NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
214 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [VII, III
at the Ahmednagar Stud Farm. Concerning this last, the Veterinary Officer,
Ahmednagar Remount Depôt, furnished the following interesting information in a
letter dated the 15th September 1936 :—
" The case under consideration is of interest, as it is improbable though not im-
possible that infection could have been carried from Australian horses to this animal.
The Stud Farm where the animal was bred is some three miles from the Australian Re-
mount Depot. The animal has never left this stud and has only been in contact with
Australian horses to a very limited degree. The number of Australian horses in this
Stud would not exceed 12, nor has any case of these ticks occurring among these horses
been found. Examinations to date have revealed the presence of Spinose Ear Tick in
one other Indian bred horse in the Stud ".
It was, however, mentioned by him that the Spinose Ear Tick occurred com-
monly amongst Australian horses, some eight or nine cases having been found during
the preceding two years when the average yearly strength of the Depôt
was 750.
As the species seemed to be of more than sporadic occurrence in India, com-
munication was at once entered into with the Director of Veterinary Services, Army
Veterinary Department, with a view to obtaining some indication of the extent to
which this parasite had established itself as a pest of domesticated animals in this
country. At our request, instructions were kindly issued by him to the Veterinary
Officers in command of the different stations under him to carry out, as opportun-
ity occurred, an examination of the ears of horses and cattle in their charge for
the presence of these ticks. This examination, which has now been completed,
has revealed the existence of the Spinose Ear Tick in three stations, namely,
Saugor, Mhow and Ahmednagar. The details are as follows :—
(1) At Saugor.—Out of 523 animals examined, sixty-eight (or 13 per cent)
were found infected, and out of the latter, about 50 per cent were of Australian and
an equal number of Indian breed. The infected animals did not " display any
definite symptoms, their condition remaining good. Some resented handling of
heads and ears and a few were excitable, while some had discharges from the affect-
ed ears ".
(2) At Mhow.—Out of fifty-five horses examined, four (or 7.3 per cent)
were found infected, but none of these showed any untoward symptoms. Speci-
mens of ticks were also taken from the ears of a private charger that had developed
a violent shaking of the head as a result of the infestation.
(3) At Ahmednagar.—Out of 250 Australian horses examined during January
to March 1927, twenty-two (or 8.8 per cent) were found infested, the maximum
number of ticks found in any one ear being forty-eight. None of the affected
animals developed any clinical symptoms.
OCCURRENCE OF SPINOSE EAR TICK IN INDIA
215
As to the manner in which O. megnini came to be introduced into India,
three possibilities suggest themselves : that it may have been brought (1) with mules
coming from America; (2) with stock coming from South Africa, where the tick
was first seen in 1898 [Bedford, 1917] ; or (3) with horses imported from Australia.
It would, however, appear from a communication, dated the 13th November 1936,
received from the Chief of Division of Animal Health, Australia, that the parasite
is quite unknown in that country, so that it may be reasonably concluded that it
has been introduced with stock coming from one or both of the other two countries
mentioned above. This conclusion would seem to find support from a statement,
which we have received through the courtesy of the Director of Veterinary Services,
Army Veterinary Department, and which shows that the number of American and
South African mules received and dealt with by the Ahmednagar Remount Depôt
during the past thirteen years was eighty-two and 729 respectively.
From the foregoing, it would appear that the parasite is fairly widespread in
this country, and in view of its importance as a pest of domesticated animals, it
would seem desirable that veterinary workers in India were made acquainted with
the habits and the general features of this tick and also with the symptoms known
to be produced by the infestation.
It is my pleasant duty to express my grateful thanks to Mr. F. Ware, C.I.F.,
F.R.C.V.S., F.N.I., I.V.S., Director of the Imperial Veterinary Research Institute.
Mukteswar, for the keen interest with which he has watched the progress of this
investigation. In feeding the ticks on horses, I have received much help from
Mr. J. A. Idnani, Veterinary Inspector, for which I am deeply indebted to him.
My thanks are due to Mr. Ahmed Bakhsh, Artist, for the illustrations, which he
has drawn in original from specimens bred out in the laboratory.
DISTRIBUTION
It is generally agreed that the original home of the Spinose Ear Tick is the
United States of America, where it is particularly prevalent in certain south-western
semi-arid sections. According to Imes [1918], the climatic conditions in parts of
Texas, Oklahoma, New Mexico, Arizona and California are favourable for the
rapid multiplication of these ticks. Nuttall and his collaborators [1908] quote
Dugès [1883] as having first described the tick from Mexico, where it is reported to
be abundant in the State of Guanjuato. The tick is also known to occur in South
Africa, where, according to Bedford [1917], it was probably introduced with stock
coming from America. Although it is not known when the tick was actually in-
troduced into that locality, Bedford mentions Theiler as having found it at Vryburg
in 1912 and he further refers to Manley as having first seen this species in Cape
Colony in 1898.
216 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [VII, III
HABITS OF THE TICKS AND THEIR EFFECTS UPON THEIR HOSTS
As the name Spinose Ear Tick implies, O. megnini is characterized by the
possession of spines on its body in its nymphal stage and it has the peculiar habit
of locating itself deep inside the ears of its hosts, which include cattle, horses, mules,
sheep, goats, dogs, rabbits and man. Story [1920] states that the tick occasional-
ly feeds on the skin in the case of sheep. In cases of gross infection, the ears may
be packed full of these parasites, which frequently crawl into the ear-canal and
even attack the ear-drum. According to Pierce [1921], the ears of infected animals
are droopy, hair rough, fattening is difficult, and under range conditions, death is
not infrequent. In horses and mules marked shyness is observed, and " this is
sometimes so extreme that it is almost impossible to halter or bridle an infested
animal ". The symptoms are graphically described by Imes [1918] as follows :
" The infested animal usually shakes its head and repeatedly turns it from side to
side, meanwhile inverting first one ear and then the other. When irritation and itching
are more intense on one side, the animal often turns its head so that the more seriously
affected ear is held inverted. There is a tendency to run and scratch the ears, and
young animals often run as though endeavouring to relieve the nervous tension.
Horses and dogs seem to be more sensitive than cattle to the pain and irritation.
They scratch and rub their ears, shake their heads, and often lie down and roll,
rubbing their ears on the ground "
Story [1920] states that young calves suffer most from this pest, its bite
producing swelling and abscesses in these animals.
DESCRIPTION OF THE DIFFERENT STAGES
The morphological features of the different stage of O. megnini have been fully
described by Nuttall and Warburton [1908] and a brief and useful description of
these stages has also been given by Bedford [1912]. In the description that
follows, only such features of the morphology of the tick will be dealt with as are
likely to be of use to the veterinary worker in recognizing the parasite under
field conditions in India.
Egg (Plate XIII, fig. 1).—The egg is circular in shape and measuring about
0.3 mm. in diameter. Like the eggs of other species of ticks, it is dark-brown
in colour, which does not appear to alter in intensity during the incubation period.
Larva (Plate XIII, fig. 2).—Elongate oval and white in colour, with a long
terminal capitulum and with the integument finely striated and provided with
bristle-like hairs, Palpi slightly longer than the capitulum, hypostome armed and
the digits of chelicerae fairly conspicuous. Legs long and pulvilliform. When
unfed, the larva measures about 0.75 mm ; when engorged, it is egg-shaped and
measures 2 to 4 mm. in length.
DIFFERENT STAGES OF THE SPINOSE EAR TICK
Ornithodorus megnini
FIG. 1. Egg. ×67.
FIG. 2. Larva, unfed, dorsal view. × 67.
ch., distal extremity of chelicera, enlarged ;
t., tarsus I in profile, enlarged.
FIG. 3. Nymph, dorsal view. × 6.
h., bristly hairs, enlarged ; sp., spines, enlarged ;
t., tarsus I in profile, enlarged.
FIG. 4. Nymph, ventral view. × 6.
c., capitulum ; s., spiracle.
FIG. 5. Nymph, mouth-parts (chelicerae omitted). × 67.
hyp., hypostome ; p., palp.
FIG. 6. Adult, dorsal view. × 6.
Ind. Jour. Vety. Sci. & Anim Husb , Vol. VII, Pt. III.
PLATE XIII.
OCCURRENCE OF SPINOSE EAR TICK IN INDIA
217
Nymph (Plate XIII, figs. 3, 4 and 5).—The most characteristic feature of the
nymph is that its body is beset with a number of posteriorly-directed spines, from
which, as already mentioned, the Spinose Ear Tick derives its common name.
These under high magnification appear horn-like with a ringed base and are present
both on the dorsal and ventral surfaces and also on the sides of the body, which is
conspicuously constricted behind the hind legs. In addition to the spines, there
are a number of much smaller bristly hairs covering the whole skin of the nymph.
Capitulum sub-terminal or slightly projecting anteriorly, hypostome armed and
palpi thick. Genital aperture absent. The spiracles are characteristic, being
situated on tubercles between coxae III and IV, somewhat ventral to the dorso-
lateral border. Legs fairly stout, with well-developed terminal claws. Colour
of engorged nymph dark-brown. The measurements of four replete specimens
were as follows: 8.5 × 5.5 mm. ; 10 × 6.5 mm. ; 8.5 × 5.5 mm. ; and
7.5 × 4.5 mm.
Adult (Plate XIII, fig. 6).—Body fiddle-shaped, slightly attenuated anteriorly,
but rounded posteriorly and sharply constricted behind legs IV. Unlike the
nymph, the integument of the adult is provided with small, shallow, circular pits,
whilst its dorsal surface is with at least four pairs of symmetrical depressions.
Capitulum short and. hypostome unarmed, so that the adult is incapable of
feeding. Eyes absent. Spiracles circular. Anus situated centrally in a
depression posterior to Legs IV. Genital aperture between first pair of coxae.
Legs pale-yellow, rather thin, each tarsus being provided with a dorsal protuber-
ance. Colour brown or slate. Size 8 × 5 mm.
LIFE-HISTORY
The female ticks lay their eggs in cracks and crevices of buildings, fences and
trees. According to Story [1920], the favourite hiding place of adults is loose, dry
manure between stones at the bottom of kraal wall. On hatching out from the
eggs, the active larvae, which are six-legged, crawl about and enter the ears of
their hosts and become fully engorged in a week or two. The engorged larvae are
grub-like and inactive, and after a period of quiescence, they shed their skins and
turn into eight-legged nymphs, which may remain attached to their hosts for from
one to seven months [Imes, 1917]. When fully engorged, the nymphs leave
their host and migrate to a sheltered spot where they moult to the adult stage.
In such places, both mating and oviposition occur, for, as already mentioned,
the adults never feed and do not, therefore, require a host.
At the Mukteswar Laboratory, one male and one female nymph were found
moulted to the adult stage on the 2nd May 1936. These were kept together in a
tube and the first batch of eggs was deposited by the female about the 26th May
218 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [VII, III
and the emergence of the first batch of larvae occurred on the 18th July. On the
29th July, about thirty of the larvae were introduced into the ear of a country-bred
pony, the following device being adopted to prevent the ticks from escaping. The
larvae were loosely held inside a small piece of muslin-gauze and the latter was then
folded over to immobilize the larvae momentarily. The piece was now quickly
inserted into the ear and the opening of the latter closed up by means of a piece
of finely-meshed muslin glued on with Chatterton's compound. As an additional
precaution, the ear, with its gauze-cover, was enclosed in a strong cloth bag, any
damage to the latter being prevented by making the animal wear a specially made
hood, as shown in the illustration (Plate XIV). When the ear of the animal was
examined at the end of thirty-five days, four of the larvae were found to have
changed to fully-engorged nymphs. A batch of larvae was also introduced into the
ear of a rabbit, which was kept under observation for about a month, but the
larvae died without developing. In this case, the rabbit was made to wear a card
board collar to prevent it from scratching the infected ear.
TREATMENT
According to the Bureau of Animal Industry, United States of America, an
effective remedy against ear-ticks is a mixture of two parts by volume of ordinary
commercial pine tar and one part by volume of cotton-seed oil. The remedy is
applied by means of a metal or hard-rubber syringe capable of holding one to two
ounces, the mixture being warmed to ensure its ready flow. Story [1920] stresses
the desirability of taking care that the mixture is not smeared on the hair in the ear;
otherwise when the car is flapped, the mixture may get into the eye and cause
irritation.
REFERENCES
Bedford, G. A. H. (1912). A Tick New to South Africa. Union S. Africa Dept.
Agric. Second Report, pp. 343-344.
Bedford, G. A. H. (1917). The Spinose Ear Tick, Union S. Africa Dept. Agri,
Local series, No. 18, pp. 1-6.
Imes, Marion (1918). The spinose Ear Tick and Methods of treating Infested
Animals. U. S. A. Dept. Agric. Farmers' Bull. 980,
pp. 3-8.
Kingston, J. S. (1936). Spinose Ear Tick in India. J. Roy. Army Vet. Corps.
7, 142-143.
Nuttall, G. H. F., Warburton, C., Cooper, W. F. and Robinson, L. E. (1908).
Ticks : A Monograph of the Ixodoidea, pp. 71-77.
Pierce, W. D. (1921). Sanitary Entomology, pp. 444-445.
Story, C. (1920). The Spinose Ear Tick. Practical Suggestions for Suppression.
Union S. Africa J. Dept. Agric. 1, 647-654.
Ind. Jour. Vety. Sci. & Anim. Husb., Vol. VII, Pt. III ]
PLATE XIV.
Infected pony with hood.
EXPERIMENTS ON THE TRANSMISSION OF RINDER-
PEST THROUGH THE AGENCY OF STOMOXYS
CALCITRANS LINN*
BY
S. K. SEN, M.Sc., F.R.E.S.
Entomologist
AND
ABDUS SALAM, L.V.P.
Punjab Research Scholar
Imperial Veterinary Research Institute, Mukteswar
(Received for publication on 24th April 1937)
(With one text-figure)
THE possibility that biting flies are involved in the transmission of rinderpest
in cattle has been stressed by more than one worker, but the work so far carried out
to explore this possibility cannot be regarded as having been extensive. The
results—for the most part negative—that have been obtained by different workers
in transmitting the disease have already been summarized by Hornby [1926], Sen
[1926] and Bhatia [1935]. A notable positive result recorded in this connection
was that by Hornby, who succeeded in transmitting rinderpest in East Africa
through the bites of Glossina morsitans. Quite recently, on a suggestion made by
Crawford [1933] in Ceylon that the larger biting flies may be the transmitters of the
disease in India, Bhatia [1935] carried out a series of transmission experiments
with Tabanus orientis and Stomoxys calcitrans, the flies being made to bite by the
so-called " interrupted " method. In the case of the former, he succeeded in ob-
taining positive results in one instance, but his results with S. calcitrans were of an
entirely negative order. With the latter species, he carried out a series of four
experiments, the number of flies used in each ranging from ten to fourteen. It was,
however, considered desirable to carry out a more extensive series of experiments
with this species before eliminating it as a transmitter of the disease. As will be
seen from what has to be stated later, the results obtained by the present writers
*Paper read at the Indian Science Congress held at Hyderabad-Deccan, January
1937,
( 219 )
I
220 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [VII, III
were negative and are, therefore, in accord with those recorded by Bhatia. Apart
from reporting these results, one of the objects of this brief note is to describe
a method which has proved satisfactory for the purpose of feeding a large number of
flies by the " interrupted " method within a limited period of time, for it is almost
needless to stress the desirability of employing a method that would substantially
reduce the amount of time usually taken in carrying out feeding work of this kind
and at the same time make it possible to determine, with a fair degree of certainty,
what proportion of flies have actually fed.
MATERIALS AND METHODS
In the present trials, only wild specimens of S. calcitrans were used, these being
of common occurrence on animals, notably buffaloes, grazing in the station area at
Mukteswar during the summer months. The flies were kept singly in glass tubes
measuring one inch in diameter and four inches in length, the mouths of the tubes
being closed with mosquito netting with meshes (about eighteen to a linear inch)
sufficiently large to permit of the flies biting through them. In order to provide
moisture to the flies, the tubes containing them were kept inverted over moistened
cotton wool in a tray, a sheet of wire-gauze being interposed between the tubes
and the wool to prevent the flies from coming in direct contact with the moisture
[cf. Sen, 1926]. By this means, it was possible to keep a large proportion of the
flies alive for at least ten days. The mortality was high on cold, cloudy days, or
when the moisture was completely evaporated off during the night and was not
replenished in due time. Specimens which persistently refused to bite on any
one day were allowed to suck a drop or two of cane sugar solution placed at the
mouth of the tube. Each tube was numbered, so as to make it possible to
maintain an accurate history of individual flies.
The flies received their infective feeds on bulls artificially infected with a
virulent strain of rinderpest virus, and in all cases due care was taken to choose
good reactors. After being partially fed on rinderpest-infected bulls, they
were allowed to complete their feed on a young, healthy bull, housed in a small
shed (chupper), at a convenient but safe distance from infected sheds, in order to
prevent it from contracting infection by means other than through the experimental
flies. Throughout the observation period, a record was kept of the morning and
evening temperature of this animal, as also its general condition.
For feeding the flies, the glass tubes containing them were inserted through
circular holes bored in a cork-sheet measuring 7 in. × 3½ in. × 1/5 in., the diameter
of each hole being slightly less than an inch, so that the tubes fitted somewhat
tightly in them. A cork-sheet of the dimensions mentioned above has been found
capable of holding at least ten tubes (Fig. 1).
EXPERIMENTS ON THE TRANSMISSION OF
RINDERPEST
221
Fig. 1.—Feeding tubes arranged on cork-sheet
The animal intended to provide the infective feed was cast and immobilized
by tying it down by means of a good length of rope. A fairly large area on its
abdomen was now closely clipped by means of a pair of clipping scissors, and the
whole set of tubes was inverted simultaneously over the clipped area, the cork-
sheet being manipulated in a manner so as to cause it to assume the requisite degree
of curvature, so that each fly was enabled to obtain its feed at the same time. No
fly was allowed to feed for more than one minute, at the end of which the tube con-
taining it was pulled up through the hole so as to ' break ' i s contact with the body
of the animal. A maximum of ten minutes was allowed to each fly to commence
its feed, but it was observed that those that did not feed during the first five minutes
seldom did so afterwards. It is simple for one man to operate two cork-sheets
simultaneously, and by this method, the writers have, on bright sunny days,
succeeded in feeding a large number of flies within a short space of time. The flies,
after being infected in this manner, were allowed a maximum of ten minutes
to complete their feed on a healthy animal, and seldom has any difficulty been
experienced in inducing such " interrupted " feeders to feed again. The interval
between the two feeds ranged from fifteen to forty-five minutes.
In the beginning, it was a matter of some difficulty to determine with cer
tainty whether a particular fly had actually fed on the infected animal, but with
experience, this became comparatively easy. The appearance of droplets of blood
on the bitten spot, the ' prodding ' of the proboscis through the meshes of the net-
ting, defecation by the fly after an apparent bite—these, either singly or in combina-
tion, were taken to be diagnostic of a feed. In the case of flies that had fed par-
tially, distension and reddening of the abdomen is not always apparent, and ex-
perience has shown that a good criterion of a feed is the occurrence of haemorrhage
on the spot where the bite has been inflicted. In practice, however, it was not
always easy to ascribe a haemorrhagic spot to the particular fly that had caused it.
This difficulty was overcome in the following manner: A thick sheet of paper
cut to the size of the cork-sheet and containing an equal number of holes of the
same diameter was interposed between the cork-sheet and the clipped area. In
order to ascertain whether a particular fly had fed, the cork-sheet, together with
222 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [VII, III
the tubes, was partially raised without displacing the sheet of paper and the
clipped area examined through the holes for the occurrence of haemorrhagic
spots.
EXPERIMENTAL OBSERVATIONS
As mentioned earlier in this note, only one healthy bull was used in these
experiments, but, as will be seen from the tables that follow, the number of infective
bites inflicted on it was sufficiently large to admit of definite conclusions being drawn
as to the possibility of S. calcitrans being involved in the spread of the disease.
In the experiments, three batches of flies were employed, those of the first two being
fed singly by the method described above, but in the case of the third batch, the
flies were fed en masse, this being considered desirable in order to hasten progress
of the work, particularly when it was found that a total of as many as 411 individual
bites (infra) failed to produce any apparent effect on the experimental animal. In
the ' massive ' feeding, the flies, numbering about 300, were enclosed in three
cloth cages, each containing approximately 100 flies, and the cages were then
applied directly on a closely clipped area on the body of an infected animal and
allowed to remain there for from one to one minute and a half, and an approximate
count was made of the number of flies found feeding during that period. They
were then allowed to complete their feed on the healthy bull, it being assumed from
previous experience gained in feeding individual flies that they had done so. The
numbers of infecting bites inflicted on the healthy animal on different dates are
shown in the following three tables :—
TABLE I
Number of infective bites inflicted by flies of the first batch (fed singly)
Date
Number
of bites
April
12
5
13
11
14
18
15
8
16
5
17
5
18
6
19
4
20
8
21
..
22
4
23
..
24
18
25
31
26
25
27
15
28
..
29
12
30
7
May
1
2
Total number of bites . . . . . . . .
Total number of days over which the bites were spread
.
.
184
17