Viral Exanthems

Question 1

What is the etiology, taxonomy, genome, and morphology of rubeola?

Answer 1

measles virus, paramyxoviridae, morbillivirus, RNA single strand (-) sense, enveloped

Question 2

what are the three major membrane associated proteins of rubeola? RNA associated?

Answer 2

F (fusion) H (Hemagglutinin), M (Matrix), N (Nucleoprotein), P (Phosphoprotein), and L (Large protein)

Question 3

What are the features of F protein in rubeola?

Answer 3

surface glycoprotein, allows viral envelope to fuse with cell membrane, responsible for giant cell (syncitia formation),

Question 4

What are the features of H protein in rubeola?

Answer 4

surface projection glycoprotein, hemagglutinin inhibition assay

Question 5

What are the features of M protein in rubeola?

Answer 5

inner surface membrane, non-glycosylated, required for proper assembly of nucleocapsids and progeny release

Question 6

What are the features of N protein in rubeola?

Answer 6

protects viral RNA

Question 7

What are the features of P protein in rubeola?

Answer 7

replication of viral genome, RNA-dependent RNA polymerase

Question 8

What are the features of L protein in rubeola?

Answer 8

not bale to classify well, possibly part of transcription complex

Question 9

what are the physical properties of rubeola?

Answer 9

extremely liable, sensitive to: heat, UV, ether, and trypsin

Question 10

How is rubeola transmitted?

Answer 10

airborne droplets from respiratory secretions (contact epithelium of nasopharynx or conjunctivae, stay suspended in air 2 hours), one of most communicable diseases, most infectious in late prodrome

Question 11

what is the incubation period and most infectious period for classic rubeola?

Answer 11

“classic measles”, incubation- 7-21 days from exposure to onset of fever, contagious- 4 days before rash to 4 days after appearance of rash

Question 12

What are the signs and symptoms of classic rubeola?

Answer 12

fever (crescendo, pk 5-6d), coryza (w/in 24 hr fever, sneeze, mucopurulent nasal drain), conjunctivitis, cough, koplik’s spots (2d b4 rash, oral mucosa by molars), rash (3-4d after illness onset, start hairline, spread down, feet= 3d, fade head to toe)

Question 13

Who is likely to get modified rubeola? How does it differ from classic?

Answer 13

pts who have been passively immunized (Ig), infants with maternal Ab; disease milder and shorter duration

Question 14

What childhood exanthema disease was declared eliminated in US only to rise again due to antivaccination? Which one is eliminated globally?

Answer 14

rubeola; small pox

Question 15

What are some complications seen with rubeola?

Answer 15

otitis media, pneumonia, acute encephalitis (0.1%), subacute sclerosing panencephalitis (1:100K, progressive personality change, irreversible and fatal, CNS can’t clear due to M protein not expressed, see 7-10y after measles)

Question 16

What type of immunity is seen with rubeola?

Answer 16

humoral response (IgG and IgA produced due to infection, long term protection) and cell mediated (T cell, major importance in recovery from acute, lack or poor T cell= persistent infection and often death)

Question 17

What labs are used to diagnose rubeola?

Answer 17

PCR, serology (single IgM= acute, 4x rise in IgG titer w/ convalescent- 28d later), detect virus in resp or urine culture

Question 18

What is the therapy for rubeola? prevention?

Answer 18

supportive and Vit A (50% reduction in mortality and morbidity i.e. blindness); passive Ig after exposure, active measles vaccine (live- not in pregnancy and severe immunodefficient, some HIV kids ok)

Question 19

What is the etiology, taxonomy, genome and morphology or Rubella?

Answer 19

rubella virus (German measles), togaviridae, rubivirus, (+) single strand RNA, spherical, enveloped (lipid bilayer)

Question 20

What are the important viral proteins in Rubella?

Answer 20

membrane glycoproteins E1 (hemagglutinin, surface projection), and E2 (membrane), nonmembrane protein C

Question 21

What are the physical properties of Rubella?

Answer 21

relatively labile, sensitive to: heat, UV, Lipid solvents

Question 22

How is postnatal Rubella infection spread? Prenatally?

Answer 22

droplets from respiratory secretions, prenatally infected cases multiple cases multiple tissues are persistently infected and serve as foci for transmission (urine)

Question 23

What is the clinical course of Rubella?

Answer 23

incubation 12-23d, infectious 7d before and 7d after rash onset

Question 24

what are the signs and symptoms of Rubella?

Answer 24

fever (normal or mild elevation), lymphadenopathy (begin 5-10d before rash, occipital, post-auricular, cervical chains), leukopenia and rash

Question 25

What are the features of rash with Rubella?

Answer 25

maculopapular, 3 day rash, begins on face and spreads down, gone by 3rd day (comes on and resolves quicker than Rubella)

Question 26

what are the complications of postnatal Rubella infection?

Answer 26

arthralgia/arthritis (kids rare, female adults up to 70%), Thrombocytopenia (1:3K), enceohalitis (1:5K), neuritis (r), and orchitis (r)

Question 27

What is infected with congenital/prenatal Rubella?

Answer 27

serious damage to fetus, greater risk earlier in pregnancy (0-2wk 80%, by 14wk 6-10%, 20-30% overall), all germ layers affected (2ndary to cell necrosis, gen. vascular damage, chromos. aberrations, noncytolytic infection- virus persists)

Question 28

What are the signs and symptoms (or lasting effects) of congenital Rubella?

Answer 28

growth retardation, cataracts, glaucoma, retinopathy, micropthalmia, deafness, Cardiac (PDA, VSD, PS), psychomotor retardation, microcephaly, spastic quadriplegia, MR, bone lessions, hepatomgaly, hepatitis, splenomegaly, and thrombocytopenia

Question 29

What does the immune response look like for postnatal Rubella?

Answer 29

humoral- IgM tends to be short lived, no more than 8 weeks, IgG continues to be present; cell mediated- CD4+ and CD8+

Question 30

What does the immune response look like for congenital Rubella?

Answer 30

humoral- both transplacentally acquired from mom and made by fetus, IgG (B), IgM (F), IgA (F), IgM prolonged up to up to 6 mo (most) or 2 yr (few) due to latent infection; Cell mediated- decrease rubella specific response

Question 31

How is Rubella diagnosed? Prevented?

Answer 31

viral isolation in culture, PCR and serology (acute and convalescent); active immunization (contraindicated in pregnancy and sever immunodeficiency- some HIV kids ok)

Question 32

What is the etiology, taxonomy, genome, and morphology of varicella?

Answer 32

“chickenpox”; varicella-zoster (HHV3), herpesviridae, dsDNA, enveloped

Question 33

What is the mechanism of transmission of varicella?

Answer 33

airborne from respiratory secretion or aerosols from disrupted lesions, or direct contact with lesions (one of most communicable), contagious 1-2d before rash until lesions dry

Question 34

What are the clinical manifestations of varicella?

Answer 34

incubation:10-21d (may be 10-28d if VZIG given), fever, central rash- starts on trunk moves to extremities, lesions in all stages or crops, macular -> papular -> vesicular -> pustular

Question 35

How is varicella treated? prevented?

Answer 35

acyclovir (for severe or immune compromised); passive- VZIG, active- live, attenuated vaccine (Varivax), conatrindicated if pregnant, immmunodefficiency, some HIV kids ok, paired w/ MMR

Question 36

What are some complications with varicella?

Answer 36

B superinfection (staph or strep, bulous varicells, cellulitis, sepsis) pneumonia, encephalitis, hemorrhagic, death (rare in kids, increased for adults and immune comp.)

Question 37

What is the virus and mechanism behind zoster?

Answer 37

shingles, reactivation of latent HHV3 from sensory ganglion, pain generally precedes vesicular rash which is dermatomally restricted

Question 38

What is the etiology, taxonomy, genome and morphology of roseola?

Answer 38

HHV6, herpesviridae, HHV6a and b, dsDNA, enveloped

Question 39

How is roseola transmitted? Epidemiology?

Answer 39

respiratory droplets and salivary secretions; nearly 100% newborns gave maternal Ab wane by 6 mo, 90% seropositive by 2 and ~100% by 3

Question 40

what is the incubation period and clinical disease features of roseola?

Answer 40

approx. 9-10d; fever- abrupt onset, very high, continuous 3-4d, exanthema- appearance corresponds with fever subsidence, macules or maculopapules (rose-pink), trunk-> neck-> upper extreme> face and lower extreme (Fever, Fever, Fever Rash!)

Question 41

What are the complications seen with Roseola?

Answer 41

febrile seizures 10-15%, encephalitis (more severe and very rare)

Question 42

What are the viral features, transmission and epidemiology of fifth disease (Parvovirus)?

Answer 42

human parvovirus B19- non-enveloped, icosahedral, small (22nm), ssDNA; respiratory droplet; late winter-spring, age 2-12 (peak @ 7y)

Question 43

What is the incubation period and symptoms with 5th disease (parvovirus)?

Answer 43

6-14 days; mild or no systemic symptoms- most infectious prior to rash, rash- “slapped cheeks”, cephalocaudal spread, maculopapular

Question 44

What are some complications seen with 5th disease (parvovirus)?

Answer 44

aplastic crisis (pt w/ hemaglobinopathy [sickle cell] @ increased risk), arthritis- poyarthropathy, most common in adult females (70%), and intrauterine infection- non-immune hydrops (severe anemia, can lead to miscarriage, serial ultrasounds)

Question 45

what is the disease, family, genus, genome, morphology and replicative place of Variola?

Answer 45

small pox; poxvirus; orthopoxvirus (variola, vaccinia- cow or monkey); dsDNA linear; brick shaped; cytoplasm

Question 46

What is the clinical manifestation of small pox?

Answer 46

incubation 7-17d, prodrome 2-3d w/ fever spike in middle;

Question 47

What is the pathogenic course of small pox?

Answer 47

Infection 3d- nose, mouth pharyngeal mucosa-> regional lymph node then Latent period 4-14d, viremia, spread to spleen, liver and reticuloendothelial system finally prodromal 2-3d viremia to dermis, abrupt onset of headache (severe), backache, fever 40C, enanthema- change in mouth, tongue and oropharynx

Question 48

What are the phases of the exanthem associated with small pox?

Answer 48

follows prodrome; eruption maccules 1-2d, papules 1-2d, vesicles 2-3d, pustules 5-8d, crusts 5-7d, and desquamation weeks; lesions all evolve together

Question 49

What are some additional clinical manifestations of small pox?

Answer 49

panopthalmitis-1%, keratitis-1%, arthritis-2% of kids, Encephalitis-<1%, 2ndary B infection, and pockmarks- 65-80%

Question 50

What are the 5 classifications of spall pox (WHO) an differences?

Answer 50

Variola- most common, 30% mortality; Modified- milder, 25% vaccinated individuals, rarely fatal; Hemorrhagic- <1%, difficult to diagnose, presumed to be related to immune status of host, always fatal; Variola sine eruption- previously vaccinated, infants w/ maternal Ab, transmission not documented; and Flat- flater lessions, evolve slow, coalesce, large areas desquamation, 7% unvaccinated, very high mortality (90-97%)