NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
7
be observed, also, that the excretion of the bacilli in some cases is intermittent.
The full details of the results of the examination of each case of bacillary dysentery
are given in Table I, Appendix.
The Widal reaction in bacillary dysentery was tested in a number of cases.
It was not possible to separate an in fection with B. dysenteriœ( S h i g a ) f r o m a n
infe:tion caused by B . d y s e n t e r i œ( F l e x n e r ) b y t h i s r e a c t i o n o w i n g t o t h e g r o u p
agglutination : as a method of diagnosis it is of less utility in dysentery than in
enteric fever.
IV.—Amœbi c Dysentery.
Whilst the bacillary dysentery has been studied by a number of competent
observers, and an intelligent application of the principles founded on these
investigations to particular cases will solve the problems connected with its
prevention in most cases, on the other hand, when the subject of amœbic
i nfecti on i s approached, i t i s evi dent that a great many l acunæ i n our knowl edge
sti l l remai n to be fi l l ed i n. Our i nformati on regardi ng am cebæ at the present ti me
may be compared to that of intestinal bacteria of some years ago. At that time
the B. coli communis represented the so-called non-pathogenic intestinal organism
and was compared with one standard type of pathogenic intestinal organism,
the B. typhosus. At the present day the list of intestinal bacteria, which have been
described, make a formidable array, and to the single pathogenic organism, the
paratyphoid bacilli A, B and C and, others must be added. This has been brought
about mainly by the use of improved technique, but finality has not yet been
r e a c h e d . As r e g a r d s a mœb æ a t t h e p r e s e n t t i me , mo s t t e x t b o o k s d e s c r i b e a n d
contrast a pathogenic type (the En t a mœb œ h i s t o l y t i c a) a n d a n o n - p a t h o g e n i c
type (the Ent amœba col i ) . V e r y r e c e n t w o r k , h o w e v e r , h a s t e n d e d t o e x t e n d
these arbitrary limits and there can be little doubt that, as special technique
improves, and further investigations are carried out, the number of amœbæ
associated with dysentery will increase and the individuals in the group will be
described more accurately.
There appears to have been a tendency in this field of investigation to adhere
too rigidly to the conclusions arrived at by the eminent protozoologist, Schaudinn,
although he himself admitted that lacume in our knowledge of the subject still
remained to be filled in. Accordingly, it is interesting to note that Elmassian 1 ,
in a recent paper describing a new species of pathogenic amœba, makes the follow
-ing important remarks in this connection
"Si l es t ravaux de Schaudi nn ont en l e grand méri t e de met t re en l umi ère ce f ai t capi t al :
l a d i v e r s i t é d e s e s p è c e s a m i b i e n n e s c h e z l ' h o m m e , i l s e n o n t e u b e a u c o u p m o m s d ' a p r è s n o u s
1
C e n t r a l b . f . B a k t . , e t c . , O r i g . E d . 5 2 . H e f t 3 , 1 9 0 9 .
9
(b) Seasonal Prevalence of Amœbæ.
To determine this a portion of the stool of every fresh case of dysentery which
came under observation was cultivated at room temperature on the agar medium
o f Mu s g r a v e a n d Cl e g g ; t h i s p r o c e d u r e wa s c a r r i e d o u t d a i l y f o r e i g h t mo n t h s ,
April to November 1909. The cultures were kept under observation and the
pr es enc e or abs enc e of amœbæ det er mi ned. I n t hi s way we wer e abl e t o obt ai n
t he mont hl y i nci dence of amœbæ i n dysent er i c st ool s over t hr ee seasons i n
Bombay : (1) The hot weather, April to middle of June. (2) The monsoon,
middle of June to end of September. (3) The period after the rains, October
and November. Further, we obtained the daily records of temperature and
humidity for the period under observation from the Meteorological Department,
Bombay.
The following chart shows the monthly variations from the mean of amœb
i c i n f e c t i o n i n c a s e s o f d y s e n t e r y e x a m i n e d a m o n g s t t h e C i v i l p o p u l a t i o n i n B o m b a y ,
and the monthly variation of temperature from the mean in Bombay :—
CHART I.
AMŒBIC. PREVALENCE.
TEMPERATURE.
80 I F.= MEAN TEMPERATURE.
C
10
The following chart shows the monthly variation from the mean of amœbic
infection in cases of dysentery examined amongst the Military population in
Bombay, and the monthly variation of temperature from the mean :
—
CHART II.
AMŒEBIC PREVALENCE.
TEMPERATURE.
8 0 I . F . = M E A N T E M P E R A T U R E
The following chart shows the monthly variation from the mean of amœbic
infection in cases of dysentery amongst the Civil population in Bombay, and the
monthly variation of humidity from the mean :
—
CHART III.
AMŒBIC PREVALENCE.
HUMIDITY (THE MEAN=80).
11
The following chart shows the monthly variation from the mean of amœbic
infection in cases of dysentery amongst the Military population in Bombay, and
the monthly variation of humidity from the mean :
—
CHART IV.
4
AMŒBIC PREVALENCE.
HUMIDITY (THE MEAN=80).
From a study of these charts it will be noted :
—
(1). That amœbic infection shows a marked seasonal variation.
(2). That this variation is closely associated with the variations in humidity.
(3). That curves showing the variations in the amœbic infection and tem
-perature do not correspond.
The i nt i mat e r el at i onshi p of amœbi c i nf ect i on t o moi st ur e i s si gni f i cant ,
because moisture plays an important part in connection with the stage of encyst
- m e n t o f a m œ b æ . I f t h e m e d i u m i n w h i c h t h e a m œ b æ a r e d e v e l o p i n g b e a l l o w e d
to dry, encystment is brought about readily. This stage in the life cycle of the
a m œ b æ w i l l b e d i s c u s s e d l a t e r . I n c o n s i d e r i n g t h e s e a s o n a l p r e v a l e n c e o f a m œ b i c
i nf ect i on i n cases of dysent er y, al l amœbæ, whi ch coul d be cul t i vat ed f r om t he
stools on Musgrave and Clegg's medium, have been taken into account, not merely
particular species, pathogenic or not. We have studied the natural conditions
affecting the class as a whole. The peculiarities of individuals may form the
subject for future investigation.
It is of interest and importance, further, to determine what relation the curve
of amœbic infection bears to the curve of dysentery incidence in Bombay. To
c 2
12
ascertain this the average admissions for dysentery to the Bombay Prisons for ten
years, 1897-1906, were obtained for each month of the year from the Reports of
the Sanitary Commissioner with the Government of India. These averages were
added together and divided by the number of months, giving a mean admission
rate for the period. The monthly variations from this mean were plotted out
and a curve was obtained showing the seasonal variations of dysentery in the
Bombay Prisons. On comparing this with the curve of amœbic infection it is
noteworthy that there is a very close correspondence.
In both cases during the dry season the curve is below the mean, whilst in the
wet season both are above. It indicates that the conditions necessary for the
production of dysentery in the Jails in Bombay, as shown by the admission rate
over a period of ten years, are favourable, also, to the life of amœbæ.
The following chart shows the monthly variations from the mean of the
admissions for dysentery into the Jails of Bombay (1897-1906) :-—
CHART V.
ADMISSIONS FOR DYSENTERY.
B O M B A Y P R I S O N S ( 1 8 9 7 - 1 9 0 6 ) .
M E A N = 3 9 .
The study of the i ntesti nal fauna, especi al l y of amœbæ, has recei ved l i ttl e
or no attention so far. In the tropics, particularly, the subject would repay a
careful investigation by competent observers and fresh ideas and conceptions
might be expected to result from it.
15
2. MOVEMENTS.
When seen i n stool s, pus, and i n cul tures, the amœbæ are acti vel y moti l e as
a rule. The movement is brought about by the throwing out of pseudopodia.
Often the pseudopodium when first protruded is quite clear and hyaline, but the
coarser granul es f rom t he body of t he amœbæ rapi dl y st ream i nt o i t .
3. MORPHOLOGY.
( 1 )
S i z e
. — T h i s v a r i e s c o n s i d e r a b l y a c c o r d i n g t o t h e s t a g e o f g r o w t h o f t h e
ani mal as wi l l be seen i n Pl ates 1 and 2. The youngest amœba measures three
to four mi crons (Fi gures 3 and 4, Pl ate I), the ful l y grown amœba bei ng from
thirty to forty microns in diameter, not including the pseudopodia (Figures 1 and
2, Plate I). It is important that this fact should be clearly realised, because in a
stool or in pus from a liver abscess these small forms may predominate, and if
the possibility of their presence is not appreciated a faulty d
iagonsis as regards
amœbic infection may be given.
( 2 )
E n d o p l a s m
. — T h i s i s g e n e r a l l y c o a r s e l y g r a n u l a r , o f g r e y i s h a n d s o m e t i m e s
greenish tint (Figure 7, Plate I).
( 3 )
E c t o p l a s m
. — I n s o m e c a s e s i t i s d i f f i c u l t t o o b s e r v e a d i s t i n c t i o n , b u t w h e n
the pseudopodia are protruded the ectoplasm will be determined readily as a
clear hyaline strip. it can be seen, also, in the stained preparation (Figure 7,
Plate I).
( 4 )
C o n t r a c t i l e v a c u o l e s
. — T h e s e w e r e o b s e r v e d i n t h e a m œ b æ g r o w n o n a g a r ,
and, occasionally, in those in the stools. As a rule contractile vacuoles have not
been recorded i n parasi ti c amœbæ, but Noc 1 a n d P o r t e r
2 h a v e d e s c r i b e d
them. They vary in number from one to three or more, they contract suddenly,
once i n 15—30 seconds. They appear to have a pi nki sh ti nt and are refracti l e.
The number varies in the same amœbæ at different times.
( 5 )
N u c l e u s
. — T h i s i s e x c e n t r i c a l l y p l a c e d a t t h e b o u n d a r y b e t w e e n t h e
endoplasm and ectoplasm and is rich in chromatine which stains deeply, and which
is sometimes seen to be surrounded by a clear unstained zone. The changes under
- g o n e b y t h e n u c l e u s , w h i c h a r e e x t r e m e l y i m p o r t a n t , w i l l b e d e s c r i b e d b e l o w . A t
certain stages a clear space is seen in the centre of the chromatine and a nucleolus
may be observed also (Figures 1, 2, Plate I).
(6) Encystment and reproduction.—These processes require to be studied
with great care as they form a method of classifying the various amœbæ.
Schaudinn is of opinion that the study of the life-cycle of pathogenic protozoa
should precede all experimental researches. To render clear the various
1A
n n a l . d e L ' I n s t i t u t P a s t e u r
, No. 3, Mars 1909.
2 Journal of Parasitology, Vol.II 1909.
16
stages of the life-cycle of the amœbæ now being described the following diagram
is given :—
DIAGRAM.
LIFE CYCLE OF AMŒBA.
1—5 = Reproduction byb u d d i n g .
6 — 8 =
S t a g e o f e n c y s t m e n t .
9—10 = Reproduction by equal division.
If a culture of amœbæ of 24 to 48 hours growth be examined, the presence of a
number of cysts will be observed. The cysts vary in shape, some are quite round,
others are octohedral. They have a well marked double contour wall (Figures
13, 14, 15, 19, Plate I). In the octohedral form the outer part of the wall appears
to be folded (Figure 15, Plate I), as if the inner wall had shrunk. In size they vary
f rom 7 t o 12 mi crons i n di amet er. When t he amœba i s about t o encyst , i t becomes
spherical and the outer part condenses, forming the cyst wall. When such a cyst
is placed under favourable conditions an interesting series of changes may be
observed (Figure 28, Plate II). At first an irregular slow to and fro streaming
of the cyst contents is observed, later these movements become very active and a
17
bud of protoplasm is protruded through the cyst wall at one point. This bud
shows amœboid movements and rapidly increases in size ; at the same time the
contents shrink from the cyst wall and an outward streaming of granules occurs.
W h e n t h e a m œ b a h a s e s c a p e d , t h e e m p t y c y s t ' c a s e ' r e m a i n s , a n d a s m a l l a p e r t u r e
at t he poi nt of exi t of t he amœba i s obser ved. The cyst ' case ' appear s t o be
composed of a chitinous material. The whole process as above described took
about two hours, the cysts being kept under observation at room temperature.
all the time (Figure 28, Plate II).
4. PRACTICAL IMPORTANCE OF CYSTIC STAGE.
Apart from the scientific interest, the cystic stage has a considerable practical
significance, because in the stools this phase is not associated, as a rule, with active
symptoms such as would lead to the detection of the case. Such individuals
h a r b o u r i n g c y s t s o f a mœb æ a r e " Ca r r i e r s , " a n d ma y b e a me a n s o f p r o p a g a t i n g
the disease. Hence the necessity for a careful examination for cysts of the stools
of cases conval escent f r om amœbi c dysent er y. Fur t her , as Noc 1 h a s p o i n t e d
out, the cysts are a source of danger not only to the community, but to the indi
- v i d u a l , b e c a u s e t h e y o c c a s i o n t h e r e l a p s e s s o f r e q u e n t l y m e t w i t h i n a m œ b i c
dysentery. When conditions of the bowel are favourable the cystic stage of the
amœba ends and a phase of active reproduction begins, this latter stage is depen
- d e n t o n f a c t o r s w h i c h w i l l b e e x p l a i n e d l a t e r . M y r i a d s o f y o u n g a m œ b æ m a y b e
seen in the stool, which resembles a rapidly growing culture (Figure 21, Plate I).
In such a case the relapse may be rapid and exceedingly grave and the lesions
found post mor t ema r e e x t e n s i v e a n d s e v e r e . H e n c e i n t h e i n t e r e s t s o f t h e p a t i e n t
bef or e decl ar i ng a case ' cur ed " a car ef ul exami nat i on of hi s f æces shoul d be
made.
Having considered the phase of encystment we pass to consider a very im
-portant process i n the l i fe-cycl e of amœbæ namel y :—
5. REPRODUCTION AND NUCLEAR CHANGES.
I n t he exami nat i on of cer t ai n amœbæ ( Fi gur es 1, 2, 3, 4, Pl at e I ) t he endopl asm
is seen to contain a large number of particles of chromatine, each surrounded by a
minute portion of protoplasm. This round corpuscle measures 3—7 microns in
diameter. If observed in the fresh state the corpuscles may be seen to make their
way t o t he per i pher y of t he amœba ai ded by t he movement s of t he ect opl asm,
and finally separate from the parent and move away (Figures 3 and 4, Plate I).
1A
n n a l , d e L ' I n s t i t u t P a s t e u r
. N o . 3 , M a r s 1 9 0 9 .
18
These 'buds,' which become young amœbæ, are, generally, more or less spherical
in form and the contour is defined (Figures 3 and 4, Plate I). The process is
precisely similar to that described by Schaudinn, with this important difference
that, in the amœba found in India by us, the ' buds ' become young amœbæ,
whilst in E. histolytica the ' buds ' develop a wall of double contour and
become cysts. Schaudinn describes the process in E. histolytica thus : " Slowly,
2—3 hours, under the influence of active currents of endoplasm, many small
buds are expelled ; arriving at the periphery of the amœba they are finally elimi-
nated as spores of concentric structure 3—7 microns in diameter." In the case
of the amœba which we are at present considering the whole animal becomes
enclosed in a cyst (Figure 22, Plate II). In this way it is distinguished from
E. histolytica. In addition to reproduction by budding the amœba may divide
into two daughter amœbæ, and as seen in Figures 5 and 20, Plate I, one or other
daughter amœba may reproduce at once by budding.
By a careful study of numerous preparations fixed wet with alcohol acetic
sublimate solution, and stained by Heidenhain's iron hæmatoxylin method, it
has been possible to observe the nuclear changes which take place in the above-
mentioned processes of reproduction. There is a clear space in the centre of the
nucleus which varies in size, the chromatine being arranged in a circular manner
round it (Figures 1, 3, 4, 7, Plate I). The karyosome is seen to undergo a reduc-
tion into fine chromidia. These chromidia pass through the fine nuclear membrane
and become diffused in the substance of the endoplasm. The original karyosome
seldom disappears completely, and in most cases a portion remains. The grains
of chromatine are contained in the endoplasm in small spherical masses of pro-
toplasm, and constitute the 'internal buds '; in some cases (Figure 23, Plate II)
these 'internal buds ' are very numerous, filling up the whole parent, which
appears to be made up of these, and Noc l has named them 'merozoits,' which
indicates the result of a division without expressing an opinion on the nature of the
bodies. This unequal division of the nucleus appears to be the most frequent
but, in addition, division by constriction (Figure 5, Plate I) into two equal parts
followed by division of the protoplasm has been observed. Two daughter amœbæ
result from this division. Noc1 has observed division by karyokinesis with the
formation of a regular nuclear spindle with two poles of chromatine and many
grains of chromatine round the equator. We have noted, also, this form of nuclear
division (Figure 29, Plate II), but division by amitosis appears to be more common
than by mitosis. Noc also considers that the large number of chromidia emitted
by a nucleus with a large karyosome explains, how in certain cases, the multiplica-
tion of amœbæ may be rapid and capable of producing more severe lesions than
a simple bacterium ; the young amœbæ, issuing from the 'merozoits,' increase
1
A n n a l . d e L ' I n s t i t u t P a s t e u r N o . 3 , 1 9 0 9 .
19
rapidly, and being young, nuclear division is favoured and premature buds are
produced.
An examination of cysts, fixed and stained by various methods, shows that
the endoplasm of the amœbæ contained in them may be rich in chromidia, and,
consequently, as soon as the amœba escapes from the cyst, it begins to bud
rapidly (Figure 22, Plate II). The cysts of the dysentery amœba of Manilla des-
cribed by Musgrave and Clegg' measure 10—12 microns, likewise in the amœbæ
investigated by Lesage2 hence these amœbæ cannot be the same as E. his-
tolytica. Craig3 has studied the budding in amœbæ. The spore which he
figures free does not correspond conclusively with the buds still adherent to the
amœbæ. Walker 4 refutes the conclusion of Schaudinn in regard to the emis-
sion of buds which transform into cysts. From the above statements it will be
seen that some subsequent observers have not been able to confirm the results
of Schaudinn in regard to spore formation in E. histolytica. He himself
recognised the lacunæ in his description of the life-cycle of E. histolytica and
these still await filling in by zoologists.
(d )Amœbæ in Water.
In addition to dysentery stools and liver pus, ordinary Bombay tap water
was examined for amœbæ. The method adopted was to take 2-3 litres of tap
water and add a small quantity of ordinary nutrient broth to it. This was set
aside at room temperature for about a week. Then from the surface several
loopfuls were taken and plated on the special agar medium, and in the course of a
few days a growth of amœba was obtained, if amœbæ were present in the water.
A study of the amœba grown from water shows that it presents apparently similar
characters to the amœba obtained from the stools of dysentery cases and from
the pus of a liver abscess, hence it is unnecessary to repeat the description already
given. The detection of this amœba in drinking water is a matter of interest.
Further minute protozoological study will be required before the identity of the
water amœba with those of dysentery and liver abscess can be established. Noc5
from his observations in Cochin China considers that the amœba found in
water is identical with the amœba found by him in dysentery stools and pus from.
1 Bureau of Government Laboratory, No. 18, Manilla, October 1904.
2 Ann. Inst. Pasteur, January 1905, XIX and C. R. Acad. de Sci. 26, December 1904.
3 Journal of Infect. Dis., June 1908.
4 Journal of Med. Research, Vol. XVII, No. 4, February 1908.
5 Ibid.
D 2
20
liver abscesses. The following table, taken from his paper, shows the presence or
absence of amœbæ in the water of Cochin China month by month:—
Month.
Wells exposed to soilage.
Town water supply.
January .
.
.
.
. Cysts of amœba few .
.
. No amœba.
February .
.
.
.
.
Ditto fewer
.
.
Ditto.
March
.
.
.
.
. None
.
.
.
.
.
Ditto.
April .
.
.
.
.
. None
.
. .
.
.
Ditto.
May .
.
Period of excerba-
tion of epidemic
dysentery.
Cysts present .
.
.
. Cysts and motile amœbæ.
June
.
Cysts numerous
.
.
. Abundant cult of amœba.
July
.
Ditto
.
.
.
Ditto.
August
.
Ditto
.
.
.
Ditto.
September .
Ditto
.
.
.
D i t t o .
October
.
.
.
.
. Cysts less numerous .
.
.
Ditto.
November .
.
.
.
. Cysts few .
.
.
.
. Cysts few.
December .
.
.
.
.
....
None.
It is interesting to compare this table with the charts Nos. 1 , 2, 3, 4, 5, pages
14—16, showing the incidence of amœbic infection and dysentery in man in
Bombay. It will be seen that the season of the year during which the amœbæ are
most numerous in the water of Cochin China and amœbic dysentery becomes
epidemic, is the rains, and exactly corresponds to the period of greatest amœbic
infection and highest dysentery incidence in man in Bombay. Therefore, in the
present state of our knowledge, until further protozoological work on amœbæ is
carried out in the East by trained protozoologists, and until such investigations
conclusively show that the amœbæ of dysentery are absolutely distinct from
those found in water, it will be necessary, in the interests of public health, to
regard water as an important channel of conveyance of infection. That
contamination of various foods may be brought about also by water is obvious,
and therefore the taking of raw articles of food in epdemic areas in India is not
free from danger in regard to dysentery. It is of importance further in this
relation to remember that the amœba forms cysts by which it is enabled to
resist adverse conditions in nature, e.g., absence of moisture, etc.
(e) Distribution of Amœbæ in Healthy Animals.
As amœbæ are found in drinking water it is obvious that they should be ob-
tained from the contents of the alimentary tract of many animals. It is interesting