Skin Pathogens-Childhood

Question 1

Measles/Rubeola Virus General

Answer 1

• (-)ssRNA enveloped Paramyxovirus
• 2 Spikes:
• _{^{H <u>(hemaglutinin)</u> binds to CD46-Inhibit Comp receptor}}
• _{^{F <u>(fusion)</u> cell-cell fusion=Syncytium}}
• Transmission: Resp droplets
• High risk: unvaccinated/Malnourished
• Symptoms:
• _{^{Inhalation, virus enters cells of resp tract, <u><em>replicates in epi cells</em></u>}}
• _{^{Spreads to local <em><u>lymph-systemic=blood</u></em>}}
  
  • _{^{<strong>Skin, mucous membrane, CNS, UT</strong>}}
• _{^{<u><em><strong>Rash=</strong></em></u>Tcell CD8 attach infected endo cells<strong>(small BV)</strong>}}
• Presentation-(7/13 days incubation)
• _{^{Prodrome high fever w/CCC & P<u> (cough, coryza, conjunctivitis &amp; photophobia)</u>}}
• _{^{Mucous membrane lesions=<u>Koplik spots </u>(throat & buccal)}}
• _{^{Maculopapular skin rash (12-24hr) after Koplik spots-1<u>st neck/ears</u>}}
• _{^{Bacterial pneumonia (60% of deaths)}}

Question 2

Measles/Rubeola Virus Clinical

Answer 2

• Post measles encephalitis (RARE)
• Giant cell pneumonia w/o rash
  
  • _{^{Children <u>lacking T-cell immun</u> w/<u>use of live vaccine</u>}}
• Atypical Measles: Acute & intense rash
• _{^{Occurs in pts <u>w/inactivated vaccine</u> w/insuff immune then infected w/wild type virus}}
• _{^{urticarial rash <u>(hives)</u> w/same symptoms}}
• Subacute sclerosing panencephalitis (SSPE): 1-10 yrs after initial infection
• Fatal CNS disease
• _{^{Due to defective form of measles virus in brain<u>-Progressive virus replication</u>}}
• _{^{High Risk if pt aquired primary measles @ early age under 2 yrs old}}
• Diagnosis: RT-PCR
• Treat: Antipyretics w/Fluids
• Vaccine: Live attenuated/MMR ^{<u>(measles, mumps, Ruebella)</u>}

Question 3

Togaviridae Rubella Virus General

Answer 3

• “German Measles”=ELIMINATED
• SS(+) linear RNA-Enveloped
• ONLY ONE serotype NO viral polys
• Virus NOT cytolytic
• Transmission:
• ^{_{Resp Droplets}}
• ^{_{<em>T<u>ransplacental (congenital</u>)</em> in unvacc mothers}}
• _{^{<strong>once infected=Life long immunity</strong>}}
• High risk: Children 5-9 & 2005 eliminated
• Pathogenesis:
• _{^{Inhalation, resp tract, replicates in epi cells}}
• _{^{SPREADs to local lymph=Lymphodenopathy}}
• _{^{<u><em>Viremia (blood)</em></u>=Systemic}}
• _{^{Cell mediated immun/HS rxn responsible for disease}}
• _{^{Rash=<em><u>Ag/Ab complex formation</u></em>}}
• Presentation: (3 days)
• ^{_{<em><u>Children-</u></em>Low fever, maculopapular rash}}
• ^{_{<em><u>Adults-</u></em>More severe, arthralagia, P<u>OST infectious encephalopathy</u>}}

Question 4

Rubella Virus Clinical

Answer 4

• Cong Rubella syndrome:
• Infection 1st trimester w/cong birth defects
• ^{_{<em><strong>Heart=</strong></em>PDA}}
• ^{_{<em><strong>Eyes=</strong></em>Cataracts, glacoma, blindness}}
• ^{_{<em><strong>CNS=</strong></em>Mental retardation, microcephaly,<u><strong>deafness</strong></u>}}
• Shedding of virus days before symptoms
• Skin presentation similar to Rubeola, BUT lesions are less RED & less groupings
• Diagnosis: RT-PCR
• Serology: BEST ID 4x increase in IgG/IgM
• Prevention: Live & attenuated=MMR
  
  • _{^{12-15 mnths & 4-6 yrs old}}
  • _{^{Not recommended for immunocomprimised & pregers}}

Question 5

Parvovirus B-19 General

Answer 5

• Parvoviridae family-NON-enveloped DNA
• Smallest DNA virus
• Infects host cell’s with mitotic activity
  
  • I^{_{mmature erythoid progenitor in bone marrow or lukemia cells<u> (cancer)</u>}}
  • ^{_{Binds to P-Ag}}
• Disease caused by direct killing of these cells & immune complex deposition (rash/Arthralgia)
• Has 2 stages-_{^{<em><strong>Lytic (infectious) & non-Infect-immuno</strong></em>}}
• Transmission:
• Resp drop, Oral secretions, Blood, TRANSPLACENTAL
• High risk:
• Children 4-10
• Chronic / Sickle cell anemias

Question 6

Parvovirus B-19 Clinical

Answer 6

• Erythema infectiosum (5th): _{^{after lytic stage}}
• _{^{Fever, coryza (URT), headache, sore throat}}
• Slapped cheek syndrome:
• _{^{2-5 days}}
• _{^{Macular rash can spread to extermities}}
• Athralgia: Adult women
• Aplastic crisis: occurs in pts w/underlying anemias _{^{(transfusion for survival)}}
• Hydrops fetalis: Fluid accumulation in several fetal tissues
• _{^{Secondary to congestive heart failure}}
• _{^{1st trimester=Death}}
• _{^{2nd trimester= Hydrops fetalis}}
• Diagnosis: PCR
• Prevention: NO vaccine available BUT infection provides life long immunity

Question 7

Parvovirus B-19 Stages of disease

Answer 7

• Pathogenesis:
• Incubation period-Inoculation in Upper resp tract = 8-11 days
• Lytic period infection spread person to person
  
  • ^{_{Viremia & Infection of bone marrow}}
  • _{^{<strong>Decreased reticulocyte/Hb lvls</strong>}}
  • _{^{<strong>Virus in throat</strong>}}
  • _{^{<strong>Non-specific flu like symptoms</strong>}}
• _Immunoligical period_ non-infectious r_ash appears 2-5 days_ after prodrome_ _{^{(Type 3 HS)}}___NO spread = **17-24 days **
  
  • _{^{Virus IgG Ab present}}
  • _{^{Arthalgia (1+ joint pain)}}
  • ^{_{<strong>After 14 days difficult to isolate virus</strong>}}

Question 8

Herpesviridae-Varicella/Zoster General

Answer 8

• HHV 3-ds Linear DNA, Enveloped
• Alpha class=Infect epithelial cells
• Life long latent (90% sero +)
• Transmission: **Highly contagious **
  
  • _{^{Direct/indirect contact of mucosa}}
  • _{^{Exudate from skin lesions}}
• High risk: children under 10 & elderly adults shingles
• Thymidine kinase:
• _{^{Catalyzes phos of thymidine in DNA synthesis <em><u>(tissues undergoing growth/regeneration)</u></em>}}
• _{^{Key enzyme mediating replication in herpes}}
• _{^{Anti-viral drugs <u>(acyclovior)</u> activated by TK=Only affected cells are targeted}}
• Infects- _{^{epi cells, fibroblasts, T-cells, neurons}}
• Lytic/Latent infection in neurons (_{^{<u>dorsal root &amp; cranial nerve ganglia)</u>}}

Question 9

Herpesviridae-Varicella/Zoster Clinical

Answer 9

• Varicella (chickenpox): Primary infection
• _^Childhood
• _{^{Prodrome=Flu-like symptoms}}
• _{^{Rash=Skin & mucosal area <u>due virus replication</u>}}
• _{^{Possible to get secondary skin infection-<u><em>Strep A</em></u>}}
• _{^{Itchy->papulo-vesicular->Crusts (dew drop on a rose)}}
• ^{_{Begins on face & Trunk}}
• Interstitial pneumonia & encephalitis:
• _{^{Fatal in immunocompromized}}
• _{^{<em><u>Reyes syndrome </u></em>due to Aspirin use w/children 12 & under}}
• Zoster (shingles): Adult onset/latent
• ^{_{Painful vesicular lesion on dermatome of skin}}
  
  • _{^{Bumps>Blisters>Pus>Crust>Takes 1 month}}
• _{^{<strong><u>Postherpetic neuralgia</u>-Pain due to nerve damage</strong>}}
  
  • _{^{Lasts weeks/years after rash is gone}}

Question 10

Herpesviridae-Varicella/Zoster Treatment

Answer 10

• Diagnose (same as Herpes simplex):
• Tzanck test=scraping of ulcer to see Tzanck cells _{^(syncyathia)}
• Cowdry(A) bodies=eosonophilic nuclear inclusions
• Treat:
• Children (pox) supportive care
• _{^{Do NOT treat with ASPIRIN=<strong>Reyes syndrome</strong>}}
• Adults (shingles) prevent dissemination-
  
  • _{^{Acyclovir/Famciclovir (targets TK)}}
  • _{^{Passive immunization=<u>Varicells immunoglobulin (VZIG)</u>}}
• _Prevention: _
• _{^{<em>2 live attenuated vaccines</em> based on <u>OKA strain </u>(stonger than regular strain)}}
• _{^{<u>Varivax</u>=Prevent primary infection (pox) children above 2 yrs}}
• _{^{<u>Zontavax</u>=Prevent zoster (latent) adults for immunocomprimised VZIG}}

Question 11

Herpesviridae-Roseolovirus

Answer 11

• Herpes 6 & 7 Beta=Lymph
• “Sudden rash”-Beta class infects lymphoid cells
• Adults are 100% sero+ = latent infection of T-cells & monocytes
• Transmission: Replicates in salivary glands
• HIgh risk:
• Children (6-24 months)-_{^{Febrile seizures}}
• Reactivation in immunocomprimised adults
• Appears @ 6 months due to Maternal Ab gone
• Incubation 4-7 days=High fever
  
  • _{^{24-48 hrs <u>rash appears</u>}}
  • _{^{Recovery w/no complications}}
  • _{^{OR high fever can cause seizures}}
• No treatment or lab work