<prompt> The infectivity of chicken pox lasts forTill the last scab falls6 days after onset of rash3 days after onset of rashTill the fever subsides  <response>: Period of communicability: Chicken pox: 1-2 days before to 4-5 days after appearance of rash. Measles: 4 days before to 5 days after appearance of rash. Diphtheria: 14-28 days from disease onset Poliomyelitis: 7-10 days before and after onset of symptoms. CHICKEN POX: Also known as ;Varicella; Causative agent: Varicella Zoster Virus Human alpha Herpes Virus-3 Secondary attack rate: 90 Incubation period : 14-16 days. Rash : Chicken Pox rash Small pox Rash Dew drops on rose petal appearance Centripetal distribution Pleomorphic rash No dew drop Centrifugal distribution Non-pleomorphic MC late complication of chicken pox: Shingles caused by reactivation of the virus decades after the initial episode of chicken pox Aspirin must not be given to children with chicken pox: Risk of Reye Syndrome. Strain of live attenuated chicken pox vaccine: OKA strain Congenital Varicella: Most threatening if transmitted in 1st trimester of pregnancy. Ref: Park 25th edition Pgno: 157 