The freedom from complications in the whole series is remarkable, although the epidemic did not appear to have been one of a milder type than usual, as indicated by the cases which were not inoculated.
Observations of AttenuationThe following conditions were observed to be attendant on the use of the serum:1. Lower temperature, fewer constitutional disturbances, quicker recovery.2. The rash is noticeably different. It is much more discrete, rather more ham-or copper-coloured. It persists a long time on the face and is not so profuse or well marked on the trunk and limbs.3. There was at first a suspicion that the incubation period is delayed; the rash appeared slow to come out, even for measles. This suspicion was not borne out by subsequent observations. We had, in fact, been prepared to accept the view that the serum conferred some degree of immunity when used before infection. The steady curve of the incidence graph does not support this. The inoculation of fifty boys on the same date might be expected to produce a definite flattening of the incidence curve if temporary immunity was a result of inoculation.The real problem in aiming at attenuation in this type of school is to select the right moment to give the serum. The ideal from the treatment point of view would be the certain infection of the largest number from the first case. In a preparatory boarding school it would probably be wise to use serum without delay.There is no reaction to the injection. It is well to give it before bedtime. There is some stiffness locally some four hours after injection, and a few boys were allowed to stay in bed for breakfast. Two patients had chicken-pox concurrently with measles.In all cases with ear symptoms of deafness, discomfort, or pyrexia the drum is incised as soon as any bulging is observed. If the fluid evacuated has passed the serous stage we are disappointed at not having been earliei in intervention. The importance of the early treatment of middle-ear inflammation is not sufficiently insisted upon in the standard works on medicine used by medical students. It is worth recording in this connexion that in fifteen years' experience of measles epidemics in this school we have never had a case of mastoid infection requiring operation. Conclusions The use of adult serum has a marked effect in attenuating the disease and in decreasing the incidence of complications.In the epidemic here recorded there was no evidence of temporary immunity resulting from the use of the serum. Early treatment of middle-ear infection by incision of the drum will greatly reduce the risk of mastoid infection.