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Flashcards in Lecutre 18 Deck (28)
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1

What are common sites of respiratory virus infection?

The middle ear and sinuses of the head

2

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

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.

3

What does influenza attach to?

Sialic acid

4

What does Respiratory Syncytial virus attach to?

Heparin-like glycosaminoglycan

5

What does Rhinoviruses attach to?

Intercellular adhesion molecule 1

6

How does Respiratory Virus pathogensis

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

7

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

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

8

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

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

9

Most frequently managed problems
in NZ general practice

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

10

What bacteria are the Common causes of respiratory infections?

Streptococcus pneumonia

Haemophilus influenzae

Moraxella catarrhalis

Streptococcus pyogenes

11

What viruses are the Common causes of respiratory infections?

Rhinoviruses
Coronaviruses
RSV
Influenza virus

12

Which infections are almost always due to viruses?

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

13

Influenza A structure?

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

Segmented genome = 8 RNA molecules

14

Describe the drift in influenza viruses

gradual accumulation
of mutations in genes with minor changes in HA and NA

15

Describe the shift in influenza viruses

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

16

What happens during influenza infections and what would you do?

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

17

What symptoms do you see during influenza?

Abrupt onset

Fever, chills, headaches, myalgia, malaise

Dry cough, pharyngeal pain, nasal discharge

Recovery with immunity

18

How do you diagnose influenza diagnosis?

Clinical presentation

Virus isolation on cell cultures

Detection of influenza antigens

PCR of influenza RNA

Serology

19

When and what happens when antibodies work?

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

20

What injections would you give for influenza?

Modestly effective treatment

Oseltamivir = “Tamiflu”

Moderately effective vaccine

changed annually

to anticipate drift in circulating strains

21

What are Respiratory syncytial virus? Stats?

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

22

How does respiratory syncytial virus work?

Causes disease of any part of airway from nose and
middle ear to lungs

23

What disease does RSV cause and what are the consequences?

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

24

How do you treat bronchiolitis?

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

The arrows
show
inflammation
of the
bronchioloes

some benefit from corticosteroid therapy

25

What are rhinoviruses derived from?

picoviruses - tiny

26

What are rhinoviruses?

Very small RNA viruses

99 serotypes

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

Nasal and
maxillary
sinus disease
in adults
with cold

27

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

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

28

What are the treatments for Rhinoviruses?

Recovery with long-lasting immunity to that
serotype.

Symptomatic treatment

No effective antiviral treatment

No effective vaccine