SALIVARY DIAGNOSIS OF MEASLES - A STUDY OF NOTIFIED CASES IN THE UNITED-KINGDOM, 1991-3

Objectives-To validate a method for salivary diagnosis of measles and to assess the diagnostic accuracy of notified cases of measles. Design -Blood and saliva samples were collected within 90 days of onset of sy mptoms from patients clinically diagnosed as having measles and tested for specific IgM by antibody capture radioimmunoassay. Setting-17 dis tricts in England and one in southern Ireland during August 1991 to Fe bruary 1993. Subjects-236 children and adults with measles notified by a general practitioner. Results-Specific IgM was detected in serum in only 85 (36%) of the 236 cases.In cases associated with outbreaks and tested within six weeks of onset, 53/57 (93%) of samples were IgM pos itive, thereby confirming the sensitivity of serum IgM detection as a marker of recent infection. The serological confirmation rate was lowe r in cases with a documented history of vaccination (13/87; 15%) than in those without (70/149; 47%) and varied with age, being lowest in pa tients under a year, of whom only 4/36 (11%) were confirmed. Measles s pecific IgM was detected in 71/77 (92%) of adequate saliva samples col lected from patients with serum positive for IgM. In cases where measl es was not confirmed, 6/101 had rubella specific IgM and 5/132 had hum an parvovirus B19 specific IgM detected in serum. Conclusions-The exis ting national surveillance system for measles, which relies on clinica lly diagnosed cases, lacks the precision required for effective diseas e control. Saliva is a valid alternative to serum for IgM detection, a nd salivary diagnosis could play a major role in achieving measles eli mination. Rubella and parvovirus B19 seem to be responsible for a mino rity of incorrectlydiagnosed cases of measles in the United Kingdom an d other infectious causes of measles-like illness need to be sought.