<prompt> Which among the following is true regarding ExathemRoseola infantum is fifth diseaseKoplick spot cannot occur before rashForreschmier spot is petechial spot in soft palate in rubellaSymptoms of vaccine Breakthrough chickenpox is similar to unvaccinated type  <response>: Ans c forreschmier spot is pelecliial...RefNelson 18th ed pl339, 1317, 1357Human herpesvirus 6 HHV-6 is a dominant cause of roseola infantum which is also known as exan them subitum or sixth disease. Parvovirus B19 is the cause of erythema infectiosum or fifth disease,Rubella or German measles or 3-day measles is a mild, often exanthematous disease of infants and children that is typically more se-vere and associated with more complications in adults.About the time of onset of the rash, examination of the throat may reveal tiny, rose-colored lesions Forchheimer spots or petechial hem-orrhages on the soft palate.Koplik spots, is the pathognomonic sign of measles and appeals 1 to 4 days prior to the onset of the rash. They first appeal as discrete red lesions with bluish white spots in the center on the inner aspects of the cheeks at the level of the premolars.They may spread to involve the lips, hard palate, and gingiva. They also may occur in conjunctival folds and in the vaginal mucosa. Koplik spots have been reported in 50-70 of measles cases but probably occur in the great majority. Varicella in Vaccinated Individuals or Breakthrough VaricellaVaccine is 95 effective in preventing severe varicella and is most commonly about 80 effective at preventing all disease after expo-sure to wild-type VZV. This means that following close exposure to VZV, as may occur in a household or an outbreak setting in a school or daycare center, 1 of every 5 vaccinated children may develop breakthrough vari-cella. Exposure to VZV may also result in asymptomatic infection in the previously immunized child.In contrast, breakthrough disease is varicella that occurs in a per-son vaccinated 42 days before rash onset and is caused by wild-type VZV.The rash in breakthrough disease is frequently atypical, predomi-nantly maculopapular, vesicles are seen less commonly, and the illness is most commonly mild with 50 lesions and little or no fever. Breakthrough cases are less contagious than wild-type infections within household settings.Children with breakthrough disease should be considered poten-tially infectious and excluded from school until lesions have crusted or, if there are no vesicles present, until no new lesions are occurring. Trans-mission has been documented to occurfrom breakthrough cases in house-hold, child-care, and school settings. 