Viral Infection Of The Upper Respiratory Tract

Question 0

What are the viral causes of the common cold?

Answer 0

Rhinovirus- 30-50%
Coronavirus- 10-15%
Influenza virus- 5-15%
RSV- 5%
Parainfluenza 5%
Adenovirus <5%
Metapneumovirus unknown
Unknown 20-30%

Question 1

What is the impact of viral respiratory infections in the US?

Answer 1

• colds: 62 million, 20 million schools are lost
• flu: 36,000 dead, seasonal influenza hospitalized 200,000 more
• croup: 125,000 children in hospital, nearly all children become infected with RSV by age 2, globally, RSV affects 64 million people and causes 160,000 deaths each year, parainfluenza virus now thought to be the primary cause of croup

Question 2

What are the frequent symptoms of a rhinovirus infection

Answer 2

Most-common cold
Occasional-exacerbation of chronic bronchitis and asthma
Infrequent- pneumonia in children

Question 3

What are the frequent symptoms of a cornavirus infection?

Answer 3

Most- common cold
Occasional- exacerbation of chronic bronchitis and asthma
Infrequent- pneumonia and bronchioles is

Question 4

What are the frequent symptoms of human respiratory syncytial virus infection?

Answer 4

Most- pneumonia and bronchiolitis in young children
Occasional- common cold in adults
Infrequent- pneumonia in elderly and immunosuppressed

Question 5

What are the most frequent symptoms for parainfluenza virus infection?

Answer 5

Most- croup and lower respiratory tract disease in young children
Occasional- pharyngitis and common cold
Infrequent- tracheobronchitis in adults, lower respiratory tract diseased in immunosuppressed patients

Question 6

What are the most frequent symptoms for adenovirus infection?

Answer 6

Most- common cold and pharyngitis in children
Occasional- outbreaks of acute respiratory disease in military recruits
Infrequent- pneumonia in children; lower respiratory tract and disseminated disease in immunosuppressed patients

Question 7

What are the frequent symptoms of influenza a virus?

Answer 7

Most-influenza
Occasional-pneumonia and excess mortality in high risk patients
Infrequent- pneumonia in healthy individuals

Question 8

What are the symptoms of a influenza b infection?

Answer 8

Most- influenza
Occasional- rhinitis or pharyngitis alone
Infrequent- pneumonia

Question 9

What are the features of a respiratory infection?

Answer 9

• virions reach respiratory tract by fomites or aerosol transmission
• epithelial cells are the first site for virus and there’s s host interaction
• incited epithelial cells release cytokines that cause typical symptoms of viral: fever, aches etc
• temperature differential between upper (cooler) and lower respiratory tract has consequences for pathogenesis- rhinovirus replicate preferentially in URT, differential basis for attenuated viral vaccines
• age effect: infants and elderly have more severe infections

Question 10

Which viruses cause rhinitis, pharyngitis and laryngitis?

Answer 10

Rhinovirus
Cornavirus
Parainfluenza virus
RSV
Influenza virus
Adenovirus 
Herpes simplex virus
EBV

Question 11

Which viruses cause tracheitis, bronchitis, bronchiolitis, bronchopneumonia?

Answer 11

Parainfluenza virus
RSV
Influenza virus
Adenovirus

Question 12

What is the pattern for an acute infection in respiratory tract?

Answer 12

• acute infection with replication confined to respiratory mucosal surface
• picornaviris(rhinovirus), coronavirus, paramyxovirus (parainfluenza and RSV), orthomyxovirus

Question 13

What is the pattern of persistent virus infection in respiratory tract?

Answer 13

• persistent replication on respiratory mucosal surface

- EBV, Adenovirus, papilloma virus

Question 14

What is the pattern of systemic replication in respiratory tract?

Answer 14

• dissemination after primary replication in respiratory tract
• paramyxovirus (mumps, measles), herpesviruses (EBV, VZV, HHV6, CMV), rubella, picornaviris(polio)
• other viruses: bunya, arena, parvo, pox, reo

Question 15

What is the virology of coronavirus?

Answer 15

• named for their crown of spikes
• assRNA virus
• most strains cause cold-like symptoms
• rare new strains cause lethal respiratory diseases: SARS in 2003; MERS in 2013 (fruit bats -> camels -> humans)

Question 16

What does myxovirus name mean?

Answer 16

Myxo, Greek for mucus

These viruses bind to mucin protein on RBCs

Question 17

What does ortho mean?

Answer 17

Straight right proper

Influenza virus is the right one

Question 18

What does para mean?

Answer 18

Besides resembling

Measles virus is a bit like orthomyxovirus but not the same

Question 19

What are the differences between orthomyxovirdae and paramyxoviridae?

Answer 19

Ortho- genus influenza virus, types a b and c; nuclear replication; segmented -ssRNA genome*; enveloped

Para- 3 genera: paramyxovirus, (mumps, parainfluenza virus 1-4, Newcastle disease variant) morbillivirus (measles,rinderpest, canine distemper); pneumovirus (RSV); cytoplasmic replication; non segmented -ssRNA genome*; enveloped

Question 20

How does influenza virus cause disease?

Answer 20

• dying epithelial cells
• interferons
• T cells

Question 21

What are some results of influenza infection?

Answer 21

• secondary bacterial infection leading to pneumonia
• primary viral pneumonia
• CNS or muscle involvement

Question 22

What are some treatments for the flu?

Answer 22

Tamiflu(oseltamivir)- influenza a and b

Relenza (zanamivir)- influenza a and b

Question 23

How can we prevent the flu?

Answer 23

Flu zone- trivalent inactivated
Flu mist live attenuated vaccine
2014-2015 trivalent vaccines A/California/7/2009 (H1N1); A/Texas/50/2012 (H3N2) this has mutated now so the vaccine doesn’t help this strain but still vaccinating and just treat suspected cases of flu with antivirals; B/Yamagata lineage

Question 24

What is the virology of paramyxoviridae?

Answer 24

- non-segmented negative sense ssRNA genome - little genetic variation - 3 subfamilies- pneumonoviriniae(RSV), paramyxovirinae(mumps and parainfluenza virus); morbillivirus(measles, canine distemper) - MMR vaccine for measles and mumps (and rubella)

Question 25

What is croup?

Answer 25

Laryngotracheobronchitis caused by parainfluenza virus and respiratory syncytial virus - peak in winter - starts like a cold in adults and infants - commonly treated at home with steam and humidifiers - complications include pneumonia and respiratory distress

Question 26

What are respiratory infections caused by adenovirus like?

Answer 26

- icosahedral naked DNA virus - widespread in nature infecting birds, mammals and humans - isolated in 1953 from humans by investigators trying to establish cell lines from adenoidal tissue - 100 serotonergic, 47 can infect humans - most people have been infected with at least 1 type by age 15 - adenovirus infections are very common but most are asymptomatic - most infections involve the respiratory or GI tract or the eye

Question 27

What are the diseases caused by adenovirus?

Answer 27

``` Febrile upper tract infection Pharyngoconjunctial fever Acute disease Pertussis like disease Pneumonia Acute hemorrhagic cystitis Epidemic keratoconjunctivitis Gastroenteritis ```

Question 28

What is the adenovirus mechsnism of disease?

Answer 28

- transmitted by aerosol, close contact, fecal-oral, or fingers and ophthalmologist instruments - virus infects muco epithelial cells of respiratory and go tract, conjunctiva, cornea - virus persists in lymphoid tissue (tonsils, adenoids,Peyers patches) - antibody is essential for recovery from infection

Question 29

What is the epidemiology of Adenoviruses?

Answer 29

Transmission: respiratory droplets, fecal matter, fomites, close contact, poorly sanitized swimming pools Distribution of virus: ubiquitous, no seasonal incidence At risk or risk factors: children younger than 14, military recruits, swimming clubs Vaccines- live attenuated vaccine serotypes 4 and 7 for the military