MEASLES REPORTING COMPLETENESS DURING A COMMUNITY-WIDE EPIDEMIC IN INNER-CITY LOS-ANGELES

A study was undertaken to determine the extent of measles underreporti ng among preschool-age children. In two community surveys conducted in innercity Los Angeles during 1990 and 1991, respondents were asked wh ether preschool-age children in their households had ever been ill wit h measles. Information about measles episodes was obtained and medical records were reviewed, when available. A probable measles case was de fined as having 3 or more days of rash with fever of 38.3-degrees cent igrade or greater, and either cough, coryza, or conjunctivitis. To det ermine the proportion of cases reported, probable measles cases identi fied were matched with measles cases reported to the Los Angeles Count y Department of Health Services. Of the 947 children ages 6 weeks thro ugh 59 months included in the surveys, 35 children had experienced an illness episode which met the probable measles case definition. Ten (2 9 percent) of the 35 probable measles cases were reported to the healt h department. Hospitals reported 9 (69 percent) of 13 probable measles cases evaluated while private physicians' offices reported 0 (0 perce nt) of 12 evaluated (Fisher's exact test, P < 0.001), although 5 child ren were seen by private physicians before rash onset. Reporting was m ore complete for cases occurring during 1990 and 1991 (33 percent) tha n from 1987 through 1989 (18 percent). The hospitalization rate for pr eschool-age children with probable measles cases in the catchment area was estimated to be 8 percent (95 percent confidence interval = 0 to 18 percent). Although measles is a serious communicable disease which is almost completely preventable, cases of it among preschool-age chil dren in this high-incidence area were substantially underreported, esp ecially by private physicians. Due to reporting bias, reported measles cases were representative of more severe cases than all the cases tha t occurred.