Simonsen Flashcards
What are the characteristics of the measles virus?
- paramyxoviridae family
- ssRNA (-)
- enveloped
- extremely labile
- “rubeola”
What are the major proteins of the measles virus?
- F protein - allows fusion to form syncitia
- Hemagglutinin - surface protein for binding
- M protein - inner surface protein for assembly of nucleocapsid
- N protein - nucleo protein to protect RNA
- P protein - RNA dependent RNA polymerase
- L protein - large, part of transcription
What is the method of transmission of the measles virus?
- airborne droplets (aerosolized)
- very communicable
- infectous during prodromal phase (4 days before and after rash appearance)
What are the clinical signs and symptoms for Classic Measles?
- fever crescendo to max at day 5 (104)
- Sneezing and cough from onset of fever
- rash starting 4 days after fever and existing for 5 days
- Koplik spots - day 3-6
What are Koplik’s spots?
- white spots inside the mouth on the buccal mucosal
What is distinctive about the measles rash?
- appears on day 4 thru 9
- has a descending onset and fades in the same fashion
What is meant by modified measles?
- pts have been passively immunized: have maternal antibodies
- disease of milder and shorter duration
What are some complications associated with measles?
- otitis media
- pneumonia
- acute encephalitis
- subacute sclerosing panencephalitis - progressive neurologic degeneration
How is the measles virus prevented or treated?
- Vaccination with live (or by passive means) vaccine
- Supportive care while immune system treats
- Supplemental vitamin A
What are the characteristics of Rubella?
- Togaviridae family
- ssRNA (+)
- enveloped
- Labile
What are the viral proteins associated with Rubella?
- E1 - hemagglutinin
- E2 - membrane associated
- C - non-membrane protein
What is the route of transmission of Rubella?
- large droplets from respiratory secretions
- infectious for 7 days before and after the rash appears
What are the clinical signs and symptoms associated with a Rubella postnatal infection?
- mild fever associated with rash
- Lymphadenopathy - begins 5-10 days prior to rash (most often post auricular)
- Leukopenia
- diffuse rash
What are the characteristics of the rash associated with Rubella?
- maculopapular
- descending in onset and fading similarly
- rash will only last 3 days
What are the characteristics of a prenatal Rubella infection?
- risk is greatest in early pregnancy
- all germ layers are infected: necrosis, vascular damage and chromosomal aberrations
- Growth retardation, Cataracts, Patent Ductus Arteriosis
What is the immune response to Rubella infections?
- humoral response but must need CD$ and CD8 involvement
- congenital immunity from mom (IgA)
How is Rubella prevented or treated?
- Active immunization with live vaccine
What are the characteristics of the varicella virus?
- HHV 3 - Chickenpox
- Herpesviridae family
- dsDNA
- Enveloped
How is varicella virus transmitted?
- airborne spread from respiratory secretions or direct contact with lesions
- contagious 1-2 days prior to rash and until lesions are dried
- incubation period of 10-21 days
What are the clinical manifestations of the varicella virus?
- fever
- central rash
What are the characteristics of the rash of a varicella infection?
- central onset
- lesions are at all stages
What is the treatment or prevention of a varicella infection?
- acyclovir is a treatment for severe cases
- Active immunization with live virus
What are some complications associated with varicella infection?
- bacterial superinfection
- pneumonia
- reactivation = Zoster = shingles
What are the characteristics of Roseola virus?
- herpesviridae family
- HHV6
- dsDNA
- enveloped
How is HHV6 transmitted?
- respiratory droplets
- salivary secretions
- many newborns have maternal antibodies to protect
What are the clinical manifestations of HHV6?
- Fever - abrupt and extreme for 3-4 days
- Rash after fever subsides
What are the characteristics of the rash?
- trunk first and then to neck and extremities
- appears after fever subsides
What are the complications associated with HHV6 infections?
- seizures
- encephalitis
What are the characteristics of human parvovirus B19?
- parvovirus family
- ssDNA
- non-enveloped icosahedral neucleoprotein
How is parvovirus transmitted?
- respiratory droplet
- during late winter and spring
What is the disease associated with parvovirus?
- Fifth disease
What are the clinical manifestations of a parvovirus infection?
- slapped cheek rash
- fever
What are some complications related to parvovirus infection?
- Aplastic crisis - with pre-aplastic pts
- Arthritis
- Intrauterine infection
What are the characteristics associated with the Variola virus?
- poxviridae family
- dsDNA with DNA polymerase protein
- replicate in the cytoplasm
How does the variola virus infect an individual?
- first it is inspired and infects pharynx
- Lymphnodes are then infected and lead to viremia
- Secondary organ is then infected and leads to second viremia
- Leads to infection of skin and pustule formation
What are some clinical manifestations of smallpox infection?
- Early - headache, fever redness in oropharynx
- Late - skin papules-vesicles-pustules-crusts-desquamation
What are the five types of smallpox?
- Variola major
- Modified smallpox - milder
- Hemorrhagic smallpox - related to impaired host immune response
- Variola sine eruptione - seen in previously vaccinated individuals
- Flat - flat lesions = high mortality
