NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
102
Giant Polynuclear Cell.
KRANKHEI¬
TEN, VOL.
LXI.
" Diese Plasmakugeln findet man bei allen küs-tenfieber¬
kranken Tieren und nur bei Solchen. "
JOURNAL OF
TROPICAL
VETERINARY
SCIENCE,
VOL. II,
No. I.
Lingard in writing on cattle Trypanosomiasis in India
refers to cells of a similar description. "A further fact connect-
ing the two varieties of Trypanosomiasis occurring in the blood
of cattle indigenous to countries so widely separated (S. Africa
and India), is the presence of large ovoid cells 8.20 to 9.0µ
in length which exhibit a hyaline structure and contain a con-
siderable number of darkly stained bodies (dark purplish red
after Romanowsky), single united in couples resembling large
micrococci and diplococci which seem to multiply by genera-
tion. The circular forms measure from 0.6 to 1.0µ. The
cells burst and discharge their contents, and when the bodies
become free, they appear in some instances to increase in size
somewhat before respectively coming to rest in the red
corpuscles where they undergo further changes.
" His Plate (D) contains a diagram of cells said to be
similar to those observed by Theiler in the peripheral blood
of a South African bull."
These "Plasmukgeln" appear to me to be of the same
class of cells as the one now described which is probably a large
granular polynuclear leucocyte.
PLATE D.
HORSE
No.
245. TAKEN 20TH JANUARY 1909.
PONY No. 260. TAKEN 20TH JANUARY 1909.
PONY
No. 263. TAKEN 20TH JANUARY 1909.
PONY
No. 285. TAKEN 20TH JANUARY 1909.
PONY No. 287. TAKEN 20TH JANUARY 1909.
PONY
No. 288. TAKEN 20TH JANUARY 1909.
PONY
No. 292. TAKEN 20TH JANUARY 1909.
Indian Civil
Veterinary Department
Memoirs
NO. 2
COLLECTED NOTES
PRINTED BY
THACKER, SPINK & CO., CALCUTTA
FOR THE
INDIAN CIVIL VETERINARY DEPARTMENT
INDIAN CIVIL
VETERINARY DEPARTMENT
MEMOIRS
NO. 2
COLLECTED NOTES
PRINTED BY
THACKER, SPINK & CO., CALCUTTA
FOR THE
INDIAN CIVIL VETERINARY DEPARTMENT
CALCUTTA:
PRINTED BY THACKER, SPINK AND CO.
ERRATA.
Page 13, line 26, after "buffaloes" add the words "and
camels".
Page 22, line 38, for "Few" read "small."
EXPERIMENTS REGARDING THE NATURAL
TRANSMISSION OF SURRA CARRIED
OUT AT MOHAND IN 1908.
BY
A. S. LEESE, I.C.V.D.
LAST winter it was decided that in the following hot
weather and rains I should carry out an investigation in
some well-known surra zone with the following principal
objects:—
(1.) To settle, if possible, the question whether biting-
flies are chiefly responsible for the spread of surra under
natural conditions, it being now well established that in
laboratory experiments Tabanus is capable of conveying the
trypanosomes from an infected animal to a healthy one,
if both animals are bitten within a short interval of
time.
(2.) To ascertain what kinds of biting-flies are to be
found in a surra zone, both in and out of the "surra
season;" to note their habits as regards biting of domes-
ticated animals; to carry out transmission experiments with
those varieties of flies which the above observations would
indicate to be possibly involved in natural transmission, it
being known from an investigation of a natural outbreak of
surra in Kathgodam that surra can continue to spread
amongst horses in the absence of Tabanus.
a-1
2
Mohand was chosen as the best situation in which to
carry out the work; it is on the Saharanpur-Dehra Dun
road, at the foot of the Siwalik Range and at the south end of
the Mohand Pass. Some years ago, before Dehra Dun was
connected by railway to Lhaksar, there was a large amount
of traffic on this road and there was enormous loss from surra
in tonga ponies working on the stages in the Pass in the
months of July, August and September (during and after
the rains); at the present time the traffic in this season is
confined to a very few bullock carts per diem, horse traffic
being practically nil, as the railway has completely superseded
the tonga service. This fact enabled us to expose surra
cases and create a limited outbreak of our own with the
least possible danger of the disease being carried outside our
stable, such as might well have occurred in such a situation
as the Kathgodam-Naini Tal road.
I arrived on 27th April; this left two months for observa-
tions on the biting-flies before the onset of the surra season.
The "surra season" in Mohand corresponds with that at
Kathgodam; it is in fact the rainy season, and the month
or so following it; the earliest recorded case in the Pass
(Lingard's Surra Report, Vol. 2, Part I, page 23) was found
on 15th July. There was no recorded case of surra in the
Pass occurring in May or June.
I remained at Mohand until 24th September; the
experience of Dâk proprietors of former years shows this to
be two or three weeks before the end of the normal surra
season in the Pass.
The present condition of Mohand in connection with
surra is as follows:—
The traffic in the rainy season has been insignificant for
years because of the construction of a railway to Dehra
Dun; the Tonga-service has been abandoned now for about
8 years, and the bullock cart traffic in the surra season is
very small indeed. The only equine traffic is a drove or two
daily of pack animals. Only the older inhabitants of
Mohand know anything about surra; and although about
10 ponies are kept by the villagers and are constantly in
contact with the milch-cows and buffaloes of the village, no
losses now occur in the rains, This is interesting and
3
indicates that owing to the scarcity of "reservoirs of
infection" (i.e., cattle and buffaloes working through Mohand),
the danger to local animals has been largely removed.
Camels always leave this road from about 15th May to
October; none are kept anywhere in the neighbourhood
between these dates.
The country consists of first class jungle, full of game,
but the latter evidently do not act to any great extent
as dangerous reservoirs of infection to domesticated animals.
I had a temporary stable put up a quarter of a mile
from the village: until the rains there was no standing water
near it. Ponies for experiment were purchased locally, but
the camels which had been under observation for some time
previously, were marched down by road from Lahore. The
disease did not occur in the village and the outbreak was
confined to our stable.
Experiment 1.—To demonstrate the rôle of biting Diptera
in the transmission of Surra under natural conditions.
The rains began on 28th June. The following ponies
were then placed in the stable:—
One pony (No. 3), which had some time previously been
inoculated with surra from a camel and was affected with the
disease.
Two ponies (Nos. 4 & 6), healthy, and placed in stalls
protected by mosquito netting.
Three ponies (Nos. 1, 2 & 5), and 1 foal (all healthy), to
act as controls.
The two ponies (Nos. 4 & 6) remained under the mosquito
curtains from 28th June to 17th September, but did not
contract the disease; they were afterwards proved by
inoculation to be susceptible to it.
All the controls became naturally affected with the
disease, trypanosomes first appearing as follows:—
No. 5
No. 1
No. 2
Foal
Pony
„
„
... 4th August.
... 5th
„
... 9th
„
... 17th
„
4
The following are the details of the conditions under
which the animals were kept:—
The two ponies under the nets were fed and watered in
their stalls, the entry of the syces being made by means of
double doors of mosquito netting. The ponies' blood was
examined daily and the temperature taken twice daily; and on
each occasion on which the nets were entered for these purposes
a sharp watch was kept for flies inside the net or the marks
of their bites on the ponies. The protecting netting proved
very efficient; on a few occasions a stray mosquito was found
to have penetrated the net; sand-flies could get through
the meshes, but did so only in very few numbers; only four
specimens of Stomoxys, and a few non-biting flies, obtained
access to the ponies on the entry of the syces during the
whole period. The drinking-water of one of the ponies was
boiled before giving; that of the other was taken from the
common source and unboiled. They had gram and bran
from the same store as the controls, they had bhoosa from the
same store as the controls up to 4th and 11th August respec-
tively, after which they have received jungle grass instead,
from low-lying situations.
The controls received gram, bran, and bhoosa, and the
only one that had any grass at all was the foal, which was
also suckled by pony mare No. 1.
The gram and bran were bought in Dehra Dun and
stored by us in rat-proof bins for at least seven days before
use. All the bhoosa used was stored in the local godown
before the end of May.
Control ponies Nos. 2 and 5 and the foal had water
brought to them from the stream and were not taken down
to be watered in the stream. Control pony No. 1 had all
its drinking-water boiled before use.
None of the ponies did any work.
The control ponies, therefore, lived under similar general
conditions as did the tonga ponies here years ago, with
the exceptions (i) that the first case of surra was imported
and was infected directly with the camel strain, which could
not occur naturally in Mohand; and (ii) that they received no
grass and did no work.
PLATE I.
1—4. TABANUS POUND IN MOHAND.
5
The disease spread so promptly and thoroughly to our
controls that there can be no reasonable doubt that it did so
by the same agency as that operating from horse to horse in
entirely natural outbreaks. So that out of six ponies kept in
contact with surra in a surra-zone and in the surra season,
the only two which did not become affected were those protected
from biting-flies. The gram, bran and bhoosa had no
influence since the supply for all ponies was from the same
source; but dry food cannot now be regarded as an agent
worthy of consideration in surra transmission in practice,
whether it contains the excrement of rats or not, in the face
of the fact that camels which are resting and tree-grazing at
this season, and not receiving any ration of dry food, suffer
so severely from the ravages of surra.
That grass grown on inundated land is not the agent of
infection is shown by the fact that all the controls became
affected with the disease, although only one out of
the four had access to grass, the three others receiving
bhoosa.
The water-supply cannot be blamed since the water of
control pony No. 1 was always boiled before use ; and further,
the villagers' horses, which watered from the same source as
my ponies, did not contract the disease.
Inoculation through the agency of brushes, curry-combs,
or syce's hands, and infection by means of buckets, etc., appa-
rently is not the usual method of transmission of disease,
because the two ponies in the nets were as much subject
to this as the controls, but remained free from the
disease.
Inoculation by means of harness or through harness
galls evidently also is an unimportant method of transmission
in natural outbreaks, since all the exposed ponies in our
experiments promptly contracted surra, although there was
no harness and they had no galls.
Transmission of trypanosomiasis by means of non-biting
flies, acting by proceeding from a wound on a surra animal
to a wound on a healthy one, had been proved by laboratory
experiments (Musgrave and Clegg Report on Trypanosoma
and Trypanosomiasis in Philippine Islands, 1903) to be
possible, but our experiments indicate that this method of
a—2
6
infection is of minor importance in practice also, because our
control ponies which were doing no work were kept absolutely
free from visible wounds (with one exception a slight scratch),
and moreover, the animal from which infection apparently
took place (No. 3), was entirely free from such wounds.
One must admit, however, the remote possibility of occasional
transmission by non-biting flies, with the drop of blood exud-
ing from the recent puncture made by a biting-fly as the
source of infection.
None of the ponies had lice. With regard to ticks,
Hyalomma ægyptium was the only common one, but this
(unlike the dog-tick) was nearly as numerous in the hot dry
weather before the rains as it was afterwards (it was also
very numerous on camels in Lahore district in March and
April in spite of the previous drought). The time of its
occurrence does not therefore agree with the seasonal occur-
rence of surra, and this is the strongest possible argument
against the existence of any cycle of development of T. evansi
in the body of the tick Hyalomma ægyptium. The habits
of ticks render them practically incapable of transmitting
trypanosomes mechanically under natural conditions.
Other ticks were found, but only occasional specimens
of each (a Rhipicephalus and Hæmaphysalis bispinosa).
The ponies had little chance in the rains of picking up speci-
mens of ticks, except Hyalomma ægyptium, for they stood
in the stable, so as to avoid them and were not exercised
during the rains.
OBSERVATIONS.
In the hot weather (May and June), when many Hya-
lomma ægyptium were present, I kept five ponies in the open
jungle on the same ground as was used for a parao by our
camels with surra (and infested also with this tick) for 45
days; and for 17 of these days they were also in contact with
a pony affected with inoculated surra. Their blood was
daily examined, but no case of surra occurred among them
within 37 days of the completion of this observation.
Note 1. The ponies used in Experiment 1 were of the
pack or ekka types and were purchased in the district; none
of them proved immune from surra.
7
Note 2. The evidence points to its being the camel
"strain" of surra which spread amongst our ponies, because
the only surra with which they were in contact seems to
have been in our pony No. 3 (inoculated from a camel) and
in our camels themselves. The villagers' cattle occasionally
strayed near the stable, but I have already said that
the villagers' horses remained healthy, which suggests
that the cattle, which mixed freely with them, were also
healthy.
SEASONAL PREVALENCE OF BITING-FLIES IN MOHAND.
During these observations I was much struck by the
irregularity of the daily prevalence of some varieties of
biting-flies; one cannot be certain of the absence of a given
species at a given place without a more or less prolonged stay
in that place. This remark applies especially to Tabanus
and Hæmatopota.
In these notes I have called the period from 1st May
to 28th June, the "hot weather;" and the period from 28th
June to 24th September, "the rains." The rains broke
on 28th June.
The biting-flies found in the hot weather were Tabanus
Hæmatopota (a large new species), Stomoxys, Hippobosca, a
"new fly" of new genus, Hæmatobia. As to mosquitoes, I
believe they were sometimes present near water, but only
one specimen (Stegomyia) was found at our parao during the
hot weather.
The biting-flies found in the rains were Tabanus,
Hæmatopota (three or four varieties), Stomoxys, Hippobosca,
the "new fly;" Hæmatobia, Lyperosia, sand-flies, and
Chrysops, and mosquitoes (biting animals) of the genera
Anopheles, Culex, Stegomyia and possibly others.
One biting-fly was found in uniform numbers in the hot
weather and in the rains; namely, Hippobosca maculata;
this fly was very numerous all the time and is parasitic on
cattle and horses.
It is convenient here to consider the habits, etc., of this
fly. As is well known, it does not readily change its host,
but when horses are tied up in lines, it is likely that some
interchange takes place.
8
When not feeding, it lives under the dock or in the
perineal region. It will bite anywhere on the body and
sometimes leaves a drop of blood at the seat of puncture.
The fact that its occurrence is uniform in the hot
weather and rains does not entirely preclude the possibility
of its being sometimes a transmitting agent of surra; in the
hot weather, its chances of acting in this way would be small,
for it would have to be from an ox to a horse; in the
rains, however, with surra once started in horses in a
locality or stable, it might play some small part in trans-
mitting from horse to horse.
There is no species of Hippobosca in Mohand, special to
the camel as occurs in North Africa. Hippobosca macu-
lata was only seen occasionally biting on the camel, and
it certainly does not live on him for long; it could not
play any part in transferring surra from camel to camel
in Mohand.
Hippobosca does not live on the buffalo; the habits of
that animal render it impossible. It may occasionally bite
the buffalo.
The above considerations show that if Hippobosca ever
takes part in the transmission of surra in practice, it could
not possibly be a specific agent and could, at the most, cause
an occasional case by mechanical transmission. Further, its
capability of transferring the surra trypanosome from one
animal's blood to another has not been proved. In the hot
weather, five healthy ponies and one with surra were exposed
together to its frequent bites for 17 days, but no new case of
surra occurred.
One fly of a new genus was more numerous in the hot
weather than in the rains and can, therefore, have no special
influence on the spread of surra. It bites horses, camels
and oxen.
The following flies were always so scarce that they could
hardly play any important part in the transmission of surra
in Mohand:—Chrysops (two specimens seen during 4½
months, both on camels); Hæmatobia and Lyperosia.
There remain for serious consideration :—Tabanus,
Hæmatopota, Stomoxys, mosquitoes and sand-flies. The
PLATE II.
5—7. TABANUS FOUND IN MOHAND.
9
first four were scanty in the hot weather, but their numbers
increased enormously in the rains.
The following chart shows the prevalence of the three
former genera at Tunbara in the valley of Mohand Pass in
the hot weather of 1908 before the surra season :—
If Tabanus, Hæmatopota or Stomoxys transmit surra
under natural conditions, one might expect an occasional case
to occur in the hot weather before what is known as the
surra season since the flies, though scanty, are present.
There is no mention in any record of such a case in Mohand,
but this is no proof that it has never occurred. There would
not be enough flies to cause more than one or two cases and
the diagnosis of an isolated case would offer considerable
difficulty in the days of the Tonga service.
I attempted to prove that surra might be transmitted
in this season in the presence of the necessary biting-flies,
but unfortunately the experiment was not absolutely conclu-
sive, and it is therefore not quoted ; the reason being that
although the subject of the experiment, a camel, was pre-
viously severely tested by blood examinations for 63
consecutive days and by three inoculations of its blood
into small animals for the purpose of proving it free from
surra, before the experiment, this test was subsequently
found to be insufficient for that object in the case of
camels.
a—3
10
The following chart shows the prevalence of the biting-
flies under consideration in the surra season ("rains") in the
valley generally:—
The rains were exceptionally heavy this year and lasted
from 28th June to the middle of September. In 1907, the
previous year, there had been a failure of the rains. In
1908, the villagers said that the number of Tabanus was
less than usual.
The daily variations in numbers of flies were too great
to be shown on the chart.
Tabanus and Stomoxys increased suddenly on the 3rd
day of the rains; mosquitoes appeared on the 4th or 5th day
of the rains, sand-flies about the 8th day, Hæmatopota
increased slowly in numbers and were not numerous until
about three weeks after the break of the rains.
Our ponies were all kept in the stable from 28th June
to 19th July ; it was then found that few biting-flies ventured
into it, so on and after 19th July we tied up the surra pony
and controls immediately outside the stable when the
weather permitted, but still in close contact with the two
11
net-protected ponies. As has already been mentioned,
trypanosomes first appeared in the controls on the following
dates :—4th, 5th, 9th and 17th August.
A glance at the fly chart will show that it was impos-
sible to say merely by observations whether any particular
biting-fly appeared to be responsible, because during the last
fortnight of July all the biting-flies under consideration were
at their height in numbers. The comparative numbers were
as follows :—
Swarming :—
Sand-flies, Stomoxys, mosquitoes, and small Hæma¬
topota.
Frequent :—
Large Hæmatopota and Tabanus.
During our stay in Mohand, about 18 varieties of
Tabanus were found; those varieties of Tabanus which were
most common in the hot weather were rare or absent in the
rains and vice versâ.
OBSERVATIONS ON THE HABITS OF THE BITING-FLIES LEFT UNDER
CONSIDERATION AS REGARDS DOMISTICATED ANIMALS.
Tabanus.—Bites horse, ox, buffalo, camel, elephant, and
man.
In the horse and camel alarm is shown at its approach
and the animal does its best to dislodge it; this causes the fly
to go readily from one animal to another in a short space
of time.
It bites anywhere on the body, but favours the belly,
legs and sheath. Blood exudes from the seat of puncture.
It does not appear to seek its victim for more than about
a quarter of a mile from water, but was occasionally carried
on an animal for half a mile from water. Its favourite times
for biting are 6 to 8-30 A.M. and 4 to 6 P.M.; it generally rests
in the middle of the day during the great heat.
Hæmatopota.—Bites the horse, ox, buffalo, camel and
elephant, also man. In animals the approach of the fly
causes no alarm, but when it bites, attempts are made by
12
the victim to dislodge it. When the camel is attacked by
large numbers of small Hæmatopota ("andhimakhi"), he
soon becomes exhausted by his efforts to defend himself
from their bites and lies down, feebly kicking or rolling at
intervals and giving rise to lugubrious moans. In these
circumstances I have found the temperature of healthy
camels to reach 104° F. in the evening. The fly chiefly bites
on the body and head. Like Tabanus, it does not go far from
water; its favourite times for biting are those of Tabanus,
but it is often also seen biting in the evening after dark.
It takes a long time to fill itself with blood and so is liable
to be dislodged before finishing a meal, and may then seek
a new victim.
At Mohand, the occurrence of the larger varieties
corresponded approximately in time and number with the
occurrence of Tabanus; but the smaller varieties were only
found for about two weeks in the rainy season, during which
short period they were swarming.
Stomoxys.—Bites the horse, ox, buffalo and camel.
Its favourite feeding time is from 4-30 P.M. to dusk, but
it is to be found at other times of the day. It often leaves
a small drop of blood at the seat of puncture. It will bite on
any part of the body, but especially the forelegs below the
knee. It is certainly not confined to the vicinity either of
stabling or of water, and was found in numbers on camels or
cattle grazing in the jungle two miles from any habitation.
It will enter a stable for the purpose of biting the
horses therein, but much prefers to feed in the open: it
rests on leaves of trees during the hottest part of the day.
A horse exposed to the attentions of large numbers
of Stomoxys will, at first, by continual movements of head,
tail, feet and skin, prevent them from filling themselves with
blood, and there is no doubt that when horses are standing
in lines, one animal is often bitten by a fly which has just
had a partial feed from the blood of a neighbouring animal.
A healthy horse's temperature will rise as much as 2° F.
above normal from the mechanical irritation and the efforts
to get rid of the fly.
In captivity, it will take a full feed once in every 40
to 48 hours; one or two specimens lived for three weeks.
PLATE III.
8—10. TABANUS FOUND IN MOHAND.