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92 Cards in this Set

  • Front
  • Back
Pathology and Epidemiology
- Pathology - scientific study of disease
- Etiology - study of the cause of the disease
- Pathogenesis - how the disease developed
- Concerned with structural and functional changes caused by disease and bodily effects
- Infection- invasion of body by pathogenic microorganisms
- Disease - infection causes any change from state of health.
Normal Flora
- Microorganisms that reside or colonize on the body but do not produce disease under normal conditions.
- Microbial antagonism- the result of the normal flora preventing the overgrowth of harmful microorganisms.
Inflammatory Bowel Disease
Excessive hygiene and antibiotic usage might help contribute to allergies and IBD's.
- IBD's and allergies both charcterized by inappropriate immune responses to harmless environment antigens
- Exposure to key microbes during childhood may be critical for directing the mature gut immune system to develop tolerance to commensal flora.
Inflammatory Bowel Disease
(IBD) (continued)
- Disrupting the interactions between commensal bacteria and intestinal immune cells by exposure to broad spectrum anitbiotics or excessively clean environments may compromise the development of normal, measured immune responses to commensal gut bacteria.
IBD - Continued
- To counteract IBD, one should promote the growth of a more favorable intestinal flora
- Probiotic - advantageous microbes.
- Prebiotic- foods that allow probiotics to grow.
Bowel Cancer
- Colorectal tumors are considered the second most prevalent form of cancer in humans and responsible for 1 in 5 fatalities in the U.S. components of the gut flora have the capacity to produce carcinogens and tumor promoters.
Microbe - Host Relationship
- Symbiosis - relationship between normal flora and host
- Commensalism - one benefits, one does not
- Mutualism- both benefit
- Parasitism- One benefits at the expense of the other - disease causing organisms.
Opportunistic Pathogens
The microorganism does not normally cause disease in thier normal habitat in a healthy person but may do so in a different environments
- E.coli in large intestine is harmless, entry into blood to other organs can cause illness.
Classify Infectious Diseases
- Behave within the population
- Occurance
- Severity or duration
- Extent of host involvement
Infectious Disease behavior
- Communicable disease - any disease that can spread from one host to another - herpes, TB
- Contagious disease - Diseases that easily spread from one to another - measles
- Noncommunicable disease - disease not spread from on to another - tetanus
Disease Occurrence
- Incidence, number of people in a population who develop a disease in a particular time period. Indicated spread of the disease
- Prevalence - number of people in a population who develop a disase at a specific time. Indicated how serious and how long a disease affects a population. It includes old and new cases.
Frequency of Disease Occurrence
- Endemic disease - disease constantly present in population - common cold
- Epidemic disease during a short period of time, a large number of people come down with disease - influenza
- Pandemic disease - epidemic disease that occurs worldwide - influenza, AIDS
Extent of Host Involvement
- Local (limited area) vs. systemic (throughout body)
-Bacteremia - bacteria in the blood
-Septicemia - bacteria multiply in blood
- Toxemia - toxins in blood (tetnus)
- Viremia - viruses in blood
Predisposing Factors
- Factor that makes the body more susceptible to a disease and may alter the course of the disease
* Gender
* Genetics
* Climate
* Nutrition
* Age
* Preexisting illness
Disease Development
- Incubation period- time between initial infection and first sypmtoms
- Prodromal period - usually short period early, mild symptoms
- Illness period - all symptoms develop shortly
- Decline period - symptoms subside
- Convalescence period - regain strength and health
Reservoirs of Infection
- A continual source for the disease organisms, conditions for survival, multiplication, and opportunity for transmission
- Humasn reservoirs - carriers
- Animal reservoirs - zoonoses
- Nonliving reservoirs - soil water
Disease transmission
- Contact transmission- direct, indirect, droplet
- Vehicle transmission - water, food air
- Vectors - insects. mechanical - microbe spread via insect walking on food. Biological biting or defecating on host or wound.
Nosocomial Infection
- hospital, nursing home, Health care facility acquired infection. The patient exhibited no symptoms prior to admission
- These facilities possess many pathogenic microbes, direct and indirect contact transmission common patients are compromised-resisteance is low due to disease, therapy, burns.
- 5-15% of all hopsital patients (2 mil per year) 90,000 deaths, approx 7 billion dollars per year are the results from nosocomial infection
Nosocomial Control
- Hand washing is single most important control measure
- Disinfect surfaces
- Clean respirators, humidifiers
- Anything touching patients should be sterile, disposible units
- Immediately dispose sharps, correctly, do not sheath used needles.
- Use protective barriers to prevent exposure to blood and other body fluids.
Types of Nosocomial Infection
- Exogenous - infection caused by pathogens from health care environment
- Endogenous - infection caused by microbes on patient's body
- Iatrigenic - infection caused by use of catherters, invasive diagnostic procedures, surgery
- The study of where and when diseases occur and how they are transmitted in a population.
- Deals with etiology and other possible important factors and patterns of victims.
- Deals with methods to conctrol a disease.
Types of Epidemiology
- Descriptive: detailed analysis of data of disease. Look at all factors - age, sex, etc. Look for index case (first case)
- Analytical: take descriptive info, determine probable cause, mode of transmission, possible means to prevent disease.
- Experimental: test hypothesis concerning cause of disease; develop experiemtns or studies to prove conclusion of descriptive and analytical.
Epidemiological Control of Diseases
- Case reporting - certain diseases are required to be reported to state health authroities. In this way , patterns, increases in these diseases are detected and then attempts are made to control them. Investigations, patient interviews, sample collections are carried out.
- Extremely small
- Obligatory intracellular parasites that require living host cells
- Contain single type of nucleic acid
- Protein coat that surrounds nucleic acid
- Multiply inside living cell using cell's processes to multiply
- Synthesis of specalized structures to transfer viral nucleic acid to other cell
Size and structure
- Size range from 20 to 1400 nm
- Virion - complete, fully infections viral particle
- Capsid - protein coat surrounding nucleic acid
- Envelope - if present, lipid, protein carbohydrate structure that surrounds capsid.
- Based on : nucleic acid type
how it replicates
morphology of capsid
- Viral species - group of viruses sharing same genetic information and ecological niche; example- HIV,HIV-1
- Past: embryonates eggs
- Now: cell cultures - cells (human, other animal) grown in culture media
- Primary cell lines - from tissue slices
- Diploid cell lines - from embryo
- Continue cell ines - cancer cells
- Cytopathic effect (CPE) - cells deteriroate due to viral infection
- Virus that infects bacteria, also called phage
- Multiply by two means
- Lytic cycle - lysis and death of cell
- Lysogenic cycle - host remains alive
Lysogenic Cycle
- Viral DNA incorporates into bacterial DNA
- Viral DNA called prophage
- Divides with bacterial DNA into new bacterial cells. This gives the bacterial cell now properties
- Can change to lytic cycle
Lysogeny Results
- Cells immune to reinfection by phange
- Phage conversion - cells exhibit new properties. Examples - Corynebacterium diphtheriae; Vibrio cholerae
- Specalized transduction - bacterial genes picked up and transferred to another bacterium through phage infection
Animal Viruses Infection steps
- Attachment - to cell's protein and glycoproteins of plasma membrane
- Penetration - endocytosis - plasma membrane folds inward to form vesicles. Fusion- enveloped viruses can fuse with plasma membrane and release capsid into cells cytoplasm
- Uncoating - separation of viral nucleic acid from its protein coat
DNA viruses
- Viral DNA enteres nucleus - begins to make its own DNA and proteins primarily using cell's enzymes
- In cytoplasm - capsid proteins made, then migrates to nucleus complete virion formation
- Released from cell
Types of DNA Viruses
- Adenoviridae - adenoids, respiratory disease - common cold
- Poxiviridae - small pox
- Herpesvirdae 0 herpes 1 & 2 (HHV), varicellaviruses - chicken pox
- Papovaviridae - warts
- Hepadnaviridae - hepatitus B only
RNA viruses
- Multiplication and formation occurs in the cytoplasm, use of mRNA and viral RNA
Types of RNA viruses
- Picornaviridae - polio virus
- Togaviridae - arboviruses - West Nile Virus
- Rhabdoviridae - rabies
- Rcoviridae - cause respirator and intestinal disease
- Tertoviridae Lentivirus - HIV-1, HIV-2
Influenza Virus
- Influenza A and B are the two types of influenza viruses that cause epidemic human disease (there is also a type C in other animals, mild or no illness in humans)
- Influenza A viruses are further categorized into subtypes on the basis of two surface antigens: hemagglutinin (H) and neuraminidase (N).
- Influenza B viruses are not categorized into subtypes.
- Two pandemics of influenza have swept the world since the "spanish flu" of 1918 (up to 40 million deaths).
- The Asian flu pandemic of 1957 and the "Hong Kong" flu pandemic of 1968.
- Epidemics of influenza typically occur during the winter months and have been responsible for an average of approximately 36,000 deaths/year in the US during 1990-1999. 200,000 hospitalizations per year.
Influenza Virus
- The flu usually starts suddenly and may include these symptoms:
- Fever (usually high)
- Headache
- Tiredness
- Cough
- Sore throat
- Runny or stuffy nose
- Body aches
- Diarrhea and vomiting also can occur but are more common in children
Release of Virions
- Budding part of cell's plasma membrane now containing viral proteins develops around the capsid - released to outside. Membrane becomes viral envelope. This may not kill cell.
- Non- enveloped viruses are released through newly formed holes in membrane- usually kills cell.
Viruses and Cancer
- Not all virons lead to cancer
- May take long time after infection to develop cancer
- Not apper to be contagious
- Oncogenes - selections of DNA that if altered can lead cell to cancer state
- Oncogenic virus- virus that can induce cancerous tumors
Oncongenic Viruses
- DNA viruses - papillomavirus - cervical cancer; Epstein-Barr (EB virus - infectious mono, but also two cancers; hepatitus B virus - liver cancer
- RNA viruses - Retroviridae - human T-cell leukemia viruses- HTLV-1, HTLV-2
Types of Viral Infection
- Latent infection - virus in host cells throughout life - reactivated by stress or immunosupression (herpes and AIDS) (chickenpox and shingles)
- Persistent viral infection - prolonged disease process, occurs over long period of time. Viruses gradually increase in numbers unlike latent infection.
Viral Disease ID
- Serological test- look for virus or antibodies
- Cytopathic effects
- Restriction Fragment Length Polymorphisms (RFLPs)
- Polymearse Chain Reaction (PCR)
- Proteinaceous infectious particle discovered in 1982
- Infectious agent is pure protein
- Cause nine neurological diseases called spongiform encephalopathines
- Mad cow disease
- Creutzfield-Jakob Disease (CJD) in humans
- May be genetic factors for some of them
- Not known how cell is damaged or destroyed.
Human Immunodeficiency Virus (HIV)
- Relatively benign virus that were infecting monkeys and chimpanzees entered human population thru skinning and butchering for food.
- Probably happened around 1930, virus spread once small villages became "urbanized"
- Genus Lentivirus, a retrovirus, RNA virus with phospholipid envelope
- Virus possesses gp120 glycoprotein which reacts with receptor(s) on human cell. Major human receptor is CD4 which can be on T-cells, macrophanges and dendritic cells
HIV Hides from Immune System
-Viral RNA becomes incorprated into cell's DNA called Provirus
- Creates viral particles that are not released immediately
- Cell-cell fusion: virus moves from infected cell directly to another
- Rapid or frequent antigenic changes
- Subset of HIV-infected cells becomes long-lived memory T-cells. Latent HIV can persist for decades
HIV- Major Types
- Types HIV-1 and HIV-2. Within types Distinctive groups or Clades
- Viral variation of 15%-20% within clade
- In US 90% of cases are HIV-1, clade 2
- HIV-2 are rare in US
HIV stages of Infection
- Category A: asymptomatic or swollen lymph nodes
- Category B: persistent microbial infections. Candid albicans in mouth, throat, vagina. Other- shingles, diarrhea; precancerous conditions of cervix
- Catergory C: clinical AIDS; C.albicans throat, bronchi, lungs, TB, Pneumocystis pneumonia; viral - Kaposi's sarcoma
HIV Stages of Infection T-Cell Population
- CDC also classifies infection based on the T-cell population. Normal: 800-1000 CD4 T-cells/mm
- A count below 200 CD4 T-cells/mm is diagnostic for AIDS.
HIV Disease Progression/Diagnosis
- Typically, it takes ten years from initial infection to AIDS
- 99% of HIV infected cells are CD4 T-cells. The disease devastates the immune system- body unable to respond to pathogens.
- Diagnosis: ELISA, Western Blot, PCR
HIV Transmission
- Infection body fluids
blood: 10x3-10x5 viruses/ml
semen: 10-50 viruses/ml
-Sexual contact, blood contaminated needles, transplacental infection of fetus, organ transplants, atrificial insemination, blood transfusion
Saliva - 1 virus/ml; kissing not known to transmit virus
Aids Worldwide/Vaccines
- 20 million deaths, 40 million infected with HIV. Approximately 14,000 new cases daily
- Vaccines - Most difficult due to life cycle, mutation rate, mutiple means of transmission results in difficult vaccine effectiveness. Full protection system after exposure
HIV Treatment
- Drugs to inhibit viral DNA formation and inhibit formation of capsid
- HAART - highly active antretroviral therapy - combination of different types of drugs to treat the virus.
- Difficult to administer and very costly. because of viral mutations, resistance likely to occur.
- Data shows increase of multiple antiretroviral agents containing protease inhibitors decreased mortality from HIV
Hepatitis A Virus
- RNA Picovirus: Single serotype worldwide, Acute disease and asymptomatic infection
-No chronic infection, Protective antobodies develop in response to infection - confers lifelong immunity.
Hep B Virus (DNA ONLY)
- Sexual
- Parenteral: exposure other than by oral route
- Perinatal: three months before to one month after birth.
Hep B
- Persons with Chronic HBV infections are ofeten asymptomatic but these persons are at high rish for developing chronic hepatitis and approximately 15-25% may die prematurely from either cirrhosis or liver cancer.
Concentration of Hep B Virus in Various body fluids
- High: blood, serum wound exudates
- moderate: Semen, vaginal fluid, saliva
- Low/Not detectable: urine, feces, sweat, tears, breast milk
Hep C Virus infection
- Hep C (HCV) infection is the most comon chronic bloodbourne viral infection in the United States
- First identified in 1988, HCV is the causative agent for what was formerly known as non-A non-B hepatitis and is estimated to have infected as many as 242,000 Americans annually during the 1980's
- Since 1989 the annual number of new infections has declined by more than 80 percent to approximately 41,000 by 1988.
Genus Norovirus (previousaly "Norwalk-like virus" (NLV, family Caliciviridae are a goup of related , singlestranded RNA, nonenveloped viruses that cause acute gastritis in humans.
- Also referred as the Calci virus and as small round structured virus or SRSV's.
- Cause of "the stomach flu" or the "the stomach bug"
Norovirus infection usually presents as acute-onset vomiting, watery non-bloody dirrahea with abdomonial cramps and nausea. Low grade fever. Dehydration is the most common complication.
-Transmitted primarily through the fecal oral route. Environmental and fomite contamination may also act as a source of infection. Highly contagious. Presymptomatic viral shedding may occur shedding usually begins with onset of symptoms and may continue for 2 weeks after recovery. CDC estimates that 23 million cases of acute gastritis are due to norovirus infection.
Herpes Virus (DNA)
HHV1- Cold sores
HHV2- Cold sores and genital
HHV3- Varicellavirus - chickenpox
HHV4- Lymphocryptovirus: infectious mononucleosis
HHV5- Cytomegalovirus: CMV inclusions
HHV6- Roseolovirus - roseola
HHV7- primarily infant infection - rash
HHV8- Kaposi's sarcoma AIDS patients
Herpers viruses
Genital herpers- herpes simplex virus type 2 is one of the most common sexually transmitted deisease in the United States.
- Symptoms of herpes-recurrent painful ulcers can be treated, but the infection cannot be cured. Most people with herpes have no symptoms and are unaware of thier infection
Herpes Virus
Disease can be transmitted between sex partners, from mothers to newborns and can increase a person's risk of becoming infected with HIV. May play a role in heterosexual spread of HIV. More than 4.5 million people are infected. More common in women than men. Male to female transmission is more efficient than transmission from females to males.
Medically Improtant Fungi
- Mycology is the study of Fungi.
- Fungi can be very beneficial: decompose dead plant water, help plants absorb minerals and water, some animals use fungi to break down plant material, food source for humans (mushrooms), Usen in production of other foods: beer, bread, cheese. Used to produce drugs: penicillin
Fungal Identification
yeasts - Based on biochemical reactions
Multicelular fungi - based on physical apperance and reproductive spores
-Nonfilamentous, unicellular, spheres or ovals
- Can reproduce by buddig or by fission
- Some yeasts produce pseudohyphae "fake hyphae" (C. albicans)
- If o2 present, yeasts produces c02 and h2o (bread)
- If no o2 is present yeast produces ethanol and co2 (beer,wine)
Multicellular fungi - Molds
-Body is composed of hyphae
-Hyphae can show cross-walls (be septate) or appear continuous (be coencytic)
- Hyphae can be vegetative (absorb nutrition) or ariel (reporductive)
- Aerial hyphae produce spores form sexual/asexual reproduction
- Mycelium is the mass of hyphae visible to unaided eye - the mold colony
Dimorphic Fungi
- Can grow as yeast or mold depending on tempreture
- At high temp (37 deg C) grows as yest
- At low temp (25 deg C) grows as mold
- Most human pathogens are dimorphic
- Although spores can be either sexual or asexual in lab setting we usually see asexual which is what identification is based upon.
Asexual Spore Identification
Condispore: produced in a chain, not enclosed in a sac (Aspergillus, Penicillium)
Specialized condiospore is an arthorospore, in which seperate hyphate break up into spores resembling barrels (Coccidioides).
Blastoconidia: buds coming off parent cell (Candida, Cryptococcus)
Chlamydospore is thick-walled spore formed within a hyphal segment (C.albicans)
- Sporangiospore: Contained within a sac at the end of aerial hyphae (Rhizopus)
Mycosis: Fungal Disease
- Usually chronic (long-lasting) because fungi grow slowly, may take awhile to respond to antimicorbial treatment
- Five classifications depending on degree of tissue involvememnt and mode of entry: systemic, subcutaneous, cutaneous, superficial or opportunisitc
System Mycoses
Deep within body, affecting a number of tissues or organs
- Usually caused by soil fungi - spores are inhaled
- Infection begins in lungs and spreads
- Not transmissible to others
- Example: Histoplasmosis (Histoplasma capsulatum)
Coccidioidomycosis (Coccidioides immitis)
Main System Pathogens
- Blastomuces dermatidis
- Histoplasma capsulatum
- Coccidioides immitis
- Cryptococcus neoformans

All systemic pathoges are inhaled and ifection spreads thorugh body in bloodstream.
Cryptococcus neoformans
- Yeastlike fungus with very thick capsule which will not stain when palced in a dark suspension like, India ink
- Associated with pigeon droppings
- Spores inhaled, infection spreads through bloodstrean to spinal fluid, resulting in meningitis which is fatal in untreated.
*Creates leisons in a renal transplant patient and in lung tissue*
Histoplasma capsulatum
- Dimorphic fungus that is yeat-like in body
- Common in areas east of Mississippi in US and Worldwide in specific foci, where bats and birds are numerous
- Infection occurs when airborne conidia re inhaled, can be confined to lungs or disseminate throughout body
- Hazzard for miners, bird breeders, chicken farmers
Coccidioides immitis
- Dimorphic fungus which forms sperules (thick walled bodies full of spores) in tissure
- Found in dry soil of American Southwest
- In soil forms arthrospores which become airborne on wind; simply driving through area or flying over in small plane can result in infection.
- Mold form is very dangerous to lab workers
Blastomyces dematitidis
- Dimorphic fungus usually found in Mississippi Valley
- North American Blastomycosis
- Most infections are asymptomatic, although there are some fatalities annually
- Begins in lungs can spread rapidly, causing cutaneous ulcers & abscesses
Subcutaneous Mycoses
- Infection beneath skin - directly implanted by puncture
- Caused by saprophytic fungi living in soil or on vegatation
Subcutaneous Pathogens
- Main cause in US is Sporpthrix schenckii, a simorphic fungus found in soil
- Causes "sporptrochosis"
- Must be "inoculated" into tissue by a cut- seen in gardeners, esp. rose gardeners
- Forms small ulcer at site of innoculation, travels up lymph system and causes lesions along this pathway
- Diseasae can take years to develop, diagnose and cure.
Cutaneous Mycoses
- Also knows as Dermatophytes
- Only infect epidermis, hair or nails
- Secrete keratinase, which degrades keratin, a protein found in hair, skin and nails
- Can be transmitted by direct contact
Cutaneous Pathogens
- Caused by dermatophytes, fungi that can grow in the keratin of hair, nails and skin
- Three main species: Micosporum, Epidermophyton & Trichophyton
- Causes tinea capitis (ringowrm of scalp) tinea cruris (jock itch), tinea pedis (athlete's foot) tinea unguium (nails)
Cutaneous and subcutaneous Mycoses
Caused by common soil saprobes, but diseases are not common because infection requires introduction of fungi beneath outer, dead layers of skin
- Most lesions remain localized in the subepidermal tissues in teh skin, though infections may rearely become systemic.(fonsecaea pedrosi)
- Fungal mycetoma - tumor-like infections of skin and bones surrounding initial site of infection (madurella mycetomatis)
Opportunistic pathogens
- Harmfuul only to immunocompromised
- Stachybotrys, Mucor, Aspergillus, C. albucans, Pneumocystis
Opportunistic Pathogens
- Candida albicans - espically common in diabetics
- Pneumocystis jiroveci
- Rhizopus spp
- Mucor spp
-Aspergillus spp
Candidia albicans
- normal flora of skin, mucus membranes, bacterial normal flora keeps growth of yeast down
- If bactera are eliminated due to antibiotic treatment, yeast can then overgrow
- Yeast infection in mouth, esp in newborns (thrush) or in female vagina (vaginitis) any moist skin
- responsible for 10% of nosocomial acquired infections
Pneumocystus jiroveci
- Once considered a protozoan, but actually closely related to yeast
- Infection occurs throughout world, but only causes diesase in immunosuppressed.
- Infects lung tissue, forms thick walled cysts
- Next to C.albicans this is the most comon cause of opportunistic fungal infections
- Several species can cause diesase: A fumigatus, A flavus, A niger
- Found in decaying vegetation like compost, farmers and gardners may breathe in an infective dose of spores.
- Can produce aflatoxins when grown on food some of which are carcinognens
Salem Which and Claviceps
- Claviceps purpurea is a fungus which grows on rye, producing a substance, ergot, chemically related to LSD
- When animals or people eat rye prepared from infected grain, it can result in delusions, convulsions, abortions, even death.
Toxic Mold
- Several types of fungus are blamed for "sick building syndrome"; most common is stachybotrys
- Results from moisure in walls, ceilings from leaking pipes or roof causing overgrowth of mold which then releases airborne toxins (mycotoxins) into lungs
- Symptoms include headaches, nosebleeds, coughing, sneezing, dizziness, fatigue, memory loss, learning disabilities in children.
Treatment of Fungal Diseases
Fungi difficult to treat than bacterial infections
- Amphotericin B: antibiotic produced by streptomyces, a soil bacteria. Combines with sterols in fungal plasma membranes, making cell excessively permeable. mainstay for treatment of systemic disease, but toxic to kidney
- Imidazole & trazole also interfere with sterol syntheses. Used topically for treatment of cutaneous mycoses (athletes foot, vaginal yeast infections)
- Voriconazole, as well as ketoconazole, flyconazole, and intraconazole can be taken orally for systemic infections as less toxin alternatives to amphotericin B
- Produced by species of Penicillium
- Acts against dermatophytic infections of hair and nails
- Taken orally, drug selectively binds to keratin, builds up to therapeutic fungal gorwth
Fungal Allergies
- 80 genera of fungi can cause allergies
- Reactions - asthma, eczema, hay fever rare lung involvement and death.