pharyngitis • conjuctivitis • pneumonia • cystitis • otitis media • vaginitis • Colitis • Gastritis • encephalitis

11. Disease A harmful alteration of host tissues (arthritis) or metabolic processes (Diabetes/hyperglycemia.)

12. The Nature of Infectious Disease • Causation of Disease: Etiology • Study of the cause of disease • Germ theory of disease – disease caused by infections of pathogenic microorganisms • Robert Koch developed a set of postulates one must satisfy to prove a particular pathogen causes a particular disease

13. The Nature of Infectious Disease [INSERT TABLE 14.7]

14. The Nature of Infectious Disease [INSERT TABLE 14.6]

15. Infection Entry, manifestation, proliferation of an infectious agent within a host. Infectious agent has to enter, begin to grow and continue grow in host tissues.

16. Infectious Agents Linked to Malignancies Infectious diseases have been linked to other Diseases • HPV  cervical cancer • H. Pylori  gastric cancer • Hepatitis B  liver cancer

17. Infectious process Microorganism must enter host tissues. Microorganism must establish itself and begin to propagate (grow) Microorganism must have access to Nutrients If one of these three processes is not met an infection will not manifest In host tissues. • Ex. – HIV needs nutrients (T4 helper) in order to propagate.

18. Intoxication Effects on the body by a toxin produced by a biological agent. Enterotoxin F is produced by Staphylococcus aureus, causes toxic shock syndrome.

19. Intoxication Versus Infection Difference Between food Poisoning and FoodborneInfecton Condition Time until sick Length (process) Symptoms Intoxication by S. aureus 4 hours 24 hours Vomiting food poisoning) Infection by Salmonella 3-14 days until treated Cramps (food borne illness) Fever Diarrhea Dehydration Tenesmus Stool sample is taken to look for infectious agent then treated with antibiotics.

20. Attack of the Pathogens A pathogen (infectious agent) or (more commonly) germ, is a biological agent that causes disease or illness to its host. There are several molecules that microorganisms produce that allows invasion into tissues or a means to exert its pathological affect on the body.

21. Virulence Factors Virulence factors are molecules expressed and secreted by pathogens (bacteria, viruses, fungi and protozoa) that enable them to achieve the following: • colonization of a niche in the host (this includes adhesion to cells) • evasion of the host's immune response • entry into and exit out of cells (if the pathogen is an intracellular one) • obtain nutrition from the host.

22. Virulence Factors of Infectious Agents • Pathogenicity – ability of a microorganism to cause disease • Virulence – degree of pathogenicity • Virulence factors contributing to an organism’s virulence • Adhesion factors • Biofilms • Extracellular enzymes • Toxins • Antiphagocytic factors

23. Virulence Factors Virulence factors are very often responsible for causing disease in the host as they inhibit certain host functions. Pathogens possess a wide array of virulence factors. Some are intrinsic to the bacteria (e.g. capsules and endotoxin) whereas others are obtained from plasmids (e.g. some toxins).

24. Virulence Factors

25. The Role of Adhesion in Infection • Process by which microorganisms attach themselves to cells • Required to successfully establish colonies within the host • Uses adhesion factors • Specialized structures • Attachment proteins

26. Virulence Factors of Infectious Agents • Toxins • Chemicals that harm tissues or trigger host immune responses that cause damage • Toxemia refers to toxins in the bloodstream that are carried beyond the site of infection • Two types • Exotoxins • Endotoxins

27. Endotoxins The endotoxin is the lipopolysaccharide (LPS), which is part of the bacterial cell wall of Gram-negative bacteria. It is the Lipid A component of the LPS that has the toxic properties. The LPS is a very potent antigen and, as a result, stimulates an intense host immune response. As part of this immune response cytokines are released which cause the fever and other symptoms seen during disease. If a high amount of LPS is present then septic shock (or endotoxic shock) may result which, in severe cases, can lead to death.)

28. Exotoxin Exotoxins, on the other hand, are actively secreted by some bacteria and have a wide range of affects including inhibition of certain biochemical pathways in the host. The two most potent exotoxins known to man are the tetanus toxin (tetanospasmin) secreted by Clostridium tetani and the botulinum toxin secreted by Clostridium botulinum. Exotoxins are also produced by a range of other bacteria including Escherichia coli; Vibriocholerae (causative agent of cholera); Clostridium perfringens (causative agent of food poisoning as well as gas gangrene) and Clostridium difficile (causative agent of pseudomembranous colitis).

29. The Nature of Infectious Disease [INSERT TABLE 14.8]

30. Comparison of Toxins

31. Enzymes Microorganisms can producenumerous enzymes (proteins that break down substances) • Lipase – breaks down oleic acids which has many antimicrobial properties and protects our skin. • Produced by Staphylococcus • Coagulase – coagulates plasma • produced by Staphylococcus aureus • Hyaluronidase – known as “spread factor.” Hyaluronic acids holds cells together and Hyaluronidase destroys the cement that holds the tissues together. • Produced by Streptococcus pyogenes and Staphylococcus aureus

32. Virulence Factors of Infectious Agents • Extracellular enzymes • Secreted by the pathogen • Dissolve structural chemicals in the body • Help pathogen maintain infection, invade further, and avoid body defenses

33. The Body Fights Back The body contains many natural orders of defense against some of the common pathogens in the form of the human immune system and by some "helpful" bacteria present in the human body's normal flora.

34. Defense Mechanisms of the Host Figure 14.1

35. Non specific physical barriers • Skin (largest organ of the body) • Mucous membranes – openings to body (ears, mouth, anus, urethra)

36. Barriers at the Portal of Entry: A First Line of Defense Figure 14.2

37. Flushing Mechanism • Sneeze • Cough • Lacrimation (tears) • Sweat • Ear wax • Salivation • Defecation • Peristalsis – movement of food material in the intestinal tract

38. Figure 14.3

39. Nonspecific Chemical Defenses • Sebaceous secretions and specialized glands- antimicrobial • Lysozyme in tears • Lactic acid and electrolyte concentrations of sweat • Skin’s acidic pH and fatty acid content • HCl in the stomach • Digestive juices and bile in the intestine • Semen- antimicrobial chemical • Acidic pH in the vagina

40. Complement Complement cascade – entire immune system is turned on Functions – neutralizes viruses, enhances phagocytosis, damages plasma membrane, can destroy (lyse) microorganism

41. Complement: A Versatile Backup System • At least 26 blood proteins that work in concert to destroy bacteria and certain viruses • Cascade reaction • Three different pathways that all yield similar end results • Classical pathway • Lectin pathway • Alternative pathway

42. Interferon Antiviral properties – good in fighting cancer and viruses Body produces minute amounts Interferes with transcription and translation of mRNA

43. Interferon: Antiviral Cytokines and Immune Stimulants • Interferon (IFN): involved against viruses, other microbes, in immune regulation and intercommunication • Three major types • Interferon alpha • Interferon beta • Interferon gamma • All three classes produced in response to viruses, RNA, immune products, and various antigens • Bind to cell surfaces and induce changes in genetic expression • Can inhibit the expression of cancer genes and have tumor suppressor effects

44. Figure 14.18

45. Non specific biological barriers Normal flora – bacteria or plants. These organisms are with you for your entire life. They keep infectious pathogens in check. Natural resistance –resistance you’ve acquired throughout your life (adult) Resistance acquired from mother (child.)

46. The Immune System • Immunology: the study of all features of the body’s second and third lines of defense • Healthy functioning immune system is responsible for: • Surveillance of the body • Recognition of foreign material • Destruction of entities deemed to be foreign

47. Self and Nonself White blood cells must distinguish self from nonself cells Evaluates cells by examining markers on their surfaces

48. Figure 14.4

49. Blood components White blood cells • B lymphocytes • T lymphocytes