Salivary diagnosis of measles: a study of notified cases in the United Kingdom, 1991-3

Abstract

Objectives-To validate a method for salivary diagnosis of measles and to assess the diagnostic accuracy ofnotified cases ofmeasles.Design-Blood and saliva samples were collected within 90 Conclusions-The existing national surveillance system for measles, which relies on clinically diagnosed cases, lacks the precision required for effective disease control. Saliva is a valid alternative to serum for IgM detection, and salivary diagnosis could play a major role in achieving measles elimination. Rubella and parvovirus B19 seem to be responsible for a minority of incorrectly diagnosed cases of measles in the United Kingdom and other infectious causes of measles-like illness need to be sought.

A school outbreak of parvovirus B19 infection investigated using salivary antibody assays

“…This is reminiscent of a previous study using saliva to diagnose measles where only a minority of the rash illness reported as measles could be confirmed by the average II days after onset. As expected, during an laboratory [3], illustrating the inaccuracy of clinical diagnosis of childhood exanthems. Assays for B19 infection should, therefore, be included in the surveillance of measles and rubella based on salivary testing.…”

“…Saliva was collected with a specially designed foam swab by wiping the swab along the gingival margin as described previously [3]. Fluid collected by this method, although referred to as saliva, is actually a transudate of plasma proteins and therefore reflects antibody responses in blood [4].…”

Predicting the impact of measles vaccination in England and Wales: model validation and analysis of policy options

“…The value of this vaccine efficacy, p, is set at 90 %. This is at the lower limit of most published estimates, which are based upon clinical diagnosis [25] [15,26,27]. The proportion of susceptibles who, following vaccination, remain able to transmit the infection, 1-p, enter the vaccine failure class, Xv (Fig.…”

“…In 1991 the model significantly underestimates cases in children of less than 2 years of age. However, some of this discrepancy can be accounted for by age-related inaccuracy in clinical diagnosis recently identified by a PHLS study [15]. Whilst it is probable that there has always been a level of misdiagnosis in reported cases which is biased towards the youngest age classes, its importance will have increased with the decline in the circulation of measles accompanying high MMR vaccine coverage, and with the sporadic nature of measles infection.…”

“…Specifically, for measles, a set of age-stratified notification data has accumulated since the introduction of national vaccination in 1968 by which to validate model predictions. Unfortunately, notification data is of questionable reliability due to, for example, age-specific bias in reporting [14], and alteration in the efficiency of reporting following the introduction of mass vaccination and the proportion of cases misdiagnosed [15].…”