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cases. It was also significant that during the Easter and summer
vacations notifications dropped considerably.
Table II relates the number of persons in family to the total
number of primary notifications and their secondary cases. The
secondary attack rate has been calculated by dividing the number
of secondary cases by the number of persons at risk and multiplied
by 100. It will be seen that generally, the larger the number of
persons per family the greater the secondary attack rate, viz., the
secondary attack rate was greatest in families of five, six and seven
persons per family.
The next table, Table III, attempts to relate housing density
to incidence of primary and secondary cases and it will be seen that
whereas according to the 1951 census the average density in Greenwich
was 0.83 persons per room, the average density of the 218
families of which we have reliable details was 1.3 persons per room
In actual fact, 88.5% of dysentery families were living in more
overcrowded conditions than the Borough average. More detailed
analysis shows that 80% of dysentery families live in densities of
between one and two persons per room, whereas in Greenwich
generally the figure is 45.2%.
A surprising feature of the outbreak is that lack of sanitary and
ablutionary facilities do not appear to be as potent a source of spread
as one might imagine, because 148 out of 250 families under analysis
were living in modern, self-contained properties. Of the remainder,
a substantial proportion had apparently satisfactory standards of
hygiene.
Table IV indicates the duration of the illness in weeks after the
institution of treatment by the family doctor and it will be seen
that a substantial proportion of cases took from four to eight weeks
before two consecutive negatives were obtained, and in one case
it took 31 months to obtain negative stools.
Our general experience has been that appropriate sulphonamide
drugs were satisfactory after two to three weeks in about 55% of
cases, but approximately 15% required chloramphenicol or other
suitable antibiotic before treatment was considered complete.
Generally speaking, the antibiotic seemed to be more effective and
more rapid in action than any of the sulphonamide drugs.
In all, a total of 2,747 faecal specimens were taken for examination
which figure includes 373 taken from ' suspects ' at the request
of local practitioners. In 2,033 cases the results were negative but
in 713 instances the causal organism was identified as Shigella
sonnei and in one as Shigella flexneri. (In the latter case the
patient had recently returned from a holiday in Spain).