Gibbs, Gibbs, and Rosenthal,1 in a survey of children clinically ill with measles, demonstrated that 50% showed electroencephalographic (EEG) slowing. In a similar survey of children immunized with the Enders attenuated strain of measles virus causing modified measles, they failed to find any EEG abnormality attributable to the vaccine. This study was undertaken to determine whether a difference between the Enders attenuated strain and "wild measles" virus carried in tissue culture could be demonstrated by EEG in monkeys.
Except for very preliminary exploratory work where rhesus monkeys were used, all monkeys were African green (Cercopithecus aethiops) which had been held in isolation for a period prior to infection. Only those monkeys with no demonstrable complement fixing antibodies for measles were used for EEG studies. Animals weighed between 1.5 and 5 kg. All monkeys were bled at the end of the experiment, and the sera were tested for complement