Investigating, etc., of infectious disease.
Appx.XIX.
DYSENTERY.
18. Spread.— By carriers infecting food and drink, either directly
or through the agency of flies. Flies are probably the principal agent
by which both types of dysentery are spread in India.
Bacillary dysentery is the prevailing type in Eastern countries
including India and accounts for approximately 80 per cent. of all
dysentery cases. In epidemic form dysentery is invariably bacillary.
Amoebic dysentery accounts for approximately 20 per cent. of all cases.
Bacillary dysentery.— The great majority of cases are due to infec-
tion. with B dysenterica
for 15-20 per cent. Cases vary from a mild diarrhoea with traces of
blood and mucus in the stools (usually flexner infections), to cases
very severe in nature (either shiga or flexner infections). Flexner
infections are seldom fatal in adults, but tend to relapse more fre-
quently than shiga infections. The microscopic appearance of the
mucus in the usual type of bacillary infection is quite typical of bacil-
lary dysentery, i.e ., large numbers of cells, mainly polymorphonuclear
leucocytes, large endothelial cells (often mistaken for amoebae) and
epithelial cells. The exudate in very mild cases of Flexner dysentery
may not show this typical picture and may be indistinguishable micros-
copically from the exudate of amoebic dysentery, unless E. histolytica
is found. The mucus in bacillary cases is alkaline or neutral in reaction.
Amoebic dysentery.— Due to Entamoeba histolytica. The mucus
is usually acid in reaction and very few cells are present on microscopic
examination. Beyond the actual presence of E.histolytica there is
nothing characteristic in the cellular exudate of the majority of such
cases. No cell should be diagnosed as E. histolytica unless it is motile
and contains red blood corpuscles. E .histolytica cysts are not present
in the mucus of acute cases.
Dysentery group.— In all cases in which a typical bacillary exudate
is absent and in which E. histolytica is not found of er frequent examina-
tions, formed stools during convalescence should be examined for the
presence of cysts on several occasions: if cysts are not discovered
after several examinations the case has probably been of a mild bacil-
lary (Flexner) type. Such cases are commonest among Indian troops.
No case of dysentery should be diagnosed as other than " dysentery
group " unless in the acute stages of the disease the specific bacillus
or E. histolytica cysts has been found or E. histolytica cysts during
convalescence. In those 'cases in which a typical cellular exudate or
bacillary dysentery is present, the words " bacillary exudate " should
however be added within brackets, e.g., " Dysentery group (bacillary
exudate)". When a typical bacillary exudate is absent, the diagnosis
should be " Dysentery group (indefinite exudate)".
19. Preventive measures. —Disinfection will be carried out as indi-
cated in para. 554. All cases of irregular diarrhoea in the tropics
should be regarded as possibly dysenteric in nature whether blood and
mucus have been seen in the stools or not. Particular attention
should be paid to protection of food and water supplies, and to al
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