Exam #4: Viral Infections of the Resp. Tract Flashcards Preview

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Flashcards in Exam #4: Viral Infections of the Resp. Tract Deck (44):
1

What are the symptoms of the common cold? What symptoms differentiate a cold from a more serious infection?

- Rhinitis (inflammation of the nasal passages)
- Pharyngitis (sore throat)
- Mild cough

Lack of:
- High fever
- Lower respiratory tract involvement
- Dyspnea

2

What are considered severe respiratory tract infections?

Bronchiolitis
Pneumonia

3

What complications can be associated with the common cold?

- OM
- Sinus Infections
- Exacerbations of asthma (seen in Rhinovirus C in school age children) & COPD in adults

4

What viruses are associated with the common cold?

- Rhinovirus*
- Non-SARS Coronavirus
- Adenovirus
- Coxsackievirus
- Influenza B & C vs. A
- Respiratory Syncytical Virus
- Parainfluenza

5

List the characteristics of the Rhinovirus?

- Picornavirus family member
- Non-enveloped (stable in environment)
- +ssRNA
- Binds ICAM-1 receptor

6

What are the three types of Rhinovirus?

A, B, & C species

Note also that there are over 100 serotypes; thus, the immune system does generate a memory response, but there the response is serotype specific

7

How are Rhinoviruses transmitted?

- Shed in respiratory secretions
- Transmission though direct contact with nasal secretions, large droplets, & contaminated fomites
- Extremely low incolum needed for infection
- Incubation period is 1-3 days

8

Describe the Rhinovirus mechanism of action.

1) Virus attaches to cilia in the respiratory tract via ICAM-1
2) Absorption
3) Replication
4) Replication causes tissue damage & disruption of the epithelial layer= clear fluid out-pouring from the lamina propria
5) Host defenses activated from viral out-poruing & immune system begins to combat the virus
6) Antibody production leads to recovery & epithelium regenerates

9

How is the Rhinovirus treated?

- Antihistamines
- NSAIDs
- Oral Decongestants

Symptomatic treatment only; NO antibiotics

10

Characteristics of the Non-SARS coronavirus.

- Coronavirus (named by "corona" appearance under EM"
- Enveloped
- +ssRNA genome

11

Describe the mechanism of action of the Coronavirus. How is Non-SARS different from SARS?

- Replicate in epithelial cells of respiratory tract
- Optimal temp. for replication is 33-35 degrees C i.e. the cooler upper respiratory tract (vs. SARS that replicate better at body temperature)

12

How is the coronavirus transmitted?

Large droplets

*Infection more common in infants & children

13

What is the difference between the long term immune response to coronavirus & rhinovirus?

- Rhinovirus= long term immune response to species
- Coronavirus= no memory response & reinfection to coronavirus can occur despite circulating antibodies

14

List the characteristics of the Adenovirus.

- Adenovirus
- Non-enveloped
- dsDNA
- Contains adenoviral fiber proteins that are used for attachment & are toxic to cells

Only DNA virus that causes the common cold

15

Which serotypes of Adenovirus most commonly cause infection of the respiratory tract?

1, 2, & 5

vs. 40 & 41 that more frequently cause gastroenteritis

16

How is the adenovirus transmitted?

Oral droplets, inhalation, & conjunctiva

17

How does the pathology of adenovirus differ from rhino & corona?

- May enter lymphoid tissues following acute infection
- Individuals can shed the virus for up to 18 months following infection (asymptomatic)
- No seasonal pattern of disease i.e. patient with cold in the summer is more likely to have adenovirus than Rhinovirus or Coronavirus

18

What are the other illness associated with Adenoviruses?

- Pharyngoconjunctival fever
- Croup, bronchiolitis, & pneumonia
- GI disease

19

Which Adenovirus serotypes are associated with GI disease?

40 & 41

20

To which of the viruses that cause the common cold is a vaccine avaliable?

Adenovirus 4 & 7 (live oral vaccine, given to military recruits)

21

List the characteristics of the Coxsackievirus.

- Enterovirus, a subfamily of picornovirus (like Rhinovirus) that can pass through the GI tract and remain infectious
- Nonenveloped
- +ssRNA
- survive low pH of GI tract
- Replication is fast & occurs in the cytoplasm

22

What is the mode of transmission of the Coxsackivirus?

Fecal to oral transmission

23

What can the Coxsackieirus cause in addition to the common cold?

- Herpangina
- Meningitis or encephalitis (rare)
- Hand-Foot-&-Mouth

24

What is Herpangina?

- Abrupt onset fever
- Small vesicles on soft palate that rupture & from white ulcers
- More commonly a pediatric disease

25

What are the symptoms of Hand-Foot-&-Mouth Disease

- Fever
- Vesicular lesions on soles of hand & feet on oral areas
- More commonly a pediatric disease

26

What is croup? What are the symptoms of croup?

- Acute larygotracheobronchitis ( due to swelling of the subglottic region of the larynx)
- Inspiratory stridor
- "Seal-bark" cough

Note that a prodrome of common cold symptoms precipitates

27

What is a classic radiographic sign of croup of CXR?

"Steeple Sign"

28

What should be included in your differential diagnosis of croup?

- FB airway obstruction
- Bacterial epiglotittis (HiB)

29

How is croup treated? What is the important factor in the diagnostic algorithm?

Does the patient have stridor at rest?

Yes=
1) Oxygen
2) Racemic-Epi
3) Glucocorticoids

No= Humidified Air Hydration

30

What is croup most commonly caused by? Specifically, what serotype of the virus is associated with acute croup?

Parainfluenza Virus
- Type 1 is the most common cause of acute croup
- Type 2 & 3 can also cause croup, but Type 3 is more commonly associated with lower respiratory tract infections

Also, RSV & Measles can cause croup

31

List the characteristics of Parainfluenza.

- Paramyxovirus family
- Helical nucleocapsid
- Envelope contains hemagglutinin & neuraminidase--targets for the immune system to recognize the virus
- -ssRNA
- RNA synthesis occurs in the cytoplasm

32

How is the parainfulenza virus transmitted?

Large droplets & direct contact

33

Describe the Parainfluenza virus mechanism of action.

Infection & replication in the ciliated epithelium of the respiratory tract

34

What are the symptoms of influenza?

- Myalgia
- Headache
- Fever/ shaking chills
- Cough peaking between days 3-5
- Fatigue & malaise

35

How does the flu differ from the common cold?

- Flu generally lasts longer than the common cold
- Increased severity of symptoms
- Pandemic outbreaks

36

What is a pandemic?

An epidemic of infectious disease that has spread through human populations across a large region; for instance multiple continents, or even worldwide.

37

What is the definition of pneumonia?

Inflammation of the lung parenchyma leading to abnormal gas exchange

38

What are the symptoms of pneumonia?

- Fever
- Chills
- Cough
- Pleural chest pain
- Increased respiratory rate
- Wheezes & crackles
- Hypoxia & cyanosis

39

What virus typically causes primary influenza virus pneumonia?

Influenza Type A

40

What are the symptoms of primary influenza virus pneumonia?

1-4 days following flu symptoms:
- Increased cough
- Tachypnea
- Dyspnea
- Acute respiratory distress

High Fatality Rate & typically a progressive decline in patient's status

41

How is primary influenza virus pneumonia diagnosed?

Sputum Gram Stain
- Abundant PMN cells
- Without significant number of bacteria

CXR
- Bilateral, midlung or lower lung infiltration that is more of an interstitial pattern (like atypical pneumonia) rather than a lobular or typical pneumonia

42

What is bacterial influenza-associated pneumonia?

Pneumonia that onsets a week after influenza symptoms

43

What are the symptoms of bacterial influenza-associated pneumonia?

Influenza symptoms that lessen, but are then followed by:
- Increased cough
- Return of fever
- Respiratory distress

"Biphasic"

44

What bacteria are most commonly associated with bacterial influenza-associated pneumonia?

1) S. pneumoniae
2) S. aureus & H. Influenza

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