Micro 120

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Micro 120
2010-12-14 19:32:18
Micro120 Final

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  1. • Mucus to trap microbes
    • Ciliary movement to move mucus to noseand mouth for elimination
    • Streptococci, lactobacilli and Moraxellacatarrhalis in upper respiratory tract
    • Lower respiratory tract and sinuses aresterile
    • Alveolar macrophages
    • IgA in secretions
    Defenses and normal flora
  2. • Upper respiratory infection
    • Symptoms:– Sneezing– Nasal congestion– Excess nasal mucus (rhinorrhea)– Sometimes: sore throat, fever, headache• Cause: Rhinovirus, coronavirus– Picornavirus– ~100 different Rhinovirus serotypes– Coronavirus: glycoprotein spikes on surface• Transmission:– hand-to-hand-to-nose– fomites
    • Occurrence:– October-April in northern hemisphere: coldtemperatures– Infect all populations (only humans)• Host defense:– IgA antibodies in nasal mucosa– Interferon• Prevention & Treatment:– Hand washing– Decontaminate fomites– Interferon
    rhinitis common cold
  3. • Transmission– Aerosolized droplets from mouth and nose
    • Occurrence:– epidemics and pandemics– Bird and swine reservoirs– Human virus and bird virus mix in swine
    • Host defense:– Antibodies against HA & NA– Antigenic drift and antigenic drift: reinfection• Diagnosis– In the clinic by symptoms– For epidemiological monitoring: Culturing virus or identifying viralantigens•
    Prevention & Treatment– Annual vaccination (cultured in egg: egg
    allergens)– Antivirals administered early in infection or before
    infection– New vaccine in development:• cultured in monkey cells• Protective against multiple strains
    • Lower respiratory tract infection• Symptoms:– Fever– Headache– Muscle ache– Cough• Cause– Influenza virus– Strains A, B, & C, RNA virus
  4. • H1N1 and H3N2 caused infections• H3N2 and Strain B did not match vaccinestrain
    2007 to 2008
  5. Vaccine includes H1N1, H3N2 and strain B
  6. • Lower respiratory tract infection• Symptoms:– Wheezing in infants– Mild form in children & adults
    • Cause– Respiratory syncytial virus (RSV)– Causes formation of large cells with multiple nuclei inrespiratory tissue• Transmission– Hand contact– Respiratory droplets• Occurrence:–
    Late winter and early spring– All ages– In the US, RSV causes about
    90,000 hospitalizationsand 4,500 deaths per year in children under 5 yr.• Host defense– No lasting immunity• Prevention & Treatment– Hand washing– Supportive care and oxygen to aid breathing
    Bronchiolitis (RSV)
  7. • Upper respiratory tract infection
    • Symptoms– Swollen throat– Toxin damages cells, cells produce apseudomembrane of dead cells– Sudden death by suffocation
    • Cause– Corynebacterium diphtheriae– Gram positive, rod– Diphtheria toxin
    • Gene carried on a bacteriophage
    • AB toxin
    • A subunit enters host cell and disrupts protein synthesis
  8. • Transmission– Humans are only host– Respiratory droplets from carriers and patients
    • Occurrence– Among unvaccinated children
    • Host defense– Antibodies that bind toxin
    • Prevention & Treatment– Vaccine; requires a booster every 10 years– Antitoxin soon after infection
  9. • Upper respiratory tract infection• Symptoms– Sore throat, fever, chills, headache– Inflamed pharynx, White exudate on tonsils– Swollen lymph nodes in neck
    • Cause– Streptococcus pyogenes– Gram positive cocci found in chains– Group A, beta-hemolytic on blood agar
    • Transmission– Person to person by respiratory droplets– Contaminated food– Unpasteurized milk
    Streptococcal pharyngitis
  10. • Occurrence– School age children humans are the only host
    • Diagnosis– Culturing organism in the lab followed by diagnostic tests– Rapid latex agglutination kits
    • Prevention & Treatment– Antibiotics
    Streptococcal pharyngitis
  11. • Complications– Scarlet fever:
    • Caused by strains that secrete an erythrogenictoxin that kills cells
    • Toxin on prophage
    • Causes Intense inflammation
    • Rash and fever– Rheumatic fever
    • Inflammation in multiple organs: joints, skin, brain
    • Damage to heart valves
    • Leading cause of heart disease in children
    • Prevented by using antibiotics
    • Recurrence can be fatal, maintenance antibiotics
    Streptococcal pharyngitis
  12. – Acute poststreptococcal glomerulonephritis
    • Sudden kidney failure
    • Urine becomes scant & dark
    • Body swells from retained fluids
    Streptococcal pharyngitis
  13. • Cause– Streptococcus pneumoniae– Gram positive cocci, occur in pairs– Have a thick capsule
    • Transmission– Respiratory droplets
    • Lower respiratory tract infection• Symptoms– High fever– Chest pain– Fluid in alveoli• Occurrence– All ages, especially elderly and children– Recovery confers immunity• Host defense– Inflammatory response which caused symptoms– Phagocytes ineffective because of capsule– Antibodies• Prevention & Treatment– Antibiotics– Vaccination
    Pneumococcal pneumonia
  14. • Lower respiratory tract infection• Symptoms– Slow onset headache– Mild symptoms fever– Atypical/ walking pneumoniacough• Cause– Mycoplasma pneumoniae– Grows in trachea
    • Transmission– Respiratory droplets
    • Occurrence– Alls ages especially school age children, teenagers
    • Host defense
    • Prevention & Treatment– Tetracyclines and erythromycins
  15. • Lower respiratory tract infection– July 1976, 182 people took ill and 26 died during a American Legionconvention in Philadelphia
    • Symptoms– Weakness Chills– Headache Cough– High fever
  16. • Cause– Legionella pneumophila– Small, aerobic, rod– Fastidious, grown in fertilized eggs and guinea pigs
    • Transmission– Grows in standing water– Survives heat & chlorination: becomes aerosolized– Grows in cooling towers
    • Occurrence– Any age– Elderly and smokers are more susceptible• Diagnosis– ELISA, RIA– Antibody staining of clinical specimens– Culturing in the lab• Prevention & Treatment– Antibiotics: erythromycin because of resistance to
  17. • Lower respiratory tract infection
    • Symptoms– Sore throat– Tiredness– Cough progressing to choking cough & suffocation
    • Cause– Bordetella pertussis– Small Gram negative coccobacillus– Exotoxin: pertussis toxin causes symptoms– Cytotoxin: kills cells of trachea
    Pertussis (Whooping cough)
  18. • Transmission– Respiratory droplets– Humans are sole hosts
    • Occurrence– Infants and young children– Unimmunized people– Older adults– Highly contagious and fatal
    • Diagnosis– PCR of bacterial DNA– Antibody titers in ELISA
    • Prevention & Treatment– Vaccination (DPT, DTaP), booster required– Supportive & erythromycin
    Pertussis (Whooping cough)
  19. • Lower respiratory tract infection– Leading cause of infectious disease death worldwide
    • Symptoms-none
    • Cause– Mycobacterium tuberculosis– Rod shaped, obligate aerobe– Waxy coat:
    • Slow growth (20 hr generation time)
    • Does not stain well (Acid fast stain)
  20. • Occurrence– Anyone exposed to the bacterium
    • Host defense– Cellular immunity (T cells producelymphokines)
    • Prevention & Treatment– Bacille Calmette-Guerin (BCG) vaccine– Tuberculin skin test to monitor infections(delayed hypersensitivity reaction)– Isoniazid or multidrug– Emergence of multidrug resistant TB
  21. • Lower respiratory tract infection
    • Symptoms– Flu-like illness: fever, chills, cough, shortness of breath– Immunocompromised people develop chronicrespiratory illness or disseminated infection
    – Occurs in three forms:
    • Acute Histoplasmosis• Chronic Histoplasmosis
    • Disseminated Histoplasmosis
  22. • Cause– Histoplasma capsulatum– Grows as single cells (yeast) and mycelia in soil– Found in soil rich in bat & bird droppings
    • Transmission– Inhalation of spores
  23. • Occurrence– People exposed tocontaminated soil– Exploring caves, barns etc where bats & birds dwell
    • Prevention & Treatment– Amphotericin B orKetoconazole for people withnormal immune system
  24. • Lower respiratory tract infection
    • Symptoms– Fluid accumulation– Tissue scaring– Respiration compromised– Low blood oxygen
    • Cause– Pneumocystis carinii– Opportunistic pathogen
    Pneumocystis pneumonia
  25. • Transmission– Found in the lungs of most peoplefrom an early age
    *Occurrence– Disease in immunocompromised people
    • Host defense– Cytotoxic T cells, Interferon gamma
    • Prevention & Treatment– Nothing much, treatments not tolerated byAIDS patients
    Pneumocystis pneumonia
  26. • Seamless epithelial layer
    • Peristalsis movement
    • Bacteriocidal chemicals– Lysozyme in saliva– Bile– Hydrochloric acid in stomach
    • Secretory IgA
    • Esophagus, stomach & upper smallintestine have no resident microbes
    • Exchange of genetic material betweenbacteria in intestine
    defenses and normal flora
  27. Streptococcus salivarius, Staphylococcusepidermidis, Moraxella catarrhalis, Lactobacillus,Candida albicans
  28. Anaerobes: BacteroidesBifidobacterium,Fusobacterium, ClostridiumFacultative anaerobes: E. coli, Proteus spp.,Klebsiella spp., S. aureus, Lactobacillus spp.,
    intestinal tract
  29. • Symptoms– Swelling of salivary glands– Fever, headache, tiredness
    • Complications– Meningitis– Inflammation of testicles (orchitis)– Inflammation of ovaries and breasts– Spontaneous abortion– Permanent deafness
    • Cause– Mumps virus– Helical, enveloped, single stranded RNA virus• Transmission– Respiratory droplets– Fomites– Person is infectious 3 days before to 9 days after symptoms appear
  30. • Occurrence– Unvaccinated population
    • Host Defense– Interferon– T & B cell response– Life long immunity
    • Diagnosis– Clinical symptoms– Lab detection of viral antigens & antibodies
    • Prevention & Treatment– MMR vaccine (live attenuated virus)– No treatment
  31. • Symptoms– Diarrhea - Dehydration– Vomiting– Abdominal discomfort– Fever
    • Cause– Rotavirus– Damages the epithelial cells of the intestine
  32. • Transmission– Fecal oral– Very infectious: epidemics– Fomites
    • Occurrence– Young children, 2.7 m cases per year in US among <5yr– Day care settings– Winter
  33. • Host Defense– IgA– Breast feeding protects infants
    • Diagnosis– Symptoms– ELISA if needed
  34. • Prevention & Treatment– Rehydration and supportive care– Good hygiene– Live attenuated oral vaccine with 5 strains of rotavirus (RotaTeq)Withdrawn– New vaccine approved Feb 2008: live oral (Rotarix)
  35. • Symptoms– Diarrhea - Headache– Vomiting - Abdominal cramps– Tiredness - Low fever
    • Cause– Norwalk virus/ norovirus– Non-enveloped, RNA virus
    • Transmission– Fecal oral– Contaminated food and water, uncooked food– Aerosolization of vomit
    norwalk virus
  36. • Occurrence– Older children and adults– Highly infectious– Cruise ships/ schools
    • Host Defense– Antibodies are not protective– Repeated infection by same anddifferent strains
    norwalk virus
  37. • Diagnosis– Symptomatic– RT-PCR, ELISA
    • Prevention & Treatment– Supportive– Good hygiene– Safe water and food handling– Virus is resistant to freezing, hightemperature (60°C), chlorine (10 ppm)
    norwalk virus
  38. • Symptoms– Diarrhea - Nausea & vomiting– Jaundice from liver impairment– Fatigue - Loss of taste and smell– Not a chronic infection
    • Cause– Hepatitis A– Small, non-enveloped RNA virus– Picornavirus, enterovirus
    hep a
  39. • Transmission– Fecal oral– Oral-anal sexual contact– Excreted in feces
    • Occurrence– All ages– Children often asymptomatic
    • Host Defense– Antibodies to HA– Protective (no reinfection)
    hep a
  40. • Diagnosis– Symptoms– Anti-HA titer
    • Prevention & Treatment– Vaccine– Good hygiene, Proper sanitation– Avoid risky behavior
    hep a
  41. • Symptoms– Jaundice - abdominal pain– Fatigue - Nausea & vomiting– Liver cirrhosis, liver cancer
    • Cause– Hepatitis B virus– DNA virus, hepadnavirus family,– HBsAg, HBcAg, HBeAg found in serum– Dane particles: empty
    hep b
  42. • Transmission– Blood & bodily fluids - Sharing needles– Sexual– Mother to baby during birth
    • Occurrence• Host Defense– T & B cell
    • Diagnosis Detecting HBsAg and antibodies to it
    hep b
  43. • Prevention & Treatment– Hepatitis B vaccine (rHBsAg protein)– Antivirals for chronic infection– Don’t share needles– Engage in safe sex, monogamy
    hep b
  44. • Symptoms– Asymptomatic at initial infection– Chronic hepatitis years (>20 years) later– Liver cirrhosis and cancer in a small percentage
    • Cause– HCV virus– Enveloped RNA virus
    hep c
  45. • Transmission– Transfusion with contaminated blood– Sharing needles with an infected person– Organ transplants from infected person
    • Occurrence– >3.2 million chronic infections in the US (CDC, 2006)
    • Host Defense– Ineffective immune response because the virus constantlychanges
    hep c
  46. • Diagnosis–Serology to detect anti-HCV antibodies• Less sensitive, delay for antibody development– PCR to detect viral RNA
    • Prevention & Treatment– Limit exposure to blood– Don’t share needles– Treated with multidrug combination that cures– No vaccine
    hep c
  47. • Symptoms– Diarrhea and Dysentery– Abdominal pain & cramps– Fever, vomiting
    • Cause– Shigella sonnei, S. flexneri, S. boydii– 9-15 bacteria can cause disease– Produce Shiga or shiga-like toxin, all are AB toxins
    • Transmission– Fecal oral route– Humans are only host (and primates)– Contaminated food and water
  48. • Occurrence– In places with poor sewage or water treatment– Daycare facilities, families
    • Host Defense– Non-specific and specific responses– Antibodies to LPS, proteins, toxins
    • Diagnosis– Shigella in fecal sample– Blood and neutrophils in stool– Symptoms
    • Prevention & Treatment– Antibiotics– Good hygiene
  49. • Symptoms– High fever– Headache, tiredness– Diarrhea
    • CauseSalmonella typhimuriumcauses salmonellosis– Salmonella typhi– Bacteria shed by patients and carriers
    • Transmission– Fecal oral– Contaminated food and water
    typhoid fever
  50. • Occurrence– Imported cases in the US– Relatively common in developing countries
    • Host Defense– Humoral antibodies, protective
    • Diagnosis– Stool tested for S. typhi
    • Prevention & Treatment– Antibiotics– Vaccine for travelers, S. typhi Ty21A– Avoid potentially contaminated food & water
    typhoid fever
  51. Symptoms– Profuse ‘rice water’ diarrhea– Loss of skin elasticity
    • Cause– Vibrio cholerae– Gram negative curved rod– Grows in brackish water– Shell fish contaminated with Vibrio– Cholera toxin (AB toxin)
    • Transmission– Fecal-oral– Contaminated water & food
  52. • Occurrence– In endemic areas: children– Everyone during epidemics– 1991 American epidemic
    • Host Defense– Antibodies to surface antigens
    • Diagnosis– Symptomatic
    • Prevention & Treatment– Good hygiene, sewage treatment– Clean water,– Rehydration– Oral vaccine for travelers,
  53. • Diseases– Enterotoxigenic (ETEC)
    • Watery diarrhea, similar to cholera
    • Caused by toxins
    • Occurs in children & travelers
    • Antibiotics shorten duration, rehydration– Enteropathogenic (EPEC)
    • Diarrhea in infants
    • Virulence factor is an adhesin on the outer membrane
    • Destroys the microvilli of small intestine– Enteroinvasive (EIEC)
    • Dysentery, inflammation, fever
    • Bacteria invade the cells of the intestinal wall
    • Toxin genes similar to Shigella toxins and found on plasmid
  54. – Enteroaggregative (EAEC)
    • Chronic watery diarrhea in infants– Enterohemorrhagic (EHEC) O157:H7
    • Bloody diarrhea, Hemolytic uremic syndrome (HUS)
    • Caused by Vero toxin (toxin acquired from Shigella)
    • Antibiotics early, supportive
    • Transmission– Fecal oral– Contaminated food or water
    • Diagnosis– Symptomatic
    • Prevention & Treatment– Good hygiene - Hand washing– Supportive (rehydration) - Antibiotics for high risk populations
  55. • Symptoms– Chronic gastritis– 15-20% develop ulcers– Gastric carcinoma
    • Cause– Discovered by Marshall & Warren, Nobel 2005– Lives only in humans, stomach & duodenum– Virulence factors• Adhesin to attach to stomach epithelium• Enzyme urease: splits Urea into CO2 &ammonia that increases pH
    • Transmission– Unknown, presumed fecal-oral, mouth tomouth– Found in feces and mouth
    helicobater pylori
  56. • Occurrence– Present worldwide in most people– H. felis (cats) & H. helmanii (dogs) can infect humans
    • Host Defense– Cellular and humoral immune response
    • Diagnosis– Labeled urea converted to CO2 by H. pylori breath test– Serological tests
    • Prevention & Treatment– Combination therapy:• Antibiotics to kill bacteria• Chemicals to reduce acid• Compounds to protect the stomach lining
    heicobater pylori
  57. • Symptoms– Diarrhea– Abdominal pain– Colitis (inflammation of the colon)– Pseudomembranous colitis
    • Cause– Clostridium difficile– Gram positive, endospore former– Exotoxins A (enterotoxin) causes fluid secretion– Exotoxin B (cytopathic) causes inflammation
    • Transmission– Contact with feces or feces contaminated fomites
    clostridium defficile
  58. • Occurrence– Following prolonged antibiotic use– In hospitals– Elderly• Host defense– No immunity– Normal flora
    • Diagnosis– Symptoms following antibiotic use– Serology for exotoxin
    • Treatment and prevention– Stop antibiotics– Rehydration– Antibiotics to target anaerobic bacteria– Restore normal flora in severe cases
    Clostridium defficile
  59. • Symptoms– Gingivitis: red swollen bleeding gums– Tissue and bone loss– Loss of teeth
    • Cause– Bacterial plaque with Porphyromonas gingivalis• Transmission– Mouth-mouth
    • Occurrence– Usually adults– Smokers more susceptible– Diabetes, certain medications, stress (weakimmune system)
    periodontal disease
  60. • Diagnosis– Clinical presentation
    • Prevention & Treatment– Brush and floss teeth– Antibiotics– Pocket reduction, grafts, dental implants
    periodontal disease
  61. • Symptoms– Appear 2 weeks after infection– Explosive, foul smelling watery diarrhea– Bloated stomach, foul smelling gas– Long term: Abdominal pain, nausea,occasional diarrhea
    • Cause– Giardia lamblia– Protozoan
    • Transmission– Water contaminated with cysts– Person-person contact– Oral-anal sex
  62. • Occurrence– Campers who ingests contaminated water– Cities if water supply is contaminated
    • Host Defense– IgA– Inflammation at site of attachment• Diagnosis– Cysts in stool sample (infected & carriers)– ELISA for G. lamblia antigens
    • Prevention & Treatment– Boiling or filtering water– Chlorination does not kill cysts– Hand washing & personal hygiene– Avoid risky sexual behavior– Metronidazole
  63. • Symptoms– Intense itching around the anus– Disturbed sleep– Irritability– Vaginal irritation if worm enters vagina– (Loss of appetite and weight)
    • Cause– Enterobius vermicularis– Small white worm, mates in the intestines,females lay eggs near the anus
    • Transmission– Fecal oral– Eggs can survive for up to two weeks onclothes
  64. • Occurrence– School age children– Preschoolers and their caregivers• Host Defense– Unknown
    • Diagnosis– Scotch tape test in the morning– Worms on skin or bedclothes
    • Prevention & Treatment– Changing undergarments everyday– Wash hands– Wash all clothes during and after treatment– Mebendazole; Two doses separated by two weeks
  65. • Symptoms– Itchy migrating skin lesion at site ofinfection– Mild diarrhea or cramps– Anemia, tiredness, weight loss– Severe cases:• Stunted development• Difficulty breathing• Enlarged heart
    • Cause– Ancylostoma duodenale– Necator americanus
    • Transmission– Larvae in soil borrow into bare skin– Eggs voided in feces
  66. • Occurrence– Humans and other mammals– People who work with soil– Children playing in contaminated soil• Diagnosis– Eggs in feces
    • Host defense– IgE
    • Prevention & Treatment– Don’t walk barefooted in contaminated soil or work with barehands– Treated with two doses Mebendazole– Iron supplements for anemia
  67. • Bladder and kidneys are normally free ofmicroorganisms
    • Vagina is colonized by Lactobacilli (maintain low pH),aerobic Streptococci & Staphylococci, anaerobicBacteroides & Clostridium, fungi Candida albicans
    •Urine washes microbes out of the bladder.
    • Microbes usually enter the urinary system throughthe urethra.
    • Microbes usually enter the reproductive systemthrough the vagina (in females) or urethra (in males).
    normal flora and host defenses
  68. • Symptoms:– Frequent urination fever & pain near kidneys– Pain while urinating
    • Types of infections– Any or all parts of urinary tract are infected– Cystitis: common bladder inflammation
    • E. coli--most common
    – Urethritis: infection of urethra
    – Pyelonephritis: infection of kidneys
    • E. coli 75%
    • P-fimbriae
    urinary tract infection
  69. • Occurrence– Females more than males– Pregnant women– Catheters– Anatomical abnormalities or obstructions
    • Diagnosis– Symptoms– Bacteria in urine– Urine culture
    • Treatment/ prevention– Antibiotics– Good hygiene– Drink plenty of fluids
    urinary tract infection
  70. • Cause– Neisseria gonorrhoeae– Infects the urethra
    • Epidemiology– 300,000 cases/yr; 60% age 15-24– Males:
    • 80% show symptoms
    – Females:
    • Often asymptomatic• leads to pelvic inflammatorydisease
    – infants:• ophthalmia neonatorum
  71. • Transmission– Sexually transmitted disease– From mother to infant at birth
    • Symptoms
    – Men:• burning sensation when urinating• a white, yellow, or green dischargefrom the penis• Sometimes painful or swollentesticles
    – Women:• painful or burning sensation whenurinating• increased vaginal discharge• vaginal bleeding between periods.
  72. • Occurrence– Sexually active people of all ages
    • Treatment & Prevention– Antibiotics: patient and all sexual partners– Condoms
    • Complications– potential for systemic infection• gonorrheal endocarditis• gonorrheal meningitis• gonorrheal arthritis
  73. • Cause:– Treponema pallidum– Spirochete
    • Congenital STD– Transmission from mother to fetus– Latent stage: Neurological damage– Primary/ secondary stage: stillbirth
    • Diagnosis– Microscopic examination of exudate forTreponema.– Serological tests for antibodies
    • Treatment & prevention– Antibiotics: Benzathine penicillin (effective for 2weeks)
  74. • Primary stage: several weeks– Hard based chancre– Infectious serous exudate– Bacteria enter blood and lymph
    • Secondary stage: 6-8 weeks– Disseminated skin rash– loss of hair– malaise, mild fever– Spirochete in lesions
    • Latent period
    • Tertiary phase: years later– <50% of untreated cases– T-cell immunity--gummus (rubbery mass)
  75. • Cause– Usually follows gonorrhea– Also caused by Chlamydia trachomatis– Any organism that causes urinary or genital infections
    • Symptoms– Inflammation of the infected organs– Severe pain in the lower abdomen
    • Infection beyond vagina– Uterus– fallopian tubes– ovaries
    • Increased risk if untreated– Infertility– ectopic pregnancy
    Pelvic Inflammatory disease
  76. • Cause– Chlamydia trachomatis
    • Occurrence– coinfection with N. gonorrhoeae– most prevalent STD– many cases go untreated– Transmitted to infants at birth• Neonatal eye infection– leading cause
    • Infertility• ectopic pregnancy
  77. • Caused by
    – Herpes simplex virus
    – HSV-2: normally genital tract
    – HSV-1: normally mouth and face• cold sores, fever blisters– latency• moves from nerve ending to nerve ganglion• reactivates to epithelial tissue
    – Neonatal herpes• Fetus or newborn• brain and internal organs• lifelong disabilities– No cure--controlled with acyclovir
    Genital Herpes
  78. • Human Papilloma virus (HPV)– Over 65 types--based on DNA
    • Diseases– benign wart– cervical carcinoma
    • Replication– proliferation of cells– basal layer of epithelium• no progeny virus in these cells– cells differentiate• virus replicates in later cells--shed from surface
    • Prevention– Vaccine
    genital warts
  79. • Disease– Acquired immunodeficiencysyndrome (AIDS)
    • Epidemiology– Crossed from animals to man1930– US since 1970s, first case 1980s
    • Cause– Human immunodeficiency virus(HIV)– Infects and replicates in CD4 Tcells– Spreads through out the bodyvia blood
    HIV Aids
  80. • Stages of HIV infection
    – Acute:• Fever fatigue rash headache
    – Chronic:• CD8 T cells kill virus infected cells, not symptomatic,• CD4 count decreases
    – AIDS:• CD4 <200 per cc, viral load increases• opportunistic infections, death