E.D. Acheson, D.M., M.R.C.P.:
Department of Medicine, State University of New York, College of Medicine of New York, and
Department of Medical Services, Maimonides Hospital, Brooklyn, New York
Of the fourteen outbreaks considered in this
paper, seven occurred amongst the staff of
hospitals; one in an army barracks; two in
small towns; two in semi-rural communities
and two in the populations of large cities.
On the basis of case to case contact, attempts
have been made to fix the incubation period of
the disorder. In the Iceland6, Bethesda15, Royal
Free Hospital27 and Punta Gorda16 outbreaks
the evidence indicated an incubation period of
less than one week, probably five to six days.
In Los Angeles5 the information on this point is
incomplete, but a few patients became ill four
days after their first exposure, indicating the
minimum incubation period. On the other hand,
the Middlesex Hospital8 and Durban18 reports
suggested a longer period of two to three
weeks. An incubation period of fourteen days
was present in the single case in which isolated
contact occurred in the small second outbreak
in the Royal Free Hospital in 1956.