Viral infections Flashcards
Single-stranded RNA virus
Measles, Mumps, Rubella, Enteroviruses
2 most important structural proteins of measles virus important for induction of immunity
H protein and F protein (hemagglutinin and fusion)
Portal of entry of measles virus
Respiratory tract or conjunctiva
Patients with measles are infectious when
3 days before up to 4-6 days after onset of rash
Pathognomonic of measles
Warthin-Finkeldey multinucleated giant cells resulting from fusion of infected cells
4 phases of measles
Incubation, prodrome, exanthematous phase, recovery
Primary viremia spreads the measles virus to what organ system
Reticuloendothelial
Secondary viremia spreads measles virus to what organ system
Body surfaces
Pathognomonic sign of measles
Koplik spots
Koplik spots appear when
1-4 days prior to the onset of the rash
Rash of measles fades over how many days
~7 days
Of the major symptoms of measles, ___ lasts the longest`
Cough, up to 10 days
T/F Persons with inapparent or subclinical measles do not shed measles virus and do not transmit infection to household contacts
T
What is atypical measles
More severe form of measles seen in children who had received the original formalin-inactivated measles vaccine (1963-1967)
Symptoms of atypical measles
1) High fever, cough, and abdominal pain 2) Maculopapular, petechial, vesicular or urticarial rash begins on the limbs and spreads centripetally 3) Swelling/edema of the hands and feet4) Pneumonia may persist for 3 months or more
Measles IgM appears when
1-2 days after onset of rash
Measles IgM remains detectable for how long
1 month
Serologic confirmation of measles infection
(+) IgM and fourfold rise in IgG antibbodies in acute and convalescent specimens collected 2-4 weeks later
Complications of measles are largely attributable to pathogenic effects of the virus on which organ systems
1) Respiratory tract 2) Immune system
Morbidity and mortality from measles are greatest in what population of patients
<5 years (especially <1 y/o) and > 20 years
MCC of death in measles
Pneumonia
MC complication of measles
OM
Virus associated with giant cell pneumonia
Measles virus
MC bacterial pathogens that complicate measles pneumonia
S. pneumoniae, H. influenzae, and S. aureus
Final common pathway to a fatal outcome following severe measles pneumonia
Bronchiolitis obliterans
T/F Measles encephalitis is due to a direct effect of the measles virus
F, immunologically-mediated process
Severe form of measles that manifests as a hemorrhagic skin eruption and is often fatal
Black measles or hemorrhagic measles
T/F Antiviral therapy is NOT effective in treatment of measles in otherwise normal patients
T
Vit A Treatment in Measles: Indications
1) 6m-2y hospitalized with complications (croup, pneumonia, diarrhea) 2) >6m not already receiving vit A supplementation and have risk factors - immunodef, clinical evidence of vit A def, impaired intestinal abbsorption, mod to severe malnut, recent immigration from areas with high mort rates attributable to measles
Vit A Treatment in Measles: Regimen
50,000 IU PO single dose for infants <6m; 100,000 IU PO single dose for children 6m-1y; 200,000 IU PO single dose for children ≥1y; REpeat the next day and 4 weeks later for children with ophthalmologic evidence of vitamin A deficiency
Patients shed measles virus when
7 days after exposure to 4-6 days after onset of rash
Measles vaccine: what
Live attenuated, available as monovalent or with mumps, rubella, varicella
Measles vaccine: when
6m during outbreaks, 1st dose at 9m, 2nd dose as MMR at 12m, 3rd dose as MMR (2nd dose MMR) at 4-6y but may be given earlier with min 4 weeks interval
Measles vaccine: how
SC; MMR may be given as an alternative to monovalent measles vaccine; MMRV may be given as an alternative to MMR and Varicella vaccines
Minimum interval between MMRV doses
3 months
MMRV must be given at a minimum age of ___ and a maximum age of
12 months, 12 years
Measles vaccine is effective in prevention or modification of measles if given within
72 hours of exposure
Measles post exposure prophylaxis
1) Vaccine within 72h 2) Ig within 6 days
Indications for measles Ig
Susceptible household contacts especially infants <6m, pregnant women, and immunocompromised persons
SSPE results from
Persistent infection with an altered measles virus harbored intracellularly in the CNS
SSPE: After ____ years, virus apparently regains virulence and attacks cells in the CNS that offered it protection
7-10
Clinical manifestations of SSPE begin insidiously when
7-13 yrs after primary measles infection
Hallmark of 2nd stage of SSPE
Massive myoclonus
Massive myoclonus in the 2nd stage of SSPE coincides with extension of inflamm process to
Deeper structures in the brain including the basal ganglia
Stage of SSPE: Massive myoclonus
2
Stage of SSPE: Involuntary movements disappear
3
Stage of SSPE: Lead pipe rigidity
3
Stage of SSPE: Choreoathetosis
3
Stage of SSPE: Loss of critical centers that support vital signs
4
Criteria for diagnosis of SSPE
1) Compatible clinical course 2) At least 1 of the following: Measles Ab in CSF, characteristic EEG, typical histo findings in and/or isolation of virus or viral Ag from brain tissue obtained by biopsy or postmortem exam
CSF analysis in SSPE
Normal cells with elevated IgG and IgM Ab titers in dilutions of 1:8
EEG findings in SSPE
St 1 - normal; Suppression-burst episodes in the myoclonic phase (characteristic but not pathognomonic)
SSPE prognosis
Most die within 1-3 yrs of onset fr infection or loss of autonomic control mechanisms
T/F Rubella is typically more severe and associated with more complications in adults
T
Major clinical significance of Rubella
CRS
Rubella, family
Togaviridae
Rubeola, family
Paramyxoviridae
3-day measles
Rubella
Rubella virus replicates where
Respiratory epithelium
Rubella: Viremia ensues and is most intense when
10-17 days after infection
Rubella: Viral shedding from the nasopharynx
~10 days after infection and detected up to 2 weeks after onset of rash
Rubella: Period of highest communicability
5 days before to 6 days after appearance of rash
Rubella: Most important RF for severe congenital defects
Stage of gestation of infection
Rubella: Results in the most severe and widespread defect
Maternal infection during 1st 8 weeks of gestation
Most distinctive feature of congenital rubella
Chronicity
Rubella: Incubation period
14-21 days
In children, 1st manifestation of rubella is usually
Rash
Forchheimer spots
Rose-colored or petechial hemorrhages on the soft palate of patients with rubella seen at about the time of onset of the rash
T/F Rash of rubella usually fades without desquamation
T
MC diagnostic test for rubella
IgM
Most serious complication of postnatal rubella
Encephalitis
Extremely rare complication of either acquired or CRS
PRP (progressive rubella panencephalitis)
T/F Onset and course of PRP is similar to that of SSPE
T
CRS: Single most common finding
Nerve deafness
CRS: MC occular abnormality
Salt-and-pepper retinopathy
CRS: Most serious eye finding
Unilateral or bilateral cataracts
CRS: Late-onset manifestations
DM, thyroid dysfunction, glaucoma and visual abnormalities associated with the retinopathy
Rubella: Treatment
Supportive
Rubella: Patients with postnatal infection should be isolated from susceptible individuals for how long
7 days after onset of rash
T/F Routine Ig for susceptible pregnant women exposed to rubella is recommended
F, considered only if termination of pregnancy is not an option because of maternal preferences
Bilateral or unilateral parotid swelling
Mumps
Mumps, family
Paramyxoviridae
Mumps: Appears in the saliva
7 days before to as long as 7 days after onset of parotid swelling
Mumps: Period of maximum infectiousness
1-2 days before to 5 days after onset of parotid swelling
Mumps: Incubation period
12-25 days, usually 16-18 days
Mumps: Prodrome
1-2 days, constitutional
Mumps: Parotitis becomes bilateral in ___%
70
Mumps: Peak of parotid swelling
~3 days then gradually subsides over 7 days
Mumps: Confirmation of presence of parotitis
Elevated serum amylase
Mumps: Virus can be isolated from what specimens during acute illness
Upper respiratory tract secretions, CSF, urine
Mumps: Establishes diagnosis
Significant increase in serum mumps IgG between acute and convalescent specimens
Mumps: Close ddx
Purulent parotitis
Purulent parotitis: Caused by
S. aureus
Purulent parotitis: Characteristics
Unilateral, extremely tender, elevated WBC, purulent drainage from Stensen duct
Mumps: MC complications
Meningitis w/ or w/o encephalitis and gonadal involvement
Mumps: T/F Maternal infection results in increased fetal wastage
T
Mumps: Thought to enter the CNS via
Choroid plexus
Mumps: T/F CSF pleocytosis can be found in mumps parotitis even without CNS symptoms
T, in 40-60%
Mumps: Meningoencephalitis commonly manifests when
5 days after parotitis
Mumps: 2nd MC finding to parotitis
Orchitis
Mumps: T/F Majority of orchitis is bilateral
F, ≤30% only
Mumps: T/F Sterility is rare in cases of orchitis, even with bilateral involvement
T
Mumps: T/F Pancreatitis may occur with or without parotitis
T
Mumps: Management should be aimed at
Reducing pain and maintaining adequate hydration
Mumps: Acceptable presumptive evidence of immunity to mumps
1) Documentation of adequate vaccination 2) Lab evidence of immunity 3) Birth before 1957 4) Documentation of physician-diagnosed mumps
Enteroviruses: Family
Picornaviridae
T/F Humans are the only known reservoir for human enteroviruses
T
Enteroviruses: Incubation period
3-6 days
MC symptomatic manifestations of enterovirus infection especially in infants and young children
Nonspecific febrile illness
Hand-foot-and-mouth disease
Coxsackievirus A16
Sudden onset fever, sore throat, dysphagia, and lesions in the posterior pharynx
Herpangina
Paroxysmal thoracic pain due to myositis involving chest and abdominal wall muscles
Pleurodynia (Bornholm disease)
Pleurodynia
Coxsackie B and Echoviruses
Acute hemorrhagic conjunctivitis
Enterovirus 70 and Coxsackievirus A24/A24
Account for ~25-35% of myocarditis and pericarditis with proven cause
Enteroviruses
2nd to mumps as MC cause of orchitis
Coxsackie B
MCC of viral meningitis
Mumps
MCC of viral meningitis in mumps-immunized populations
Enteroviruses
Account for up to 90% or more of viral men cases in which a cause is identified
Enteroviruses
Responsible for ≥10-20% of enceph cases with an identified cause
Enteroviruses
Mainstay of treatment of enterovirus infection
Supportive care
Erythema infectiosum or fifth disease: Caused by
Parvovirus B19
Single stranded DNA virus
Parvovirus B19
Parvovirus B19: T/F benign viral exanthem in healthy children
T
Affinity to RBC progenitor cells
Parvovirus B19
Aplastic crisis in patients with hemolytic anemias
Parvovirus B19
Double-stranded DNA virus
HSV, VZV
Leading cause of sporadic, fatal enceph in children and adults
HSV
Fever blisters or cold sores
HSV
Fetal anemia and hydrops fetalis
Parvovirus B19
Cell receptor for parvovirus B19
Erythrocyte P antigen
Replicates in actively dividing erythroid stem cells
Parvovirus B19
Parvovirus B19: Mode of transmission
Respiratory secretions and blood product transfusions
Parvovirus B19: Incubation period
4-14 days, rarely 21 days
Parvovirus B19: 3 stages of rash
1) Slapped cheek with circumoral pallor 2) Symmetric maculopapular truncal rash 1-4 days later3) Central clearing of preceding rash, now lacy and reticulated, lasting 2-40 days, may be pruritic, DOES NOT DESQUAMATE, and may recur with exercise, bathing, rubbing, or stress
Parvovirus B19: T/F Transient neutropenia and thrombocytopenia also commonly occur
T
Parvovirus B19: Treatment
No specific therapy
Parvovirus B19: Prognosis
Excellent
Parvovirus B19: T/F teratogenic
F
Parvovirus B19: Population at greatest risk and from whom
Pregnant women from infected children 5-7 y/o in the household, at daycare, and in schools
Parvovirus B19: T/F Exclusion of affected children from school is recommended
F, children are generally not infectious by the time the rash is present
Occurs in individuals previously infected with 1 type of HSV who have become infected for the 1st time with the other HSV type
Nonprimary 1st infection
During primary and nonprimary initial infections, HSV establishes latent infection where
Regional sensory ganglion neurons
HSV: Targets for antiviral drugs
DNA polymerase and thymidine kinase
HSV: Targets for humoral immunity
Glycoproteins
T/F Neonatal herpes is uncommon but potentially FATAL infection of the fetus or newborn
T
HSV: T/F Viremia or hematogenous spread of the virus does not appear to play an important role in HSV infections in the IMMUNOCOMPETENT HOST
T
Hallmarks of common HSV infections
Skin vesicles and shallow ulcers
Acute oropharyngeal infections caused by HSV resolves in 7-14 days UNTREATED
T, although lymphadenopathy may persist for several weeks
HSV: Presentation in older children and adults rather than gingivostomatitis
Pharyngitis and tonsillitis
MC manifestation of recurrent HSV-1 infections
Fever blisters and cold sores
HSV: Herpes gladiatorum is associated with what sport
Wrestling
HSV: Scrumpox is associated with what sport
Rugby
Term generally applied to HSV infection of fingers or toes
Herpes whitlow
___% of individuals with genital HSV infection are unaware that they are infected
90%
Course of classic primary genital herpes from onset to complete healing is
2-3 weeks
T/F Conjunctivitis or keratoconjunctivitis caused by HSV is usually unilateral
T
Conjunctivitis or keratoconjunctivitis with preauricular lymphadenopathy
HSV
Leading cause of sporadic, nonepidemic enceph in children and adults in the US
HSV
HSV enceph is an acute necrotizing infection generally involving the ___
Frontal and/or temporal cortex and limbic system
Beyond the neonatal period, HSV enceph is almost always caused by
HSV-1
MCC of recurrent aseptic meningitis
HSV
Mollaret meningitis
HSV
3 patterns of neonatal HSV infection
1) Localized to skin eyes or mouth (SEM) 2) Enceph with or without SEM 3) Multiple organs
Infants with HSV enceph typically present on ___
8-17 days of life
HSV present with clinical findings suggestive of
Bacterial meningitis
Test of choice in examining CSF of infants suspected to have HSV encephalitis
PCR for detection of HSV DNA
3 antiviral drugs available for the mgt of HSV infections
Acyclovir, Valacyclovir, Famciclovir
HSV Mx: Gingivostomatitis
Acyclovir 15mkdose 5x a day PO for 7 days (max 1g/day) started within 72 hrs of onset
HSV Mx: Herpes labialis
Oral treatment superior to topical
T/F Suspected first-episode genital herpes should be treated with antiviral therapy
T
3 strategic options re mgt of recurrent HSV infections
1) No therapy 2) Episodic therapy 3) Long-term suppressive therapy
HSV Mx: Herpes encephalitis
IV acyclovir 10mkdose q8 as 1 hour infusion for 14-21 days EXCEPT FOR NEONATES
HSV Mx: Infants with proven or suspected neonatal HSV infection
High-dose IV acyclovir 60mkday q8
HSV Mx: Infants with HSV limited to SEM, duration of treatment
14 days
HSV Mx: Infants with disseminated HSV or CNS disease, duration of treatment
21 days
HSV Mx: Pregnant women with active genital herpes at time of delivery
Vertical transmission can be reduced but not eliminated by cesarean section within 4-6hr of rupture of membranes
Neurotropic virus
HSV, VZV
Varicella vaccine: what
Live attenuated
Varicella vaccine: when
1st dose minimum @ 12 mos as MMRV or Varicella monovalent, 2nd dose at 4-6 yrs but anytime with an interval of 3 mos from 1st dose; if 2nd dose is given 4 weeks from 1st dose, it is considered VALID; For children 13 yrs and above, recommended min interval between doses is 4 weeks
Varicella vaccine: how
SC
Max age for MMRV
12 y/o
Recommended min interval between doses of MMRV
3 mos
Zoster vaccine is recommended for
Adults ≥60y (reduces both frequency of herpes zoster and its most frequent complication)
Most frequent complication of herpes zoster
Postherpetic neuralgia
VZV: Incubation period
10-21 days
VZV: Replicates where
Local lymphoid tissue > subclinical viremia > RES > mucosa of upper respiratory tract and orophayrnx
Person with VZV is infectious
1-2 days before appearance of rash
Varicella: Clouding and umbilication of the lesion begin when
24-48HR
Simultaneous presence of lesions in various stages of evolution
Varicella
Centripetal
Varicella, atypical measles
Centrifugal
Smallpox
What is breakthrough varicella
Varicella in a person vaccinated >42 days bbefore rash onset
1 dose varicella vaccine is ___% effective in preventing severe varicella and ___% effective in preventing all disease after exposure to wild-type VZV
≥97, 85
Breakthrough varicella is caused by
Wild-type VZV
Characteristics of breakthrough varicella
Mild, fewer than 50 skin lesions, afebrile or low-grade fever, shorter duration of illness, rash more likely maculopapular than vesicular, less contagious in general but dependent on number of lesions
T/F Neonatal varicella has a high mortality rate
T
Infants of mothers that develop varicella during this period are at high risk for severe varicella
5 days before and 2 days after delivery
1 vial VariZIG ASAP is indicated for neonates who
1) Are born to mothers who demonstrate Varicella 5 days before to 2 days after delivery 2) Are born at <28 weeks to a mother with active varicella even if maternal rash has been present for >1 week
When pregnant women contract varicella early in pregnancy, experts estimate as many as ___% of fetuses may become infected
25
Congenital varicella syndrome: Clnically apparent disease is uncommon
T
Congenital varicella syndrome: Characteristic skin lesion
Cicatricial or zigzag scarring in a dermatomal distribution, often associated with atrophy of affected limb, and neurologic and eye abnormalities
T/F Almost half of elderly with herpes zoster experience complications
T
What is postherpetic neuralgia
A painful condition that affects the nerves despite resolution of shingles skin lesions
Lab evaluation is not necessary for HEALTHY children with varicella or herpes zoster, but acute infection can be confirmed by
Fourfold or greater rise in VZV IgG
T/F Antiviral treatment modifies course of varicella infection
T
T/F Antiviral treatment modifies course of herpes zoster infection
T
The only drug available for the treatment of acyclovir-resistant VZV infections
Foscarnet
The only antiviral drug for Varicella that is available in liquid form and licensed for pediatric use
Acyclovir
To be most effective, antiviral treatment for Varicella should be initiated ASAP, preferrably
Within 24hrs of onset of exanthem
T/F Use of corticosteroids in children for treatment of herpes zoster is NOT recommended
T
Primary varicella has lowest case fatality rate among what population
1-9 y/o
