Adaptation of a commercially available indirect fluorescent antibody slide test for measuring measles-specific immunoglobulins

Detection of IgM antibodies specific for measles virus by capture and indirect enzyme immunoassays

During a measles outbreak, 112 serum specimens from 88 hospitalized patients were received in our laboratory for investigation of a morbilliform rash. These specimens (88 acute- and 24 convalescent-phase) were tested for the presence of measles-specific IgM antibodies by a capture EIA (enzyme immunoassay) using peroxidase-conjugated measles virus antigens and by an indirect EIA. Commercially available indirect EIA kits for measles-specific IgM antibodies were also used and compared with our homemade EIAs. Specificity studies included a collection of serum specimens containing rheumatoid factor, antinuclear antibodies or IgM antibodies specific to other viruses, and sera from blood donors and healthy children. Sensitivity of capture EIA and indirect EIA to detect measles IgM was 91.8 and 90.3%, respectively, and specificity was 98.2% for both tests. Specific IgM antibodies were detected in 70.5% of serum specimens at the first day after rash onset and were present for a month following the rash. Among the commercial measles IgM detection assays, EIA "Behring" was found to be a valid alternative for detection of measles virus-specific IgM.

Comparison of the MEASLESTAT M test kit with the sucrose density gradient centrifugation-hemagglutination inhibition method for detection of measles virus-specific immunoglobulin M

A new commercial kit, MEASLESTAT M (Whittaker Bioproducts, Inc.), was compared with the sucrose density gradient centrifugation-hemagglutination inhibition method for the detection of measles virus-specific immunoglobulin M. Overall agreement between the two procedures was 97.1% for 104 single and paired serum samples tested. The sensitivity and specificity of MEASLESTAT M were 98.4 and 95.2%, respectively.

Evaluation of a commercial measles virus immunoglobulin M enzyme immunoassay

Paired serum samples from 93 patients suspected of having measles were assayed for measles virus-specific immunoglobulin M (IgM) antibodies by an enzyme immunoassay (EIA), and the results were compared with results from a complement fixation assay and an EIA for measles virus IgG. By using significant serologic rises as the standard for comparison, the IgM EIA assay had a sensitivity of 85.7%, a specificity of 81.3%, a positive predictive value of 95.7%, and a negative predictive value of 54.2%. This assay can be expected to perform well in outbreak situations.

Comparison of immunofluorescence and enzyme immunoassay for detection of measles-specific immunoglobulin M antibody

During a measles outbreak, 283 serum specimens from 221 suspected cases of measles were tested by immunofluorescence and enzyme immunoassay for the presence of measles-specific immunoglobulin M (IgM) antibodies by using commercially available reagents. There was 97% agreement between the two assays; thus, the choice of the method for diagnostic testing is a matter of convenience and experience. In all 62 cases of measles from which a single blood sample was available, measles IgM-specific antibodies were detectable by both methods. Fifty percent of the 62 cases were positive within 3 days after onset of the rash. This increased to 91% 10 days after onset of the rash.

Seroconversion after administration of measles vaccine to central Australian Aboriginal children at nine months of age

A simple procedure for examining the seroconversion rates to measles vaccines in outlying communities is described; this involves the storage and transportation of dried-blood samples on filter paper, which is followed by the detection of measles-specific antibodies by means of a commercially-available immunofluorescence assay. Among 82 susceptible central Australian Aboriginal infants who were vaccinated at nine months of age, 76 (93% [95% confidence limits, 84.9%-96.6%]) children demonstrated seroconversion as a result of the vaccine, which is a figure that is similar to those that have been reported from some developing countries. The implications for a measles-vaccination policy are discussed.