1911 First Report of the Director of Veterinary Research, August 1911

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Contentes Pages: Onderstepoort Journal of Veterinary Research, Vol ??, 19??

CONTENTS

Letter of transmittal	Theiler, A	1

Further investigations into anaplasmosis of South African cattle	Theiler, A	7

Progress report on the possibility of vaccinating cattle against East Coast fever	Theiler, A	47

Some observations concerning the transmission of East Coast fever by ticks	Theiler, A	208

The development of Theileria parva, the cause of East Coast fever in cattle in South Africa - Part 2	Gonder, R	223

The transmission of Amakebe by means of Rhipicephalus appendiculatus, the brown tick	Theiler, A	229

The culicidae of the Transvaal	Theobald, FV	232

On an infectious foot disease in sheep	Theiler, A	273

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On an infectious foot disease in sheep
(Pretoria : Government Printer and Stationery Office, 1911) Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Dept. of Agriculture
The culicidae of the Transvaal
(Pretoria : Government Printer and Stationery Office, 1911) Theobald, Fred V.; Union of South Africa. Dept. of Agriculture
This study was to find out which mosquitoes would feed on horses and accordingly which mosquitoes can be connected to horse-sickness. This report is a complete list of the adult Culicidae so far recorded in the Transvaal
The transmission of Amakebe by means of Rhipicephalus appendiculatus, the brown tick
(Pretoria : Government Printer and Stationery Office, 1911) Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Dept. of Agriculture
Experiments were done to see if the disease Amabeke of Uganda is the same as East Coast fever of South Africa.
Further investigations into anaplasmosis of South African cattle
(Pretoria : Government Printer and Stationery Office, 1911) Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Dept. of Agriculture
(1) The transmission of Anaplasma marginale is only possible with blood containing red corpuscles. Filtrated blood failed to produce the disease when inoculated, the injected animals not showing any lesions at all and proving susceptible to subsequent blood inoculation (heifer 1211). (2) The incubation period after the injection of blood containing anaplasms varies in length and depends on the quantity of blood injected, being shorter after an injection of a large quantity of blood and after the anaplasms have passed through a number of animals. (3) Distinction has to be made between varieties of anaplasms. In this article one variety has been distinguished as Anaplasma marginale and the other as Anaplasma marginale (variety centrale ). (4) The distinction is based (1) on the different position the two parasites take up within the red corpuscle; (2) on the difference in size, there being slightly smaller individuals in the centrale variety; (3) on the different virulency, the centrale variety having caused neither death nor any serious lesions; (4) on the fact that a recovery from an infection from Anaplasma centrale does not cause complete immunity. (5) Anaplasmosis was transmitted in four instances by means of Boophilus decoloratus larvae, and once by Rhipicephalus simus larvae, the mothers of which ticks were collected off immune animals. (6) The incubation times after tick infection varied from between a few days under two months to a few days over three months. (7) It has been noticed in one case (heifer 935) that when a very heavy infestation of ticks is made, an animal may die as a result of loss of blood due to the repletion of the engorged females. (8) The Anaplasma centrale infection transmitted either by ticks or by inoculation, in no instance caused the death of any of the thirty-nine English heifers. Accordingly an inoculation with Anaplasma marginale (variety centrale ) can be made use of as a practical method of inoculation against anaplasmosis. (9) Recovery from Anaplasma centrale infection gives so much protection that a subsequent inoculation of Anaplasma marginale no longer causes death or any serious lesions. (10) Animals which were immune to Babesia bigemina could easily be infected with anaplasmosis, either by means of ticks or by injection of blood. (11) Animals which were immune to the anaplasma infection could easily be infected with Babesia bigemina , either by means of ticks or by blood inoculation. (12) Injected animals can be exposed to natural infection before the Anaplasma centrale reaction has run its course. The anaplasmosis infection due to ticks having a long incubation time (55 to 100 days) will not develop severely in the inoculated animal, in which the disease runs with a shorter incubation time (16 to 40 days). (13) All animals which have passed through an attack of anaplasmosis and redwater conveyed by inoculation and exposed to natural infection for over a year are still alive. (14) The anaplasmosis transmitted by ticks was that of the type centrale and marginale . (15) To judge by the blood smears obtained from the cattle exposed in the veld, a double infection is frequently met with. (16) Animals immune to Anaplasma and Babesia bigemina infections could easily be infected with Babesia mutans . (17) As an accidental occurrence in some instances the larval ticks of Boophilus , collected off immune cattle, transmitted an infection of Spirochaeta theileri in typical time. In one instance the inoculation with blood of a horse in which the spirochaetes were noted, the pure infection was transmitted to a susceptible animal. (18) For the requirements of the conditions of South Africa, it is necessary to combine the immunization against anaplasmosis with an inoculation against redwater. (19) The redwater inoculation can be done before or after the anaplasmosis inoculation, but it is practical to do both at the same time. (20) The redwater, having a shorter incubation time, will develop first, and a recovery will usually be effected before the anaplasmosis reaction sets in. (21) In applying this method to the practice, it is necessary to keep the animal during the redwater reaction (about fifteen days) under close observation and to check any unusual reaction by means of a trypan blue injection, and whilst the animal is undergoing the anaplasmosis reaction it will have to be well fed.
Progress report on the possibility of vaccinating cattle against East Coast fever
(Pretoria : Government Printer and Stationery Office, 1911) Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Dept. of Agriculture
Summary of conclusions:(1) The injection of spleen or gland pulp (of coarse or fine grain) into the jugular vein can be carried out with but little risk provided microscopical examination proves that such material is not contaminated with bacteria or micrococci (2) The presence of an Endocarditis verrucosa, due to the injection of such material, was only noted in one instance, and that was a case of a double injection into the jugular vein of 20 c.c. spleen pulp. (3) The highest percentage of artificial infection, calculated on both deaths and immunity due to such injections, was obtained by the intrajugular method (vide Table A). (4) Of the intrajugular injections, the most certain method of transmission was noticed after the injection of coarse-grained spleen pulp, and coarse-grained spleen and gland pulp (mixed) (vide Table B). (5) The percentage of survivals amongst the animals treated by intrajugular injections, arranged according to the amount of material used, was as follows :- In the dose of: 40 c.c. Nil survived out of 1 treated 0 % 25 c.c 2 survived Out of 7 treated 28 % 20 c.c 13 survived Out of 41 treated 32 % 15 c.c. 3 survived Out of 9 treated 33 % 10 c.c. 16 survived Out of 31 treated 51 % 30 c.c 9 survived Out of 13 treated 70 % 5 c.c. 24 survived Out of 34 treated 71 % (6) The results of the intrajugular injections in the different experiments, arranged according to the immunity conferred, vary from nil to 100 per cent. (vide Table C). (7) The highest percentage of transmission was obtained by the addition of peptone to the material injected (compare Table D). (8) The material which transmitted the disease in the majority of cases was taken from cattle suffering from East Coast fever, which had been killed from the 25th day onwards after the infestation of ticks, or fourteen days onwards after the first rise of temperature (vide Table E). (9) The inoculation was either succeeded by (a) a typical East Coast fever reaction, ending in death, and accompanied with the presence of plasma bodies; or (b) by typical East Coast fever reactions, accompanied with parasites, and ending in recovery; or (c) by mild or irregular reactions, accompanied with the presence of parasites, and ending in recovery; or (d) by reactions indicative of East Coast fever, but without plasma bodies; or (e) by irregular reactions; or (f) by no reactions (vide Summary of Experiment and Tables). (10) Of animals inoculated in various ways, and exposed to tick infestation or natural infection, the least mortality occurred amongst those which had shown plasma bodies in the lymphatic glands as a result of the injection (vide Table G). (11) An observation of fundamental importance is the fact that an animal which contracted the disease from ticks (viz., in the natural way) contracted it a second time and died when exposed to natural infection on the veld. In other words, animals which have recovered from a natural attack, due to tick infestation, may contract the disease again, although this seems to be a rare exception. (12) A further fact of importance is the observation that five animals which contracted the disease from the injection, accompanied with the presence of plasma bodies in the lymphatic glands, and recovered, again contracted East Coast fever when exposed to natural infection, of which three died and two recovered. (13) In the foregoing experiments, 224 animals were used in all, of which 180 were injected either once only, or twice within sixteen days, and forty-four were injected repeatedly. (a) Of the 180 animals, nineteen died, chiefly from accidents resulting from inoculation, the cause of death being septic pneumonia, due to embolism with contaminated material. Thirty-nine contracted the disease from the inoculation and died. Forty-seven contracted the disease from injection and recovered. Of these forty-seven, three died before they could be tested, three died of relapses, that is to say, again contracted the disease in the field (breakdowns in immunity), two showed relapses and recovered, and six died of other causes after the critical period of the test had elapsed. Twelve did not react typically to the injection, and died of other causes before they could be tested, or before the critical period of the test had elapsed. Sixty-three animals which did not react typically to the inoculation were tested by the infestation of ticks and exposure to natural infection; twenty-eight contracted the disease and died, three contracted the disease and recovered, and thirty-two proved to be immune. Of the thirty-five, eight died later of other causes. (b) Of the forty-four animals which were injected repeatedly, fourteen died, chiefly from accidents resulting from inoculation, the cause of death being septic pneumonia, due to embolism with contaminated material. Seven did not react typically to the injection, and died of other causes before they could be tested, or before the critical period of the test had elapsed. Twenty-three did not react typically to the injection, and were tested by the infestation of ticks or by exposure to natural infection, of which fifteen contracted East Coast fever and died, and eight proved to be immune; of these eight, two died later of other causes. (14) The final result amongst the inoculated animals that were exposed to tick infestation and natural infection is :- One hundred and thirty exposed, of which forty-six died of East Coast fever from tests, and eighty-five survived the critical period of the test, the net result of animals which survived injection and tests being eighty-four out of one hundred and seventy, or 50 per cent. (15) For the present, a practical method of inoculation, which can be reasonably expected to confer immunity to the extent of 60 to 70 per cent., would consist in the injection of a quantity of not less than 5 c.c. of spleen or of a mixture of spleen and gland pulp (coarse grain) taken from an animal in the last stage of the disease, mixed with peptone and injected intrajugularly. This method can be applied in all cases of emergency as a last resource, that is to say, in cases where there are no opportunities for dipping, or moving the cattle, the artificial immunization can be adopted in order to save the greatest possible number of animals.
The development of Theileria parva, the cause of East Coast fever in cattle in South Africa - Part 2
(Pretoria : Government Printer and Stationery Office, 1911) Gonder, Richard; Union of South Africa. Dept. of Agriculture
This report deals with the forms of Theileria parva found in the blood corpuscles and their further development within the transmitting agent.
Some observations concerning the transmission of East Coast fever by ticks
(Pretoria : Government Printer and Stationery Office, 1911) Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Dept. of Agriculture
In the experiments it has been proved: (1) That brown tick imagines which as larvae had become infected with East Coast fever and which had transmitted the disease in their nymphal stage were no longer infective for susceptible cattle. Four batches of ticks proved their infectivity in the nymphal stage on eight animals, but in their adult stage failed to transmit the disease to two susceptible animals. (2) Ticks belonging to the same batches which were feeding on two animals rendered immune to East Coast fever by inoculation in the nymphal stage did not transmit the disease in their adult stage to six animals, thus proving that the brown tick which has become infected in one stage cleans itself in the following stage by feeding on an immune or susceptible animal. (3) Ticks which became infected with East Coast fever in their larval stage and which passed their nymphal stage on a rabbit did not prove to be infective in their adult stage for susceptible cattle. This conclusion bears out that given above (2): showing that a tick loses its infectivity the first time it feeds on an animal susceptible or immune to East Coast fever. (4) Clean or infective ticks feeding on an animal which has recovered from an attack of East Coast fever do not transmit the disease in their next stage. This conclusion is in support of experiments undertaken eight years ago (vide Annual Report of the Government Veterinary Bacteriologist, 1904-05). (5) It has been demonstrated that certain batches of ticks collected at the same time and which fed under similar conditions do not transmit the disease in their next stage, even when infested in great numbers and on numerous animals. Other batches of ticks reared in exactly the same way and under similar conditions only infected a few animals, whilst again other ticks proved infective in almost every instance even when a minimum number were used. It is difficult to give an explanation of this fact, but it is quite likely that outside conditions have some influence. The ticks which did not transmit the disease were bred during the coldest time of the year. This may perhaps explain the fact that during the winter months the infection in the field is not so active as during the summer months, remembering at the same time that during the winter months tick life is generally weaker than in the summer.
Letter of transmittal
(Pretoria : Government Printer and Stationery Office, 1911) Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Dept. of Agriculture

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