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44 Cards in this Set
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- Back
Measles Clinical features
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- respiratory exposure
- 10-14 day incubation - then 'ratcheting' high fever, cough, coryza and conjunctivitis - unique red lesions (Koplik's spots) with white centers, appear on buccal mucosa(charicteristic of measles) - rash first on head and neck |
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Measles Complications
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- encephalomyelitis
1)Post-infection encephalitis (auto-immune,PIE) 2)Measles inclusion body encephalitis(rare, MIBE) 3)Subacute sclerosing panencephalitis (SSPE)-rare, 7-10yrs after 1o - 1o measles or giant-cell pneumonia in immunodef - 2o bacterial pneumonia - keratoconjunctivitis in kids with nutritional deficiencies |
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atypical measles
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- in persons who received killed measles vaccine during 1963-1967 then got infected
- atypical rash (no Koplik's), and serious pneumonitis - no longer use killed vaccine |
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Measels Virus properties
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- pleomorphic morbillivirus
- one molecule of (-) ssRNA - a viral-encoded RNA dependent RNA polymerase - a helical nucleocapsid - a lipoprotein envelope (know more about spikes) |
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Measels Viral envelope Spikes
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- one with hemagglutinating (H glycoprotein) activity
- one with cell-fusing (F glycoprotein) activity - F displayed on infected cell - Morbilliviruses have NO neuraminidase(N) activity on spikes - Morbilliviruses induce BOTH nuclear and cytoplasmic inclusion bodies - F is inactive precursor (Fo) cleaved by host in Golgi - envelope must fuse to host (via F) to penetrate/infect - F prot on surf of infected cells, cause cell-cell fusion-> means for cell-cell spread and giant multinucleate cell formation |
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Measels Pathogenesis
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- inhalation
⇒ RT mucosa ⇒ regional LNs ⇒ primary viremia ⇒ ReticuloEndoth system ⇒ 2o viremia ⇒ lymphoid cells(including skin) ⇒ lesions - rash from CMI response - kids' infections probably involve CNS (usually asymptomatic) and growth curve is arrested, but later catches up |
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Measels Immunity
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- only one serotype
- natural infection produces lifelong permanent immunity - neutralizing Ab directed at H - maternal Ab can cross placenta (6 mos protection) - agammaglobulinemics demonstrate a normal disease course - cell-mediated immunodef ⇒ persistent infection (w/ complications) - concomitant depression of CMI to a wide variety of non-measles antigens |
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Measels Epi
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- most contagious, from aerosolized droplets (sneeze/cough)
- survives in droplets for hours - infectous from 4 days before rash to 4 days after rash is apparent - high mortality from lack of adequate nutrition and health care, its immunosuppressive - only become endemic in conc group of hosts: 1)high rate of contagion 2)no animal reservoir 3)rapidly “burns itself out” in isolated rural areas |
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Measels Diagnosis
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Clinical symptoms
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Measels Treatment
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- no therapy
- A two day course of vitamin A reduces severity in kids - prevent w/ attenuated vaccine (MMR) |
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Measels Vaccine
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- give first dose at a min of of 12 months (circulating maternal Ab can inhibit vaccine efficacy)
- give second dose at least 12 months later; usually 4-6 yrs - window of susceptibility (b/w maternal wearing off and first MMR, or b/w maternal wearing off and 2nd MMR) - more than >90% covered by age 3 |
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Mumps Clinical Features
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- 18 day incubation
- viremic spread to parotid and presents as swollen salivary glands(characteristic) - 1/3 infections subclinical - can involve the epithelial cells of organs(testes, ovaries, kidneys, etc. |
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Mumps Complications
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- orchitis(Inflamed ball) in 25% of males, worse and more common if post-puberty -> sterility
- aseptic meningitis in up to 50%, usually subclinical, resolves w/o perm damage |
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Mumps Viral Properties
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- pleomorphic paramyxovirus
- transcription, replication and assembly in cytoplasm like the measles virus - envelope has 2 glycoprot spikes - one with BOTH hemagglutinating(H) and neuraminidase(N) activities - the other w/ cell fusing(F) activity |
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Mumps Pathogenesis
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- replicates in URT
⇒ LNs which drain the region ⇒ viremia ⇒ replicates in the epith cells of various organs (parotid) ⇒ cell lysis and multinucleated giant cells (cell fusion) |
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Mumps Immune response
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- only one serotype
- immunity lifelong - neutralizing Abs directed at the HN envelope protein - Ab in saliva signals the end of virus excretion - maternal Ab can cross placenta |
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Mumps Epi
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- spread via aerosolized droplets, esp in winter and spring
- shed for 7-10 days, beginning 6 days prior to symptoms |
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Mumps Diagnosis
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- clinical symptoms alone - swollen parotid in mumps susceptable individual
- virus may be cultured - antiviral Abs may be found in the convalescent serum |
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Mumps Treatment
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- immunization with live attenuated vaccine (MMR)
- no antiviral therapy |
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Rubella Clinical Features
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- normally like measles
- 14-21 day asymptomatic incubation - most cases subclinical - starts w/ rash (face(slapped) ⇒ extremities) and lasts 3 days(may confuse w/ viral/drug rashes) - if acquired later in life (by males or non-pregnant females) its uncomplicated - if pregnant/non-immune, high risk of Congenital Rubella Syndrome or spontaneous abortion - congenital often results in hearing loss or cataracts - can take months to manifest - congenital kids are often persistent carriers and constantly shed infectious virus |
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Rubella Virus Properties
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- spherical nucleocapsid w/ envelope
- Togaviridae family - no RNA-dependent RNA polymerase in the virion - one molecule of (+) RNA - replication and maturation are confined to the cytoplasm - infectious virions bud from the cytoplasmic membrane |
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Rubella pathogenesis
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- aerosolized droplets
⇒ nose and local LN ⇒ viremia ⇒ organs and skin - no fusion protein, so no cell to cell spread - viremia! critical for systemic inf - shed for 1 week after rash cessation - infection -> lifelong immun - Abs cross the placenta |
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Rubella Epi
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- springtime epidemics every few years
- endemic worldwide - unique among togaviruses b/c it neither infects nor is transmitted by arthropod vector - outbreaks due to gaps in our vaccine coverage are a concern |
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Rubella Diagnosis
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- usually clinical symptoms
- tests for immune status of women of childbearing age - can be cultured in lab |
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Rubella Treatment
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- vaccination of children
- medical people are often required to be immune - vaccine is very effective and long-lived(when introduced, 12.5mill cases/yr in US ⇒ 300cases/yr) - CDC is about to study if vaccine procedure fully eliminates CRS in US |
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Human Herpesvirus 6 and 7 Clinical Features
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- 6th disease or "roseola" in kids under 2
- high fever and a red rash - resolves in 3-5 days without complications or sequelae - most are asymptomatic - 50% of initial febrile episodes in infants due to HHV-6 - lifelong protection, so 1o infection in immunocompetent adults is rare |
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Human Herpesvirus 6 and 7 Properties of the Virus
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- replication & structure like other herpesviruses
- icosahedral capsid and spiked envelope - latent after 1o infection - 1 case of virus-associated hemophagocytic syndrome (VAHS) from reactivation - prominent phagocytosis of erythrocyts/nucleated BCs in bone marrow and LNs |
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Human Herpesvirus 6 and 7 Pathogenesis
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- respiratory route ⇒ oropharynx ⇒ many cell types including lymphocytes (esp CD4+ T-lymphocytes), Macs, epi and endo cells
- a tiny fraction of these cells become infected during childhood roseola |
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Human Herpesvirus 6 and 7 Epi
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- transmitted by salivary droplets
- requires close contact - infection is universal - usually presents in infants soon after maternal Ab waned - most 1o infections are subclinical or febrile illnesses without the rash |
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Human Herpesvirus 6 and 7 Diagnosis
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clinical presentation
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Human Herpesvirus 6 and 7 Treatment
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- no antiviral therapy yet
- but Ganciclovir (GCV) has been via IV to suppress HHV-6 replication in lifethreatening CNS infections in bone marrow recipients - HHV-6 is more sensitive to GCV than ACV but GCV has more toxic side effects - no vaccine, but most newborns have maternal Ab - most infants seropositive by 13 months |
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Parvovirus B19 Clinical Features
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- 5th disease (age 1-5 years)
- "slapped-cheek" rash and rash on the trunk w/ low fever - adults asymptomatic or have arthralgia then flu-like - if hemolytic disorders(SS, thalassemia) -> transient aplastic crisis, from viral impact new erythrocyte prod, combined w/ the reduction in existing ones - can infect in utero 1) persistently viremic infants w/ severe anemia, so transfusions 2) can cause death (hydrops fetalis) |
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Parvovirus B19 Properties of the Virus
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- typical parvovirus
- small, no enveloped icosa. - 1 molecule of + or - ssDNA - replication and assembly in the nucleus only during S phase - uses host enzymes - no integration into host DNA |
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Parvovirus B19 Pathogenesis
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- narrow specificity for host cells in bone marrow, fetal liver or heart
- directly cytotoxic, rapid killing of host cells(erythropoeitic cells) - causes high titer viremia w/ bone marrow depression thats short-lived, ending due to the development of Ab - rash and adult rheumatic syndrome due to immune-complex formation - infection -> lifelong immun. - w/o hemolytic disorder->no aplastic crisis |
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Parvovirus B19 Epi
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- respiratory droplets->URT->bone marrow
- infected spreading virus w/in 5-6 days of infection until sufficient Abs (10-14) - widely disseminated in community-wide epidemics via school-age children - can survive pasteurization of blood products |
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Parvovirus B19 Diagnosis
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- clinical presentation
- isolated cases are commonly misdiagnosed as measles, etc. |
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Parvovirus B19 Treatment
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- typically not treated
- transient aplastic crisis is readily treated by blood transfusion |
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Coxsackievirus Clinical Features
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- serogroup A and B (each w/ multiple serotypes)
- can be severe in both kids and adults - may present as isolated cases or as an epidemic - infections of NS and URT, LRT, rashes, myocardial disease and conjunctivitis |
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Coxsackievirus Serogroup A
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1) herpangina
- fever, sore throat, vesicles in oropharynx; acute onset 2) hand foot and mouth disease w/ ulcerative vesicles on buccal mucosa, and vesicular rash on hands and feet 3) aseptic meningitis - typically, uneventful recovery 4) epidemic conjunctivitis - some forms hemorrhagic 5) infantile diarrhea |
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Coxsackievirus Serogroup B
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1) pleurodynia - acute chest pain and fever - 2-14 days
2) myocarditis and pericarditis - acute and chronic forms, fever, chest pain (due to CTL response) 3) neonatal infection can be inapparent to fatal - resp and CV involvement - from the nursery or transplacentally - associated with juvenile diabetes |
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Coxsackievirus Properties of Virus
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- typical enteroviruses
- naked, icosahedral - 1 molecule of (+) RNA - replication confined to the cytoplasm like polioviruses |
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Coxsackievirus pathogenesis
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replicates in Oropharyngeal and GI lymphoid tissue
⇒ the RES ⇒ skin, myocardium and CNS |
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Coxsackievirus Epi
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- fecal-oral mainly, but also inhalation of droplets
- active infection may block poliovirus vaccine - concurrent enterovirus infections can interfere with replication among each other; one enterovirus infection then dominates |
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Coxsackievirus Diagnosis and Treatment
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- can be isolated from stool samples, pharyngeal secretions and vesicular fluids
- serum typed for presence of convalescent antibodies - no antiviral drugs or vaccines available |