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56 Cards in this Set
- Front
- Back
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Name the RNA viruses that cause respiratory infections.
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Orthomyxo
Paramyxo Picorna Corona Reo |
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Name the DNA viruses that cause respiratory infections.
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Adeno
Herpes |
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Describe respiratory syncytial virus.
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Paramyxovirus family
-ssRNA subtypes A&B Enveloped |
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What are the antigenic glycoproteins found in the RSV envelope?
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G glycoprotein (attachment)
F fusion protein (syncytium formation) |
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When does RSV most often occur?
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midwinter to early spring
global occurrence |
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At what age does primary infection occur?
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Primary infection occurs in virtually all children by 2 years of age.
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What is the pathophysiology of RSV infection?
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1. Tropism for ciliated respiratory epithelium
2. Necrosis of epithelium with destruction of cilia 3. Obstruction of small airways |
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Describe some of the clinical manifestations of RSV infection.
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Upper respiratory infection
Poor feeding, lethargy, apnea in neonoates and premature infants Usu. minimal fever |
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What is the preferred specimen for diagnosis?
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Nasopharyngeal washing for Rapid Diagnostic test (DFA, ELISA)
- can isolate virus in culture and look for syncytium formation |
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How do you treat RSV?
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AB therapy not indicated - treat symptoms
In complicated infections = ribavirin |
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What preventative therapy options are available for RSV?
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Vaccine not commercially available.
Passive immunity via RSV hyperimmune Ig or RSV mAb --> for high risk individuals during peak season |
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What are the characteristics of influenza virus?
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Orthomyxo family
pleomorphic, segmented -ssRNA enveloped surface proteins have biologic and antigenic properites 3 antigenc types: A,B, & C |
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What is special about the influenza surface proteins?
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Variation in the neuraminidase and hemagglutin results in antigenic drifts and shifts
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What is antigenic drift?
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Minor changes in the NA and hemagglutin without changing the subtype
--> type A & B |
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What is antigenic shift?
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Major changes in NA and hemagglutin that result in change in subtype
--> causes epidemic, only in type A |
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When is flu season?
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midwinter
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Pathophysiology of Influenza.
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1. Infects ciliated respiratory epithelium
2. Necrosis of nasal and tracheal ciliated epithelium 3. Bacterial superinfection |
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What are clinical symptoms of influenza infection?
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Begin 1-4 days p.i.
chills, non-prod cough, headache, sore throat, malaise, congestion, vomiting, diarrhea, myalgia, dizzy, eye irritation, fever |
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What are some complications of influenza infection?
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Bacterial superinfection
myositis with type B Reye's syndrome neurologic (G-B syndrome) Cardiac |
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How is diagnosis made?
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Presumptive based on season and clinical manifestations
Definitive using culture, serology or immunofluorescense |
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What is treatment for influenza?
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Amantadine, ramantidine for influenza A only. Must be administered within 48 hr of infection. --> prevent uncoating
Zauamivir (relenza), Oseltamivir (tamiflu) = influenza A&B --> neuraminidase inhibitors |
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How can influenza infection be prevented?
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Chemoprophylaxis with rimantidine, amantidine
Vaccination: inactivated and live, attenuated *inactivated assoc with Bell's palsy due to adjuvant |
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Why can influenza cause pandemics?
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The genome is segmented so allows for reassortment and major antigenic shifts.
Antigenic shifts occur approx every 10 years |
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What are the characteristics of parainfluenza virus?
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Paramyxo family
-ssRNA non-segmented, enveloped Four types: 1, 2, 3, 4 antigenically stable - NA, hemagglutin and fusion proteins |
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When do types 1 and 2 occur?
type 3? |
1&2 occur in late summer/early fall
3 occurs in spring/early summer |
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How is parainfluenza virus spread?
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Person-person by direct contact with secretions, aerosolization, fomites
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what are the clinical presentations of parainfluenza?
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URI
laryngotracheobronchitis - "Croup" Bronchiolitis & pneumonia |
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How is diagnosis of parainfluenza made?
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Presumptive based on season and clinical presentation
Definitive with rapid diagnostic tests |
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How is parainfluenza treated?
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AB only if bacterial superinfection
Antiviral = ribavirin effective in vitro but has not been put to clinical trial Croup = humidified air, epinephrine or corticosteroids |
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What is the age-related incidence of parainfluenza?
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Type 3 occurs earlier in life than types 1&2.
Type 1&2 infection occurs between ages 2 - 6. (Type 2 is less severe) |
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How is parainfluenza prevented?
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WASH HANDS!
Vaccine not commercially available. |
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What are the characteristics of rhinovirus?
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"common cold"
picorna family = small RNA CPE = acid lability and grows @ 33 non-enveloped +ssRNA over 100 serotypes |
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When does rhinovirus occur?
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spring to early fall - summer colds
--> 30-50% of acute resp illness |
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Who has the highest incidence of rhinovirus infection?
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Young children
50% spread among families; 100% spread in day cares |
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How is rhinovirus spread?
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person-person; aerosolization
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What is the pathophysiology of rhinovirus?
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incubate up to 7 days
replication peak at 2-3 days **may shed virus up to 1 month p.i. IgA appear @ 1 week in nasal secretions Serum Ab @ 1 week and peak @ 1 month |
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What are the clinical manifestations of rhinovirus infection?
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infants: fever with Upper resp symptoms
children, adults: afebrile URI |
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What are complications of rhinovirus?
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exacerbation of asthma
otitis media sinusitis |
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how is diagnosis made?
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Presumptive based on clinical presentation and season --> mainly differentiate from bacterial infection
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How is rhinovirus infection treated?
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Treat symptoms = decongestant
No specific antiviral therapy, IFN may be promising |
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How is common cold prevented?
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WASH HANDS.
No vaccine Lack of envelope makes it resistant to common disinfectants! |
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What are the characteristics of coronavirus?
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Large, +ssRNA
enveloped - distinct spikes = peplomers give solar corona appearance 2 strains in human disease: 229E and OC43 |
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What is the peak incidence of coronavirus?
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Distinct winter peak in US
--> no peak seen in Europe |
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What are clinical manifestations of coronavirus infection?
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URI and LRI
- pneumonia in infants GI tract - nonbloody diarrhea in infants Cofactors for neurolgic disease? |
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How is diagnosis made?
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Presumptive based on clinical syndrome
-tissue culture and serology not helpful |
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How do you treat coronavirus?
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treat symptoms.
no specific antiviral IFN is effective |
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How can coronavirus be prevented?
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WASH HANDS
no vaccine available |
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What is SARS?
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A coronavirus. spread by droplet nuclei. high fever, diarrhea, head/body aches. treat with IFN
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What are the characteristics of Adenovirus?
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Large, NAKED dsDNA virus
Over 100 serotypes - 47 infect humans Grow well in tissue culture (except enteric serotypes 40, 41) |
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What is the incidence of adenovirus?
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5-8% of resp illnes
Infection occurs 6 mo - 5 yo Year round |
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How is adenovirus transmitted?
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Direct or indirect contact with secretions
Fecal-oral route |
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What is the pathophysiology of adenovirus infection?
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Replicates in resp or GI epithelium
Necrosis of epithelium Viremia Pulmonary = intranuclear inclusion bodies |
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What are some other syndromes associated with adenovirus?
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GI, GU, Ocular, CNA, Cardiac
--> can cause meningitis |
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How is adenovirus diagnosed?
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tissue or cell culture, EM, ELISA, DNA hybridization, DFA, serology
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How can adenovirus infection be treated?
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no specific antiviral
high dose Ig has been used in immunocompromised |
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How can adenovirus be prevented?
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No commercial vaccine
Infection control |
