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Flashcards in Resp Viruses Deck (36)
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1
Q

Resp Tract Broken Down

A
  • _Upper Resp: _
  • Nose (mouth)
  • Throat
  • Epiglottis
  • Larynx
  • Middle ear & paranasal sinus
  • Lower resp:
  • Trachea
  • Brochi
  • Bronchioles
  • Alveoli
  • Deaths by resp infections #1 among low income populations
2
Q

Defense against infections

A
  • Nose: Hair, cilia, turbinates or nasal concha/mucus filter dust & particles = Sneezing
  • Change in direction: airway from sinuses to pharynx deposits particles @ **back of throat **
  • Lymphoid tissue:
  • Adenoid gland: Between nose & throat @ end of soft palate
  • Tonsils: Both sides of pharynx
  • Trachea: layer of mucus & ciliated cells=Coughing
  • Resp secretions: Lysozyme (gram+ bacterial cell walls), IgA, lactoferrin, mucus
  • Alveolar macrophages: Lower resp tract
  • Normal flora: upper resp tract
3
Q

How Pathogens avoid immune defense

A
  • Avoid mucus = NOT being expelled out
  • Avoid phagocytosis & multiply/divide in phagocytic cell
  • Major virulence factors(mol secreted by pathogens):
  • Bacterial adherence-surface structures
  • Extracellular toxins-Cytoxins
  • Growth in host tissue-intracellular
  • Evasion of hose defense:
    • Capsules-multiple types
    • Production of IgA proteases
  • TB avoiding immune defense w/granuloma
  • Multiple strains of strep (94)
4
Q

Syndromes of Upper Resp

A
  • Defense = Normal Flora
  • Common cold
  • Pharyngitis
  • Influenza
  • Diphtheria
  • Sinusitis & Otitis Media
  • Rhinocerebral mucrormyosis
    • **Effects immunocomprimised **
  • Epiglottis
  • Croup/laryngitis
5
Q

Syndromes of Lower Resp

A
  • Defense: Macrophages
  • Whooping cough
  • Bronchitis/Brochiolitis
  • Influenza
  • Pneumonias
  • Typical
  • Atypical (walking) develops from bacteria, viruses, fungi not common typical (chlamydo, mycoplasma, legionella)
  • Community/Nosocomial (hospital)
  • Occupational-Bacillus anthracis/Chlamydophila psi
  • Regional
  • Opportunisitc-Aspergillus spp/pneumocystis Jiro
  • Pulm TB = Myobacterium TB
6
Q

Etiologic Agents of Resp Infections

A
  • Microbal toxins that cause disease-Viruses, bacteria, fungi, Protozoan(unicellular), Helminthes
  • Viruses more common
  • Bacterial infection more serious=life threatening diseases
  • Many of upper resp tract pathogens ALSO cause lower resp tract infections
  • Influenza can effect BOTH lower/upper
  • Vocal cords are a marker for upper & lower resp tract
  • Bacteria:
  • Staph aureus-major cause of pneumonias
  • Francisella tularensis-gram(-) lethal cases of pneumonias
  • Coxiella burnetti-Gram(-) bio weapon
7
Q

Common Cold

A
  • Acute viral infection of resp tract w/inflammation in some or ALL airways (nose, paranasal, throat, middle ear, larynx)
  • Symptoms:
  • Nasal discharge & obstruction
  • Sneezing
  • Sore/scratchy throat
  • Cough
  • Chilly sensation w/slight fever
  • Etiology: Multiple agents 90% viral
  • Rhinovirus (common)
  • Coronavirus (SARS-10-15%)
  • Influenza (25-30%)
  • Adenovirus (5-10%)
  • Also less common chlamydia
  • Human Metapneumoviruses (influenza)
  • Complications: Sinusitis & otitis media Both Viral/Bacteriral w/asthma
  • Treat w/1st gen anti-histamines or NSAID
8
Q

Pharyngitis

A
  • Divided into Naso, Oro, Laryngo (top-bottom)
  • More common in children & @ winter time
  • Symptoms: “Sore throat”
  • Dysphagia (pain w/swallowing)
  • Fever & headache
  • Enlarged lymphnodes(neck)
  • Occasional runny nose/post nasal drip
    • Pus or no pus
  • Etioloic agents:
  • Adenovirus
  • Coxsackie
  • Epstein Barr (mono)
  • Strep pyogenes
  • Corynebacterium Diph <u><strong>(mycobacterium)</strong></u>
9
Q

Sinusitis & otits media

A
  • Occurs after viral infections
  • Sinusitis: Inflammation & obstruction of sinuses due to pus_(may follow tootch extraction due to normal flora)_
  • Fever-headache
  • Thick colored post nasal discharge
  • Halitosis
  • Otitis media: Inflammation & obstruction of middle ear due to pus behind tympanic(NOT present in viral)-sharp pain w/hearing loss, vomiting (anorexia)
  • Pathogens:
  • Strep pneumoniae (normal flora)
  • Haemophilus influenzae (normal flora)
  • Moraxaella catarrhalis <strong>(common)</strong>
    • gram(-) aerobic
  • Pseudomonas aeruginosa <strong>(common)</strong>
    • Immunocomprimised
10
Q

Croup: Laryngotracheobronchitis

A
  • Area between pharynx/trachea contains vocal cords w/mucous membrane
  • Symptoms: Resp obstruction swelling
  • Follows upper resp infection
  • Breathing diff, hoarseness w/Seal’s bark cough, Inspiratory stridor (high pitched-vibrating)
  • Gets worse laying down
  • High risk in 3 months-5 years
  • Exam: Restrictions on breathing, PROLONGED inspiration/expiration, wheezing
  • Sucking in of skin on inhalation-increased use of chest wall muscles
  • X-ray-Steeple sign (narrowing of upper trachea)
  • Etiology: Parainfluenza virus (80%), RSV, measles, adeno, influenza
11
Q

Bronchitis/Bronchiolitis

A
  • Inflammation of bronchial tubes-occurs after upper resp
  • Symptoms:
  • Fever, cough, & sputum production
  • Sore throat
  • Runny or stuffy nose
  • Headache
  • Muscle aches & extreme fatigue
  • Etiology: Virus & bacteria
  • RSV (syncytial-COMMON)
  • Parainfluenza/Influenza
  • Mycoplasma pneumon
  • Chlamydophilia (community)
12
Q

Pneumonias Classification

A
  • Infection of alveoli or walls
  • Could involve interstital (between alveoli)
  • Classification:
  • Location-Community or nosocomial
  • Oset-typical (acute), atypical (gradual), Chronic
  • Site affected- lobular, multilobular, broncho, interstitial
  • Regional- found only certain areas
  • Occupational-zoonotic <strong>(cross species)</strong>
  • Aspiration-Normal flora from Upper
13
Q

Symptoms of Pneumonia

A
  • Typical: rapid onset, high fever/chills, dyspnea, productive cough (blood), wheezes/cracks
    • X-ray: Dense consolidation
  • Atypical: moderate onset, low fever/chills, sudden attack cough w/moderate sputum
    • X-ray: Vague-patchy consolidation
  • Chronic: Gradual onset, night sweats, low grade fever, weight loss w/productive cough
14
Q

RNA virus Rhino (Non-enveloped-Picornav fam)

A
  • ss(+) RNA & 100 types known
  • Replication in cytoplasm RNA-dep/RNA poly
  • Reservior: Humans/Chimpanzees
  • Transmission: Worldwide, seasonal(summer-fall), Direct contact, resistant to drying/Detergents
  • Pathogensis: receptor on host ICAM-1
  • Low infectious dose/Nose, eye, mouth
  • Infected cells make-histamine/bradykinin
  • Replicates @ 33C better for upper resp
  • Acid labile-Killed in stomach
  • Diagnosis: Rarely done
  • Viral isolation-swabs saliva, nasal, pharyngeal
  • Serology-confirm virus as infection & assessment of immune status
  • Treatment: Hand washing w/NO vaccine due to so many serotypes
15
Q

RNA virus Corona (enveloped-Coronavir fam)

A
  • Spikes on surface due to large glycoprotein=Looks like *corona/crown *
  • (+) ssRNA virus replicated in cytoplasm w/RNA dependent RNA poly
  • optimum temp 33-35C=Upper resp
  • S protein for attachment coating itself resemmbling Fc-gamma receptors on immunoglobulins
  • Reservior-Corona(Human)
  • SARS-Cov(bats, cats, raccoon)
  • MERS-NCOV(middle east bats, camels)-Immunocomprimised
  • Transmission-Airborne droplets nasal or Oral-fecal (winter-spring)
  • SARS-COV: kills alveolar cells w/diarrhea
  • High fever, sore throat, ATYPICAL pneumonia, dyspnea
  • RT-PCR w/ELISA Ab=Diagnosis
  • Treat: Interferon-Ribavirin
16
Q

DNA virus (non-enveloped) Adenovirus life cycle

A
  • Icosahedral shape w/hexon capsid proteins
  • Peplomers: Pentons @ apices w/protuding fibers=attachment (HE)
    • Purified fibers toxic to human cells
  • Reservoir: Humans w/asymptomatic shedding
  • Receptors on host cells:
  • CAR-Coxsackie: Glycoproteins in Ig super family (CAR used by Coxsackie virus too)
  • CD46 (membrane co-factor protein)
  • MHC class 1
  • Integrin (internalization)
  • Sialic acid (RBC & Upper resp)
  • Endocytosis-Repication in nucleus
  • Early protein synthesis FOLLOWED by replication THEN late protein synthesis
17
Q

DNA virus (non-enveloped) Adenovirus Pathogenesis

A
  • Lytic: Permissive cells=host cell death
  • Target cell-muco-epithelial cells in resp tract (upper & lower), GI, Urinary
  • Latent: non-permissive cells=recurrence in immuno comprimised pts
  • Target cell-Infections in lymphoid cells (tonsils, adenoid, peyer’s patches)
  • Transforming infection: Cancer @ the site on incoculation <strong>(hamsters only)</strong>
  • Transmission: Close contact, aerosol, fecal-oral
  • Resists dryness, deteregents, mild Cl- (survive up to 90 days in pools)
  • High Risk: Children, crowded areas, SWIMMING clubs
18
Q

DNA virus (non-enveloped) Adenovirus Clinical

A
  • Pharyngitis=1,2,3,5,7:
  • Common cold symptoms
  • Fever, Sore throat, Inflammed Pharynx
  • Pharyngoconjunctival fever=3,7:
  • Assoc w/pools
  • Conjunctivitis, fever, vocal cord inflamm
  • Acute resp disease=4,7,21:
  • Military recruits
  • 3rd week of training
  • Fever, malaise, sore throat
  • Sudden drop in O2 in blood
  • Vaccine available (made of 4&7) oral & replicate in GI bypas resp
  • Pneumonia=1,2,3,7:
  • Mostly children and severe
  • GI(diarrhea)=40,41
  • Diagnosis: Immunoassay fluorescent Ab or ELISA or PCR
19
Q

RNA virus Coxsackie (Non-eveloped Picornaviri)

A
  • (+)ssRNA w/2 types A & B
  • Reservoir: Humans
  • Transmission: P to P, fecal-oral, Airborne
    • Ex. Diaper changing stations
  • High risk: infants & young children in Summer/Fall seasons
  • Treatment: COXA self-limiting (4-7days)
  • No vaccines
  • Prevention: Proper hygiene, boiling utensils
  • Herpangina: Vesicular pharyngitis
  • Sudden fever, headache, Sore throat, Dysphagia
  • Ulceration/Rash in pharynx, tonsils, mouth
  • Hand-foot-mouth: mild fever, vesicular lesion-hand, foot, mouth, tongue
  • Caused by type COXA16
20
Q

DNA virus Herpes (enveloped) General

A
  • Large w/linear dsDNA
  • Lytic, persistant or latent transforming infections
  • Vesciles seen in HSV1/2
  • HSV 1=Cold sores-latent in trigenminal
  • Grouped on what cell types they infect
  • Alpha herpes(infect epi cells):
  • Simplex (HSV-1 & 2)-Upper resp
  • Zoster-varicella (HHV 3)
  • Gamma herpes(infect vareity cells):
  • Epstein-Barr (HHV4)
  • Kaposi sarcoma (HHV8)
  • Beta herpes(infect lymphoid cells):
  • Cytomegalovirus (HHV5)-Upper resp
21
Q

DNA virus Herpes (enveloped) Epstein Barr

A
  • ds linear DNA-Enveloped HHV4
  • Asymptomatic shedding w/saliva w/lifelong infection
  • Transmission-P to P saliva
  • High risk-Young adults not infected <strong>(mono)</strong>
  • Infections in infants (when maternal Ab stops) or early childhood life long immunity
  • Cell infected = Epithelial (oro/Naso) & B-lymph
  • Virual gp350 attaches to comp C3b receptor-CR2(CD-21)->Gp42->MHC2
  • Permissive(productive): replicates/lysis of infected cells contain-
  • Early Ag, Viral capsid Ag, Membrane Ag
  • Non-permissive(latent):B cell mitogen (uncontrolled prolif) EBV DNA in nucleus, NOT integrated w/chromosome
  • Epstein barr nuclear Ag & Latent membrane protein = Immortal growth
22
Q

DNA virus Herpes (enveloped) Epstein Barr Clinical

A
  • Acute: Infectious Mono=Heterophile Ab (+) sheep blood agar (paul-bunnel test)
  • Fever, Sore throat, Lymphadenopathy, Splenomegaly & FATIGUE 1-4 weeks
  • Chronic: Recurrent-Fatigue, low grade fever, sore throat
  • Ampicillin<strong>(beta-lactam)</strong>rash seen in pts under treatment
  • Additional diseases associated:
  • Leukemia/Lymphoma-T-cell def or Immunosuppresed
  • Burkitt’s-Tumor of Bcell, Jaw/face, Africa-malaria belt
  • Nasopharyngeal carcinoma-Cancer of epi, Asia, genetic
  • Oral Hairy leukopenia-AIDS pt, Wart like growth, multiplies in epi cells
23
Q

DNA virus Herpes (enveloped) Epstein Barr Diagnosis

A
  • Incubation time 2 months or more
  • Hematologic:
  • Atypical T lympho (Downey cells)
  • T cells are larger w/vacuolated cytoplasm & basophilc inclusions
  • Serology:
  • Heterophile Ab: non specific IgM Ab-Bind to paul-Bunnel Ag on horse, sheep RBC
    • Monospot test(horse)-quick
  • EBV specific Ab test: IgM active infection against viral capsid Ag or Early Ag
    • IgG & AntiEBNA for chronic
  • Treatment: Self-limiting or Steroids for controlling swelling
24
Q

RNA virus (enveloped) Paramyxoviridae

A
  • (-) sense ssRNA & non-segemented
  • Cytoplasmic replication
  • Buds from plasma membrane
  • 3 genera cause Resp tract infections
  • Paramyxovirus: Parainfluenza/Mumps
  • 2 spikes:
  • F peplomer spike=fusion results in multinucleated cells (synctia)
  • Posses spike=Hema & Neuraminidase
  • Pneumovirus: Resp syncytial & Metapneumo
  • Morbillivirus: Measles
25
Q

RNA virus (enveloped) Parainfluenza Clinical

A
  • Transmission: inhalation of large droplet
  • High risk: Children 6mos-12yrs, short term immunity after disease
  • Pathogenesis: Inside epi cells-form giant cell & lysis
  • Adhesion mediated by Hemagglutnin-binds to sialic acid
  • Neuraminidase clips sialic acid for virus release
  • Clinical: Croup & Laryngotraceobronchitis
  • Mild cold-like upper resp infection
  • Can extend to larynx, trachea, & bronchial tree = CROUP or bronchiolitis & pneumonia
  • Croup=cough is sharp like seal’s bark due to subglottal swelling=High pitch
  • X-ray steeple sign
26
Q

RNA virus (enveloped) Parainfluenza diagnosis

A
  • Best specimens are nasopharyngeal secretions
  • Ag detection: Immunofluorescence
  • Serology: Hemagglutination inhibition test, ELISA
  • Treatment:
  • Hospitalization-Treat symptomatically & monitor airway continuosly
  • Cold or warm mist (humidirfier)-Croup tent
  • O2-may have intubated due to narrowing of trachea
  • IM dexamethasone (corticosteroid) & inhaled epinephrine (pediatric)
  • NO vaccine & re-infections common
27
Q

RNA virus (enveloped) RSV General

A
  • (-) ssRNA w/surface spikes only F protein (NO HG or Neuraminidases)
  • F protein: fusion multinucleated (syncytia)
  • Reservior: Humans everyone infected by age 3
  • Subtype B: asymptomatic affect majority of population
  • Subtype A: More severe & dominant in most outbreaks
  • Transmission: Inhalation of large droplets-Peaks in winter
  • High Risk: Premies-more severe w/lower resp=Brochiolitis
  • Common cause of acute FATAL resp tract infections
  • Adults: Mild symptoms, common-cold like. Very few infections are life threatening
28
Q

RNA virus (enveloped) RSV Pathogenesis

A
  • Cause of fatal acute resp tract infection in infants
  • Infects epi cell & make giant cells & kills cells
  • Immuno mediated (CD-8) cell injury-necrosis/sloughing of bronchiolar epi
  • Formation of plugs-Mucus, fibrin, necrotic material obstructs airway=Bronchiolits
  • More dangerous in infants due to smaller peripheral airways than adults
  • Symptoms: Mild Upper resp infection progress to cough->wheeze->dyspnea
  • Increased resp rate=Tachypnea
  • Rales, fever->turns into Lower resp=Pneumonia
  • RSV sign: intercostal/substernal retraction
  • Long-term=Asthma & pulm deficits
29
Q

RNA virus (enveloped) RSV Diagnosis

A
  • Ag detection assays (immuno)-
  • Cytophatic effect=Multinucleated cells w/basophilic cytoplasmic inclusion bodies
  • Treatment:
  • Symptomatic-Bronchodialators (metaproterenol/Albuterol) helps relieve chest congestion & wheezing
  • Severe cases=O2 therapy, Aerolized Ribavirin (analogue of guanosine)
  • Passive immunization: Hyperimmune globulin against RSV (Respigam)
  • Prevention: Infection for re-infection
  • Immuno-prophaylaxis-Children under 2 who have chronic lung disease
  • Monoclonal Ab against F-protein(palivizumab)
30
Q

RNA virus (enveloped) Metapneumovirus

A
  • ss(-) RNA from family paramyxoviridae
  • Recently recognized pathogen
  • Could cause 15% of children’s colds
  • Can cause:
  • Bronchitis (mucous membranes)
  • Bronchiolitis (small bronchioles)
  • Pneumonia
  • Very common-children by age 5 are seropositive
31
Q

RNA virus (enveloped) Influenza-General

A
  • ss(-)RNA & 8 Segmented RNA
  • Replicates in nucleus<strong>(instead of cytoplasm)</strong>
  • Has RNAdep-RNApoly
  • Matrix proteins important in uncoating:
  • HA (hemagglutinin)
  • Initiate by binding to sialic acid on epi cells
  • Agglutinates clumping-RBC
  • NA (neuraminidase)
  • Cuts sialic acid to release virus/dissolves mucus
  • Vaccines target these proteins (no binding=no infection)
  • 3 types based on variation of matrix proteins & nucleocaspid proteins (viral penetration into host nucleus)
32
Q

RNA virus (enveloped) Influenza-Life Cycle

A
  1. HA sticks to sialic acid on host cell-Virus enters by fusion into endosome (storage b4 nucleus)
  2. Matrix proteins=uncoating
  3. Nucleocapsid to host cell nucleus, viral polymerases require methylated cap of RNA (Cap-mRNA-Poly A) of host cell. Cap region of RNA for binding to ribosomes.
  4. (+) RNA made from each segment=viral polymerase on each segment(-)sense RNA for viral progeny made=viral Shedding
  5. +mRNA proteins in cytoplasm.
  6. Early proteins (polymerases and NP) for transcription and replication go to nucleus and mix w/–ssRNA.
  7. HA and NA , M proteins transported to host cell membrane.
33
Q

RNA virus (enveloped) Influenza-Types

A
  • Type A ONLY one w/sub-types based on variation on HA/NA Ag
    • 16 HA sub = H1-H16
    • 9 NA sub = N1-N9
  • Found in many species_-Native host is duck_
  • Type A assoc w/Pandemic <strong>(Spanish Flu)</strong>
  • Reassortment Antigenic shift:
  • Abrupt change when 2 strains infect one cell=RNAs mix giving rise to NEW strain
  • ONLY A
  • Type B ONLY humans
  • Point mutation/Antigenic shift:
  • Type A&B-Yearly epidemics occur
  • RNA segments are altered affect major Ag sites for glycoproteins
  • RNA virus prone to more mutations than DNA
  • Peplomers mutation=Cross species infect
34
Q

RNA virus (enveloped) Influenza-Clinical

A
  • Incubation 1-4 days
  • Fever, headache, sore throat, muscle pain, DRY cough
  • Recovery 7-10 days
  • Severity in young & elderly ALSO pts w/chronic cardio-pulm diseases
  • Pneumonia caused by Influenza
  • Pneumonia caused by secondary bacterial infection-MOST COMMON (Staph aureus, Staph pneumoniae, H. Influenzae)
  • Reye’s syndrome-Acute encephalomyelitis(inflammation of CNS)in children-assoc w/aspirin use
  • CNS issues-Seizures, weakness in periphery, hallucinations
35
Q

RNA virus (enveloped) Influenza-Diagnosis

A
  • Nasal/throat swabs, sputum
  • Detection=Ag/genome DFA, ELIZA, RT-PCR specific ID for types or subtypes
  • Fast results-used in screening during epidemics
  • Viral isolation & ID-Cell/egg culture:
  • Hemagglutination or Hemabsroption assay NOT specific
  • Serology: measure Ab lvl (titer)-Acute hemagglutination inhibition assay, Comp fixation
  • Treatment: neuraminidase inhibitors stop viral release given 48 hrs of onset
    • Oseltamivir(tamiflu)-oral
    • Zanamivir(Relenza)-inhaled
  • Stop uncoating-block martix proteins_ONLY A_
  • Amantadine or Rimantadine
36
Q

RNA virus (enveloped) Influenza-Vaccine

A
  • Flu shot-Inactivated vaccine (killed virus)
  • Composed of H1N1, H3N2 + type B
  • Nasal spray vaccine:
  • Live attenuated=Reconstructed from mutant strain & virulent strain (weak)=Reassortment
  • Mutant strains does NOT grow well above 25C=Cold adapted mutant
  • Will grow in upper BUT not Lower resp making it less virulent