From: Sebastiana <pienaar@omen.net.au>

So measles 'in the old days' is now not measles. So how do we know how well the vaccine has worked?

http://www.ozdoctor.com.au/

Australian Doctor

The Independent Weekly Newspaper for Australian GPs
                                               18 Febuary 2000


 Measles diagnosis unreliable
 By Helen Francombe

 MJA Only about one in 20 clinical measles diagnoses are actually correct now
 that the disease has become so rare, researchers have reported in the Medical
 Journal of Australia (7 February).
 Given the unreliability of clinical clues alone, confirmation of measles with
 serology was vital, they said.
 For the study, all Victorian measles notifications and the subsequent serology
 results from 1997 and 1998 were analysed.
 Even when the analysis was limited to cases that met the NHMRC clinical
 case definition (morbilliform rash, fever present at rash onset, and cough), the
 accuracy of clinical diagnosis was still only 14%.
 An editorial by infectious diseases experts in the same issue of the MJA said
 diagnosis on clinical grounds was correct only half the time even in the early
 1990 s before any major measles control campaigns were in place.
 As measles becomes rarer, clinical diagnosis becomes increasingly
 inaccurate.
 For example, in countries such as the UK and Finland where indigenous
 measles transmission no longer existed, the accuracy of clinical diagnosis was
 as low as 1%, the editorial said.
 The incidence of measles had declined in Australia after the second dose of
 MMR vaccine was introduced in 1994 and the national campaign targeting
 primary school children began in 1998.
 Because the probability that patients who presented with fever and rash had
 measles was lower, the approach to suspected measles, especially in general
 practice, needed to change, the editorial said.
 Awareness that many viral infections in children could appear like measles
 was now more important.
 Clinicians should be aware measles was also more likely in older children and
 young adults than in infants.
 The 1999 outbreak in Victoria, in which 84% of cases were aged 1 8-30,
 indicated the likely future pattern of measles in Australia, the editorial said.
 MJA 2000; 172:103-04, 114-18.