NOSOCOMIAL MEASLES INFECTION IN A PEDIATRIC HOSPITAL DURING A COMMUNITY-WIDE EPIDEMIC

Martha Elisa Rivera, MD. Wilbert Henry Mason, MD. Lawrence Alan Ross. MD, and Harry Tucker Wright Jr. MD. MPH

From the Department of Pediatrics, Division of Infectious Dis­eases, Children's Hospital of Los Angeles and University of Southern California School of Medicine, Los Angeles, 1991, J. Ped. V. 119, № 2.

From Jan. 1, 1988, through Dec. 31, 1988, a total of 89 cases of measles were observed at Children's Hospital in Los Angeles, and 37 patients were admitted to the hospital. Of the 37 patients, six were not initially thought to have measles, which resulted in exposure of 107 patients and 24 personnel. Of the exposed patients, measles developed in four. One nospcomially infected infant died of pneumonia. Another ex­posed patient was subsequently admitted to another hospital with unrecognized measles, which led to exposure of an additional eight patients. Of seven employees in whom measles developed, two required hospitalization because of pneumonia. Two hundred eleven employee days were lost because of

Measles exposure or infection. Infection control interventions included prophylaxis of exposed patients, employee education, and measles immunization for susceptible personnel. Of 1103 hospital personnel considered susceptible to measles, 800 received monovalent measles vaccine. No secondary cases of measles occurred in hospital personnel who received appropriate prophylaxis. We conclude that infection control programs aimed at mandating measles immunity in hospital employees at risk should be instituted. (J. Pediatr, 1991; 119; 183-6.)

Despite the introduction of measles vaccine in the United States in 1963, outbreaks continue to occur, especially in large urban areas. Such an outbreak has occurred in Los Angeles County since 1988. Although measles transmission in recent years has occurred mainly in schools or at home, as many as 3% to 5% of cases have resulted from nosocomial transmission to susceptible patients and employees in a variety of medical settings. We describe the impact of a measles epidemic in Los Angeles County on achildren's hospital and how infection control measures were implemented to impede the spread of measles to both susceptible patients and employees.

BACKGROUND

In 1988 a measles outbreak occurred in Los Angeles County; a provisional total of 513 cases was reported to the Los Angeles County Public Health Department .between Jan. 1, 1988, and December 31, 1988. Sixty-three percent of the patients reported were younger than 5 years, and 42% were 15 months of age or younger. At Children's Hospital of Los Angeles (CHLA), a 331-bed urban pediatric teaching hospital, 89 cases of measles were identified in 1988.

METHODS

Epidemiologic investigation.Medical records of patients with suspected measles were reviewed for clinical or serologic confirmation of the diagnosis. Measles was diagnosed in patients having an acute febrile illness with morbilliform or maculopapular rash (per­sisting for 3 or more days), cough, coryza, conjunctivitis, or Koplik spots.

Patients and employees were considered susceptible to measles if they were born after 1956 and had not had physician-diagnosed measles or received live measles vaccine after 12 months of age. The same criteria for measles susceptibility were applied to patients who were immunodeficient as to those who were immunocompetent.

A search of personnel records was undertaken to identify susceptible employees, that is, those born after 1956, with no documentation of immunization with live measles vaccine or physician-diagnosed measles.

Measles exposure was.considered to have occurred in patients and personnel when they were in contact with persons in whom measles was^! ultimately diagnosed and who were not in respiratory isolation at the time of- contact. Patients and employees present on the same ward area (including contiguous units) with a patient with measles were considered exposed.

After the first case of nosocomial measles was recognized, the hospital infection control officer and the department of quality assurance developed a protocol aimed at controlling the further spread of measles to susceptible patients and employees. Prophylaxis for exposed susceptible patients was carried out in three ways as recommended in the Report of the Committee on Infectious Disease of the American Academy of Pediatrics:

1. Monovalent measles vaccine was given to children 6 to 12
months of age.

2. Measles-mumps-rubella Vaccine was given to children older
than 12 months.

3. Patients from birth to 6 months of age who were exposed
received intramuscularly administered^ y-globulin.

4. When live vaccines were contraindicated, y-globulin was
administered intramuscularly.

The infection control program for hospital employees included vaccination and education. Monovalent measles vaccine was recom­mended for exposed susceptible hospital personnel if exposure was within 72 hours. If the exposure was assessed to have been between 72 hours and 6 days, y-globulin was given intramuscularly in an effort to prevent or modify the infection. An extensive educational program was initiated that included instructions to hospital admitting personnel and ward staff on the recognition and appropriate isolation of patients with measles.

RESULTS

From Jan. 1, 1988, to Dec. 3_%1, 1988, a total of 89 cases of measles were observed at CHLA (Figure). Sixty-two percent of patients were <15 months of age (Table). The age and gender distribution, and ethnic background were similar to those in the community as reported by the Los Angeles County Department of Health Services. Thirty-seven patients were admitted to the hospital; of these, six were not recognized as having measles at the time of admission. The admitting diagnoses of these six patients were

sepsis, pneumonia, bacteremia, esophagitis, roseola infantum and mastoiditis. Lack of appropriate respiratory isolation of these patients led to exposure of susceptible patients and. employees.

Seventy-eight patients susceptible to measles were exposed to five of the six patients who were not appropriately isolated. An accurate assessment of exposures to the sixth patient was not available; this patient was first seen in the prodromal stage without rash, and many of the exposed patients were discharged home before the diagnosis of measles was established.

During the study period, seven hospital personnel had measles. Four cases resulted from exposure to patients, two occurred after household exposure, and a rotating surgical resident acquired the illness from an unknown source. A nurse had atypical measles after contact with a patient with acquired immunodeficiency syndrome with unrecognized measles, and a radiology technician was infected in the radiology suite by a child with unrecognized measles. These two hospital employees required hospitalization because of respi­ratory complications, including the nurse who had atypical measles. All hospital employees who acquired measles were born after 1956. The hospital employees who acquired measles subsequently exposed an additional 15 hospitalized patients, none of whom acquired measles.

A 10-morith-old girl hospitalized with intractable diarrhea of infancy was exposed in a waiting room area to a child with unrecognized measles. Measles-related pneumonia developed in the girl and she subsequently died. She exposed an additional 14 susceptible hospitalized patients, one of whom acquired measles. Therefore a total of 107 susceptible hospitalized patients are known to have been exposed to measles during 1988.

A teenage girl exposed to measles before discharge from CHLA was admitted to another hospital with fever and uncontrolled diabetes mellitus. Her febrile illness was subsequently diagnosed as measles, and during the admission she exposed eight additional patients.

Of оцг 107 exposed patients, 54 received prophylaxis: y-globulin was given intramuscularly to 31 patients, and measles vaccine, monovalent or combined with mumps and rubella va'ccines, was administered to 9 patients; an additional 14 patients received prophylaxis, but the type was not specified in the medical record. Measles was not recognized in the patients who received prophylaxis. Of the 53 patients who received no prophylaxis, 4 secondary cases of measles occurred, for an attack rate of 7.5%.

A hospital wide measles vaccination program was begun in September 1988. A complete search of personnel records revealed that 1108 employees were born after 1956, and these individuals

were interviewed regarding measles susceptibility. Approximately 800 doses of monovalent measles vaccine were administered to hospital personnel. Susceptible employees who received measles vaccination within 72 hours from the time of exposure were permitted to continue their regular work schedule; however, sus­ceptible employees were precluded from work if they did not receive active immunization within 72 hours. No secondary cases of measles occurred in personnel who received appropriate pro­phylaxis.

The major cost associated with measles control was related to removing the exposed employees (17) from work during the incubation period for measles (days 8 to 18 after exposure) or when they had acquired measles (7). Their job descriptions included nurse (13), Jab technician (2), radiology technician (2), clerical staff (5), respiralory therapist (1), and physician (1). Twenty-four hospital employees were furloughed from work either because of having measles or because of measles exposure and lack of appropriate prophylaxis. Two hundred eleven employee-days were lost because of measles exposure or acquisition of the disease.

The estimated cost to the hospital for time lost by employees who were susceptible to me'asles or who acquired measles was $18,000. The estimated cost of vaccine and gammaglobulin was $10,750.

After the hospital wide vaccination program and educational activities, 10 children were admitted with measles. Despite educational efforts, one patient was admitted with unrecognized measles and was not appropriately isolated. Thirty-two susceptible patients were exposed to measles, but no susceptible hospital personnel were exposed and no case of measles occurred with these exposures.

DISCUSSION

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

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