Pediatric emergency room visits: a risk factor for acquiring measles.

In recent years, measles outbreaks have occurred among unimmunized children in inner cities in the United States. From May 1988 through June 1989, 1214 measles cases were reported in Los Angeles, and from October 1988 through June 1989, 1730 cases were reported in Houston. More than half of cases were in children younger than 5 years of age, most of whom were unvaccinated. Of cases of measles in preschool-aged children, nearly one fourth in Los Angeles and more than one third in Houston were reported by one inner-city emergency room. To evaluate whether emergency room visits were a risk factor for acquiring measles, in Los Angeles, 35 measles patients and 109 control patients with illnesses other than measles, and in Houston, 49 measles patients and 128 control patients, who visited these emergency rooms, were enrolled in case-control studies. Control patients were matched to case patients for ethnicity, age, and week of visit. Records were reviewed to determine whether case patients had visited the emergency room during the period of potential measles exposure, which was defined as 10 to 18 days before rash onset, and whether control patients had visited 10 to 18 days before their enrollment visit. In Los Angeles, 23% of case patients and 5% of control patients (odds ratio = 5.2, 95% confidence interval = 1.7, 15.9; P less than .01), and in Houston, 41% of case patients and 6% of control patients (odds ratio = 8.4, 95% confidence interval = 3.3, 21.2; P less than .01), visited the emergency room during these periods.(ABSTRACT TRUNCATED AT 250 WORDS)