Endemic measles in Karachi, Pakistan and validation of IMCI criteria for measles

Aim: To estimate the incidence of measles in Karachi, Pakistan and to determine the proportion of children with measles based on the WHO integrated management of childhood illness (IMCI) criteria with a positive IgM for measles or dengue. Methods: Patients up to 14 years old were screened for febrile rash illnesses at five Karachi hospitals. Active measles cases were classified as measles, measles with eye and mouth complications, or severe complicated measles using IMCI criteria. Results: Screening 1 219 061 patients over a 39-month period identified 3503 qualified children. Most (76.8%) measles cases occurred in children under five years of age. The average annual incidence rate was 0.68 per 1000 in year 1; 0.19 in year 2 and 0.08 in year 3 of surveillance. Pneumonia and diarrhoea were the most common complications. Of 18.1% hospitalized, 1.6% died. Of 2286 children tested, 1599 (69.9%) were measles IgM positive. Of 542 measles IgM negative children, 66 (12%) were dengue IgM positive. The predictive positive value for the IMCI case definition was 75%. Conclusion: The IMCI case definitions for measles is reasonable but may overestimate measles incidence. Measles continues to be a public health problem in Pakistan; increased efforts to control measles are urgently needed.