Respiratory Viral infections Dr. Roane Flashcards
What typically causes the common cold and bronchiolitis?
-rhinovirus typically causes the common
cold
-respiratory syncytial virus (RSV) causes bronchiolitis
Characteristics of the common cold
-acute, usually afebrile (no fever), self-limited
-upper respiratory symptoms: rhinorrhea, cough, and sore throat
-Treatment is supportive
Viruses causing the common cold
50% of all common cold cases are caused by the >100 serotypes of rhinoviruses
-Coronaviruses
-Influenza
-parainfluenza viruses
-enteroviruses
-adenoviruses
-respiratory syncytial viruses (RSV)
-metapneumovirus
-> may manifest as the common cold
Bronchiolitis
-acute viral infection of the lower respiratory tract (bronchioles - smallest branch)
-affecting infants <24 months
-respiratory distress (fluid leak into the lungs), wheezing, and/or crackles
-tolerated well, but can be dangerous
What causes Bronchiolitis?
-respiratory syncytial virus (RSV), can be identified with a rapid assay (diagnosis is often suspected during an outbreak)
-treated supportive with oxygen and hydration
What causes Croup?
-caused by parainfluenza virus type 1 infection
Characteristics of Croup
-acute inflammation of the upper and lower respiratory tracts
-Brassy, barking cough and inspiratory stridor (noisy breathing)
Treatment of Croup
antipyretics (reverse fever mediated increased body temperature)
-hydration
-nebulized racemic epinephrine
-corticosteroids
How is Pneumonia diagnosed?
X-ray
Clinical findings (patient presentation)
What are the factors determining the type of Pneumonia?
-bacterial, mycobacterial, viral, fungal, or parasitic
-where acquired? community (CAP), hospital (HAP), ventilation (VAP)
-is the patient immunocompromised?
-differ in Causes, symptoms, treatment, preventive measures, and prognosis
What is the leading infectious cause of death?
-Pneumonia with Influenza
-9th leading cause of death
-leading in infectious cause of death
-most fatal hospital-acquired infection
What is the most common pathogen that causes Pneumonia?
Streptococcus pneumoniae
(pathogens of every sort, from viruses to parasites, can cause pneumonia)
Community-acquired pathogens (CAP)
-Bacterial: Streptococcus pneumoniae, Haemophilus influenza, Moraxella catarrhalis
-atypical bacteria: (ie, Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella species)
-viruses: Coronavirus, RSV, Influenza, Adenovirus, metapneumovirus, parainfluenza
What are the most common hospital-acquired pathogens?
-gram-negative bacilli and Staphylococcus aureus
-considered hospital-acquired when developed at least 48 hours after hospital admission
What are the most common ventilator-acquired pathogens?
-gram-negative bacilli and Staphylococcus aureus
-MRSA, MSSA, Pseudomonas
-considered VAP after being intubated for more than 48 hours
What are the different types (species) of Influenza?
-Influenza A-D
-Influenza A is the common flu
How are the subtypes of Influenza A identified?
-Hemaglutinin (Hx) and Neuraminidase (Nx) on the surface of the virus
What is the Antigenic Shift seen in Influenza A?
-2 strains (f.e. pig and bird) of influenza A can mix their genome to create a new virus with different surface proteins
-> the new virus can now infect different species
How is Influenza categorized based on Pathogenicity?
Highly Pathogenicity
Low Pathogenicity
Zoonotic Influenza
Influenza viruses are transmitted from animals to humans
What is the Influenza strain with the highest Pathogenicity so far?
Highly Pathogenic Avian Influenza - HPAI
-H5N1 from China 1996 -> Bird flu 2004
Which strain is responsible for the Spanish flu?
-H1N1 (swine)
(Hong-Kong flu -> H3N2)
How does Transmission of Zoonotic Influenza occur?
Direct contact with animals (slaughterhouse, raising)
What are the symptoms of Zoonotic Influenza?
-Fever, headache, chills, dry cough
-fatigue, muscle or joint pain, chills, runny nose
MOA of Amantadine and Rimantadine
-Blocking the M2 protein, a proton pore protein (viroporin)
-Viroporin is needed to release the viral proteins and genome from the virion
MOA of Oseltamivir (Tamiflu) oral, Zanamivir (Relenza) inhaled and Peramivir (Rapivab) I.V.?
-Neuraminidase inhibitor
-neuraminidase is required for the newly formed
Virus to be released from the host cell -> detachment from sialic acid on the host cell
-the virus is stuck and gets degraded
MOA of Baloxavir
-The virus doesn’t have a starting sequence for its translation
-it uses an endonuclease to cut one from the host mRNA -> cap-snatching
-Baloxavir blocks the Endonuclease
MOA of Nirmatrelvir
-the mRNA of the virus is translated in one big protein
-the big protein needs to be cleaved into small pieces -> replication/transcription complex
-cleavage of the big protein is conducted by the viral protease
-Nirmaltrevir blocks the viral protease!
Which drug is used to treat SARS-Cov-19?
Paxlovid
-Ritonavir and Nirmaltrevir
-Ritonavir acts as a booster by deactivating CYP3A4
-Ritonavir is not active against SARS-COVID-2
MOA of Remdesavir
-IV administered nucleotide analog (prodrug) of adenosine triphosphate
-incorporated into the growing RNA chain by the viral RNA-dependent RNA polymerase
-chain termination
MOA of Molnupiravir
-Orally administered nucleotide analog (prodrug) of cytosine triphosphate
-incorporated by the RNA polymerase of SARS-COV-2
-genome error -> the cytosine analog is read as cytosine or uridine -> mutations
Study results of Molnupiravir
-did not lower hospitalization or death
-But patients recover faster
Respiratory Syncytial Virus (RSV)
-Ubiquitous -> Most children have had it by age 4
-severity is reduced due to previous exposure and antibodies
-No drug treatment
-Ribavirin has been used, but ribavirin is dangerous in healthcare providers
Why is Ribavirin dangerous for health care providers?
-Known teratogen
-Has caused testicular abnormalities
-Has 2 black boxes: hemolytic anemia, birth defects
Adenovirus
-can be asymptomatic or
-mild infections of respiratory infections, keratoconjunctivitis, gastroenteritis, cystitis, and primary pneumonia
Symptoms of Adenovirus
-mostly in children
-fever and upper respiratory symptoms:
pharyngitis, otitis media, cough, and exudative tonsillitis with cervical adenopathy
-rare in infants: severe bronchiolitis and pneumonia
Treatment of Adenovirus
Ribavirin and Cidofovir
MOA of Cidofovir and treatment
-used to treat Cytomegalovirus
-MOA: gets incorporated as cidofovir diphosphate into the growing chain -> viral DNA synthesis reduction
Which drugs work by inhibiting Neuramidase?
-Oseltamivir (Tamiflu) oral,
-Zanamivir (Relenza) inhaled and
-Peramivir (Rapivab) I.V.
Which drugs treat SARS-Cov-2?
-Paxlovid (Ritonavir and Nirmatrelvir)
-Remdesavir (adenosine analog) IV
-Molnupiravir (cytosine analog) oral
Which drugs work by incorporating nucleotide analogs?
-Remdesavir (adenosine analog)
-Molnupiravir (cytosine analog)
-Cidofovir (acyclic, incorporated as cidofovir diphosphate)
