- Email: [email protected]
Measles outbreaks: Who are at risk and why
n
Measles Outbreaks: Who Are at Risk and Why
Deanna E. Grimes, DrPH, RN, and Lynda F. Woolbert,
n
MSN, RN, CPNP
After the introduction of measles vaccine in the United States in 1963 the reported incidence of measles (rubeola) decreased substantially. The disease, however, has not been eliminated. Since 1983, when the lowest number of cases was reported, slight increases in incidence have been observed. Outbreaks are occurring among previously immunized school- and college-age children and unimmunized preschool children and infants. This article describes measles occurrence, transmission, diagnosis, development measles immunity, the 1989 Centers for Disease Control recommendations for immunization, and implications for health care providers for preventing measles outbreaks. j PEDIATR HEALTH CARE. (1989). 3, 187-l 93.
B
etween early October 1988 and early April 1989 local health officials conf!irmed more than 1450 cases of measles in Houston and in Harris County, Texas. This area reported no more than 81 cases per year throughout the 1980s. The casesoccurred in persons who ranged in age from younger than 1 year to older than 20 years. Authorities have confirmed seven deaths from complications of measles, including the deaths of a 27-year-old woman and a 13-month-old male infant (M. Canfield, ChiefEpidemiologist, Harris County Health Department, personal communication, April 3, 1989). By early April there was no sign that the outbreak was abating. Measles (rubeola, hard measles, lo-day or red measles) is an acute, highly communicable viral disease. Although measles is generally self-limiting, the disease can be particularly severe in infants younger than 2 years of age, in chronically ill children, and in undernourished children and adults. Measles can produce severe respiratory and neurologic complications as a result of viral replication and dissemination and/or bacterial superinfection. Complications include pneumonia, otitis media, encephalitis ( 1 in 2000 cases), and permanent brain damage. One rare complication, subacute sclerosing panencephalitis, a chronic degenerative neurologic disease, causes intellectual deterioration in children several years after an attack of measles in infancy. Maternal measles Deanna E. Grimes is Clinical Assistant Professor at the University Health Science Center at Houston, School of Nursing. Lynda F. Woolbert is an instructor at the University Center at Houston, School of Nursing.
of Texas
OF
PEDIATRIC
HEALTH
CARE
infection at any time during pregnancy increases the risk of spontaneous abortion, premature labor, and low birth weight. Death occurs in 1 in 3000 cases among persons of aU ages and in 1 in 1000 cases among high-risk infants (Benenson, 1985; Centers for Disease Control [CDC], 1987b). Measles is more than a simple, benign childhood disease.
early October 1988 and early BApriletween 1989 local health officials confirmed more than 1450 cases of measles in Houston and in Harris County, Texas.
Between 1938 and the licensing of measles vaccine in 1963 the annual number of reported cases in the United States ranged from approximately 400,000 to 900,000 (CDC, 1988b). By 1983 widespread immunization of infants and children resulted in a 99% decrease in the incidence of measles. A low incidence of 1497 cases was reported in that year. Since then outbreaks among previously immunized school-age children, young adults, and unimmunized preschool children and infants increased the yearly incidence (CDC, 1989). This article reviews trends in measles occurrence, measles transmission and diagnosis, development of measles immunity, recommendations for vaccination, and implications for clinic and school health care providers for the prevention of measles.
of Texas Health Science
Reprint requests: Deanna E. Grimes, DrPH, RN, Clinical Assistant Professor, University of Texas Health Science Center at Houston, School of Nursing, 1100 Holcombe Blvd., Houston, TX 77030. JOURNAL
of
n
TRENDS IN OCCURRENCE
Before widespread vaccination very few persons escaped contact with measles. More than 90% of the 187
188
Grimes
Volume 3, Number 4 July-August 1989
& Woolbert
population had the disease before their twentieth birthday, usually in early childhood. The disease was endemic everywhere, becoming epidemic every 2 to 3 years. Outbreaks were seasonal, with the greatest number of cases clustered in the late winter and early spring months (Benenson, 1985; Gershon, 1985). The present pattern of occurrence is illustrated by means of the 1987 CDC data (CDC, 1988a). In 1987, 3655 cases of measles and four deaths from it were reported. The deaths occurred in immunocompromised persons, two of whom were children with acquired immunodeficiency syndrome (AIDS). Although the nationwide cases peaked during early spring, some local outbreaks occurred during other times of the year (CDC, 1987a).
T
he disease was endemic everywhere, becoming epidemic every 2 to 3 years.
The cases in 1987 were concentrated in specific states and counties. Three fourths of the cases were from New York City and seven states: California, Texas, New Mexico, Illinois, Missouri, New Hampshire, and Wisconsin. The majority of measles cases were in the older age-groups. Nineteen percent of the total cases occurred in children 10 to 14 years of age; 29% were between 15 and 19 years old. Thirteen percent of reported cases occurred in persons older than 20 years of age. Most of the 1987 caseswere contracted in primary or secondary schools, medical settings, and colleges or universities. Some documented transmission occurred by indirect contact in health care settings and through contact with unimmunized health care providers (Remington, Hall, Davis, Herald, & Gunn, 1985; Sienko et al., 1987). Fewer than 30% of the 1987 cases were classified as preventable, according to CDC criteria (unvaccinated persons for whom vaccine is indicated by current recommendations). In contrast, 72% of the cases were classified as nonpreventable. This category includes persons born before 1957, those with a history of measles disease, persons adequately immunized, infants younger than 16 months of age, or persons exempt from vaccination for medical or religious reasons. The vast majority of these nonpreventable cases in 1987 occurred in school- and college-age persons who had been vaccinated after their first birthday. A review of measles transmission, diagnosis, immunity, and vaccination explains why these persons are at risk.
n
TRANSMISSION
The etiologic agent for measles is a virus that is present in the blood, urine, and pharyngeal secretions of infected persons. The virus can remain infective in aerosol&d mucous droplet form for several hours in conditions of low humidity. Thus transmission occurs indirectly as well as by direct contact with respiratory droplets (Gershon, 1985). Once transmitted, the virus invades the respiratory epithelium where it incubates and multiplies. The virus is then disseminated by way of the lymph system through the respiratory mucosa and to the blood, producing catarrhal symptoms and high fever within 8 to 13 days of initial viral contact. These symptoms herald the prodrome. Further viral dissemination and activity result in generalized involvement of the respiratory tract, buccal mucosa, and dermis. The characteristic measles rash appears within another 4 days. Transmission may occur before onset of the prodromal fever until approximately 4 days after onset of the rash, although it is less likely after the second day of rash (Benenson, 1985). The stages of infection and communicability are summarized in Figure 1. n
DIAGNOSIS
Measles frequently remains undiagnosed through the period of greatest communicability. The clinical manifestations of the disease during the prodrome are a moderate to severe upper respiratory tract infection with a characteristic photophobia and conjunctivitis. The diagnostic Koplik’s spots appear briefly before onset of the maculopapular rash on the fourth day. Except during times of known outbreaks, health care providers may not associate prodromal symptoms with measles, especially when the patient has been previously vaccinated.
T
he majority of measles cases were in the older age-groups.
Measles has three possible presentations: typical (previously described), modified, and atypical. The milder, modified disease results from exposure to the measles virus after injection of measles immune globulin (IG) or live attenuated vaccine/IG combination. This presentation may not include some of the classic signs of measles. Atypical measles may occur in persons who are vaccinated with the killed vaccine (available from 1963 to 1967) or the killed vaccine fol-
Journalof Pediatric
Health
Measles Outbreaks
Care
189
Incubation Period
n
FIGURE 1 Stages of infection
lowed by the live vaccine within 3 months (CDC, 1987b). Atypical measles has an unusual and severe course, with nausea, vomiting, headache, myalgia, sore throat, fever, nonproductive cough, and photophobia. Conjunctivitis and rash may not be present. The distribution and progression of the rash, when it occurs, often resemble those of Rocky Mountain spotted fever. Occasionally, the rash progresses to a vesicular stage and is misdiagnosed as chickenpox. Pulmonary involvement is frequent and severe (Reese & Douglas, 1986). Confirmed measles cases must be reported to the local health department. Measles cases are confirmed on the basis of clinical or laboratory evidence. Laboratory testing is expensive and not routinely performed. Two laboratory tests are used more commonly than others; however, accurate interpretation depends on timing of the test during the disease course (Gershon, 1985). The complement fixation detects short-lasting antibodies that appear during the time of the rash. Hemagglutination inhibition detects long-lasting antibodies. A fourfold increase in antibody titer between the acute and convalescent stage is diagnostic (Grimes, 1985). n
and communicability
of measles
measles antibodies have immunity until they are 6 to 9 months of age. If vaccinated while retaining maternal antibodies, the infant will not produce longerlasting immunity (Benenson, 1985). In like manner, antibodies received in IG interfere with vaccineinduced antibody production. Measles vaccine type has changed several times. In 1963 two types of vaccine (a killed virus vaccine and live, attenuated Edmondston B strain vaccine) were licensed for use. The killed virus vaccine was administered until 1967 (1969 in Canada) and discontinued because it induced only short-term immunity. The Edmondston B strain vaccine was used until 1972. Because of its side effects, it was frequently administered with IG, later found to interfere with effective antibody production. Two other live virus vaccines, which caused fewer side effects, were introduced in 1965 (Schwarz strain) and in 1968 (Moraten strain). The Moraten vaccine is currently used in the United States (CDC, 1987b).
C onfirmed
measles cases must be reported to the local health department.
DEVELOPMENT OF MEASLES IMMUNITY
Measles immunity develops in one of three ways. One, a person with a normal immune system who acquires measles disease produces permanent measles antibodies during the period of the rash. Second, effective artificial vaccination with the measles virus induces a mild or inapparent, vwnummunicable infection that stimulates antibody production. It is believed these antibody titers do not decrease with time (CDC, 1987b). Third, a person receives temporary antibodies through congenital transfer or administration of IG. Infants who are born of mothers with
The recommended age for immunization also changed several times as evidence emerged that maternal antibodies interfered with vaccination effectiveness. In 1965 the recommended age was changed from 9 months to 12 months, and in 1976 it was changed to 15 months. Children vaccinated between 12 and 15 months of age, however, have seroconversion rates of 80% to 95%, are considered immune, and are not routinely revaccinated (CDC, 1987b).
190
Volume 3. Number 4 July-August 1989
Grimes & Woolbert
Live measles virus vaccine is available in the measles-only form and in combinations of measles and rubella (MR) and measles, mumps, and rubella (MMR). MMR can be safely and effectively administered to persons previously vaccinated with any of the component vaccines or concurrently with other live virus vaccines (CDC, 1987b). In 1980 a stabilizer was added to measles vaccine after the discovery of deactivation of improperly stored vaccine. Although the vaccine used today is more thermostable, the temperature still must be carefully controlled to prevent deactivation of the virus. Before reconstitution the vaccine must be kept frozen. Reconstituted vaccines must be refrigerated, protected from light, and discarded after 8 hours (Benenson, 1985). On the basis of the characteristics of measles immunity, the history of vaccine use, and the characteristics of the vaccine, certain persons are likely to be at risk for measles despite previous vaccination. Others can be considered to be immune. Persons considered to be immune by CDC and those considered to be at risk are listed in the boxed material above.
. RECOMMENDATIONS MEASLES VACCINATION
FOR
As a result of recent measles outbreak the Immunization Practices Advisory Committee of the CDC recently issued changes in the vaccination schedule and outbreak control. The current 1989 recommendations for measles vaccination, vaccine precautions, and contraindications are presented in the boxed material on p. 191. . MEASLES PREVENTION: IMPLICATIONS HEALTH CARE PROVIDERS
FOR
The long period of communicability, ease of transmission, and difliculty of initial diagnosis make measles difficult to control in susceptible populations. The best strategy for control and elimination of measles is an adequately immunized population. Health care providers have a responsibility to identify and vaccinate persons at risk. Determining risk and need for vaccination (see above) requires eliciting accurate historic information regarding disease and vaccination. To avoid error the health care provider must clarify the distinction between measles (rubeola) and rubella for the
lournal 0i Pediatric Health Care
Measles
1989 ~CO~~A~ONS
Outbreaks
191
FOR AtiENGES VACCXNATION
In mm w&h marremit meArj[es t?wmkdm (wunties with mm tt!fm$ve cmestztnimgpres~ool cliilhn) (CDC, 1989) a Administer live measles vaccine on a two-dose schedule: first dose of monovalent vaccine at 9 months followed by one dose of MMR at 15 months or n If two-dose schedule is impractical, administer MMR routinety at 12 months of age.
n
Revaccinate all students and their siblings who received their most recent vaccination before 1980, giving priority to those who were vaccinated before age 15 months.
Wnebfi~eedearlier Y Vaccinate with MMR all asymtomatic children infected with human immtmodeficiency virus (CDC, 1988a). l Administer measlesvaccine to a susceptible person within 72 hours of exposure to measles. . Administer IG to susceptible persons within 6 days of exposure to measles. This includes immunocompromised persons, pregnant women, or infants under 1 year of age. If not contraindicated, mea&s vaccine should be administered 3 months after IG to persons older than 15 months of age. g Administer vaccine at least 2 weeks before administration of IG for foreign travel. e Vaccinate household contacts of any person for whom the vaccine is contraindicated, thus reducing risk of exposure to the disease(CDC, 1987b). l
Theji%w& preaaabns and wm?mb&#Gns to nax&tti~ remain in efect: = Pregnancy or anticipated pregnancy within 3 months (based on a theoretic, undocumented risk of fetal section) . Immunosuppression as a result of leukemia, lymphoma, generalized malignancy, therapies (with systemic or topical carticosteroids, alkylating drugs, antimetabolites, or radiation), The vaccine, however, is not contraimiicated for personswith asymptomatic human immunod~ency virus infection, AIDS, leukemia in remission, and chemotherapy terminated for 3 months, or for those receiving corticosteroids for less than 2 weeks. a History of anaphylactic reaction to eggs. Mild allergy to eggs or allergy to chickens or feathers is not a contraindication. l History of anaphylactic reacdon to topical or systemic neomycin. Contact dermititis from neomycin is not a contraindication. l Serious febrile illness. Mild illness is not a contraindication. l Administration of IG within previous 3 months (IG should not be administered for 2 weeks after measlesvaccine).
client or family. In addition, information on dates and age of vaccination must be reliable. Many clients are unsure of disease or immunization status and cannot provide written documentation. In such cases the health care provider should vaccinate, because revaccination presents no hazards (CDC, 1987b). Persons who may be at greater risk because of age, job, living conditions, or travel plans (see p. 191) should be evaluated and, if indicated, vaccinated. Health care workers, young parents, and college-age
persons may be at risk. Persons traveling to or from an area where measles is endemic or epidemic also are at risk. Another high-risk group are those for whom vaccination is contraindicated (see box above). The close personal contacts of these persons must be vaccinated to reduce potential for infectious contacts. It should be emphasized that recently immunized persons are not communicable and represent no risk to infants or to imnmnocompromised or pregnant women (CDC, 1987b).
192
Volume 3. Number 4 July-August 198Y
Grimes & Woolbert
Because of the severity of measles in infants, implementation of the newest CDC recommendations (see p. 191) for initial vaccination of infants at 9 months of age in endemic areas is vital. Early administration of monovalent measles vaccine does not interfere with the immune response to MMR in 15 month-old infants (CDC, 1989). When a susceptible person is exposed to measles, administration of the standard measles vaccine or IG (see p. 191) may prevent or modify the disease. IG is safe for those for whom the vaccine is contraindicated, including the immunosuppressed. Immunocompromised persons, however, require a larger dose per kilogram of body weight. Correct dosage of IG can be obtained from available references (Benenson, 1985; CDC, 1987b; Committee on Infectious Diseases of the American Academy of Pediatrics, 1986). Certain conditions are sometimes erroneously considered to be contraindications for measles vaccination. A history of febrile convulsions is not a contraindication, although parents of these children should receive special counseling and reassurance. Concurrent administration of other vaccines or previous measles vaccination are not contraindications. Household contact with an imrnunocompromized or pregnant woman is not a contraindication. Active tuberculosis is nut a contraindication for measles vaccination. A tuberculin skin test is not required before vaccination; however, it may be administered simultaneously with the vaccine. If a tuberculin skin test is administered after vaccination, an interval of 4 to 6 weeks should elapse to ensure an accurate test result (CDC, 1987b). Clinics
The clinic environment may actually increase the risk for transmission of measles from persons infected with the measles virus to susceptible patients. To limit transmission, health care workers should suspect measles during phone triage and direct potential case patients to separate waiting and examining areas. If separate facilities are unavailable, the patient with measles (or suspected to have measles) should wear a mask to limit droplet dissemination. Schools
In light of recent knowledge of past vaccination efficacy, school health care providers must reevaluate the school-age population at risk (see p. 190). Many secondary school-age children may never have been immunized because nationwide state laws requiring measles vaccine for school entry were not in place
until 1980 (Gershon, 1985). Others, vaccinated before 1968 or before they were 12 months of age (probably vaccinated before 1976), should be revaccinated immediately. During an outbreak or in endemic areas, students vaccinated before 1980 must be revaccinated according to the recommendations in the box on p. 191. Children should be excluded from school until they show proof of immunity. Unimmunized children, exempt for medical reasons from immunization requirements, should be excluded from school until 2 weeks after the onset of rash in the last measles case in the outbreak (CDC, 1987b). After an infection with measles, asymptomatic students may return to school after the fifth day following the onset of the rash.
C ertain
conditions are sometimes erroneously considered to be contraindications for measles vaccination.
Primary and secondary school health care providers can effectively initiate programs for measles prevention and control by coordinating efforts with school and local communities and the local public health department. An aggressive response to the detection of one case of measles in a school may prevent a larger outbreak. The school nurse can (a) organize a group of volunteers, (b) review all immunization records, (c) contact the local or state health department for guidance, manpower, and vaccine, (d) notify parents of immunization requirements, available clinics, consent forms, information on measles transmission, communicability, symptoms, and indications for measles management, (e) provide public education through the media, (f) coordinate with the health department or organize immunization clinics at the school, and (g) provide written information, available from the health department, on measles and vaccine side effects. Colleges and Universities
Health care providers employed by colleges and universities have responsibility for preventing and controlling measles on campus. This is of particular importance because of the severity of measles and atypical measles in young adults. The task is a challenge because of the size and age of the student body and the difficulty in evaluating those who are susceptible. Inasmuch as most colleges and universities do not require proof of immunization, there is no way to
Journaloi Pediatric
Health Care
identify students at risk during an outbreak. Many students are living away from home and do not have access to immunization records. In addition, those immunized probably received vaccine before I972 and are likely to be at risk for measles (see p. 190). Health profession students have even greater risk because of potential exposure to measles. It is prudent to vaccinate any health profession student not immunized since 1980, regardless of age.
C hildren
should be excluded from school until they show proof of immunity.
Vaccinating an entire university during an outbreak is expensive and time-consuming. The CDC Advisory Committee for Immunization Practices recommends immunization requirements for college entry (CDC, 1987b). In view of recent outbreaks on college campuses, university administrators and health service providers should implement this recommendation immediately. Summary
Despite national programs to eliminate indigenous measles from the United States, serious outbreaks continue. These can be prevented. Persons at risk for measles can be identified and vaccinated or revaccinated. New CDC recommendations have been formulated to control outbreaks in infants and in schooland college-age children. These recommendations should be implemented to control this potentially severe disease. The primary health care provider plays a critical role in measles prevention. Clinic and school settings provide important opportunities to (a) identify the disease when it occurs and prevent transmission to others, (b) evaluate the risk for measles, (c) vaccinate
Measles Outbreaks
193
according to recent CDC recommendations, (d) protect unimmunized susceptible persons from measles, (e) educate the community regarding measles, and (f) coordinate efforts with the schools, the community, and the public health departments for measles prevention. n REFERENCES Benenson, A. (Ed.). (1985). Control of wmmuntiable dtieases in man (14th ed.). Washington, DC: The American Public Health Association. Centers for Disease Control. (1987a, February 6). Measles: Dade County, Florida. IWMWR, 36(4), 45-48. Centers for Disease Control: Recommendations of the Immunization Practices Advisory Committee. (1987b, July 10). Measles prevention. MMWR, 36,(26), 409-418, 423-425. Centers for Disease Control. (1988a, September 2). MeaslesUnited States, 1987. MMWR, 37(34), 527-531. Centers for Disease Control. (1988b, September 16). Sunmary of notifiable diseases-United States, 1987. MMWR, 36(54), 53-59. Centers for Disease Control: Recommendations of the Immunization Practices Advisory Committee. (1989, January 13). Measles prevention: Supplementary statement. MMB’B, 38(l), 11-14. Committee on Infectious Diseases of the American Academy of Pediatrics. (1986). Report of the Committee on Infection Dkemes (20th ed.). Elk Grove Village, IL: American Academy of Pediatrics. Gershon, A. A. (1985). Measles virus (rubeola). In G. L. Mandell, R. G. Douglas, Jr., & J. E. Bennett (Eds.). Principles and practice of infeetiow dbeases (2nd ed., pp. 889-893). New York: John Wiley & Sons. Grimes, D. E. (1985). Infectious diseases. In J. Thompson, G. McFarland, J. Hirsch, S. Tucker, &A. Bowers (Eds.). Clinical nursing (pp. 1465-1627). St. Louis: C. V. Mosby. Reese, R. E., & Douglas, R. G., Jr. (Eds.). (1986). A pmctical approach to infectious d&eases. Boston: Little, Brown & Company. Remington, I’. L., Hall, W. N., Davis, I. H., Herald, A., & Gunn, R. A. (1985). Airborne transmission of measlesin a physician’s office. JAMA, 253, 1574-1577. Sienko, D. G., Friedman, C., McGee, H. B., Allen, M. J., Simonsen, W. F., Wentworth, B. B., Shope, T. C., & Orenstein, W. A. (1987). A measles outbreak at university medical settings involving health care providers. American Journal ofPublic Health, 77, 1222- 1224.
Measles Outbreaks: Who Are at Risk and Why
Deanna E. Grimes, DrPH, RN, and Lynda F. Woolbert,
n
MSN, RN, CPNP
After the introduction of measles vaccine in the United States in 1963 the reported incidence of measles (rubeola) decreased substantially. The disease, however, has not been eliminated. Since 1983, when the lowest number of cases was reported, slight increases in incidence have been observed. Outbreaks are occurring among previously immunized school- and college-age children and unimmunized preschool children and infants. This article describes measles occurrence, transmission, diagnosis, development measles immunity, the 1989 Centers for Disease Control recommendations for immunization, and implications for health care providers for preventing measles outbreaks. j PEDIATR HEALTH CARE. (1989). 3, 187-l 93.
B
etween early October 1988 and early April 1989 local health officials conf!irmed more than 1450 cases of measles in Houston and in Harris County, Texas. This area reported no more than 81 cases per year throughout the 1980s. The casesoccurred in persons who ranged in age from younger than 1 year to older than 20 years. Authorities have confirmed seven deaths from complications of measles, including the deaths of a 27-year-old woman and a 13-month-old male infant (M. Canfield, ChiefEpidemiologist, Harris County Health Department, personal communication, April 3, 1989). By early April there was no sign that the outbreak was abating. Measles (rubeola, hard measles, lo-day or red measles) is an acute, highly communicable viral disease. Although measles is generally self-limiting, the disease can be particularly severe in infants younger than 2 years of age, in chronically ill children, and in undernourished children and adults. Measles can produce severe respiratory and neurologic complications as a result of viral replication and dissemination and/or bacterial superinfection. Complications include pneumonia, otitis media, encephalitis ( 1 in 2000 cases), and permanent brain damage. One rare complication, subacute sclerosing panencephalitis, a chronic degenerative neurologic disease, causes intellectual deterioration in children several years after an attack of measles in infancy. Maternal measles Deanna E. Grimes is Clinical Assistant Professor at the University Health Science Center at Houston, School of Nursing. Lynda F. Woolbert is an instructor at the University Center at Houston, School of Nursing.
of Texas
OF
PEDIATRIC
HEALTH
CARE
infection at any time during pregnancy increases the risk of spontaneous abortion, premature labor, and low birth weight. Death occurs in 1 in 3000 cases among persons of aU ages and in 1 in 1000 cases among high-risk infants (Benenson, 1985; Centers for Disease Control [CDC], 1987b). Measles is more than a simple, benign childhood disease.
early October 1988 and early BApriletween 1989 local health officials confirmed more than 1450 cases of measles in Houston and in Harris County, Texas.
Between 1938 and the licensing of measles vaccine in 1963 the annual number of reported cases in the United States ranged from approximately 400,000 to 900,000 (CDC, 1988b). By 1983 widespread immunization of infants and children resulted in a 99% decrease in the incidence of measles. A low incidence of 1497 cases was reported in that year. Since then outbreaks among previously immunized school-age children, young adults, and unimmunized preschool children and infants increased the yearly incidence (CDC, 1989). This article reviews trends in measles occurrence, measles transmission and diagnosis, development of measles immunity, recommendations for vaccination, and implications for clinic and school health care providers for the prevention of measles.
of Texas Health Science
Reprint requests: Deanna E. Grimes, DrPH, RN, Clinical Assistant Professor, University of Texas Health Science Center at Houston, School of Nursing, 1100 Holcombe Blvd., Houston, TX 77030. JOURNAL
of
n
TRENDS IN OCCURRENCE
Before widespread vaccination very few persons escaped contact with measles. More than 90% of the 187
188
Grimes
Volume 3, Number 4 July-August 1989
& Woolbert
population had the disease before their twentieth birthday, usually in early childhood. The disease was endemic everywhere, becoming epidemic every 2 to 3 years. Outbreaks were seasonal, with the greatest number of cases clustered in the late winter and early spring months (Benenson, 1985; Gershon, 1985). The present pattern of occurrence is illustrated by means of the 1987 CDC data (CDC, 1988a). In 1987, 3655 cases of measles and four deaths from it were reported. The deaths occurred in immunocompromised persons, two of whom were children with acquired immunodeficiency syndrome (AIDS). Although the nationwide cases peaked during early spring, some local outbreaks occurred during other times of the year (CDC, 1987a).
T
he disease was endemic everywhere, becoming epidemic every 2 to 3 years.
The cases in 1987 were concentrated in specific states and counties. Three fourths of the cases were from New York City and seven states: California, Texas, New Mexico, Illinois, Missouri, New Hampshire, and Wisconsin. The majority of measles cases were in the older age-groups. Nineteen percent of the total cases occurred in children 10 to 14 years of age; 29% were between 15 and 19 years old. Thirteen percent of reported cases occurred in persons older than 20 years of age. Most of the 1987 caseswere contracted in primary or secondary schools, medical settings, and colleges or universities. Some documented transmission occurred by indirect contact in health care settings and through contact with unimmunized health care providers (Remington, Hall, Davis, Herald, & Gunn, 1985; Sienko et al., 1987). Fewer than 30% of the 1987 cases were classified as preventable, according to CDC criteria (unvaccinated persons for whom vaccine is indicated by current recommendations). In contrast, 72% of the cases were classified as nonpreventable. This category includes persons born before 1957, those with a history of measles disease, persons adequately immunized, infants younger than 16 months of age, or persons exempt from vaccination for medical or religious reasons. The vast majority of these nonpreventable cases in 1987 occurred in school- and college-age persons who had been vaccinated after their first birthday. A review of measles transmission, diagnosis, immunity, and vaccination explains why these persons are at risk.
n
TRANSMISSION
The etiologic agent for measles is a virus that is present in the blood, urine, and pharyngeal secretions of infected persons. The virus can remain infective in aerosol&d mucous droplet form for several hours in conditions of low humidity. Thus transmission occurs indirectly as well as by direct contact with respiratory droplets (Gershon, 1985). Once transmitted, the virus invades the respiratory epithelium where it incubates and multiplies. The virus is then disseminated by way of the lymph system through the respiratory mucosa and to the blood, producing catarrhal symptoms and high fever within 8 to 13 days of initial viral contact. These symptoms herald the prodrome. Further viral dissemination and activity result in generalized involvement of the respiratory tract, buccal mucosa, and dermis. The characteristic measles rash appears within another 4 days. Transmission may occur before onset of the prodromal fever until approximately 4 days after onset of the rash, although it is less likely after the second day of rash (Benenson, 1985). The stages of infection and communicability are summarized in Figure 1. n
DIAGNOSIS
Measles frequently remains undiagnosed through the period of greatest communicability. The clinical manifestations of the disease during the prodrome are a moderate to severe upper respiratory tract infection with a characteristic photophobia and conjunctivitis. The diagnostic Koplik’s spots appear briefly before onset of the maculopapular rash on the fourth day. Except during times of known outbreaks, health care providers may not associate prodromal symptoms with measles, especially when the patient has been previously vaccinated.
T
he majority of measles cases were in the older age-groups.
Measles has three possible presentations: typical (previously described), modified, and atypical. The milder, modified disease results from exposure to the measles virus after injection of measles immune globulin (IG) or live attenuated vaccine/IG combination. This presentation may not include some of the classic signs of measles. Atypical measles may occur in persons who are vaccinated with the killed vaccine (available from 1963 to 1967) or the killed vaccine fol-
Journalof Pediatric
Health
Measles Outbreaks
Care
189
Incubation Period
n
FIGURE 1 Stages of infection
lowed by the live vaccine within 3 months (CDC, 1987b). Atypical measles has an unusual and severe course, with nausea, vomiting, headache, myalgia, sore throat, fever, nonproductive cough, and photophobia. Conjunctivitis and rash may not be present. The distribution and progression of the rash, when it occurs, often resemble those of Rocky Mountain spotted fever. Occasionally, the rash progresses to a vesicular stage and is misdiagnosed as chickenpox. Pulmonary involvement is frequent and severe (Reese & Douglas, 1986). Confirmed measles cases must be reported to the local health department. Measles cases are confirmed on the basis of clinical or laboratory evidence. Laboratory testing is expensive and not routinely performed. Two laboratory tests are used more commonly than others; however, accurate interpretation depends on timing of the test during the disease course (Gershon, 1985). The complement fixation detects short-lasting antibodies that appear during the time of the rash. Hemagglutination inhibition detects long-lasting antibodies. A fourfold increase in antibody titer between the acute and convalescent stage is diagnostic (Grimes, 1985). n
and communicability
of measles
measles antibodies have immunity until they are 6 to 9 months of age. If vaccinated while retaining maternal antibodies, the infant will not produce longerlasting immunity (Benenson, 1985). In like manner, antibodies received in IG interfere with vaccineinduced antibody production. Measles vaccine type has changed several times. In 1963 two types of vaccine (a killed virus vaccine and live, attenuated Edmondston B strain vaccine) were licensed for use. The killed virus vaccine was administered until 1967 (1969 in Canada) and discontinued because it induced only short-term immunity. The Edmondston B strain vaccine was used until 1972. Because of its side effects, it was frequently administered with IG, later found to interfere with effective antibody production. Two other live virus vaccines, which caused fewer side effects, were introduced in 1965 (Schwarz strain) and in 1968 (Moraten strain). The Moraten vaccine is currently used in the United States (CDC, 1987b).
C onfirmed
measles cases must be reported to the local health department.
DEVELOPMENT OF MEASLES IMMUNITY
Measles immunity develops in one of three ways. One, a person with a normal immune system who acquires measles disease produces permanent measles antibodies during the period of the rash. Second, effective artificial vaccination with the measles virus induces a mild or inapparent, vwnummunicable infection that stimulates antibody production. It is believed these antibody titers do not decrease with time (CDC, 1987b). Third, a person receives temporary antibodies through congenital transfer or administration of IG. Infants who are born of mothers with
The recommended age for immunization also changed several times as evidence emerged that maternal antibodies interfered with vaccination effectiveness. In 1965 the recommended age was changed from 9 months to 12 months, and in 1976 it was changed to 15 months. Children vaccinated between 12 and 15 months of age, however, have seroconversion rates of 80% to 95%, are considered immune, and are not routinely revaccinated (CDC, 1987b).
190
Volume 3. Number 4 July-August 1989
Grimes & Woolbert
Live measles virus vaccine is available in the measles-only form and in combinations of measles and rubella (MR) and measles, mumps, and rubella (MMR). MMR can be safely and effectively administered to persons previously vaccinated with any of the component vaccines or concurrently with other live virus vaccines (CDC, 1987b). In 1980 a stabilizer was added to measles vaccine after the discovery of deactivation of improperly stored vaccine. Although the vaccine used today is more thermostable, the temperature still must be carefully controlled to prevent deactivation of the virus. Before reconstitution the vaccine must be kept frozen. Reconstituted vaccines must be refrigerated, protected from light, and discarded after 8 hours (Benenson, 1985). On the basis of the characteristics of measles immunity, the history of vaccine use, and the characteristics of the vaccine, certain persons are likely to be at risk for measles despite previous vaccination. Others can be considered to be immune. Persons considered to be immune by CDC and those considered to be at risk are listed in the boxed material above.
. RECOMMENDATIONS MEASLES VACCINATION
FOR
As a result of recent measles outbreak the Immunization Practices Advisory Committee of the CDC recently issued changes in the vaccination schedule and outbreak control. The current 1989 recommendations for measles vaccination, vaccine precautions, and contraindications are presented in the boxed material on p. 191. . MEASLES PREVENTION: IMPLICATIONS HEALTH CARE PROVIDERS
FOR
The long period of communicability, ease of transmission, and difliculty of initial diagnosis make measles difficult to control in susceptible populations. The best strategy for control and elimination of measles is an adequately immunized population. Health care providers have a responsibility to identify and vaccinate persons at risk. Determining risk and need for vaccination (see above) requires eliciting accurate historic information regarding disease and vaccination. To avoid error the health care provider must clarify the distinction between measles (rubeola) and rubella for the
lournal 0i Pediatric Health Care
Measles
1989 ~CO~~A~ONS
Outbreaks
191
FOR AtiENGES VACCXNATION
In mm w&h marremit meArj[es t?wmkdm (wunties with mm tt!fm$ve cmestztnimgpres~ool cliilhn) (CDC, 1989) a Administer live measles vaccine on a two-dose schedule: first dose of monovalent vaccine at 9 months followed by one dose of MMR at 15 months or n If two-dose schedule is impractical, administer MMR routinety at 12 months of age.
n
Revaccinate all students and their siblings who received their most recent vaccination before 1980, giving priority to those who were vaccinated before age 15 months.
Wnebfi~eedearlier Y Vaccinate with MMR all asymtomatic children infected with human immtmodeficiency virus (CDC, 1988a). l Administer measlesvaccine to a susceptible person within 72 hours of exposure to measles. . Administer IG to susceptible persons within 6 days of exposure to measles. This includes immunocompromised persons, pregnant women, or infants under 1 year of age. If not contraindicated, mea&s vaccine should be administered 3 months after IG to persons older than 15 months of age. g Administer vaccine at least 2 weeks before administration of IG for foreign travel. e Vaccinate household contacts of any person for whom the vaccine is contraindicated, thus reducing risk of exposure to the disease(CDC, 1987b). l
Theji%w& preaaabns and wm?mb&#Gns to nax&tti~ remain in efect: = Pregnancy or anticipated pregnancy within 3 months (based on a theoretic, undocumented risk of fetal section) . Immunosuppression as a result of leukemia, lymphoma, generalized malignancy, therapies (with systemic or topical carticosteroids, alkylating drugs, antimetabolites, or radiation), The vaccine, however, is not contraimiicated for personswith asymptomatic human immunod~ency virus infection, AIDS, leukemia in remission, and chemotherapy terminated for 3 months, or for those receiving corticosteroids for less than 2 weeks. a History of anaphylactic reaction to eggs. Mild allergy to eggs or allergy to chickens or feathers is not a contraindication. l History of anaphylactic reacdon to topical or systemic neomycin. Contact dermititis from neomycin is not a contraindication. l Serious febrile illness. Mild illness is not a contraindication. l Administration of IG within previous 3 months (IG should not be administered for 2 weeks after measlesvaccine).
client or family. In addition, information on dates and age of vaccination must be reliable. Many clients are unsure of disease or immunization status and cannot provide written documentation. In such cases the health care provider should vaccinate, because revaccination presents no hazards (CDC, 1987b). Persons who may be at greater risk because of age, job, living conditions, or travel plans (see p. 191) should be evaluated and, if indicated, vaccinated. Health care workers, young parents, and college-age
persons may be at risk. Persons traveling to or from an area where measles is endemic or epidemic also are at risk. Another high-risk group are those for whom vaccination is contraindicated (see box above). The close personal contacts of these persons must be vaccinated to reduce potential for infectious contacts. It should be emphasized that recently immunized persons are not communicable and represent no risk to infants or to imnmnocompromised or pregnant women (CDC, 1987b).
192
Volume 3. Number 4 July-August 198Y
Grimes & Woolbert
Because of the severity of measles in infants, implementation of the newest CDC recommendations (see p. 191) for initial vaccination of infants at 9 months of age in endemic areas is vital. Early administration of monovalent measles vaccine does not interfere with the immune response to MMR in 15 month-old infants (CDC, 1989). When a susceptible person is exposed to measles, administration of the standard measles vaccine or IG (see p. 191) may prevent or modify the disease. IG is safe for those for whom the vaccine is contraindicated, including the immunosuppressed. Immunocompromised persons, however, require a larger dose per kilogram of body weight. Correct dosage of IG can be obtained from available references (Benenson, 1985; CDC, 1987b; Committee on Infectious Diseases of the American Academy of Pediatrics, 1986). Certain conditions are sometimes erroneously considered to be contraindications for measles vaccination. A history of febrile convulsions is not a contraindication, although parents of these children should receive special counseling and reassurance. Concurrent administration of other vaccines or previous measles vaccination are not contraindications. Household contact with an imrnunocompromized or pregnant woman is not a contraindication. Active tuberculosis is nut a contraindication for measles vaccination. A tuberculin skin test is not required before vaccination; however, it may be administered simultaneously with the vaccine. If a tuberculin skin test is administered after vaccination, an interval of 4 to 6 weeks should elapse to ensure an accurate test result (CDC, 1987b). Clinics
The clinic environment may actually increase the risk for transmission of measles from persons infected with the measles virus to susceptible patients. To limit transmission, health care workers should suspect measles during phone triage and direct potential case patients to separate waiting and examining areas. If separate facilities are unavailable, the patient with measles (or suspected to have measles) should wear a mask to limit droplet dissemination. Schools
In light of recent knowledge of past vaccination efficacy, school health care providers must reevaluate the school-age population at risk (see p. 190). Many secondary school-age children may never have been immunized because nationwide state laws requiring measles vaccine for school entry were not in place
until 1980 (Gershon, 1985). Others, vaccinated before 1968 or before they were 12 months of age (probably vaccinated before 1976), should be revaccinated immediately. During an outbreak or in endemic areas, students vaccinated before 1980 must be revaccinated according to the recommendations in the box on p. 191. Children should be excluded from school until they show proof of immunity. Unimmunized children, exempt for medical reasons from immunization requirements, should be excluded from school until 2 weeks after the onset of rash in the last measles case in the outbreak (CDC, 1987b). After an infection with measles, asymptomatic students may return to school after the fifth day following the onset of the rash.
C ertain
conditions are sometimes erroneously considered to be contraindications for measles vaccination.
Primary and secondary school health care providers can effectively initiate programs for measles prevention and control by coordinating efforts with school and local communities and the local public health department. An aggressive response to the detection of one case of measles in a school may prevent a larger outbreak. The school nurse can (a) organize a group of volunteers, (b) review all immunization records, (c) contact the local or state health department for guidance, manpower, and vaccine, (d) notify parents of immunization requirements, available clinics, consent forms, information on measles transmission, communicability, symptoms, and indications for measles management, (e) provide public education through the media, (f) coordinate with the health department or organize immunization clinics at the school, and (g) provide written information, available from the health department, on measles and vaccine side effects. Colleges and Universities
Health care providers employed by colleges and universities have responsibility for preventing and controlling measles on campus. This is of particular importance because of the severity of measles and atypical measles in young adults. The task is a challenge because of the size and age of the student body and the difficulty in evaluating those who are susceptible. Inasmuch as most colleges and universities do not require proof of immunization, there is no way to
Journaloi Pediatric
Health Care
identify students at risk during an outbreak. Many students are living away from home and do not have access to immunization records. In addition, those immunized probably received vaccine before I972 and are likely to be at risk for measles (see p. 190). Health profession students have even greater risk because of potential exposure to measles. It is prudent to vaccinate any health profession student not immunized since 1980, regardless of age.
C hildren
should be excluded from school until they show proof of immunity.
Vaccinating an entire university during an outbreak is expensive and time-consuming. The CDC Advisory Committee for Immunization Practices recommends immunization requirements for college entry (CDC, 1987b). In view of recent outbreaks on college campuses, university administrators and health service providers should implement this recommendation immediately. Summary
Despite national programs to eliminate indigenous measles from the United States, serious outbreaks continue. These can be prevented. Persons at risk for measles can be identified and vaccinated or revaccinated. New CDC recommendations have been formulated to control outbreaks in infants and in schooland college-age children. These recommendations should be implemented to control this potentially severe disease. The primary health care provider plays a critical role in measles prevention. Clinic and school settings provide important opportunities to (a) identify the disease when it occurs and prevent transmission to others, (b) evaluate the risk for measles, (c) vaccinate
Measles Outbreaks
193
according to recent CDC recommendations, (d) protect unimmunized susceptible persons from measles, (e) educate the community regarding measles, and (f) coordinate efforts with the schools, the community, and the public health departments for measles prevention. n REFERENCES Benenson, A. (Ed.). (1985). Control of wmmuntiable dtieases in man (14th ed.). Washington, DC: The American Public Health Association. Centers for Disease Control. (1987a, February 6). Measles: Dade County, Florida. IWMWR, 36(4), 45-48. Centers for Disease Control: Recommendations of the Immunization Practices Advisory Committee. (1987b, July 10). Measles prevention. MMWR, 36,(26), 409-418, 423-425. Centers for Disease Control. (1988a, September 2). MeaslesUnited States, 1987. MMWR, 37(34), 527-531. Centers for Disease Control. (1988b, September 16). Sunmary of notifiable diseases-United States, 1987. MMWR, 36(54), 53-59. Centers for Disease Control: Recommendations of the Immunization Practices Advisory Committee. (1989, January 13). Measles prevention: Supplementary statement. MMB’B, 38(l), 11-14. Committee on Infectious Diseases of the American Academy of Pediatrics. (1986). Report of the Committee on Infection Dkemes (20th ed.). Elk Grove Village, IL: American Academy of Pediatrics. Gershon, A. A. (1985). Measles virus (rubeola). In G. L. Mandell, R. G. Douglas, Jr., & J. E. Bennett (Eds.). Principles and practice of infeetiow dbeases (2nd ed., pp. 889-893). New York: John Wiley & Sons. Grimes, D. E. (1985). Infectious diseases. In J. Thompson, G. McFarland, J. Hirsch, S. Tucker, &A. Bowers (Eds.). Clinical nursing (pp. 1465-1627). St. Louis: C. V. Mosby. Reese, R. E., & Douglas, R. G., Jr. (Eds.). (1986). A pmctical approach to infectious d&eases. Boston: Little, Brown & Company. Remington, I’. L., Hall, W. N., Davis, I. H., Herald, A., & Gunn, R. A. (1985). Airborne transmission of measlesin a physician’s office. JAMA, 253, 1574-1577. Sienko, D. G., Friedman, C., McGee, H. B., Allen, M. J., Simonsen, W. F., Wentworth, B. B., Shope, T. C., & Orenstein, W. A. (1987). A measles outbreak at university medical settings involving health care providers. American Journal ofPublic Health, 77, 1222- 1224.