Paramyxoviruses Flashcards
What are the characteristics of all 3 viruses?
- Enveloped, non segmented (no reassortment), and negative RNA
- Tropism restricts entry to respiratory tract cells, thus no systemic infxns
What are the virulence factors?
Fusion protein, G, and HN
What does fusion protein (F) do?
Viral entry/fusion to adjacent cells -> syncytia
What does G do?
Unknown gp where RSV binds; RSV can also bind nuclein
What does HN do?
hMNV + hPIV bind here
What is the mechanism of disease?
Virus infects airway epithelium and upper resp. tract, it then spreads to the lower reps. tract via dendritic cells. This causes sloughing of epithelium, excessive mucin production, and interstitial lung infiltrates
What’s the epidemiology of RSV?
1 cause of lower RT illness/pneumo in kids
What’s the epidemiology of hMPV?
2 cause of lower RT illness in kids
What’s the epidemiology of hPIV?
2 cause of pneumonia in kids. And it’s common in elderly/immunocompromised
What is common among all three viruses transmission?
All transmit person-person via large droplets. Very seasonal (fall/spring); and they have community emergence (not widespread like flu)
What diseases are associated with RSV?
RSV is the #1 cause of bronchiolotis and pneumonia in less than 1 yr old infants. The infection is also common in adults but it known more for children.
Where does RSV infect in the body?
RSV infects nasopharynx, which leads to a LRT. The LRTs can be permanent (chronic lung disease or asthma)
What are the predisposing factors to RSV infxn?
Prematurity, early infxn ( in infants less than 3mo), lung/heart disease, SCID, and low oxygen supply
What is the presentation of RSV?
Begins with URT symptoms -> LRT symptoms in 2 days
How do you make the Dx of RSV?
Culture from URT, ELISA for Antigen, RT-PCR
How do you Tx RSV?
No vaccine. Care is supportive (FiO2, fluids, bronchodilator).
- Palvizumab: Ab for RSV ( decrease viral loads so it’s not as severe)
- Ribavirin: nucleoside analog interferes with viral replication
What disease is caused by hMPV?
Bronchiolitis and +/- pneumonia in infants/elderly
How does hMPV present?
Similar to RSV but also may see myalgia
How do you Dx hMPV?
RT-PCT is best (Serological is bad; most kids are positive by 10yrs)
How do you tx hMPV?
No vaccine; give supportive care
What disease does hPIV cause?
hPIV2 is #2 cause of pneumonia and bronchiolitis in kids.
How does hPIV present?
Croup, hoarseness, and systemic symptoms
What’s the Dx of hPIV?
culture, RT-PCR, ELISA, or high IgG/IgM
What’s the Tx for hPIV?
No vaccine, supportive care
What protein facilitates syncytium formation?
F protein
What do you see on CXR?
Hyperinflated lungs, atelectasis, interstitial disease (not specific)
What are the two most important things to ID these viruses?
- Age of pt (kids)
2. Season (late fall/early spring)
