Armstrong – Table of Contents

(12) white mice used as controls for this group died. In this way, Armstrong defended his
methods for using white stock laboratory mice free of LCM for isolation of viruses from
infected feral mice.
It also had been noted by others (35) that an infected mother mouse might convey the
infection to her offspring, and that such congenitally infected mice carried the infection
for months. Armstrong (unpublished data) stated that these findings had been confirmed
by Victor Haas at NIH. Haas showed that such congenitally infected mice were much
more effective transmitters of infection to other mice than were artificially inoculated
animals. Armstrong’s finding of 52 per cent of mice from homes harboring mice to be
carriers of virus, in a study extending over several months, suggested to him a persistent
type of infection such as results from the congenital type of spread.
By the early 1940s the various clinical syndromes associated with LCM had been
described. Armstrong was finally able to isolate the virus from a laboratory investigator
working with LCM who presented with a “grippe-like” illness without central nervous
system or meningitis-type signs and symptoms (36). About the same time Lt. Colonel
Harry Plotz of the Army Medical Corps reported to Armstrong a similar illness in a
laboratory investigator who was studying the virus at the Army Medical Research Center
in Washington, DC. It was also becoming obvious at this time (and subsequently in the
future) that LCM presented a health hazard to laboratory personnel working with the
agent (36).
The clinical presentations gradually recognized in the early 1940s included: 1)
The “Grippal” or non-nervous system type, suspected almost initially on the basis of
surveys of random blood sample testing for antibodies. Many patients with antibodies