Respiratory Viruses Flashcards
What conditions are caused by upper respiratory virus infections?
- Sinusitis
- Common cold
- Pharyngitis
- Epiglottitis
- Laryngotracheitis
What conditions are caused by lower respiratory virus infections?
- Bronchitis
- Bronchiolitis
- Pneumonia
Which respiratory viruses have viremia that targets organs?
Measles virus
Adenovirus
Enteroviruses
Influenza viruses can have ___ subtypes of hemagglutinin (HA) and __ subtypes of neuraminidase (NA)
16; 9
Explain genetic drift
- Influenza virus genes, made of RNA, are more prone to mutations than genes made of DNA
- If the HA gene changes, so can the antigen that it encodes, causing it to change shape
- If the HA antigen changes shape, antibodies that normally would match up to it no longer can, allowing the newly mutated virus to infect the body’s cells
Explain the steps in genetic shift for influenza (using aquatic birds and humans)
- An aquatic bird passes a bird strain of influenza to an intermediate host
- A person passes a human strain of influenza to the same intermediate host (chicken or pig)
- When the viruses infect the same cell, the genes from the bird strain mix with the genes from the human strain to yield a new strain
- The new strain can spread from the intermediate host to humans
Since 2003, what two avian influenza viruses have infected humans?
Why don’t they spread as quickly as other strains of the flu?
H5N1 and H7N9
Theses strains do not transmit easily among people
How does influenza lead to cell damage?
- Virus infects ciliated epithelial cells lining the upper respiratory tract, trachea and bronchi
- Virus replication leads to destruction of respiratory epithelium
- Cell damage also due to virus activated cytotoxic T cells
Why are those with influenza virus predisposed to bacterial superinfection?
Loss of natural barriers and exposure of binding sites on epithelial cells
What secondary infections are the major cause of death in influenza?
Streptococcus pneumoniae
Staphylococcus aureus
Haemophilus influenzae
What are some rare complications of Influenza?
- Myositis and cardiac involvement
- Guillain-Barre syndrome
- Encephalitis
- Reye syndrome
What types of vaccines are use for prevention and control of influenza?
- Formalin inactiavted - mixture of prevalent antigenic types
- Attenuated infectious viruses - intranasal admin.
- Quadrivalent vaccine (2013)
What are some forms of antiviral therapy for influenza?
- Amantadine and remantadine - inhibit uncoating by blocking M2 protein
- Zanamivir (Relenza) and Oseltamivir (Tamiflu) neuraminidase inhibitors (inhibit release of progeny virus)
Rhinovirus is the cause of __% of colds
50
How is rhinovirus transmitted?
How many serotypes have been identified?
- Transmission by respiratory secretions
- directly from individual to individual
- via fomites
- 150 serotypes identified
What vaccines and antivirals exist for Rhinovirus?
none
What virus is most likely responsible for a summer cold with fever, head ache, and fatigue?
Enterovirus
What are four types of enterovirus and what vaccines are available against them?
Poliovirus
Coxsackie A virus
Coxsackie B virus
Echovirus
*no vaccine or antiviral therapy
What type of enterovirus has been confirmed in 628 people since August 2014 and has caused one death?
ED-D68
Coronavirus causes __-__% of common colds
10-15%
Coronavirus diseases are limited to which part of the airway?
upper RT
What are two recently identified coronaviruses that cause respiratory illness?
2002-2003 - SARS outbreak caused by SARS-CoV
2012 - Acute pneumonia and renal failure - MERS-CoV
SARS (Sudden acute respiratory syndrome)
- What is the fatality rate among people with the ilness?
- How is it transmitted?
- What is the source?
- What is the fatality rate among people with the ilness?
- 10%
- How is it transmitted?
- Face-to-face contact, virus in respiratory secretions and feces
- What is the source?
- Bats, and other sanimals sold in markets in China
MERS (Middle East Respiratory Syndrome)
- Species ifnected?
- Illness?
- Transmission?
- Species ifnected?
- bats, camels
- Illness?
- Acute severe pneumonia and renal failure
- Transmission?
- Does not pass from person to person readily
- Non-socomial infections documented
Parainfluenza virus
- When do infections usually occur?
- What lower respiratory complication is prevalent in infants and young children?
- When do infections usually occur?
- Fall and winter
- What lower respiratory complication is prevalent in infants and young children?
- CROUP (subglottal swelling may close airway)
What are the types of Parainfluenza virus and what illnesses are they associated with?
- Type I and Type 2 - common cause of croup
- Type 3 - similar to RSV in that is a common cause of bronchiolitis in infants
- Type 4 - usually mild disease
How might you identify a toddler with croup?
- grumpy
- little appetite
- soar throat
- sound of a barking seal
- flaring of nostrals
- high pitched noise (stridor)
Respiratory syncitial virus is a _____ infection of the respiratory tract
localized (no systemic spread)
How are the following groups treated for RSV?
Healthy infants:
Premature or immunocomrpomised infants:
Premature infants:
Healthy infants: supportive, oxygen, IV fluids, nebulized cold steam
Premature or immunocomrpomised infants: aerosolized ribavirin
Premature infants: Passive immunization with anti-RSV Ig and humanized monoclonal antibodies
*no vaccine currently available
Metapneumovirus
- Clinical spectrum of disease:
- How is it identified?
- Vaccine?
- Clinical spectrum of disease:
- Similar to RSV but generally milder, with most severe disease seen in infants, elderly and immunocompromised
- Identified by RT-PCR
- Vaccine?
- No vaccine or antiviral therapies available
Where do you find Hendra and Nipah virus?
Australia and Asia
What respiratory diseases are associated with Adenovirus
Acute respiratory disease, sometimes serious (pneumonia)
Adenoviruses 1-7 can cause…
Pharyngoconjunctival fever - sudden onset of red eyes, sore throat, fever
Adenovirus
- Spectrum of disease:
- What determines the disease?
- Vaccine?
- Spectrum of disease:
- respiratory infection, conjunctivitis, GI infections
- What determines the disease?
- tissue tropism of specific serotype
- Vaccine?
- no adenovirus vaccine for public, but new attenuated vaccine against adenovirus types 4 and 7 for military recruits
Measles virus
- Symptoms:
- Complications:
Symptoms: cough, conjunctivitis, coryza, photophobia
Complications: otitis media, croup, pneumonia
What is the most common cause of death in young children with measles?
pneumonia
How is adenovirus different from RNA viruses?
It is the DNA virus family
What are the human picornaviruses?
Enterovirus
Parechovirus
Heparnavirus
Rhinovirus
What are the paramyxovaridae (human)
Movillivirus (measles)
Parmyxovirus (parainfluenza)
Pneumovirus (RSV)
Henipavirus (Hendra, Nipah)
