Robert W. Amler

Evaluation of the Measles Clinical Case Definition

An accurate system of identifying and classifying suspected measles cases is critical for the measles surveillance system in the United States. To examine the performance of the clinical case definition in predicting laboratory confirmation of suspected cases of measles, we reviewed 4 studies conducted between 1981 and 1994. A clinical case definition was examined that included a generalized maculopapular rash, fever (>or=38.3 degrees C, if measured), and either a cough, coryza, or conjunctivitis. Serological confirmation of measles was done either by hemagglutination inhibition assay, complement fixation assay, or enzyme immunoassays. The positive predictive value of the clinical case definition decreased from 74% to 1% as incidence decreased from 171 cases/100000 population to 1.3 cases/100000 population. Sensitivity was high, and for the larger studies with the most precise estimates, sensitivity was 76%-88%. The low positive predictive value of the clinical case definition in settings of low incidence demonstrates that serological confirmation is essential to ensure an accurate diagnosis of measles when measles is rare.

Measles seroconfirmation using dried capillary blood specimens in filter paper.

Because the incidence of measles has declined in recent years, the potential for confusion of measles with other morbilliform rashes has increased. Routine serologic testing of suspected cases of measles is recommended but it has been hampered, particularly in young infants and children, by the requirement of performing venipuncture. We have compared measles hemagglutination inhibition antibody testing performed on dried capillary whole blood collected on filter paper strips with testing of serum specimens obtained simultaneously by venipuncture. We assessed overall comparability, diagnostic sensitivity and specificity and acceptability and practicality for field use. Of the 125 capillary-venous sets compared, there was a 4-fold difference in hemagglutination inhibition titer between the two types of specimens in only one set (0.8%). Diagnostic sensitivity using capillary blood was 100% and specificity was 96%. Immunoglobulin M assessments on six capillary-venous sets were in complete agreement (three positive in both, three negative in both). In a pilot program of field use, filter paper blood collection was associated with a 97% (36 of 37) success rate in obtaining specimens from individuals with suspected cases of measles. This method of blood collection and testing is an accurate, feasible and acceptable means for seroconfirmation of measles.

Measles on Campus

Abstract Campus outbreaks and campus-associated cases together accounted for 51.1% of all reported measles cases in the first 26 weeks of 1983. This proportion is of particular concern because measles is a more serious disease in adults than in schoolchildren. For a substantial number of highly mobile young adults, college may be the last opportunity to ensure protection against measles and other preventable infections. Unfortunately, immunization levels on campuses are difficult to assess because very few institutions require immunization records. Nevertheless, colleges and universities have an obligation to their students to provide a safe and healthy learning environment; they also have a need to avoid costly and disruptive outbreaks on their campuses. To break the remaining chains of measles transmission on campus, colleges and universities should require all students born after 1956 to present a complete and up-to-date immunization record for matriculation and registration. Incoming freshmen should b...

Measles in young adults: The case for vigorous pursuit of immunization

Although the incidence of measles has reached record low levels in the United States, measles continues to occur in young adults. No single public health measure can ensure immunity for young adults, as school immunization laws do for young children. Therefore, to eliminate measles in this age-group, clinicians must take the initiative to vaccinate or revaccinate patients. To facilitate containment of outbreaks of measles, clinicians should include measles in the differential diagnosis of any illness characterized by fever and a generalized rash and should promptly report these cases as suspected measles to local health departments, without waiting for laboratory confirmation. If the suspected case is indeed measles, a significant outbreak could be avoided long before the first laboratory results are known.