Respiratory Viral Infections Flashcards
1
Q
Which subtype of influenza virus is most common?
A
A, then B, then C (rare)
2
Q
Antivirals used for which respiratory viruses?
A
Influenza and RSV
3
Q
What causes congestion, rhinorrhea, and mucus production w/ colds?
A
Histamine / bradykinin
4
Q
Influenza Incubation period Sxs How long do sxs last? Pneumonia 3 main causes of secondary bacterial pneumonia Who should not get FluMist? Efficacy of vaccine 2 antivirals
A
- 1-2 day incubation period
- Specific combo of fever (up to 104), malaise, muscle aches, and cough are only seen w/ influenza
- Others: headache, dry cough, sore throat, congestion. Rhinorrhea and GI sxs are NOT common (though high fever may cause vomiting).
- Systemic sxs last 3-5 days. Respiratory sxs may last 3-4 days longer. Recovery of lung function may take weeks. May exacerbate asthma or COPD.
- Pneumonia – Interstitial pattern (not lobar). Those at risk include kids, elderly, COPD, asthma, heart disease, and pregnant women. H1N1 caused pneumonia in teens and young adults.
- Secondary bacterial pneumonia – 3 main causes are S pneumoniae, S aureus, and H influenzae. Bacterial proteases may enhance cleavage / activation of viral hemagglutinin
- FluMist (live attenuated), not to be used for kids less than 5, adults older than 50, or pregnant woman in home.
- Antivirals - Amantidine / Rimantidine bind to M2 ion channel blocking acidification and thus uncoating. Rarely used anymore due to resistance. Only work on Influenza A.
- Tamiflu (Oseltamivir) / Relenza (Zanamivir) inhibits neuraminidase, blocking release of virus from cells. Treats both influenza A and B. Oral. May be used prophylactically, such as in nursing homes.
- Antipyretics are helpful (NOT aspirin in kids due to Rye Syndrome)
5
Q
3 viruses that cause influenza-like illness
A
Influenza, parainfluenza, and adenovirus
6
Q
Respiratory Syncytial Virus Population Season Sxs Complications Diagnosis Treatment (4)
A
- Mainly infects kids 6 months - 1 year old. Infection twice as common in boys. Also a problem in pxs > 65 y/o, COPD, and asthma
- Peaks in winter.
- Starts by looking like common cold but then progresses to LRT: Nasal congestion, sore throat, fever (lower than flu), cough, followed by dyspnea and wheezing. May cause bronchiolitis, pneumonitis, and bronchitis.
- Complications - viral otitis media / sinusitis. Can also lead to secondary bacterial otitis media / sinusitis / pneumonia.
- CXR: interstitial infiltrations and hyperinflation.
- Rare to culture but may be detected w/ immunofluorescence.
- Tx w/ supportive therapy, O2, ventilator, possibly albuterol.
- Ribavirin (antiviral) used for hospitalized infants. Aerosolized nucleoside analog. Not used much anymore. Super expensive.
- RSV immune globulin used for premature infants
- Palivizumab – monoclonal Ab against F (fusion) protein used for prophylaxis in high risk kids (premature, lung disease, congenital heart disease), but SUPER expensive.
7
Q
Parainfluenza Virus Season How common? Sxs Serotypes Treatment
A
- Peaks in spring and fall.
- 2nd leading cause of LRT infections behind RSV
- Starts as a “cold”, sometimes w/ bronchitis and low grade fever.
- 4 serotypes. Type 1 / 2 cause more severe disease in boys. Type 3 has no gender diff.
- Type 1 / 3 can progress to CROUP (distinctive wheezing cough)
- Type 3 can progress to pneumonia or bronchiolitis
- Type 4 rarely causes severe illness
- Supportive care, hospitalization for severe croup.
8
Q
Coronavirus
Season
Sxs
A
- Peaks in winter and spring.
- Common sxs are “common cold” w/ headache, sore throat, cough, malaise, and sometimes low fever. Runny nose is less common than rhinovirus.
- CoV also causes gastroenteritis so diarrhea may be present.
- May exacerbate asthma / COPD.
9
Q
SARS CoV Stands for? Sxs Pathology Death rate
A
- Severe Acute Respiratory Syndrome
- Starts w/ 2-7 days of mild URT sxs. Progresses to fever, rigors, dry cough, dyspnea, malaise, headache, and influenza-like illness. Some pxs have diarrhea.
- Diffuse alveolar damage, desquamation, hyaline membranes, alveolar edema, inflammation, syncytia formation, thickened alveolar walls.
- Severe inflammatory response w/ fluid buildup in lungs = ARDS
- 10% death rate.
10
Q
MERS CoV
Transmission
Who is at high risk?
Death rate
A
- Transmitted from bats → camels → humans via camel respiratory secretions. May also be in unpasteurized camel milk.
- Does not spread efficiently from person to person, requiring prolonged close contact, meaning healthcare workers and family is at risk.
- Higher death rate than SARS (30%)
11
Q
Rhinovirus How common? Season Environment Sxs Secondary complication Treatment
A
- Most common viral infection.
- Peaks in spring and fall.
- Very common in schools / day care.
- Sneezing, runny nose, sore throat, cough, nasal congestion, headache, little / no fever, myalgia, or malaise.
- May exacerbate asthma and bronchitis by triggering eosinophil infiltration into lungs. Commonly prescribe a rescue inhaler.
- Bacterial otitis media / sinusitis commonly follow. Caused by pneumococcus, S aureus, and H flu
- Tx sxs w/ OTC antihistamines and decongestants. Zinc shows some evidence of helping. Vit C and Echinacea do not show efficacy.
- Picornaviruses replicate by making huge polyprotein, which is then cut up by a metalloprotease, so if we swap normal metal ion w/ zinc, protease doesn’t work.
12
Q
Adenovirus Site of latency Tropism Spread Environment Sxs by age Sxs in immunocompromised pxs Treatment Vaccine
A
- Latent in adenoids and tonsils.
- Tissue specific serotypes exist for GI (gastroenteritis), ocular (keratoconjunctivitis), and respiratory infections.
- Even though respiratory serotypes don’t cause GI problems, they may be shed in the stool.
- Present throughout the year but causes outbreaks in institutions, such as military boot camp.
- Infants get cough and sore throat
- Children get sore throat and tracheitis
- Young adults get more severe cough, fever, sore throat, and runny nose
- Adults get a “cold”
- Immunocompromised pxs may progress to pneumonia w/ dessemination, cystitis, and CNS infection.
- Tx sxs.
- Vaccine used for military. Swallow vaccine in capsule. Normal adenovirus (not attenuated).
13
Q
Human Metapneumovirus (hMPHV) Population Season Sxs Co-infection
A
- Most common in kids
- Peaks in winter
- Presents w/ runny nose, cough, and fever in kids. “Common cold” in adults. Acute otitis media may be present.
- Co-infection w/ pneumococcus is very common. High risk people should get pneumo vaccine. Viral infection facilitates adhesion of pneumo to respiratory epithelium.
14
Q
Human Bocavirus
Season
Sxs
Duration
A
- Peaks in winter. Almost 100% of kids are seropositive by age 6.
- URT or LRT. Usually not fatal.
- May persist in respiratory tract for long periods after sxs have stopped.
15
Q
Enterovirus
Season
Sxs
Complication
A
- Respiratory disease peaks in late summer / early fall.
- Causes undifferentiated febrile illness or “summer grippe” w/ sxs similar to colds: sore throat, cough, fever.
- Most significant complication is acute myocarditis, which can be exacerbated by exercise.
