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Microbiology Exam 2 > Viral infections in childhood > Flashcards

Viral infections in childhood Flashcards

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1
Q

List the 6 infections covered

A
  1. measles
  2. mumps
  3. rubella
  4. non-polio enteroviruses
  5. parvovirus B19
  6. HHV-6
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2
Q

Name common childhood rashes and their “numbers” and what agent causes them

A
  1. first disease; measles (rubeola); measles virus
  2. second disease; Scarlet fever; GAS
  3. third disease; rubella; rubella virus
  4. fifth disease; erythema infectiosum; parvovirus B19
  5. sixth disease; roseola infantum; HHV-6, HHV-7
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3
Q

Name the families of MMR

A
  1. Measles: paramyxoviridae
  2. Mumps: paramyxoviridae
  3. Rubella: togaviridae
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4
Q

Common properties of MMR viruses

A
  • ss RNA (MM are -, R is + sense)
  • lipid envelope
  • 1 antigenic type
  • humans are the only natural host
  • transmission via respiratory droplets
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5
Q

Important proteins of MMR

A
  • measles: hemagglutinin (H) binds to host cell receptors, fusion (F) surface protein mediated fusion, matrix M protein for virion assembly, 3 nonstructural (NP, P, L) associated with viral RNA and function in replication
  • mumps: surface hemagglutinin-neuraminidase (HN), F, M, NP, P and L
  • rubella: surface glycoprotein E1 (hemagglutinin) and E2, nucleocapsid protein (C), P150 and p90 nonstructural for replication
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6
Q

Pathogenesis of MMR

A
  • infect eyes, nose, mouth
  • replicate in nasopharynx and regional lymphnodes
  • viremia follows with infection of leukocytes
  • during viremia, viruses spread to many tissues
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7
Q

Prevaccine era: it was expected life event to get MMR; what age was the highest incidence and when during the year would it occur?

A
  • 5-9 years old

- winter and spring

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8
Q

Due to the MMR vaccine, what has been a dramatic shift in what and why is this significant?

A
  • age; teens and young adults

- they are much more likely to have severe symptoms and be sicker for a longer time

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9
Q

In countries where MMR viruses have been largely eliminated, _________ remain the most important source of infection and outbreaks.

A

-imported cases

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10
Q

Synonyms for Measles

A
  • rubeola
  • 5 day measles
  • hard measles
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11
Q

T/F: Measles has largely been eradicated world wide.

A
  • false; remains one of leading causes of death of children < 5 y.o.
  • significant localized epidemics and sustains transmission still occur today in developed countries
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12
Q

There was a measle resurgence in the US in 1989-1991. Why?

A
  • important cause was low vaccination coverage

- mainly unvaccinated or partially vaccinated children

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13
Q

Unvaccinated persons at risk for acquiring measles themselves and transmitting to others, includes what 2 populations?

A
  1. children too young to be vaccinated

2. population declining vaccination

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14
Q

Measles Illness: incubation period, prodrome, and rash(exanthem)

A

-Incubation period: 8-12 days; from exposure to prodrome
-Prodrome: lasts 3-5 days; 3 Cs of cough, coryza, conjunctivitis; ascending stepwise fever to 103. Koplik’s spots (enanthem - mouth) last from 1-2 days;** MOST INFECTIOUS PERIOD*
Rash: lasts 6-7 days; begins 12-24 hrs after koplik’s spots and on first day is when patient is most ill and fever is the highest; initially erythematous, discrete and maculopapular, progresses to confluence

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15
Q

Describe progression of rash in measles

A
  • first appears behind ears and on forehead at hairline
  • spread is centrifugal from head to feet including palms and soles last
  • initially discrete, erythematous and maculopapular but progresses to confluence in same centrifugal manner as its spread
  • follows centrifugal course of progression on its fading
  • areas may desquamate
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16
Q

When are measles patients most infectious?

A

-prodrome stage when cough and coryza is at peak

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17
Q

Describe Koplik’s spots and what illness they are pathognomonic for.

A
  • pinpoint gray-white spots on red base
  • appear on mucus membranes of cheek opposite molar teeth; resemble course grains of sand on inflamed surface
  • MEASLES!!!
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18
Q

When does exanthem period of measles begin?

A

-usually at 14th day after exposure (2-4 after prodrome) at peak of respiratory and fever

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19
Q

Describe the communicability, transmission, and risk factors of severe disease for measles

A
  • highly contagious with a 90% attach rate in susceptible population
  • spread by coughing and sneezing, close personal contact, or direct contact with respiratory secretion; AIRBORNE TRANSMISSION FOR UP TO 2 HOURS AFTER INFECTED PERSON WAS IN AREA
  • Risk factors: age (<2 or adults); unvaccinated children, nutritional status (malnourished, vit A deficiency); immunocompromised (HIV/AIDS)
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20
Q

Measles immunity and hypersensitivity

A
  • life long immunity after natural infection
  • cell mediated immunity needed to stop acute infection
  • rash may be due to hypersensitivity bc patients with cellular immunity deficiencies do not get rash and may have more severe disease
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21
Q

One or more in complications are seen in 30% of measles cases. Who gets them? give examples and which is most deadly?

A
  • more common in children 20
  • severe diarrhea, otitis media, pneumonia (viral and bacterial); acute encephalitis; subacute sclerosing panencephalitis (SSPE)
  • Pneumonia is most likely complication!!
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22
Q

SSPE

A

-rare but serious CHRONIC, degenerative CNS disease
-secondary to persistent replication of defective measles virus in brain
-occurs after natural infection;( inversely related to age and vaccine coverage)
-onset 6-9 years after measles infection
Symptoms: present with poor school performance, progressive personality changes and behavioral abnormalities, forgetfulness, physical and intellectual deterioration, poor comprehension, speech decline over 1-3 years
-develop periodic myoclonic jerks, motor dysfunction, loss of vitality, superinfection and metabolic imbalances that eventually lead to death
FATAL

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23
Q

3 forms of unusual measles presentation

A
  1. modified measles: mild form bc antibody is below level for protection for infection but sufficient to modify illness; usually in infants with residual maternal IgG
  2. atypical measles: people who received formalin-killed measles vaccine and then exposed to live virus; vaccine sensitizes recipient to measles antigens without providing immunity
  3. measles in immunocompromised (giant cell pneumonia):severe, protracted, and fatal; severe giant cell pneumonia without evidence of rash
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24
Q

Describe the atypical presentation of atypical measles

Study These Flashcards
A
  • abrupt onset of fever, abdominal pain, pneumonia, and rash which begins on extremities and progressively moves to trunk and face
  • rash can be variety of presentations
25
A strategy of the Measles Initiative is to have routine immunizations for children by what age?
-1st birthday
26
Mumps illness: incubation period, prodrome, common feature...
- 14-18 day incubation - nonspecific prodrome of low-grade fever, headache, malaise, myalgia - most common feature is painful swelling of salivary glands in 30-40%, particularly parotid glands - mainly bilateral swelling; can last a week! - way to remember this is that the verb mump means to mumble
27
T/F: if you seen parotitis, it must be mumps.
-false; this can be caused by Influenza A, parainfluenza, CMV, etc...
28
Mumps illness
- most cases are mild and self-limited with only nonspecific or primarily respiratory symptoms - 30% subclinical - severe illness more likely in adults - greatest communicability is 1-2 days before to 5 days after onset of parotid swelling
29
Common complications of mumps
- orchitis is 20-30% of infected postpubescent males - oophoritis and mastitis in 5% of postpubertal females - sterility and impaired fertility common - MENINGITIS (15%) and much smaller risk of encephalitis - pancreatitis, myocarditis, arthritis less frequent
30
Mumps orchitis
- abrupt onset of testicular swelling - testicle becomes very painful and tender - fever, nausea, vomiting are common - involved testes is warm and scrotom is warm - pain/swelling for 1 way but tenderness can continue for many weeks
31
Of the MMR vaccine, which is the least effective?
- mumps | - still see breakouts in colleges
32
Describe what other virus rubella resembles.
-mild case of measles in post natal infections
33
Postnatally-acquired rubella: incubation period, symptoms
- 14 day incubation - low-grade fever - generalized lymphadenopathy with most involving posterior auricular, posterior cervical, and suboccipital lymph nodes - discrete maculopapular, erythematous rash
34
Complications of post-natal rubella
- uncommon - transient arthritis and arthralgia frequent in adolescent and ADULT females - thrombocytopenic purpura - encephalitis
35
Congenital Rubella Syndrome
- result of utero fetal infection; usually in first 12 wks of pregnancy - can affect all organs and cause variety of malformations - congenital malformations: cardiac, ocular, hearing, CNS, bone, liver/spleen; - generalized growth retardation
36
What is the most common malformation of congenital rubella syndrome?
-deafness
37
Risk of rubella to unborn child is directly related to what?
- gestational age at which mother contracts infections | - maximal damage occurs early in pregnancy
38
Treatment and prevention of MMR
- life-long immunity after natural infection - no specific therapy; supportive care - Vitamin A for measles in places with deficiency - ACTIVE immunization of live, attenuated vaccine (2 doses) - passive immune serum globulin to prevent or modify measles in susceptible host within 6 days of exposure
39
What kind of vaccine is present for MMR? how many doses? what ages?
- live, attenuated vaccine - 2 doses - 12-15 months, 4-6 years
40
Human Enteroviruses: what family do they belong to? describe their structure, where they replicate.
- Picornavirus - small SS + sense RNA - replicate in GI tract - 102 serotypes in 4 groups!! - NO envelope (fecal oral!) icosahedral symmetry
41
What are the 4 groups that make up enterovirus?
-Human enterovirus A, B, C, and D
42
Enterovirus epidemiology
- worldwide - humans only natural host - spread by fecal-oral route - temperate climates get epidemics in summer and fall (tropical all year round) - no heterotypic immunity bc many serotypes circulate at a time - spread greatest within families from young children, closed institutions, summer camps!!
43
When do we see enterovirus breakouts/epidemics??
-summer and fall!!!!!
44
Enterovirus pathogenesis
- initially replicate in oropharynx and intestinal tract - then infect and replicate within lymphoid cells underlying intestinal mucosa, enter blood stream, and primary viremia spreads to different target tissues
45
What immune response is involved in protect and resolution of enterovirus disease?
-humoral (antibody)
46
List mild and potentially serious infections that can occur due to nonpolio enterovirus
- mild: fever, rash, hand-foot-mouth- syndrome, pharyngitis, conjunctivitis, croup - serious: meningitis, encephalitis, acute paralysis, neonatal sepsis...
47
Hand-foot-mouth disease: what does it present with and what causes it?
- vesicular lesions on hand, feet, and tonsils and palate | - coxsackie A16
48
Major EV syndromes (3)
1. nonfocal, acute, febrile illness (fever, poor feeding, abdominal distention, lethargy, hypotonia); common cause in infants, oftens leads to evaluation for bacterial sepsis and neonatal HSV, aspeptic meningitis in 50%!! 2. Aseptic meningitis (headache, fever, achiness, still neck, vomiting, photophobia, 2-6 days); most community acquired aseptic meningitis due to EV 3. Encephalitis: accounts for about 10-20% of acute encephalitis; can get brainstem encephalitis
49
What is the most common manifestation of nonpolio EV in infants?
- acute, nonfocal febrile illness | * * IN SUMMER**
50
Compare CSF glucose levels, protein levels, cell # and cell type between viral and bacterial meningitis.
- viral: normal glucose, mild increase in protein, moderate increase in cells, lymphocytes - bacterial: low glucose, high protein, high cells, PMNs
51
Parvovirus B19: family, structure, hosts, tropism
- parvoviridae - ssDNA virus; no envelope - 3 proteins in genome - humans are only natural host - Extreme cell tropism: replicates in RBC precursors in BM and causes temporary cessation of RBC production
52
5 parts of Parvovirus B19 clinical disease
- erythemia infectiosum (fifths disease) - polyarthragia, polyarthritis - aplastic crisis (severe anemia) in sick cell disease and other hemaglobinopathies - chronic anemia in AIDS - abortion, still birth, fetal hydrops
53
Erythema infectiosum is associated with what virus and what is the funny description of this rash?
- Parvovirus B19 | - "slapped cheek" rash
54
Fifth Disease clinical presentation
- distinct clinical feature: intensely red rash on cheeks - area around mouth often remains pale - lace-like rash may erupt on arms, legs, stomach - rash may itch, tends to come and go, and sometimes brought on by heat - 5-10 years old likely to catch disease, most often recognized in school outbreaks - benign disease; rarely cause for concern
55
HHV-6: what is its family, what does it infect, who is mostly affected?
- herpesviridae - lymphotrophic virus (infect CD4 and CD8, NK cells, macrophages) - infants 0-3 years
56
Clinical manifestations of HHV-6 primary infection
1. roseola infantum-rose rash of infants; also called exanthum subitum or 6th disease; in 20% of infected children 2. undifferentiated febrile illness without rase 3. febrile seizures/convulsions * *can cause primary or reactivated disease in bone marrow and solid organ transplant recipients
57
HHV-7 causes ______ % of roseola.
-10%
58
HHV-6 Exanthem Subitum (roseola)
- sometimes called baby measles - illness commonly in children 6months-2 years - rared in children before or after this age - Key clinical features: appears as fever subsides, macular or maculopapular, seen on neck, face, or trunk; spreads to extremities, persists for hours to 2 days

Microbiology Exam 2 (11 decks)

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