DISCUSSION. Transmission of measles virus in medical settings appears to be an important factor in ongoing outbreaks

Transmission of measles virus in medical settings appears to be an important factor in ongoing outbreaks. Airborne transmission of measles was documented in a physician's office more than an hour after the index case had left the location. The frequency, of measles cases transmitted in medical settings has increased from 0.7% of the total number of reported cases in 1980 to 5% in 1985, 6.8% m 1986, and 17% in 1990. From 1980 through I984, a total of 241 persons with measles in 30 states were identified as probably having acquired the infection in a medical facility. In Las Angeles County, 30% of the measles cases identified in 1988 were acquired in medical settings.

Patients who acquire measles while hospitalized tend to be very young children or adults. These age groups tend to have

higher rates of complications and mortality. The introduction of measles in our hospital resulted in four cases of infection among patients, with one death, and seven cases among personnel, two of whom required hospitalization.' Interhospital measles exposure also occurred.

The secondary attack rate of measles within our institution in patients who did not receive prophylaxis was 7.5%. This low rate is likely related to mild exposure. To maintain optimal infection control, all patients hospitalized on the same or contiguous wards of an' inadequately isolated patient with measles were deemed exposed. Many of these exposures were likely of low intensity.

Hospital personnel born before 1957 are generally considered to be immune to measles because of natural infection. Although recent data suggest that many health care workers born before 1957 lack serologic evidence of measles immunity, none of the employees who acquired measles in this study were born before 1957.

This report demonstrates the serious consequences related to transmission of measles in a hospital setting. A number of factors contributed to this phenomenon, including (1) misdiagnosis or delayed diagnosis of measles, which prevented rapid institution of control measures (2), a greater number of patients with measles seeking medical attention and requiring hospitalization and (3) the presence of a number of susceptible medical personnel who escaped natural measles infection and were either unvaccinated or inadequately vaccinated.

The risk of nosocomial measles in a hospital can be reduced by (1) infection control programs mandating measles immunization in new hospital employees born since 1956 who lack documentation of prior immunization or disease, (2) effective outpatient triage and prompt isolation of patients with suspected measles in separate rooms so that they do not sit in open waiting rooms, and (3) identification of susceptible patients and employees as soon as a suspected case of measles is seen so that appropriate and timely prophylactic measures can be initiated.

PART IV