MEASLES:- An acute highly infectious disease of childhood caused by a specific virus of group myxovirus. Clinically characterised by fever and catarrhal symptoms of the upper respiratory tract( coryza,cough), followed by a typical rash. Secondary attack rate-infection confers life long immunity as there is only one antigenic type. Incubation period-10 days from exposure to onset of fever and 14 days of appearance of rash. 3 stages:- 1. Prodromal stage. Begins 10 days after infection. Lasts till 14 days. Characterised by fever,coryza with sneezing and nasal discharge, cough, redness of eyes, lacrimation and photophobia. A day or two before the appearance of rash, kopliks spots like table salt like crystal appear on buccal mucosa opposite the first and second lower molars. They are small, bluish white spots on a red base. 2. Eruptive phase Typical dusky red maculopapular rash which begins behind the ear and spreads rapidly in a few hours over the face and neck and extends down the body . Fever and lesion disappear in another 3/4 days signalling the end of disease. During the prodromal phase and first 2-5days of rash, virus present in tears, nasal & throat secretions, urine and blood.The rash appears as a result of interaction of immune T cells with virus infected cells Just as the rash appears- circulating antibodies appear- and fever falls. Diagnosis of measles is based on the typical rash and kopliks spots seen in oral mucosa.In developed countries,IgM antibodies are used for diagnosis. 3. Post measles stage Child lose weight, remain weak for a number of days. There may be a failure to recover and gradual deterioration into chronic illness.There may be growth retardation,diarrhoea,pyogenic infection,candidiasis etc. {Reference: park&;s textbook of preventive and social medicine, 23rd edition, pg no.149}