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IAHI Block 3 > 5 - Viruses of Childhood > Flashcards

5 - Viruses of Childhood Flashcards

1
Q

What are the childhood viruses that are transmitted via the respiratory tract that replicate in the URT and can cause disease in the upper and sometimes lower respiratory tract?

A 
Influenza virus
Rhinovirus 
Coronavirus
Parainfluenza virus
Respiratory syncytial virus
Metapneumovirus
Adenovirus (sometimes)
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2
Q

What viruses undergo respiratory transmission, replicate in the upper respiratory tract, cause viremia (disseminate), and cause disease in target organs?

A 
Measles 
Mumps 
Rubella 
Parvovirus
Varicella zoster 
Human herpes virus 6
Enteroviruses
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3
Q

What viruses cause a rash in children (exanthems)? What type of virus is each?

A 
Measles (parvomyxovirus)
Rubella (togavirus)
Roseola (human herpesvirus 6)
Chicken pox (Varicella zoster virus)
Erythema infectiosum/fifth disease (parvovirus B19)
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4
Q

What is the pathogenesis of measles?

A
  1. Inoculation of RT and local replication.
  2. Lymphatic spread and viremia.
  3. Wide dissemination to conjunctiva, RT, urinary tract, small vessels, lymphatics, CNS.
  4. Virus infected endothelial cells plus T cells cause a rash.
  5. Recovery (life-long).
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5
Q

What are three very rare outcomes of measles? Describe symptoms of each?

A
  1. Postinfectious encephalitis (immunopathologic); headache, confusion, vomiting, possible coma.
  2. Subacute sclerosing panencephalitis: Defective measles virus infection of CNS; personality and memory changes; myoclonic jerks, spasticity, and blindness.
  3. No resolution of acute infection due to cell mediate immune response defect (freq fatal).
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6
Q

What are characteristics of measles? What are complications?

A

Maculopapular rash. Cough, conjunctivitis, coryza (inflammed mucous membranes), photophobia, and koplik spots.

Complications: otitis media, croup, pneumonia, blindness, encephalitis.

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7
Q

What is the MMR vaccine and when is it given? What type of immune response does it elicit?

A

Measles, mumps, and rubella live attenuated virus.

Two doses, one at 12-15 mo and a second at 4-6 yrs of age.

Induces strong, long-lasting antibody response.

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8
Q

Describe the progress that’s occurred with measles globally since 2000?

A

The estimated measles deaths has been down by three quarters by 2010

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9
Q

What are the clinical syndromes associated with mumps?

A

Infections often asymptomatic.

Parotitis: swolled parotid glands are almost always hilateral and accompanied by a fever. Swelling of other glands, orchitis (inflammation of testes) which can lead to sterility, oophoritis, mastitis, pancreatisis.

Mild meningitis, rarely encephalitis.

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10
Q

What is the pathogenesis of mumps?

A

Respiratory tract inoculation and replication, viremia, systemic infection.

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11
Q

What are common locations by which systemic mumps goes?

A

Pancreas: may cause juv. db

Testes, ovaries, peripheral nerves, eye, inner ear, and CNS.

Parotid gland: multiples in ductal epithelial cells and causes local inflammation/swelling.

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12
Q

Describe the prevention and control of mumps?

A

Effective live attenuated vaccine.

Human only host, only one serotype, lifelong immunity.

Occasional small outbreaks on college campuses.

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13
Q

What is Rubella? What is the virus family it belongs to? What are the effects of the virus?

A

A togavirus that only infects humans and has only one serotype.

Does not cause readily detectable cytopathologic effects. Can cause asymptomatic infections.

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14
Q

Who is rubella a serious concern for?

A

Women who are in their first trimester of pregnancy; it can cause congenital defects.

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15
Q

What clinical diseases are caused by the rubella virus in children, adults, and neonates younger than 20 wks?

A

Children: mild rash disease

Adults: More severe disease with arthritis or arthralgia

Neonates younger than 20 wks: congenital defects

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16
Q

What prominent clinical findings are associated with congenital rubella syndrome?

A

Cataracts and ocular defects, heart defects, deafness, intrauterine growth retardation, failure to thrive, mortality in the first year, microencephaly, and mental retardation.

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17
Q

Describe the prevention and control of rubella?

A

Very effective live attenuated vaccine, part of MMR vaccine.

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18
Q

What are structural properties of parvovirus? How does it replicate?

A

A ssDNA genome, icosahedral, no envelope.

Replicates in nucleus and is dependent on host DNA replication functions.

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19
Q

What does parvovirus B19 infect? What is their receptor?

A

Actively replicating RBC progenitors in the BM (viremia). Receptor is blood group P antigen (globoside) expressed on mature RBCs, magekaryocytes, endothelial cells, placenta, fetal liver, and fetal heart.

20
Q

What goes parvovirus require of its host?

A

That its in S phase for replication and it needs the hosts DNA polymerase to replicate.

21
Q

How does parvovirus spread in the body?

A

Replicates in RBC precursors in BM: causes slight Hb drop in healthy host or aplastic crisis in host with chronic hemolytic anemia

Viremia: replication in URT, causes rash and arthralgia (erythema infectiosum or fifth disease).

22
Q

What is the time course of parvovirus?

A

6 or 7 day incubation (long)

Lytic/infectious phase from day 5-15; non-infectious immunologic phase from days 21-28

23
Q

What are clinical features of parvovirus B19?

A

Clinically inapparent infection.

Clinically apparent disease: Erythema infectiosum (fifth disease) - bright red cheeks, maculopapular rash, circulating immune complexes that cause rash, arthralgia, and arthritis.

24
Q

What are complications of parvovirus B19 infection?

A

Anemia due to reduced cell number and Hb.

In chronic hemolytic anemia pts virus causes aplastic crisis due to destruction of RBC progenitors.

When transmitted to fetus causes stillbirth, edema, anemia, congestive <3 failure, and fetal death.

25
Q

What viruses of childhood are transmitted fecal/orally and replicate in the GI tract? What symptoms do these cause?

A

Rotavirus
Norovirus

Cause gastroenteritis, diarrhea, and vomiting.

26
Q

What is the most common agent that causes severe diarrheal illness requiring hospitalization in infants and young children?

A

Rotavirus

27
Q

What are the structural features of rotavirus? What family does it belong to?

A

Reovierus family; 11 dsRNA segments encoding 12 genes.

No envelope, 3-layer capsid, antigenic groups A-E. A most common cause of human disease.

Coinfection can lead to reassortment of segments.

28
Q

The mutation rate of RNA viruses is _____X higher than that of DNA viruses?

A

1000X

29
Q

What antigens are associated with rotavirus?

A

VP4 neutralization antigen (P-serotype-28)

VP7 neutralization antigen (G serotype-19)

VP6 subgroup antigen (A-E)

Non-structural proteins (NSPs)

NSP4 (acts as an enterotoxin)

30
Q

Describe the action of NSP4?

A

NSP4 raises intracell calcium and disrupts structure of cell and allows water and electrolytes to be released from the cells into the lumen of the intestine

It can also bind extracellularly and cause similar effects on the host cell.

Also stimulates enteric nerves to cause crypt cells to release Cl- ions.

31
Q

What are the current rotavirus vaccines?

A

RotaTeq (2006): live attenuated human-bovine reassorment mixture of 5 different virus types.

Rotarix (2008): Live attenuated single human strain based on most prevalent circulating strain globally.

32
Q

When should RotaTeq and Rotarix be given?

A

RotaTeq: 3x orally between ages 2, 4, and 6 mo

Rotarix: given 2x orally at about 2 mo and 4 mo

33
Q

What considerations should be made with the Rotavirus vacines>

A

Vaccine related intussusception.

Possible reversion to virulent striain.

Viremia, shedding of virus by vaccine recipients.

34
Q

What is the major cause of acute gastroenteritis in school-aged children and adults?

A

Norovirus

35
Q

When do people get norovirus? When can there be more norovirus illnesses?

A

You can get it any time during the year, but it’s most common in the winter.

Also, there can be 50% more norovirus illness in years when there’s a new strain of virus circulating in the population.

36
Q

How long does a norovirus infection usually last?

A

It’s short-lived.

The person feels pretty good after 2-3 days of having the infection.

37
Q

What are the characteristics of norovirus that make it easily spread to others?

A

Low infectious dose (less than 100 viral particleS)

Prolonged asymptomatic shedding

Lack of lasting immunity.

38
Q

What is the organization of the norovirus genome?

A

Similar to picornavirus, ssRNA+

Contains genes for viral proease and viral polymerase (RdRp)

Structural proteins which can be targets for virus-like particle (VLP) vaccines.

39
Q

What are viruses of childhood are transmitted fecal/orally, replicate in the GI tract, and disseminate (viremia)?

A

Poliovirus, enterovirus, coxsackie virus, and echovirus.

40
Q

What effect does the polio vaccine have on the progression of enterovirus infection?

A

Antibody blockage via vaccine prevents the primary viremia from disseminating.

41
Q

What clinical syndromes are associated with major enteroviruses (echo, polio, coxsacki)?

A

Respiratory tract infections, undifferentiated fever, encephalitis, meningitis, and paralytic disease.

42
Q

What time of year are the most enteroviruses seen?

A

July, August, September, and October.

Ie summer months.

43
Q

What is most viral meningitis caused by? Who does this occur in?

A

Enterovirus, esp. in the summer months and occurs mostly in children under 5 yrs.

Infants younger than 1 month are at risk for severe infection.

44
Q

What are common symptoms of viral meningitis in infants?

A

Fever, irritability, poor eating, and hard to awaken.

45
Q

What are common symptoms of viral meningitis in adults?

A

Headache, fever, chills, nausea, vomiting, stiff neck, and sensitivity to light.

46
Q

What is caused by coxsackie A virus?

A

Herpangina - characteristic blister-like ulcers on the roof of the mouth.

47
Q

What are symptoms of hand, foot, and mouth disease? What is it caused by?

A

Coxsackie A virus and enterovirus 71.

Symptoms: milf fever, sore throat, fatigue, loss of appetite, and vesicular lesions on the palms, feet, and mouth.

IAHI Block 3 (18 decks)

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