Immunoassay for Glandular Fever Is Preferable to Leukocyte Ratio

An immunoassay for the detection of infectious mononucleosis heterophile antibodies in whole blood was compared with the ratio of lymphocytes to white cells as diagnostic tests.

The immunoassay was a qualitative membrane strip wherein bovine erythrocyte extracted antigen is coated on the test line region of the strip. The lymphocyte counts and white blood cell ratio was calculated and compared with the monospot result to calculate the sensitivity and specificity at various ratios.

Investigators at the Mater Misericordiae University Hospital, (Dublin, Ireland), analyzed 500 positive and 500 negative monospot tests for glandular fever using "Clearview IM" detection kits (Alere Limited, Stockport, UK). These results were compared with the white cell count differentials and specifically the ratio of lymphocytes to total white cell count. The lymphocyte counts and white blood cell ratio was significantly different in the positive and negative monospot groups. The mean lymphocyte counts to white blood cell ratio in the positive group was 0.49, and the mean lymphocyte to white cell count ratio in the monospot negative group was 0.29.

The authors concluded that there is a significant difference between the lymphocyte count in patients with infectious mononucleosis and those with negative monospot tests. An increased lymphocyte count is associated with a positive monospot results and using a lymphocyte to white cell count ratio of 0.35 or greater had a specificity of 72% a sensitivity of 84% for the detection of glandular fever. A higher ratio will give a greater specificity, but a lower sensitivity, and vice versa. The study was published online in November 2010, in the journal Clinical Otolaryngology.

Glandular fever or infectious mononucleosis is caused by an infection with the Epstein-Barr virus and is characterized by fever, sore throat, and fatigue, along with several other possible signs and symptoms. The peak incidence for the onset of glandular fever is between the ages of 15 and 17 and it is estimated that 90% of adults have been exposed to the virus.

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Mater Misericordiae University Hospital
Alere Limited