MEASLES Dr. R.N.Roy, Associate Professor, Community Medicine

Measles Defn: Highly contagious acute exanthematous respiratory viral disease with varied clinical presentation and pathognomonic koplik’s spot. Agent: paramyxovirus, of genus Morbillivirus core of single-stranded RNA inactivated by heat, light, acidic pH, ether

Epidemiology Sources & reservoir:  man is only natural host  no carrier stage exist  sub clinical case can occur I.P (exposure to prodrome): 10 to12 days Seasonality : Occurs all season, more in spring & winter

Host factor Age: under five affect mostly, peak age affected 6 mo to 3 yr. Immunity- first 6-9 mo protected by maternal antibody Antibody appear 2 wks after natural infection & provide lifelong immunity Defective CMI (e.g. under nutrition) may lead to fatal progressive infection.

Transmission Virus is shed from the nasopharynx, respiratory tract and other organs Communicability: 1 day before beginning of the prodrome & 5 days after rash appear Transmitted through airborne route by droplet spread, direct contact with nasal or throat secretions Vaccinated subject cannot transmit the virus to other susceptible

Differential diagnosis Dengue fever Rubella Scarlet fever Roseola Herpes Chicken pox etc

Clinical features of measles The Prodromal Stage: fever,cough,coryza, and/or conjunctivitis. Koplik's spot (pathognomonic) appear 1 to 2 days before onset of rash Eruptive Phase:maculopapular rash appear on 4 th day of fever

Complication 30% of cases have one or more complications common among children <5 years Malnutrition Diarhhoea Infections: otitis media & pneumonia – commonest Measles encephalitis Subacute sclerosing panencephalitis (SSPE),

Laboratory methods available for diagnosis Serological assay: IgM ELISA IgG ELISA Haemaggultination inhibition test (HAI) Virus isolation PCR

Laboratory criteria for diagnosis Measles specific IgM antibodies OR Isolation of measles virus; OR At least a 4-fold increase in the IgG titre in two serum samples collected at an interval of at least 2 weeks

Case classification Suspect case: Any case with fever and rash Probable case: Any suspect case that is diagnosed by MO on basis of clinical case description Confirmed case: A case that meets the clinical case definition and which is laboratory confirmed or linked epidemiologically to a laboratory confirmed case.

Measles/Rubella IgM testing strategy from single blood sample

Management Symptomatic treatment (ORT for diarrhoea) Paracitamol for fever etc. Maintenance of nutrition Vitamin A supplementation (2 doses 24 hr apart) Appropriate antibiotics in case of complications

Vitamin A dosage schedule for measles treatment Immediately On Diagnosis <6 months: 50,000 IU 6-11 months :1,00,000 IU 12 months plus :2,00,000 IU Next Day : Repeat same dose after 24 hrs

Measles vaccine summary TypeLive attenuated freeze dried vaccine Prepar- ation Single-antigen or combined (MR or MMR). DiluentsPyrogen free double distilled water Storage & use Stored at 2 to 8°C. Reconstituted vaccine used within 4 hours. Adverse rectn Fever, rash 5-12 days later, ITP, TSS encephalitis, Contra- indication Anaphylaxis, Pregnancy, immune deficiency

Dosage and administration Age : 9-11 months; can be vaccinated up to 5 years SC injection at upper arm/ outer mid thigh Dose: single (0.5ml each), lifelong immunity

Measles Elimination In India: Goal : Reducing measles mortality by two-thirds by 2010, compared to 2000 estimates. The key strategies to achieve the goal: High vaccination coverage >90% Establish case based surveillance with virus isolation Improving cases management, including vitamin A supplementation Providing a second opportunity for immunization through routine dose or through supplemental activities

Measles outbreak When number of cases observed is greater than the number normally expected in the same geographic area for the same period of time.