Armstrong – Table of Contents

Armstrong, observing the signs and clinical illnesses in monkeys noted that, although
these features varied in degree, they were uniform in character and suggested similarities
to the illnesses seen in the human encephalitis patients. As described by Armstrong (8),
“The first significant symptoms appeared in from 8 to 14 days following the first
inoculation and began with an elevation in temperature that tended to rise on successive
days to a height of from 40.6 to 41.6 on the fourth or fifth day of the fever. When
undisturbed the animals usually sat hunched up with their eyes closed as if asleep with
their heads bent forward. When disturbed, however, the ill animals seemed alert and often
markedly excitable. Intention tremors, most notable in the forelegs and the head, usually
appeared about the second or third day and were often pronounced. Muscular weakness
of one or more extremities and occasionally definite paralyses made their appearance
during the febrile stage. Involvement of the eye muscles was not observed. The appetite
usually continued good, and the animals often would eat greedily throughout the febrile
period. Constipation was often present. Spinal fluid at the height of the fever was usually
under increased pressure, clear and commonly showed cell counts of from 150 to 350
cells.
“The animals were usually sacrificed on from the second to fifth day of fever, but in a
few instances the disease was allowed to run its course. In these instances the monkeys
recovered completely. There were no spontaneous deaths, although some of the animals
were very ill when sacrificed, and it seemed probable that some of them might have
succumbed had they not been killed.”
Armstrong carried three strains of virus through five passages and thought that the
illnesses were becoming more virulent in monkeys during the 4th and 5th passages. He