lecture 26- viral infections of the respiratory tract

Question 1

symptoms of common cold

Answer 1

• virus that gives rhinitis (inflammation of nasal mucosa)
• pharyngitis (sore throat)
• NO high fever, NO lower respiratory tract involvement and NO respiratory distress

Question 2

what seasons do the common cold peak?

Answer 2

fall and spring

Question 3

complications of common cold

Answer 3

otitis media, sinus infections and exacerbated asthma

Question 4

what causes rhinovirus? describe.

Answer 4

• picorna (small rna) virus
• single stranded RNA- NO ENVELOPE
• three species A-C
• 100 different serotypes

Question 5

what’s the incubation period of rhinovirus? how is it transferred?

Answer 5

• 1-3 days incubation period
• extremely low inoculum needed to infect
• spread via nasal and respiratory secretions or tissue (fomites)

Question 6

How does the rhinovirus infect?

Answer 6

• attaches onto cilia of the respiratory epithelium
• virus is absorbed and replicates
• cell damage with cell debris activating immune system
• IS gets rid of virus and epithelium reestablished

Question 7

treatment and prevention of rhinovirus?

Answer 7

• antihistamine and decongestants
• immune response can be long lasting but with 100+serotypes, it’s hard to protect against all
• no vaccine

Question 8

Non-sars coronaviruses

• structure
• replication area
• spread via
• incubation period
• population affected
• treatment and prevention

Answer 8

• also associated with common cold
• ssRNA
• ENVELOPE
• replicate in epithelial cells of upper respiratory tract
• spread via droplets
• incubation 3 days
• infections- mostly in infants and kids (infants and kids like drinking corona-mnemonic)
• treatment is alleviating symptoms and no vaccine is avail

Question 9

Adenovirus
enveloped?
type of DNA/RNA
distinguishing features
most disease causing serotypes
how long after having it, it is transmissible?

Answer 9

• non-enveloped
• dsDNA
• features: has fibers on capsid that help it attach to cells and are toxic to them
• 50 different serotypes
• no seasonal pattern
• mostly effects conjunctiva but also respiratory
• most respiratory disease serotypes are 1,2,5
• 18 months

Question 10

symptoms of adenovirus

Answer 10

• respiratory probs, conjunctiva probs, pharyngitis, fever, croup, pneumonia
• GI associated with serotypes 40-41

Question 11

treatment and prevention for adenovirus

Answer 11

• treatment is alleviation of symptoms

- prevention- virus from a live attenuated vaccine-oral for serotypes 4 and 7- just military

Question 12

coxsackievirus

Answer 12

• subfamily of picornavirus
• nonenveloped
• ssRNA
• replication in cytoplasm
• survive in LOW pH conditions found in GI tract!!!
• transmitted via oral-fecal route
• no vaccine and recovery in a couple wks w/o treatment

Question 13

coxsakie herpangina 
caused by
symptoms
population
can cause

Answer 13

• caused by coxsakie virus
• coxsakie virus
• small vesicles on soft palate, fever
• pop- 1-7 years of age
• can cause meningitis or encephalitis

Question 14

hand foot and mouth disease

Answer 14

caused by coxsakie virus thru fecal oral route
causes fever and vesicular lesions on palms of hands, soles of feet, and on oral areas
most common in kids

Question 15

croup

• symptoms
• incidence
• what’s it confused with?

Answer 15

• usually in kids
• causes laryngeotracheobronchitis -swelling
• symptoms- fever and distinct brassy cough (seal)
• inspiratory stridor (high pitched inhalation
• “steeple sign”- narrowing of air shadow of the trachea
• prodrome- mild cough, pharyngitis, nasal discharge
• incidence: highest in kids less than 6
• risk of hypoxia
• confused with noninfectious causes airway obstruction & bacterial epiglottitis
• caused by parainfluenza virus

Question 16

Treatment of Croup

Answer 16

• depends on if there is stridor at rest
• no- humidified air and hydration
• yes-oxygen, epi and glucocorticoids

Question 17

what viruses cause croup

Answer 17

-parainfluenza virus type 1-3, 1 being the most common cause and 3 also causing lower respiratory tract infections

Question 18

what family is croup parainfluenza virus from?
what does it have that signals the immune system?
DNA/RNA

Answer 18

-paramyxovirus family
-has a helical nucleocapsid and envelop with hemagglutin and neuraminidase
ssRNA

Question 19

what is parainfluenza virus’ incubation period?
how is it transmitted?
pathogenesis and immunity

Answer 19

• 2-10 days
• via respiratory droplets
• pathogenesis is via infection of the ciliated respiratory epithelium
• immunity lasts a short while and reinfection is not that severe

Question 20

how is influenza different from the common cold

Answer 20

it comes with headache, FEVER and cough, shaking chills, myalgia
cough peaks at 3-5 days
weakness 2-6 weeks

Question 21

peak time for influenza?

incubation time?

Answer 21

winter

2 days

Question 22

pneumonia

Answer 22

• BIGGEST complication of influenza
• inflammation of the lung
• abnormal gas exchange
• increased respiratory rate, wheezes and crackles, chills, cough, fever, pleuritic chest pain, hypoxia and cyanosis

Question 23

primary influenza virus pneumonia

Answer 23

-Primary influenza virus pneumonia- viral cause usually by INFLUENZA TYPE A with incidence higher in 40+ pop and kids
-occurs 1-4 days post influenza symptoms
-increased cough, tachypnea, dyspnea, acute respiratory distress
- sputum sample shows NO bacteria and positive for PM cells
Chest XR- bilateral lung infiltration
fatality is 50%

Question 24

two types of pneumonia

Answer 24

primary influenza virus pneumonia and bacterial influenza associated pneumonia

Question 25

bacterial influenza associated pneumonia

Answer 25

• more common than viral pneumonia
• onset usually a week after influenza symptoms
• looks like influenza symptoms that go away and come back with fever and respiratory distress =BI-PHASIC
• gram stain of sputum show-BACTERIAL CAUSE
• ASSOCIATED BACTERIA- s. pneumonia, s.aureus and H. influenza and n. meningitidis