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Lucilia sericata, Meig, and another 103 to the species Lucilia caesar, both
species being green-bottle flies; and 131 were Calliphora erythrocephala, Meig
(blue-bottles). The green-bottle and blue-bottle flies accounted for 722, and
the remaining 322 insects were spread over the other 42 species as shown in
the table. It is curious that we collected only 16 house flies (Musca domestica,
L.).
Some of the insects examined bacteriologically were found to be carrying
two or three organisms each, so that organisms were found 214 times on the
172 insects examined, but 45 of the insects were bacteriologically sterile.
On the average, organisms were found on each infected insect 1.7 times. In
all there were 25 different organisms isolated, the largest group being Strep
pneumoniae, which was isolated 32 times (Table 35). Other organisms isolated
a fair number of times were P. morgani, Coliform bacilli and Strep, faecalis.
Infectious Diseases.
We tried to collect information about as many cases of gastro-enteritis
as we could, and of any other infections which might be of interest. We invited
the medical practitioners to co-operate by notifying, under section 17 of the
Food and Drugs Act, any patient with an illness which might be due to food
poisoning infection and who exhibited symptoms of gastro-enteritis, however
vague. The Education Officer kept us informed about school children absent
from certain schools through illness for two or more days. We had information
about children similarly absent from our day nurseries. The health visitors
told us of any cases they heard of through the clinics. By these means we
learned of 529 cases of illness. The inspectors visited all the houses, but 438
of these cases proved to be non-infective ailments (accidents, etc.) and of
no value for our enquiry, leaving us with 91, representing the ascertained
incidence of gastro-enteritis in the Borough during the period (Table 37).
All except one of these patients exhibited symptoms, either of diarrhoea or
vomiting; or diarrhoea and vomiting; or diarrhoea, vomiting and raised
temperature. The exception was a child aged one, who had a Shigella Sonnei
infection without symptoms. Eight of the patients were babies under one;
47 were children aged 1-16; and 35 were persons over 16.
The inspectors used a standard form of enquiry which includes all the
accepted routine headings in the investigation of suspected food poisoning,
together with a little more detail about such conditions as chronic appendicitis,
gall-stones and allergies.
We tried to obtain a specimen of faeces from every patient with gastroenteritis
but were successful in only 62 cases. These 62 specimens were sent
to the Public Health Laboratory at Epsom for identification of organisms
where possible. Organisms were identified in 20 of these, namely: 8 had P.
morgani, 2 had Dysentery Shigella Sonnei, 3 had Amoebic Dysentery, and
7 had Samonella infections; the other 42 cases gave negative results. We also
sent for examination specimens of faeces from 99 contacts in apparently good
health, and out of these P. morgani was isolated twice.
Potential pathogens from the respiratory tract referred to in Table 35
were isolated from flies in Twickenham, and included Streptococcus pneumoniae.
This germ was responsible for an outbreak of inflammation of the eyes—
conjunctivitis—in a school in Twickenham during 1948, but no connection
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