3 RSV And Croup

Question 1

Syndrome of fever, hoarseness and barking couch in children 6-18 months of age

Answer 1

Croup - complication of URI that creates tracheal constriction below the vocal cords

Question 2

Main cause of Croup

Answer 2

Parainfluenza virus

PIV type 1 > PIV type 2&raquo_space;> RSV

Question 3

Parainfluenza is a type of ….

Answer 3

Paramyxovirus

Nonsegmented, negative sense ssRNA genome that is structurally similar to but distinct from influenza virus in biological properties and pathogenesis

Question 4

What do paramyxoviruses look like?

Answer 4

Virion is enveloped with protein spikes

Currently 4 known serotypes

Question 5

Clinical manifestations of PIV infection

Answer 5

Respiratory tract entry via droplets from infected individuals —> replication in upper respiratory tract epithelial cells (esp nasal turbinates and ciliated epithelium)

2-6 day incubation

SSx: harsh cough, rhinitis, sore throat, SOB

2-3% of total PIV infections —> Croup (where PIV invades lower airways)

Question 6

PIV illness in adults is typically experienced as …

Answer 6

No specific URI, not croup

Unless immunocompromised

Question 7

Common complications of PIV infection

Answer 7

Otitis media (PIV causes Eustachian tube dysfunction —> negative pressure in middle ear —> antagonizing clearance of nasopharyngeal bacteria)

Parotitis

Question 8

When do we see a seasonal upsurge in PIV cases?

Answer 8

Fall-winter

Prevalent in children

Question 9

What is the difference in epidemiology between the three types of PIV?

Answer 9

Types 1 and 2 exhibit a complex, sometimes alternating epidemic periodicity in autumn

Type 3 is endemic (most children will get it by age 1) with sporadic epidemic outbreaks more frequent in late winter or spring

Question 10

Do you get lifelong immunity after PIV infection?

Answer 10

Nope

Virus somehow interferes with full immune memory establishment

BUT repeat infections are usually mild

Question 11

Main reservoir for infant PIV infections

Answer 11

Adults and caregivers

Question 12

How do we diagnose PIV?

Answer 12

Direct viral isolation from nasal washings or throat swabs

PIV virions are stable and may be maintained for several days in viral transport medium

Direct fluorescent antibody or reverse transcriptase PCR tests on cells/syncytial

Question 13

How is PIV treated?

Answer 13

Supportive treatment

No vaccines

Question 14

Another paramyxovirus, very similar to PIV

Answer 14

Respiratory Syncytial Virus (RSV)

Question 15

Clinical manifestation of RSV infection

Answer 15

Viral infection in the epithelium of the nose, throat, and bronchi

SSx are actually due to the inflammatory response

SSx: Cough, dyspnea, cyanosis, and sometimes croup (but PIV much more common cause of infant croup)

Question 16

How do we diagnose RSV?

Answer 16

Rapid antigen tests available

Nucleic acid tests

Testing important - cases cannot be diagnosed based on clinical SSx

Question 17

Treatment for RSV

Answer 17

Supportive therapy for the most part but there are some meds too…

Immune globulin (monoclonal, Palivizumab) for high risk patients as a preventative measure (but must have multiple perfusion during RSV season to ensure high titer)

Ribavirin (controversial, but effective if symptomatic treatments fail)

Question 18

Most common etiology of lower respiratory tract infections in children <4

Answer 18

RSV - annual outbreaks every winter

Peak incidence is in infants <1 year

Highest rate of hospitalization is in teh 2-3 month age group

Question 19

Who is at higher risk for severe disease and complications from RSV infection?

Answer 19

Children with underlying diseases:
Premature birth
CV/Resp abnormalities (account for 50% of all hospitalizations)

Question 20

Children born when are at higher risk for severe RSV disease?

Answer 20

Those born a few months before RSV season (because maternal antibodies decline over time, leaving infant vulnerable during the height of the season)

Question 21

Novel coronavirus infection with high case fatality rate

Answer 21

SARS - an example of an emerging infection, now presumed extinct

Similar to MERS (Middle East Respiratory Syndrome