Lecutre 18

Question 1

What are common sites of respiratory virus infection?

Answer 1

The middle ear and sinuses of the head

Question 2

What size of bacteria that are deposited in upper and lower airways?

Answer 2

1-5 micrometer. Viruses in coughed secretions will be deposited in high concentrations in the upper airways but can also reach the lower airways.

To cause disease they must attach, enter cells and replicate.

Question 3

What does influenza attach to?

Answer 3

Sialic acid

Question 4

What does Respiratory Syncytial virus attach to?

Answer 4

Heparin-like glycosaminoglycan

Question 5

What does Rhinoviruses attach to?

Answer 5

Intercellular adhesion molecule 1

Question 6

How does Respiratory Virus pathogensis

Answer 6

Attach to and enter respiratory epithelial cells

Replicate inside cells

Death of infected cells

due to viral replication and release

and/or immune responses

Impaired function of respiratory tract

Death or recovery

Question 7

What are the consequences of manifestations of respiratory tract virus infections?

Answer 7

Result from damage to epithelium:
* narrowed airways due to swollen tissues
* obstructed airways due to loss of cilia,
viscous mucous, shed cells
Result from inflammation:
* fever, achiness, malaise, anorexia

Question 8

What are the consequences of manifestations of respiratory tract virus infections in young and old people?

Answer 8

Generally more severe:
in very young infants narrow airways before illness
and very old people damaged airways before illness

May include bacterial infection of affected tissues

Question 9

Most frequently managed problems

in NZ general practice

Answer 9

URTI 5.5%
Acute bronchitis 5.4%
Otitis media 4.9%
Tonsillitis 3.9%

Question 10

What bacteria are the Common causes of respiratory infections?

Answer 10

Streptococcus pneumonia

Haemophilus influenzae

Moraxella catarrhalis

Streptococcus pyogenes

Question 11

What viruses are the Common causes of respiratory infections?

Answer 11

Rhinoviruses
Coronaviruses
RSV
Influenza virus

Question 12

Which infections are almost always due to viruses?

Answer 12

Colds
Bronchitis
Pharyngitis
Influenza
 most respiratory infections don’t need an antibiotic

Question 13

Influenza A structure?

Answer 13

HA (1-16)
NA (1-9) = surface proteins

Segmented genome = 8 RNA molecules

Question 14

Describe the drift in influenza viruses

Answer 14

gradual accumulation

of mutations in genes with minor changes in HA and NA

Question 15

Describe the shift in influenza viruses

Answer 15

abrupt reassortment of
genes between two strains with major changes in HA
and NA

Question 16

What happens during influenza infections and what would you do?

Answer 16

Illness lasting 5-6 days

3-4 days in bed, off work

Morbidity, and mortality, esp in young and elderly

Episodes of illness approx every 7 years

Question 17

What symptoms do you see during influenza?

Answer 17

Abrupt onset

Fever, chills, headaches, myalgia, malaise

Dry cough, pharyngeal pain, nasal discharge

Recovery with immunity

Question 18

How do you diagnose influenza diagnosis?

Answer 18

Clinical presentation

Virus isolation on cell cultures

Detection of influenza antigens

PCR of influenza RNA

Serology

Question 19

When and what happens when antibodies work?

Answer 19

Antibodies to surface proteins:

appear at 10-14 days post infection

enhanced if previous infection with similar strain

persist lifelong

protect against recurrent infection with same strain

Question 20

What injections would you give for influenza?

Answer 20

Modestly effective treatment

Oseltamivir = “Tamiflu”

Moderately effective vaccine

changed annually

to anticipate drift in circulating strains

Question 21

What are Respiratory syncytial virus? Stats?

Answer 21

RNA virus similar to measles and mumps
viruses

In culture adjacent infected cells merge
forming syncytia

60% children infected in 1st year,

100% by 3rd year

Question 22

How does respiratory syncytial virus work?

Answer 22

Causes disease of any part of airway from nose and

middle ear to lungs

Question 23

What disease does RSV cause and what are the consequences?

Answer 23

Bronchiolitis is the most common severe illness
(also known as “croup”)

affects children aged <3 years
wheezing and breathlessness for a couple of days

no vaccine and no antiviral treatment

Question 24

How do you treat bronchiolitis?

Answer 24

Chest X ray of 
an infant with 
“croup” due to 
RSV 
bronchiolitis .

The arrows 
show 
inflammation 
of the 
bronchioloes

some benefit from corticosteroid therapy

Question 25

What are rhinoviruses derived from?

Answer 25

picoviruses - tiny

Question 26

What are rhinoviruses?

Answer 26

Very small RNA viruses

99 serotypes

Replicates in cells at
33-350C (nose not lungs)

Nasal and 
maxillary 
sinus disease 
in adults 
with cold

Question 27

How are Rhinoviruses transmitted, incubated, where, symptoms and recovery?

Answer 27

Transmitted by respiratory droplets and
contaminated surfaces

Incubation period 1-4 days

Infection of nose and sinuses

Nasal mucous, sneezing, cough, sore throat

Minor fever, muscle aches etc

Recovery in 1-2 weeks

Question 28

What are the treatments for Rhinoviruses?

Answer 28

Recovery with long-lasting immunity to that
serotype.

Symptomatic treatment

No effective antiviral treatment

No effective vaccine