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A campaign against the hypoderma bovis
ABSTRACTS AND REPORT.
agar. The growth took the form of a thick greyish-white wrinkled film, which spread very slowly. No growth was obtained upon suitable media put up under anrerobic conditions. Subsequently attempts were made to get the bacillus to grow on media which did not contain any glycerin extract. In some cases solidification of the media was effected by using a 3 per cent. watery solution of agar. This was mixed with an equal quantity of serum, together with 1 per cent. of one of the following substances in weak acid solution-somatose, Heyden's medium, Witte's peptone, Liebig's meat peptone, and nutrose. In other experiments ! per cent. dextrose and 3 per cent. glycerin were added. Broth (glycerinised) was also prepared from a tuberculous udder, and tuberculous liver obtained from cattle. Finally, attempts were" made to obtain cultures upon serum·agar, ordinary agar, broth, liver broth, etc. N one of these appeared to be suitable, save that there was possibly a slight amount of growth on the media containing somatose and Heyden's medium. Inoculation experiments into guinea-pigs failed to set up the disease, and produced at the most a small encapsuled abscess at the seat of inoculation. The yellowish-brown crumbling contents of such abscesses contained a few granular acid-fast bacilli. Experiments carried out with rabbits had similar results. Up to the present the experiments made upon calves have had the following results. All the calves used were tested with tuberculin and passed. The inoculations were made subcutaneously and intravenously, and caused no reaction. Three months later the animals were tested with ordinary tuberculin and did not react, but with avian tuberculin, three weeks later, typical reactions were obtained. Subsequently tuberculin prepared from cultures described was used, and in the case of one calf gave rise to a typical tuberculin reaction. In the others no rise of temperature was observed. Finally, experiments were carried out with guinea-pigs with the object of ascertaining whether Johne's bacillus is capable of conferring any immunity against tuberculosis. The animals received two comparatively large doses of culture, and a month later a dose of bacilli of the bovine type. Control animals were inoculated with the bovine bacilli alone. All the animals were weighed twice weekly, and it was found that the control animals commenced to lose weight sooner than the others. The author concludes that a slight degree of immunity was established. (HaIth, Zeitschr. f. Infekt. tarasi/o Krankh. u. Hyg. d. Haust., Vol. XL, NO.5, 14th May 1912, pp. 378-387.)
. A CAMPAIGN AGAINST THE HYPODERMA BOVIS. THE losses caused by this parasite fall under three headings : 1. Loss due to perforation of the hide. 2. Decrease in the production of milk. 3. General loss of condition. 1. Loss due to perforation of the hide. This has been variously estimated in the countries where the fiy occurs. In I889 it was computed that the annual loss sustained by the United States amounted to 35 to 60 million dollars. In Great Britain it has been variously estimated at from 40 to 200 millions, the latter figure appearing to be greatly exaggerated. In Germany the parasite has a very unequal distribution, and the annua]
ABSTRACTS AND REPORT.
loss is stated by Ostertag to be about 10 million francs, while in Denmark the figure is a little lower. In France it has been estimated that 10 per cent. of the hides are affected, and that the loss amounts to 10 to I7 francs per hide. This means that the annual loss is from 5 to 8 million francs. Season, tempnature, age of the animals, district, and method of stocking all have an influence on the number of hides affected. It has been ascertained that in Germany the parasite is very unequally distributed, and that, whereas in some parts of Prussia the proportion of skins affected amounts to 22 per cent., in Bavaria it is only I per cent., and that in Saxony the parasite is unknown. It is an ascertained fact that the fly does not enter buildings. It has also been shown that the eggs are laid at pasture during the hottest parts of the day, that the larvae as a rule make their escape early in the morning, and that a larva which escapes while the animals are housed does not develop. With regard to the season, it is only in the spring that perforated hides are encountered. Warbles remaining under the skin till the winter invariably become degenerated. After the escape of the larva the puncture left gradually heals and is finally completely obliterated. Warbles are particularly numerous during a spring following a very hot summer. The parasites are found principally on animals from two to four years of age, and are rare in adults and never found on old animals. 2. The persistent irritation caused by the larvae causes a serious decrease in the quantity of milk. This fact has been observed repeatedly and in large numbers of animals. 3. The loss resulting from the presence of the parasite with regard to the meat is also a well-ascertained fact, it having been computed that the loss in this connection amounts to £ I a head'. The fly is responsible also for accidents to cattle, such as fractures sustained while "gadding." Abscess formation is another condition for which the larva is responsible. There is considerable disagreement with regard to the biology of the parasite. In Europe the common fly is the hypoderma bovis, while that which is encountered in America is the hypoderma lineatum. Very little is known regarding the fiy in its natural state, but specimens may be obtained by hatching out larvae which have escaped from the skin spontaneously. Only a proportion of the larvae so obtained will attain the full development. Scarcely anything is known regarding the fiy save that, being unable to feed, its existence is a very brief one. It occurs principally on dry pastures and near woods. It does not occur on marshy land. The fiy, which is about 15 mm. in length, has the appearance of a small bee with transverse brown stripes. The abdomen of the female is prolonged into a telescopic tube 4 to 5 mm. in length. This serves for the deposition of eggs. It was for a long time supposed that by means of this tube the fiy was able to deposit eggs under or in the skin, but it is not sufficiently rigid to allow of its carrying out such a function. Nothing is kliown regarding the laying of the eggs. Whereas in the case of the gastrophilus equi the eggs are easily seen, the opposite holds good in the case of the hypoderma bovis, and nothing would have been known regarding them if they had not been obtained from the bodies of females. Brauer believes that the embryo which escapes from the egg penetrates the skin to reach the connective tissue. But this view does not explain the presence of larvae in the internal organs and their absence from the skin during the winter.
ABSTRACTS AND REPORT.
The larv~ have been found in the canal of the spinal cord, and they have been found during the autumn in the wall of the <:esophagus. The identity of these larv~ cannot be doubted, since they have been cultivated in the goat right up to the formation of the perfect insect. It appears to be highly probable that the larv~ liberated on the skin are licked off and swallowed by the host. In the <:esophagus, and possibly also in the stomach, the larv~ penetrate the mucous membrane, and come to rest in the submucous tissue. They may be found here during the winter months, surrounded by a greenish translucent jelly. In this position they increase in size from 2 to 15 mm. At the second stage the muscular wall of the <:esophagus is perforated, and the parasite may be found in the mediastinum, pillars of the diaphragm, and omentum, and its migrations towards the spinal canal can be followed. During January and February the parasite is to be found embedded in the adipose tissue surrounding the dura mater, and it appears as a yellowishgreen spot. In March it leaves the spinal canal, and, following the intermuscular septa, reaches the skin, where complete development is to take place. The times given are, of course, approximate only, and depend upon the climate, severity of the weather, and individual idiosyncrasies. The tumour-like swellings produced by the parasite under the skin occur principally on the back, loins, and shoulders, the most valuable portions of the hide. By means of the spines at its anal extremity the parasite is enabled to perforate the skin. It then moults. It changes its shape, which up to this point has been cylindrical, and becomes club-like, and at the same time acquires its chitinous covering. Two reniform stigmata make their appearance at the posterior end. After a second moult it becomes covered with small spines and black in colour. It then measures about 25 mm. in length by 12 mm. in width. Development is comr:lete by Mayor June. The parasite enlarges the opening in the skin, from which a purulent liquid escapes, and by creeping movements passes through and falls to the ground. This generally occurs early in the morning. Parasites dropped in sheds generally die. Those dropped on the pasture rapidly develop into pup~ A month later an operculum formed by the upper part of the four anterior rings gives exit to the fly. The induration of the skin disappears slowly. The openings close up, and very shortly all evidence of them disappears. In connection with the fly there is one point of the utmost importance, and that is that it is not a migratory insect. It passes the whole of its life, which is, however, very short, close to the place where it is hatched. The importance of this is that the work done by those who enter upon a campaign against the fly is not rendered void by the negligence of neighbours. Transportation of the fly to great distances is only possible through the a~ency of high winds. A point of equal importance is the question whether the parasite can develop in wild animals. It appears, however, to be certain that there is nothing to be feared in that direction. In undertaking the destruction of the parasite the ideal would be to kill the fly before it could lay its eggs. This, however, is impossible, since practically nothing is known as to its habits. Experience has shown that the provision of coverings for cattle is too onerous, and the dressing of the skin with strong smelling substances is inefficacious. 'With regard to the destruction of the eggs after they have been laid, it is known that regular grooming reduces the number of warbles. This plan, however, is quite impracticable for animals at pasture. Once the
ABSTRACTS AND REPORT.
153
larva has penetrated the body it is out of reach, but when it is preparing to make its exit again through the skin it is in a superficial part which is easily accessible and remains there for months. If spontaneous escape be waited for there is the chance that the parasite may avoid destruction, but by practising premature removal of the larv
FOOT-AND-MOUTH DISEASE IN THE HORSE. As is well known, the horse is to a certain extent susceptible to foot-andmouth disease, but such cases are very rare. De Jong records the occurrence of the disease in three foals that had been weaned a few days previously, and turned out in a field with some cattle affected with foot-and-mouth disease. The first symptoms made their appearance after an interval of five days. Prehension of food was difficult, and there was salivation. Smacking of the lips, such as is noticed in cattle, was not observed by the author. There were several vesicles on the buccal mucous membrane, some intact and some ruptured. A fortnight after being turned out one of the foals was still salivating, and the mucous membrane of the tongue and mouth still showed distinct evidence of the lesions. There were no lesions on any other part of the body or the feet. These cases prove that it is wrong to apply restrictions to cattle and pigs only in outbreaks of foot-and-mouth disease. (De Jong, Ann. de Med. Vet., No.2, February 1912, p. 90; ex. Tyds. ZI. Veeartseni.fkunde, 15th September 1911, p. 690.)
agar. The growth took the form of a thick greyish-white wrinkled film, which spread very slowly. No growth was obtained upon suitable media put up under anrerobic conditions. Subsequently attempts were made to get the bacillus to grow on media which did not contain any glycerin extract. In some cases solidification of the media was effected by using a 3 per cent. watery solution of agar. This was mixed with an equal quantity of serum, together with 1 per cent. of one of the following substances in weak acid solution-somatose, Heyden's medium, Witte's peptone, Liebig's meat peptone, and nutrose. In other experiments ! per cent. dextrose and 3 per cent. glycerin were added. Broth (glycerinised) was also prepared from a tuberculous udder, and tuberculous liver obtained from cattle. Finally, attempts were" made to obtain cultures upon serum·agar, ordinary agar, broth, liver broth, etc. N one of these appeared to be suitable, save that there was possibly a slight amount of growth on the media containing somatose and Heyden's medium. Inoculation experiments into guinea-pigs failed to set up the disease, and produced at the most a small encapsuled abscess at the seat of inoculation. The yellowish-brown crumbling contents of such abscesses contained a few granular acid-fast bacilli. Experiments carried out with rabbits had similar results. Up to the present the experiments made upon calves have had the following results. All the calves used were tested with tuberculin and passed. The inoculations were made subcutaneously and intravenously, and caused no reaction. Three months later the animals were tested with ordinary tuberculin and did not react, but with avian tuberculin, three weeks later, typical reactions were obtained. Subsequently tuberculin prepared from cultures described was used, and in the case of one calf gave rise to a typical tuberculin reaction. In the others no rise of temperature was observed. Finally, experiments were carried out with guinea-pigs with the object of ascertaining whether Johne's bacillus is capable of conferring any immunity against tuberculosis. The animals received two comparatively large doses of culture, and a month later a dose of bacilli of the bovine type. Control animals were inoculated with the bovine bacilli alone. All the animals were weighed twice weekly, and it was found that the control animals commenced to lose weight sooner than the others. The author concludes that a slight degree of immunity was established. (HaIth, Zeitschr. f. Infekt. tarasi/o Krankh. u. Hyg. d. Haust., Vol. XL, NO.5, 14th May 1912, pp. 378-387.)
. A CAMPAIGN AGAINST THE HYPODERMA BOVIS. THE losses caused by this parasite fall under three headings : 1. Loss due to perforation of the hide. 2. Decrease in the production of milk. 3. General loss of condition. 1. Loss due to perforation of the hide. This has been variously estimated in the countries where the fiy occurs. In I889 it was computed that the annual loss sustained by the United States amounted to 35 to 60 million dollars. In Great Britain it has been variously estimated at from 40 to 200 millions, the latter figure appearing to be greatly exaggerated. In Germany the parasite has a very unequal distribution, and the annua]
ABSTRACTS AND REPORT.
loss is stated by Ostertag to be about 10 million francs, while in Denmark the figure is a little lower. In France it has been estimated that 10 per cent. of the hides are affected, and that the loss amounts to 10 to I7 francs per hide. This means that the annual loss is from 5 to 8 million francs. Season, tempnature, age of the animals, district, and method of stocking all have an influence on the number of hides affected. It has been ascertained that in Germany the parasite is very unequally distributed, and that, whereas in some parts of Prussia the proportion of skins affected amounts to 22 per cent., in Bavaria it is only I per cent., and that in Saxony the parasite is unknown. It is an ascertained fact that the fly does not enter buildings. It has also been shown that the eggs are laid at pasture during the hottest parts of the day, that the larvae as a rule make their escape early in the morning, and that a larva which escapes while the animals are housed does not develop. With regard to the season, it is only in the spring that perforated hides are encountered. Warbles remaining under the skin till the winter invariably become degenerated. After the escape of the larva the puncture left gradually heals and is finally completely obliterated. Warbles are particularly numerous during a spring following a very hot summer. The parasites are found principally on animals from two to four years of age, and are rare in adults and never found on old animals. 2. The persistent irritation caused by the larvae causes a serious decrease in the quantity of milk. This fact has been observed repeatedly and in large numbers of animals. 3. The loss resulting from the presence of the parasite with regard to the meat is also a well-ascertained fact, it having been computed that the loss in this connection amounts to £ I a head'. The fly is responsible also for accidents to cattle, such as fractures sustained while "gadding." Abscess formation is another condition for which the larva is responsible. There is considerable disagreement with regard to the biology of the parasite. In Europe the common fly is the hypoderma bovis, while that which is encountered in America is the hypoderma lineatum. Very little is known regarding the fiy in its natural state, but specimens may be obtained by hatching out larvae which have escaped from the skin spontaneously. Only a proportion of the larvae so obtained will attain the full development. Scarcely anything is known regarding the fiy save that, being unable to feed, its existence is a very brief one. It occurs principally on dry pastures and near woods. It does not occur on marshy land. The fiy, which is about 15 mm. in length, has the appearance of a small bee with transverse brown stripes. The abdomen of the female is prolonged into a telescopic tube 4 to 5 mm. in length. This serves for the deposition of eggs. It was for a long time supposed that by means of this tube the fiy was able to deposit eggs under or in the skin, but it is not sufficiently rigid to allow of its carrying out such a function. Nothing is kliown regarding the laying of the eggs. Whereas in the case of the gastrophilus equi the eggs are easily seen, the opposite holds good in the case of the hypoderma bovis, and nothing would have been known regarding them if they had not been obtained from the bodies of females. Brauer believes that the embryo which escapes from the egg penetrates the skin to reach the connective tissue. But this view does not explain the presence of larvae in the internal organs and their absence from the skin during the winter.
ABSTRACTS AND REPORT.
The larv~ have been found in the canal of the spinal cord, and they have been found during the autumn in the wall of the <:esophagus. The identity of these larv~ cannot be doubted, since they have been cultivated in the goat right up to the formation of the perfect insect. It appears to be highly probable that the larv~ liberated on the skin are licked off and swallowed by the host. In the <:esophagus, and possibly also in the stomach, the larv~ penetrate the mucous membrane, and come to rest in the submucous tissue. They may be found here during the winter months, surrounded by a greenish translucent jelly. In this position they increase in size from 2 to 15 mm. At the second stage the muscular wall of the <:esophagus is perforated, and the parasite may be found in the mediastinum, pillars of the diaphragm, and omentum, and its migrations towards the spinal canal can be followed. During January and February the parasite is to be found embedded in the adipose tissue surrounding the dura mater, and it appears as a yellowishgreen spot. In March it leaves the spinal canal, and, following the intermuscular septa, reaches the skin, where complete development is to take place. The times given are, of course, approximate only, and depend upon the climate, severity of the weather, and individual idiosyncrasies. The tumour-like swellings produced by the parasite under the skin occur principally on the back, loins, and shoulders, the most valuable portions of the hide. By means of the spines at its anal extremity the parasite is enabled to perforate the skin. It then moults. It changes its shape, which up to this point has been cylindrical, and becomes club-like, and at the same time acquires its chitinous covering. Two reniform stigmata make their appearance at the posterior end. After a second moult it becomes covered with small spines and black in colour. It then measures about 25 mm. in length by 12 mm. in width. Development is comr:lete by Mayor June. The parasite enlarges the opening in the skin, from which a purulent liquid escapes, and by creeping movements passes through and falls to the ground. This generally occurs early in the morning. Parasites dropped in sheds generally die. Those dropped on the pasture rapidly develop into pup~ A month later an operculum formed by the upper part of the four anterior rings gives exit to the fly. The induration of the skin disappears slowly. The openings close up, and very shortly all evidence of them disappears. In connection with the fly there is one point of the utmost importance, and that is that it is not a migratory insect. It passes the whole of its life, which is, however, very short, close to the place where it is hatched. The importance of this is that the work done by those who enter upon a campaign against the fly is not rendered void by the negligence of neighbours. Transportation of the fly to great distances is only possible through the a~ency of high winds. A point of equal importance is the question whether the parasite can develop in wild animals. It appears, however, to be certain that there is nothing to be feared in that direction. In undertaking the destruction of the parasite the ideal would be to kill the fly before it could lay its eggs. This, however, is impossible, since practically nothing is known as to its habits. Experience has shown that the provision of coverings for cattle is too onerous, and the dressing of the skin with strong smelling substances is inefficacious. 'With regard to the destruction of the eggs after they have been laid, it is known that regular grooming reduces the number of warbles. This plan, however, is quite impracticable for animals at pasture. Once the
ABSTRACTS AND REPORT.
153
larva has penetrated the body it is out of reach, but when it is preparing to make its exit again through the skin it is in a superficial part which is easily accessible and remains there for months. If spontaneous escape be waited for there is the chance that the parasite may avoid destruction, but by practising premature removal of the larv
FOOT-AND-MOUTH DISEASE IN THE HORSE. As is well known, the horse is to a certain extent susceptible to foot-andmouth disease, but such cases are very rare. De Jong records the occurrence of the disease in three foals that had been weaned a few days previously, and turned out in a field with some cattle affected with foot-and-mouth disease. The first symptoms made their appearance after an interval of five days. Prehension of food was difficult, and there was salivation. Smacking of the lips, such as is noticed in cattle, was not observed by the author. There were several vesicles on the buccal mucous membrane, some intact and some ruptured. A fortnight after being turned out one of the foals was still salivating, and the mucous membrane of the tongue and mouth still showed distinct evidence of the lesions. There were no lesions on any other part of the body or the feet. These cases prove that it is wrong to apply restrictions to cattle and pigs only in outbreaks of foot-and-mouth disease. (De Jong, Ann. de Med. Vet., No.2, February 1912, p. 90; ex. Tyds. ZI. Veeartseni.fkunde, 15th September 1911, p. 690.)