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26 Cards in this Set
- Front
- Back
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What is first disease and what causes it?
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Measles - Morbillivirus (a paramyxovirus)
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What is second disease and what causes it?
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Scarlet Fever - Streptococcus pyogenes
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What is third disease and what causes it?
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Rubella a.k.a. German Measles - Rubivirus (a togavirus)
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What is fourth disease and what causes it?
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Doesn't exist. Initially referred to Duke's-Filatov's Disease. No identified pathogen. Term "fourth virus" is not used today, but some people have started included SSSS in this slot on the list of childhood exanthems
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What is fifth disease and what causes it?
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Eryhtema infectiosm - Parvovirus B18
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What is sixth disease and what causes it?
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Roseola infantum - HHV-6
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What kind of virus causes Rubeola, a.k.a. Measles, and what are the characteristics of this type of virus?
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Rubeola is caused by morbillivirus a;though we were not taught this and it doesn't seem to be used. It's typically just referred to the class of Paramyxovirus (Parainfluenza, RSV, mumps, measles). All are negative (-) sense ssRNA. Linear, non-segmented genome. Has lipid envelope, helical symmetry and is different from other viral types because they replicate in cytoplasm. Common Virulence Factors are Hemmagglutin and F-protein (F for Fusion. Forms multinucleated giant cells, a.k.a syncytial cells). Some also have Neurominidase, but the Rubeola virus does not. All paramyxoviruses absorb and replicate in upper respiratory tract. Most infections occur in children. Systemic viremia (rash, fever, can spread to brain, i.e. encephalitis)
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What is the is the timeline for classic measles infection?
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Incubation: 10-14 days. Prodromal: 1-12 days post-infection (lasts 3-4 days). Koplik's spots appear near end of prodrome (last 1-2 days). Rash erupts 3-4 days after prodrome begins (lasts 6 days)
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What are characteristic symptoms of measles prodrome?
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High fever. Three C's - Coryza (rhinitis), persistent Cough, Conjunctivitis. Koplik's spots near the end of prodrome.
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Describe Koplik's spots and their significance.
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Small, red lesions with blue-white centers on buccal mucosa. They are diagnostic of measles.
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Describe measles rash.
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red, flat to slightly bumpy (maculopapular). Begins below ears, spreads over forehead spreads to face, neck, trunk, extremities reaching feet in three days. Exits in same pattern and time frame. Lesions on face and back may merge to appear and large red paint splotches.
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What is atypical measles and who gets it?
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Abrubt, more sever variation of virus that infected patients who received formalin-live attenuated vaccine in 1963. Formalin denatured F-protein so virus could not form syncytial cells. Body therefore did not develop F-protein antibodies and instead actually became sensitized to the virus. Rash started at palms and soles and spared the face. Vaccine has been replaced and this is no longer a problem.
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What complications occur with measles and how prevelant are they?
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Complications occur in 30% of cases. Include pneumonia (most frequent life-threatening complication), diarrhea, acute encephalitis (0.5% of all measles infections), SSPE (subacute sclerosing panencephalitis - very rare complication but always fatal), Immune suppression prompting secondary infections
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Why does measles considered a childhood disease? When would an adult get it?
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Highly infectious (99% attack rate) and once you've had it, you're immune for life. So in nations w/o vaccines, the only real targets are new, uninffected children, bc everyone else has already had it and are now immune.
Humans are only carriers and virus cannot live outside infected host. So it needs substantial population to create unbroken chain of human infection. Therefore, possible adult cases would be someone traveling to or from and isolated small community that does not vaccinate and has not had measles during that adult's lifetime. This is VERY rare in today's world and is not a likely scenario. |
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How do you treat measles?
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Symptomatic relief. No antiviral medications.
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How do you prevent measles?
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MMR 1 and MMR 2. Note, two vaccinations needed for prolonged immunity.
MMR 1 is typically given at 12-15 months and MMR 2 is usually given prior to starting school (4-6yrs old) but can be given anytime six-months after MMR 1. |
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Who should NOT get measles vaccine?
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Pregnant women. Immunocompromised. And anyone allerigc to eggs or neomycin
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What is the relationship between Vitamin A and measles?
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Vitamin A deficiency increase measles severity. Vitamin A supplementation could reduce measles mortality by up to 50%. This may account for the high fatality rate of Measles in Tropical climates.
Tropical Measles fatality may also be due to prior infection from other diseases that sensitize population to measles or the fact that paramyoxiviridae grows very well in hot, humid climates. |
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what kind of virus causes Rubella? What are its characteristic traits?
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Rubivirus, a unique Togavirus with a respiratory route of infection. Most togaviruses are arboviruses, but humans are only host for rubivirus.
(+) sense ssRNA. Nonsegmented. Icosahedral symmetry. Replicates in cytoplasm, but lacks cytoplasmic effects. Enveloped. |
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Why is Rubella also referred to as German Measles or 3-Day Measles?
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First identified in Germany. Presents as a less severe case of measles with similar but less severe prodome symptoms and a similar rash with the same spreading pattern, but it resolves in three days instead of six. Same mode of transmission, but is less likely to develop complications
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How do you distinguish Rubella from Rubeola?
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Less severe prodrome symptoms. No Koplik's spots. 3-day rash instead of 6-day. More prominent in older patients (older children, adolescents, young adults).
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What's the big complication associated with Rubella?
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Congenital Rubella Syndrome
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Describe Congential Rubella Syndrome (CRS)
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Maternal infection can cross placenta and infect fetus and cause defects.. Heart problems, eye problems, hearing loss, retardation. Risk is greatest in early pregnancy.
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How do you treat Rubella?
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Symptomatic relief. No antiviral medications.
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How do you prevent Rubella?
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MMR1. Vaccination have virtually eliminated CRS in the U.S.
Note: Prolonged contact needed to spread disease. Less contagious than measles, but infectious period lasts longer. Isolate rubella pts for 7 days after rash resides. Infants with CRS are considered contagious for up to 20 months. |
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Who should not get rubella vaccine?
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Pregnant women. No evidence that vaccine can cause CRS, but 5-15% of pts receiving vaccine develop mild rubella symptoms so why risk birth defects. Check immune status of young women and protect nonimmune pregnant women from exposure to virus
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