Viral Pneumonia Flashcards
Influenza
• Stucture
• Transmission
• Replication Cycle
• Disease Presentation
• Pathogenic Mechanism
• Epidemiology
• Treatment
• Mortality
• Key findings/Diagnosis
Stucture (orthomyxovirus)
Helical enveloped single stranded negative-sense linear RNA virus consisting of 8 segments
Transmission
Airborne respiratory droplets
Replication Cycle
See pathogenic Mechanism
Disease Presentation
After a 24-48 hour incubation period, High fever, myalgias, sore throat, and dry cough may set in. N/V typically only seen in kids.
Pathogenic Mechanism
1Neuraminidase degrades protective mucus layer and virus gains access to cells. 2Hemaglutinin binds to cell surface receptors and promotes viral entry. The 3M2 ion channel then acidifies the phagolysosome to allow the virus to enter the cytoplasm. Neurminadase cleaves neuraminic acid to allow the virus to exit the cell. Necrosis of superficial layers of epithelium causes cytokine release leading to the characteristic myalgias.
Epidemiology
2 type: type A infects both animals and people, REASSORTMENT of genes leads to ANTIGENIC SHIFT and PANDEMICS. Type B only infects humans and can be serious.
Pregant women, morbidly obese, Nursing home residents, Native americans and Alaskan Natives are at the greatest risk.
Treatment
- *Prophylaxis and Tx: Oseltamivir or Zanamivir** (Neuraminidase inhibitors) or Amantidine/Rimantidine (rarely used)
- *Vaccinate every 6 months if 6 mo. or older.**
Mortality
0.1% of infected people die (mortality highest in children and elderly)
Key findings/Diagnosis
Dx: Clinical, RT-PCR, Rapid Viral Antigen, Direct fluorescent Ab., culture
Respiratory Syctial Virus (RSV)
• Stucture
• Transmission
• Replication Cycle
• Disease Presentation
• Pathogenic Mechanism
• Epidemiology
• Treatment
• Mortality
• Key findings/Diagnosis
Stucture
Paramyxovirus - pleomorphic, enveloped, negative-sense, single-stranded, linear RNA
Transmission
Respiratory Droplets, Direct contact
Replication Cycle
See pathogenesis
Disease Presentation
Children present with persistent cough, wheezing, fever, tachypnea, and HYPOXEMIA (low O2 sat.). Adults typicallly present with a URT infection that resolves after 4 or 5 days.
Pathogenic Mechanism
Surface spikes are proteins that cause the respiratory epithelia to fuse to form multinucleated giant cells (syncytia). Also has F (fusion) protein on its surface.
Epidemiology
Most important cause of bronciolitis and pneumonia in infants.Outbreaks typically occur in the winter. Infants bornBEFORE 35 wksare at increased risk. Additionallyless than 6 months and in daycare are at high risk and so are the Elderly.
Treatment
- *Prophylaxis** to Premature Infants: Palvizumab (mAb against F protein)
- *Ribaviron** really only used in stem cell patients
Mortality
Low 2%, those at risk are preemies under 12 wks and those with underlying disorders
Key findings/Diagnosis
Dx: RT-PCR or Rapid Antigen Test on nasal swab or
Adenovirus
• Stucture
• Transmission
• Replication Cycle
• Disease Presentation
• Pathogenic Mechanism
• Epidemiology
• Treatment
• Mortality
• Key findings/Diagnosis
Stucture
Adenovirus family, Non-enveloped, double-stranded, linear DNA virus
Transmission
Aerosol droplet, fecal-oral, direct inoculation
Replication Cycle
Not stated
Disease Presentation
Pneumonia is typically more severe in infants and may present with diarrhea and vomitting. Other diseases caused by this pathogen are URTIs, Febrile Pharyngitis, Conjuctivitis, Hemorrhagic cystitis, Gastroenterititis (under 2 yrs), and Disseminated infections in the immunocompromised.
Pathogenic Mechanism
Non-stated
Epidemiology
affects children mostly and people in the ARMY
Treatment
Supportive only
Live oral enteric-coated vaccines directed against serotypes 4 and 7 have been used for years in military recruits.
Mortality
Not stated, BUT COMPLICATIONS are Bronchiectasis and Bronchiolitis Obliterans (life-threating fibrosis and occlusion of bronchioles)
Key findings/Diagnosis
GI distress accompanied by Pneumonia
Dx: Clinical
Parainfluenza
• Stucture
• Transmission
• Replication Cycle
• Disease Presentation
• Pathogenic Mechanism
• Epidemiology
• Treatment
• Mortality
• Key findings/Diagnosis
Stucture
Paramyxoviridae: Enveloped single stranded linear nonsegmented RNA virus
Transmission
Respiratory Droplets
Replication Cycle
not stated
Disease Presentation
4 types:
Croup: hPIV 1, 2, 3 (only 2-3% of the time) - patients with croup present with a SEAL-LIKE barking cough. Stridor may also be heard when breathing. Patients will also have rhinorrhea and sore throat.
- *Pneumonia and bronchiolitis: hPIV3**
- *Mild respiratory illness: hPIV4**
Pathogenic Mechanism
Neuraminadase is used to breakdown mucous so that Hemagglutinin can bind to mucous membrane of the throat THEN they invade to the larynx and upper trachea. However, Parainfluenzae also has Protein F fusion protein.
Epidemiology
None stated, Reinfection is common
Treatment
Supportive only
Mortality
Poor outcomes are unusual
Key findings/Diagnosis
- *Seal-like barking cough and stridor**
- *CXR: STEEPLE SIGN**
- *Dx: Clinical**
Human metapneumovirus
• Stucture
• Transmission
• Replication Cycle
• Disease Presentation
• Pathogenic Mechanism
• Epidemiology
• Treatment
• Mortality
• Key findings/Diagnosis
Stucture
Family = Paramyoxviridae; enveloped single stranded RNA virus
Transmission
Respiratory Droplets
Replication Cycle
Probably has neuraminadase, hemaggluttinin. Has suface protein F, like all parainfluenza viruses
Disease Presentation
causes Upper respiratory tract infections in adults an Lower Respiratory tract infections in infants. Clinically is indistinguishable from RSV
Pathogenic Mechanism
Not stated
Epidemiology
Often the cause of flu-like symptoms when its not flu season (spring, summer)
Treatment
Not stated
Mortality
Not stated
Key findings/Diagnosis
Not stated
MERS
• Stucture
• Transmission
• Replication Cycle
• Disease Presentation
• Pathogenic Mechanism
• Epidemiology
• Treatment
• Mortality
• Key findings/Diagnosis
Stucture
Family = Coronavirus; enveloped single stranded positive-sence RNA virus
Transmission
Animal origin with human-human transmission
Replication Cycle
Not stated
Disease Presentation
Patients are severely ill with flu-like symptoms plus hemoptysis, PNA and ARDS and some had acute kidney injury along with Nausea, Vomitting, Diarrhea.
Pathogenic Mechanism
Spike (S) protein (different from spikes on RSV) are found on the coronavirus
Epidemiology
Middle East, Europe, Southeast Asia
Treatment
none stated
Mortality
HIGH mortality
Key findings/Diagnosis
Someone with flu-like symptoms + GI disturbance and ARDS who has recently traveled
SARS
• Stucture
• Transmission
• Replication Cycle
• Disease Presentation
• Pathogenic Mechanism
• Epidemiology
• Treatment
• Mortality
• Key findings/Diagnosis
Stucture
Family = coronavirus - enveloped single stranded positive-sense RNA virus
Transmission
May be held in reservoirs like the masked palm civet or horshoe bat.
Replication Cycle
Not stated
Disease Presentation
Patient will present with flu-like symptoms (probably no myalgia) an may be hypoxic. Notably they will experience a Leukopenia and thrombocytopenia.
Pathogenic Mechanism
Genetically very distinct from other corona viruses therefore immunity is low. Spike (S) protein (different from spikes on RSV) are found on the coronavirus
Epidemiology
2002-2003 China, Hong Kong, Vientnam, Singapore, Toronto
Treatment
Mortality
9% mortality rate
Key findings/Diagnosis
CXR: may have normal or diffuse interstitial infiltrates. Bilateral infiltrates common in teh middle or lower lung. May mimic acute respiratory distress syndrome.
