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Public Health Agency of Canada (PHAC)
Canada Communicable Disease Report

Volume 25-24
15 December 1999

[Table of Contents]

  

Appendix E - Measles Surveillance: Guidelines for Laboratory Support

CURRENT RECOMMENDATIONS REGARDING COMMERCIAL MEASLES IgM SEROLOGY TEST KITS

The laboratory subcommittee of the WGMEC recently completed a study on the relative performance of indirect measles IgM enzyme immunoassays (EIAs) and IgM capture assays using a total of 308 serum samples from confirmed measles outbreak cases and 454 samples from non-measles cases(2). This evaluation included the Behring, Clark, Gull, and PanBio EIAs and a commercial IgM capture assay (Light Diagnostics) along with the CDC measles IgM capture assay. Overall, the Gull and Behring EIAs (sensitivity: 88.3%, 88.6%; specificity: 99.6%, 96.7%; positive predictive value: 99.6%, 97.8%; negative predictive value: 93.0%, 94.6%, respectively) were found to be the best commercial kits for measles IgM serology. The CDC measles IgM capture assay was also found to be highly sensitive and specific. The CDC measles IgM capture procedure is available at the LCDC. Based on this data, the WGMEC currently recommends the use of either the Gull or Behring commercial EIAs for measles IgM serology.

The timing of the specimen collection was an important criterion for IgM seropositivity regardless of the test used, and the best seropositivity rates in the range of 92% to 100% were observed with samples collected 6 to 14 days after the onset of symptoms. Sera positive for other IgM markers such as rubella, parvovirus B19, EBV, and HHV-6, etc. gave false positive reactions in some of the assays including the capture assays.

Table 1 Relative sensitivity, specificity, and predictive value of measles IgM tests

 

Behring

Clark

Gull

PanBio

Light Diagnostics

CDC

Sensitivity(a)

88.6%
(85.1-92.1)(b)

82.8%
(76.6-87.0)

88.3%
(84.7-91.9)

83.1%
(78.9-87.3)

92.2%
(89.2-95.2)

87.0%
(82.3-91.7)

Specificity(c)

96.7%
(95.1-98.3)

97.1%
(95.6-98.6)

99.6%
(99.0-100)

86.6%
(83.5-89.7)

86.6%
(83.5-89.7)

94.8%
(92.4-96.8)

Positive predictive value

97.8%
(96.1-99.5)

95.9%
(93.5-98.3)

99.6%
(98.9-100)

97.7%
(95.9-99.5)

88.2%
(84.7-91.7)

96.1%
(93.3-98.9)

Negative predictive value

94.6%
(92.5-96.7)

90.2%
(87.6-92.8)

93.0%
(90.7-95.3)

91.4%
(88.8-94.0)

95.9%
(94.0-97.8)

95.7%
(93.5-97.5)

(a) Based on a total of 308 samples tested except the CDC capture assay which was tested with 200 samples.

(b) 95% confidence interval.

(c) Based on a total of 454 samples tested except the CDC capture assay which was tested with 423 samples.

 

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