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50 Cards in this Set
- Front
- Back
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what is another name for common cold?
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acute coryza
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what viruses are assoc with acute coryza?
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picornaviruses (rhinovirus and enterovirus)
coronaviruses influenza parainfluenza resp syncytial viruses |
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why is there such a lg frequency of acute coryza?
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lg number agents
reinfections (many serotypes) |
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clinical charac of acute coryza; tx
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afebrile (no fever)
infected resp tract (sneezing, sore throat, cough) inflamm of all/any airways tx is supportive |
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what are the 2 most common causes of acute coryza?
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rhinovirus
coronavirus |
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how does season factor into the differential for acute coryza?
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summer-> fall: rhinovirus
winter->spring: coronavirus |
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reservoir, transmission, prevention of acute coryza
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reservoir-upper airway kids
spread by dir contact, airborne prevention-handwashing, control aerosol spread, no vaccine |
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what is the breakdown of the Picornaviridae family?
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2 groups within:
1. enterovirus (polio, cocksackie, Hep A...) 2. rhinovirus |
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charac of rhinovirus
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picornaviridae family
non-enveloped icosahedral (survival in environ) +sense RNA replicate in cytoplasm (RNA-dep RNA poly) acid labile resists drying, detergents prefers cooler temps (URT) ~100 serotypes |
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what is the host receptor for rhinoviruses?
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ICAM-1
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transmission of rhinoviruses
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fecal-oral
direct contact inhaled aerosols fomites (non enveloped) |
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incubation and duration of coryza caused by rhinovirus
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incubation: 2 days
lasts 7 days |
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complications of rhinovirus infections
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risk factor for bacterial sinusitis and otitis media
may precipitate asthma |
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diagnosing rhinovirus infections
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isolated in swabs, saliva, aspirates (days before to 1 weeks after)
serology-confirmation and assessment culture and neutralization assay (type specific immunity) |
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tx anc control of rhinovirus infections
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self-limiting
relieve sx handwash, disinfect no vaccine |
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charac coronavirus
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+sense RNA
enveloped pleomorphic (budding) prominent peplomers in EM-> crown only 2 serogroups cause coryza transmission-airborne droplets |
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what other disease does coronavirus cause?
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SARS
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coronavirus infection in acute coryza
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infected ciliated epithelium of URT-> inflammation, diarrhea (may survive in GI)
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why is there a lot of reinfection by coronavirus?
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anitbodies arent protective
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acute rhinosinusitis
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most viral
unilateral face pain -> bacterial hold on antibiotics; sx > 7 days |
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parainfluenza virus syndromes
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common cold
bronchitis croup |
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what is croup
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laryngitis and laryngotracheobronchitis
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laryngitis: s/s
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hoarseness
tickled, sore throat dry cough |
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cause and risk factors for laryngitis
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viral
risk-having resp infection |
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tx of laryngitis
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infant w/ laryngitis assoc with croup: coticosteroid
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croup: s/s
physical exam |
BARKING COUGH
difficulty breathing swollen vocal cords wheezing prolonged inspiration/expiration |
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risk factors and differential (other causes of airway obstruction) for croup
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3 mos to 5 yo
diphtheria, epiglottitis |
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causes of croup
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parainfluenza (80%)
RSV measles adenovirus influenza virus |
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tx croup
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viral: self-limiting; children req supportive care
bacterial: prompt tx (steroids) air vaporizer, acetaminophen |
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serious croup
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fatigue
cyanotic dehydration hospitalization: epinephrine and oral steroids O2 and humidity, intubation, IV fluids |
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what is the primary cause of croup?
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parainfluenza virus
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general charac of croup
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paramyxovirus (genus)
ss neg sense RNA replicates in cytoplasm enveloped, buds off PM |
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what are the peplomers on parainfluenza and what is their fxn?
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F protein: fusion with PM to enter; pH independent
HN: hemagglutinin and neuraminidase; bind host cell receptor |
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reservoir and transmission of parainfluenza virus
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humans
inhalation of aerosol, person person contact inactivation: dryness, acid, detergent |
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infection, presentation with parainfluenza virus
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seal bark
steeple sign on Xray hypoxia, obstruction, inspiratory stridor can spread through bronchial tree from larynx remains local, not systemic |
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who is at risk and why is there reinfection?
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kids 6 mos to 12 yo
only short-term immunity after infection->reinfection; also, serotypes incubatory carriers (asx but shedding before onset of disease |
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diagnosis of parainfluenza in croup: from where is the best specimen taken?
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nasopharyngeal secretions
poor rapid tests (EM, immunoflourescence)-low sensitivity (high FN) virus isolation-culture, hemadsorption on infected cells serology-hemagglutination inhibition (HAI), hemadsorption inhibition test, C' fixation (CFT), |
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what is a hemadsorption test looking for? what abt hemadsorption inhibition test? what is the basis of the test?
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hemadsorption- virus
hemadsorption inhibition- pt Ig basis: RBCs adsorb to virus-infected cells; inhibition relies on pt serum (unknown)and Ig blocking viral proteins in host cell mbr and preventing attachment of RBCs (all washed away) |
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HAI: basis
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hemagglutination inhibition-looking for pt serum Ig (unknown)
need acute and convalescent titers (X4 to det current infection) if sera have Ig that can bind virus (known reagent), virus cant bind RBCs-> button (positive inhibition) no Ig to virus, virus binds RBCs->pale pink, diffuse |
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complement fixation test
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testing for Ig in pt sera
add sera (Ig?) plus known Ag and C'; mix with RBCs plus Ig to RBCs hemolysis of RBCs: no IC formed in first mix (no pt Ig) so RBC IC was lysed by C' no hemolysis: C' consumed in first mix by IC with pt Ig |
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how do you read a HAI dilution plate?
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left(most concentrated)-> right (least)
compare acute with convalescent titers the ability of the pt sera to inhibit agglutination at a more diluted concentration (v. acute)indicates an increase in titer |
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what does it mean if there is no difference b/w HAI in acute and convalescent titers?
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that the pt does not have Ig to the virus (known) used as the reagent; pt's disease is NOT being caused by reagent virus
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is there a vaccine for parainfluenza virus?
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no
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charac of mumps virus
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paramyxoviridae (family)
rubelavirus (genus) ss neg sense RNA enveloped; buds from PM; pH independent ONE antigenic type->good vaccine induces formation of GIANT MULTINUCLEATED CELLS |
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transmission of mumps virus
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inhalation of droplets
person to person contact winter-spring |
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spread of mumps in disease
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replicate in nasopharynx epithelial cells AND regional LN
systemic (viremia) |
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clinical diease in mumps
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parotitis and orchitis (unilateral)
incubatory carriers (contagious) |
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diagnosis of mumps
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clinical presentation
throat swab, culture, virus isolation serology-easiest presence of giant cells AND hemadsorption |
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what distinguishes mumps from respiratory syncitial virus (RSV) diagnostically?
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both form giant cells but only mumps has hemadsorption
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tx and prevention of mumps
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tx sx (analgesics)
LIVE ATTENUATED vaccine MMR -T cell mediated (CD8) to prevent spread of virus w/o an extracellular phase -mucosal immunity |
