Microbe-Human Interactions: Infection & Disease

1. Microbe-Human Interactions: Infection & Disease

2. Koch’s I. Introduction A. Recall _______ Postulates (experimental steps to establish the microbe that causes a disease) 1. isolate a pathogen from a diseased host & grow pathogen in pure culture 2. inoculate a healthy organism with the cultured pathogen 3. organism must get the same disease 4. isolate the same pathogen from the new host B. Exceptions to Koch’s postulates 1. Microbes that can’t be grown on artificial media examples: 2. More than one microbe produces the same disease examples: 3. One microbe that causes multiple diseases examples: 4. Strictly human diseases with no animal model examples: Viruses Rickettsia Treponema pneumonia meningitis Strep throat Streptococcus pyogenes Scarlet fever smallpox Rubella (German measles)

3. Normal Flora Resident Transient Colonization II. ____________ (microbes that normally live in/on the body w/o harm) A. _______ vs _________ flora (always there) (only present for a short time or on and off) B. Establishment of Normal Flora = __________ 1. Newborns are free of flora, but established as infant is exposed to organisms from _______, _____, ______ etc. 2. Colonization is a selective process due to physiological conditions in the body such as _____, ___________, ____, ________. 3. Takes about ____________ to fully establish normal flora C. __________ (different organisms living together) 1. __________ (both partners benefit) E. coli: produces vitamins K & some B, and ___________ (chemicals that ward off harmful species) 2. ___________ (one partner benefits, other is neutral) skin organisms live off of secretions/sloughed cells 3. _________ (one partner benefits while the other is harmed) many bacteria, fungi, protozoans, worms and even viruses vagina air food pH temperature O2 nutrients 12-18 months Symbioses Mutualism bacteriocins Commensalism Parasitism parasite host

4. Opportunistic habitat D. ____________ organisms (organisms that are usually nonpathogenic, but that can become pathogenic under certain circumstances) 1. when host health is compromised 2. when there is a reduction of normal flora 3. if an organism gets into a different_______ (part of the body) III. Mechanisms of ____________ (disease development) A. Production of disease is actually a process of steps 1. ____________ to a susceptible host 2. ___________ to appropriate target tissue(s) 3. ________ 4. __________ 5. ________ to host while evading defenses 6. _____ from body 7. _________ outside long enough to be transmitted to another host E. colifrom gut to urinary tract Klebsiella pneumoniae from gut to respiratory. Pathogenesis Transmission Adherence Invasion Colonization Damage Exit Survival

5. B. Transmission must be to the correct “portal of entry” 1. typically to exposed surfaces such as ______ or ______ membranes ( not an easy thing to do!) 2. entry aided by _____, ____, ________, _________. skin mucous punctures cuts bites abrasions

6. food water a. Gastrointestinal tract (via ______, _____) bacteria, especially Gram- _______ bacilli viruses such as polio and Hepatitis A protozoans such as Entamoeba and Giardia b. Respiratory tract (via ____) bacteria that cause strep throat, diphtheria, pertussis viruses such as influenza, measles, mumps, rubella, chickenpox and the common cold fungi such as Histoplasma and Pneumocystis c. Urogenital tract (most are _____) (or misplaced opportunists) bacteria such as Neisseria, Treponema, and Chlamydia viruses such as papilloma and herpes protozoans such as Trichomonas fungi such as Candida enteric air STDs

7. Gp120 spike Pink eye Middle ear Infectious dose 3. ________ ____ = minimum number of microbes necessary to insure infection (ex: only 10-100 Shigella but 1,000,000 Salmonella) C. Adherence (attachment) _________ (projections of microbe that match host receptors) 1. pili tips, surface proteins, etc. (can change b/c of mutations so previous Ab don’t recognize them!) 2. same organism can have different ligands to adhere to different parts of the body (ex: Haemophilus influenzae) 3. some ligand genes on plasmids can spread like antibiotic resistance! 4. why people don’t get a lot of other animal diseases and vice versa Ligands

8. D. Invasion (in order to establish infection) 1. high concentrations, more likely to invade successfully 2. ___________ = presence of bacteria in the blood ________ = presence of viruses in the blood E. Colonization (when conditions are such that invading microbes are successful enough to _________) __________ = blood infection where bacteria are reproducing Bacteremia Viremia reproduce Septicemia phagocytosis F. Evade host defenses (mainly by avoiding ____________) 1. ________ (Streptococcus, Salmonella, Neisseria) 2. __________ are substances that are toxic to WBCs 3. _________ breaks down H2O2 produced by phagocytes, preventing digestion of the engulfed microbe Capsules Leukocidins Catalase

9. Toxemia Toxins Exo- Hemolysins Endo- & Cause Damage/Disease 4. _______ (poisonous substances) (________ when in the blood) a. _____: toxic soluble proteins secreted (botulism, tetanus) ___________ cause lysis of RBC’s b. _____: cell wall components released when cell dies, toxic to host (lipopolysaccharides in Gram-negative cell walls) 5. ____________ (act on host cells/tissues) a. __________ activates prothrombin to coagulate fibrinogen in plasma, forming a fibrin clot that “hides” the microbe from phagocytosis b. ___________ breaks down blood clots in order to spread c. _____________ “spreading factor” breaks down hyaluronic acid (loose connective tissue), allowing organism to invade tissues *Can lead toSeptic shock Exoenzymes Coagulase Fibrinase Hyaluronidase

10. The effects of Hyaluronidase can be drastic! Late stage necrosis of epidermis, subcutaneous layers, fascia, and musculature of upper lateral leg. Necrosed peripheral nervous tissue results in no perception of pain at wound site!

16. G. Development of Disease 1. __________ period (between infection and 1st signs/symptoms) Depends on dose of microbes, which microbes, virulence, host health a. typhoid fever 10-14 days b. AIDS 10 years! (allows more spreading!) (2). _________ period of 1-2 days follows incubation in some diseases (= early, mild signs/symptoms such as _______, _______, ____________, etc. ) Incubation Prodromal malaise fatigue muscle aches Malaise = nothing specific, but you just don’t feel right

17. 3. ______ period when the disease is acute and ______most likely a. _______/______ b.  numbers of ___________ (> 10,000/ml) c. swollen _____ _____ d. ______________ e. ____________ f. severe ____ Illness Death Chills Fever Leukocytes lymph nodes Nausea/diarrhea Rashes/lesions pain

18. 4. Recovery ________ period (1-few days) when signs/symptoms are subsiding BUT most susceptible to secondary, ___________ infections ____________ period needed to regain strength Decline Opportunistic Convalescent H. Disease Terminology 1. _____ infection (limited to point of entry) Vs _____ infection (spreads to a new location) Vs ________ (infection that spreads to several sites and the blood) Local wart boil Focal rabies Hepatitis A tetanus Systemic tonsillitis appendicitis Tooth abscess measles chickenpox syphilis

19. edema inflammation fever rash lesions pus Acute 2. ______ diseases develop fast but for a short duration Vs _______ diseases develop slow but for a long duration Vs ______ diseases may be inactive for long periods of time 3. ________ (identification) of a disease is dependent upon: _________ of a disease are subjective changes in body function Vs _____ of a disease are objective (measurable) changes influenza cold Chronic TB leprosy Latent Cold sores Genital herpes Diagnosis Symptoms malaise aches pain sore throat Signs

20. Sneeze Cough A _________ is a groupof symptoms/signs characteristic of a certain disease. A _________ infection is asymptomatic, but patient is still infectious (more common in children) Syndrome Rubella syndrome Subclinical I. Exit by means of 1. ______/_______ 2. ________ 3. ____ /_______ 4. ____________ 5. _____ Diarrhea Pus Blood Insect bites Sex!

21. J. Survival outside long enough to gain entry into a new host 1. Some can also live in the environment 2. Some are hardy and can survive for as long as several weeks before a new host comes along 3. Some hang out in animal__________ 4. Some require direct contact b/c they are fragile K. Pathogenesis depends on many factors 1. Genetics, both species and individual 2. state of host health 3. age (_______& ________have less capable immune systems) 4. ________ (causes corticosteroids that are immunosuppressive) Clostridium tetani Mycobacterium tuberculosis reservoirs Rabies, RMSF Treponema pallidum Infants Elderly Stress

22. STRESS

23. Epidemiology: The study of Disease in Populations

24. Epidemiology IV. ___________ = study of frequency and distribution of disease in order to set guidelines for disease prevention and control. = like detective work to determine the cause, reservoirs, transmission, portals of entry/exit, etc. A. ____________ is essential to make predictions 1. National ________________________ & Prevention (CDC) located in Atlanta, Georgia 2. _______________________________ (MMWR) tracks over 50 diseases carefully b/c hospitals, Drs., coroners, etc. REPORT them: AIDS, STDs (such as gonorrhea, syphilis, Herpes), measles, tetanus, TB, hepatitis, rabies, chickenpox, malaria, etc. Case reporting Centers for Disease Control Morbidity & Mortality Weekly Report www.cdc.gov/mmwr/

25. World Health Organization 3. _______________________ (WHO) plans which diseases will be targeted for eradication (such as smallpox, accomplished in 1979, and polio, targeted for 2009). B. Epidemiologic Statistics: Frequency of Cases 1. __________ = total number of existing cases with respect to the entire population (usually expressed as a __________); a “snapshot” to help assess the overall impact of a disease example: 100 people have a disease………….. a. out of 500,000 people (0.02%) not a big deal, but b. out of 500 people (20%) is a big deal 2. _________ # of ____ cases in a specific time period compared with the general healthy population (usually expressed as # cases per 100,000 people) a. indicates both the _____ and ____ of infection b. also called the__________ rate or ________ rate A class of 50 students w/o influenza (P & I both 0 because 0/50 have influenza) becomes exposed to influenza 1st week, 5 students become ill. P = ____ and I = __ in 10 2nd week 5 more students become ill P = ____ and I = __ in 10 2nd week 5 more students become ill P = ____ and I = __ in 10 w/1st 5 students recovered Prevalence percentage Incidence new risk rate Disease Morbidity 1 10% 1 20% 1 10%

27. Incidence of pneumococcal disease (per 100,000 people)

28. 3. _________ rate = percentage of people who die from a disease 4. Terms that describe disease frequency a. _________ = a disease that is always present in a population (steady frequency) b. ________ = a disease that only pops up occasionally at irregular intervals in random locales c. _________ = a lot of people get a disease in a short time (increasing frequency) d. _________ = a worldwide epidemic C. Investigative Strategies of the Epidemiologist 1. Determining ________ (= continual ______ of infectious organisms) a. ________ are asymptomatic people that can spread disease (1). _________ (50% of infected females are asymptomatic!) (2). ________ Mary *precautions can be taken: *if humans are the only reservoir, it should be easier to control Mortality Endemic common cold Sporadic Typhoid fever diphtheria Epidemic Gonorrhea Chlamydia Pandemic influenza AIDS Reservoirs source Carriers Gonorrhea Typhoid

30. 3. _________ rate = percentage of people who die from a disease 4. Terms that describe disease frequency a. _________ = a disease that is always present in a population (steady frequency) b. ________ = a disease that only pops up occasionally at irregular intervals in random locales c. _________ = a lot of people get a disease in a short time (increasing frequency) d. _________ = a worldwide epidemic C. Investigative Strategies of the Epidemiologist 1. Determining ________ (= continual ______ of infectious organisms) a. ________ are asymptomatic people that can spread disease (1). _________ (50% of infected females are asymptomatic!) (2). ________ Mary *precautions can be taken: *if humans are the only reservoir, it should be easier to control Mortality Endemic common cold Sporadic Typhoid fever diphtheria Epidemic Gonorrhea Chlamydia Pandemic influenza AIDS Reservoirs source Carriers Gonorrhea Typhoid Don’t go out Don’t drink after Don’t have sex! Don’t kiss

31. A fly walked on the agar surface! b. Nonhuman animals (1) ________ vector (part of the pathogen’s life cycle) (2) _________ vector (just carriers) (3) _________ = an animal disease we can get biological mosquitoes cockroaches mechanical houseflies Zoonosis rabies anthrax plague RMSF

32. Environmental c. ____________ (soil, water, food) 2. Terms for transmission of infectious agents a. ___________ diseases are spread from one person to another b.Communicable diseases arecalled _________ if easily spread c. ______________ diseases (you cannot get them from another person) Salmonella tetanus cholera Communicable Herpes measles Common cold Contagious Chickenpox Noncommunicable tetanus botulism

33. 3. Patterns of communicable disease transmission a. _______(Physical, person-to-person) “A portal of exit meets a portal of entry!”  1 meter (close proximity) common in crowds, elevators (1) _______ spread (mother to fetus/infant) (2) _________ spread (anybody else to anybody else) Direct touch kiss sex Respiratory droplets/sneeze, cough Vertical Rubella, STDs Horizontal

34. Indirect b. ________ (1) _______ (inanimate objects) (2) ______/______ (especially GI parasites) (This transmission can be from the ________ or from __________; fecal-oral) Fomites toys used kleenex needles Toilet seats Door knobs eating utensils food water Source Preparation Salmonella eggs/chicken Typhoid Mary

35. (3) _______ nuclei (small, dried up on dust, carried by air currents) * good ventilation helpful (dilutes) * air filters help trap * pressurized air (out of operating rooms) * damp mops better than brooms Droplet

36. #cases D. Areas of Epidemiology 1. _________ epidemiology occurs after disease outbreak and describes the characteristics of ill people a. ____ b. _____ c. ____ d. _________ e. ________ f. ___________ (to help figure out reservoirs) g. ______ * Common Source Epidemic *Propagated Epidemic #cases time time Descriptive age sex race occupation Drug use? lifestyle Sexual activity? Smoker? Home location Timing Analytical 2. _________ epidemiology then determines which risk factors [identified by descriptive studies] are actually relevant by _________ those with the disease to those without the disease comparing