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25 Cards in this Set

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