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25 Cards in this Set
- Front
- Back
An 18 yo presents with coryza, hoarseness, barking cough and slight fever, forced breathing mostly on inspiration. chest x ray shows upper airway narrowing. What do you suspect? other organism should be considered?
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1) PIV
2) RSV |
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What is seen on PE in someone with PIV?
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fever, tachycardia, tachypnea, coryza, sore throat, hoarse cough that is harsh, brassy and bark like, suprasternal retractions
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What is seen on chest X ray of someone with PIV?
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upper airway narrowing known as steeples sign
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What is a distinguishing feature of PIV infection compared to influenza?
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higher fever with influenza
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How is PIV differentiated from Hib?
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children much sicker, present with drooling and often have impending respiratory failure with Hib
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What are characteristics of PIV?
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it is a paramyxovirus that is enveloped, nonsegmented, negative sense ssRNA. filamentous in appearance
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What are the envelope proteins of PIV?
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hemagglutinin H and fusion protein F
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How many antigenic type of PIV are there?
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4 labeled 1-4
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Can PIV be cultivated/
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yes
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What happens to infected cells with PIV?
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They produce syncytia which can be detected by heme absorption
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What seasons is croup commonly seen in?
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fall and early winter in temperate climates
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How is PIV spread?
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airborne
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After what age does the incidence of PIV decrease?
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6
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What is PIV infection called?
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croup
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PIV infection begins by adherence to epithelial cells in the nasopharynx. what molecules mediate this?
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PIV H protein attaches to neuraminic acid on host cells. F protein then mediates membrane fusion
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What PIV protein is responsible for generating syncytia?
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F protein
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What is responsible for coryza in PIV infection?
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nonspecific interferon response
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What is the main target area of PIV?
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larynx but may extend to trachea and bronchi
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What happens to host epithelium in PIV infection?
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loss of cilia, edema, cell damage and compromised airway flow
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What level in the respiratory tract is particularly narrowed with PIV infection?
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airway at level of cricoid cartilage
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Does PIV cause inspiratory or expiratory stridor. Why?
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inspiratory stridor because airway narrows more in inhalation
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What generates the bark like cough and hoarseness of PIV?
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edema of vocal cords and subglottic larynx
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Is there protective immunity against subsequent PIV infections?
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yes humoral immunity
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What is treatment of PIV?
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nothing specific... may give epinephrine nebulizer and glucocorticoids and humidifier
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stipple sign is associated with what?
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croup (PIV)
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