Experimental Studies on the Pathogenesis of Corynebacterium equi Infection in Foals

Four month-old foals were infected orally with 75 mL of a suspension of 5.0 × 10⁸ Corynebacterium equi per mL. Two foals were killed after ten days and had scanty number of C. equi in the caeco-colic lymph nodes. No C. equi were recovered from the other two foals, killed 20 days after infection. No gross pathological change was detected in these four foals, although mild microscopic lesions were seen in the ileum of one foal. Results of lymphocyte blastogenesis using peripheral blood lymphocytes and C. equi antigens showed, however, that lymphocytes became sensitized to C. equi following this challenge.

In a second experiment four month-old foals were given orally the same dose of organisms but on five consecutive days. Two foals were killed ten days after infection and showed mild histological changes in the large bowel mucosa and C. equi could be recovered from all intestinal lymph nodes cultured. In one of these foals moderate numbers of C. equi were present in the bronchial lymph node. Of the other two foals, one died after 22 days with severe ulcerative enterocolitis and intestinal lymphadenitis. Only one small pulmonary abscess was detected despite large numbers of C. equi in the lungs. The other foal developed similar intestinal changes and was euthanized 25 days after infection. No C. equi were detected in the lungs or bronchial lymph node. Lymphocyte blastogenesis in these animals showed a rapid rise in response to C. equi antigens.

These studies suggest that C. equi pneumonia in foals does not always arise from an intestinal infection, that minor intestinal infection causes a cellular immune response and that massive exposure of the bowel over a sustained period is necessary to induce intestinal lesions.

     

Contribution à l'étude quantitative de la flore bactérienne du gros intestin des porcs dysentériques

The bacterial flora and the pH of the large intestine of dysenteric swine during acute subacute and chronic phases have been submitted to quantitative and qualitative studies. The methods used are based on primary isolation and differentiation of the bacteria by the use of selective media and the subsequent differentiation using the replica plating technique. The most characteristic changes are the following:

1. A significant increase of the pH of the chyme in the large intestine during acute dysentery

2. A significant increase of Vibrio, Escherichia coli and Staphylococcus in the colon and cecum during acute dysentery.

3. A significant increase of Shigella in the colon and cecum during subacute dysentery.

4. The almost total disappearance of Aeromonas and of the yeasts in the large intestine during acute, subacute and chronic dysentery.

5. A significant decrease of Klebsiella, in the cecum, during acute dysentery and of the fungi during subacute dysentery.

6. Decrease of Streptococcus in the colon during acute dysentery.

7. The total quantitative flora of the large intestine do not change very much.

     

The Relationship of Erythrocyte Age and Parasitization with Plasmodium gallinaceum in Chickens

Erythrocyte labeling by random and cohort techniques was used to study erythrocyte survival in normal chickens and in chickens infected with Plasmodium gallinaceum. White Leghorn chickens, eight weeks of age, were used in this series of experiments.

In chickens given P. gallinaceum on the day following erythrocyte labeling there was destruction of labeled erythrocytes at a much more rapid rate than would result from normal ageing processes. Chickens given P. gallinaceum 12, 18 and 21 days after the labeling of the erythrocytes failed to show any greater destruction of the labeled red cells beyond that resulting from normal senescence. This result indicates that erythrocytes over 12 days of age are not destroyed by P. gallinaceum.

     

The Detection of Specific Complement-Fixing Antibodies in Serum of White-Tailed Deer (Odocqileus Virginianus) with Theileria Infection

A complement-fixation (CF) antigen which has been prepared from Theileria infected erythrocytes is capable of reacting to specific serum antibodies of deer acutely infected with Theileria.

No sera from 17 deer known to be free of Theileria infection reacted positively to the CF test. Of 35 tests on sera from 12 infected deer having a parasitemia of 2% or less and no accompanying anemia, only 10 (29%) were positive, 2 (6%) were suspicious, and 23 (66%) were negative. Of 65 tests on 8 acutely infected deer, 49 (75%) were positive, 4 (6%) were suspicious and 12 (18%) were negative. Of the 8 deer in which acute theileriasis occurred all reacted to Theileria antigen at one time or another.

A significant correlation was found between CF titers and the degree of parasitemia in acute infections.

Rabbits were hyperimmunized using erythrocytes from either normal or Theileria infected deer. Reciprocal absorption of the hyperimmune sera with Theileria and normal erythrocytic antigens demonstrated the presence of antibodies specific for Theileria.

     

Mycoplasma and Associated Bacteria Isolated from Ovine Pink-eye

A mycoplasma was recovered from the untreated conjunctival membranes of nine sheep affected by Pink-eye. It was neither isolated from the conjunctiva of treated animals which were affected nor from the conjunctiva of normal animals either in contact or not in contact with affected animals.

Bacteria found on normal conjunctival membranes were Neisseria ovis, Escherichia coli, Staphylococcus epidermididis, Streptococcus and Bacillus spp.

Bacteria found in clinical cases of Pink-eye were N. ovis, E. coli, a Streptococcus and Pseudomonas spp.

     

Parasites of Dogs from Indian Settlements in Northwestern Canada: A Survey with Public Health Implications

A total of 959 faecal samples were obtained from dogs in 12 native communities in Northern Saskatchewan, Central and Northern Alberta and the Northwest Territories. All samples were examined using a flotation technique. Samples from an area of endemic human amoebic infections were also examined by a formol-ether sedimentation method. Eighteen necropsies were performed.

Entamoeba histolytica cysts were recovered from dog faeces at Loon Lake, Saskatchewan.

Toxocara canis had low incidence in Saskatchewan and Central Alberta, and appeared to be almost non-existent further North. Toxascaris leonina was found in all areas surveyed. Canine hookworm infections were plentiful in all areas, the highest incidence being recorded from Northern Alberta and Northwest Territories. Many Taenia (or Echinococcus) infections were found consistently in all areas. Only one infection with Dipylidium caninum was discovered.

Metorchis conjunctus infections were found to be common in the Saskatchewan reserves. Infections with Diphyllobothrium sp. were found in all communities with access to good fishing. One specimen of Dioctophyma renale was recovered at necropsy.

Infections with parasites of no known zoonotic importance such as Trichuris, Alaria and Isospora species were also recorded.

     

Regional Histological Variations of the Nasal Mucosa of Cattle

Aspects of the histology of the nasal mucosa of calves from four to six months of age have been described.

The functional significance of the type of epithelium, its thickness, the degree of neutrophil invasion, and its relationship to the numbers of Pasteurella haemolytica in the nasal cavity have been discussed. In addition, the arrangement and depth of glands in the lamina propria and the presence of lymph follicles have been described.

     

Vibriosis: Demonstration of Vibrio fetus and Vibrio bubulus Organisms in Preputial Fluid by Immunofluorescence and Cultural Techniques

Fluorescent conjugates were prepared from the sera of calves immunized with four Vibrio fetus strains and one Vibrio bubulus strain. The fluorescent antibody technique (FAT) was then used to detect vibrio organisms in preputial fluid collected from 67 bulls belonging to a Canadian artificial insemination (AI) unit. The V. fetus conjugates reacted with both V. fetus var venerealis and V. fetus var intestinalis. V. fetus was found in 20 animals (29.9%), 13 of which also harboured V. bubulus. In two cases, the FAT failed to detect V. fetus which was isolated by concurrent bacteriological examinations.

It was concluded that the FAT can be a rapid method of detecting some carrier bulls but more reliable results are obtained when a combination of FAT and bacteriological methods is employed. It was found that a single sample giving negative results is inconclusive and additional tests are required before making a final diagnosis. The FAT can also be used to differentiate V. fetus isolates from V. bubulus.

     

An Attempt to Experimentally Produce Edema Disease in Swine by Oral Administration of Escherichia Coli Serotype 0139:K82:H1

Diarrhea, reduced appetite, and nervousness were observed following oral exposure of six pigs to freeze-thaw extract and living culture of E. coli strain 0139:K82:H1.

The most significance gross change was the appearance of subserosal edema of the mesentry, especially of the mesocolon.

Histological findings included perivascular edema of the brain and reticulum cells as well as lymphocytic aggregates in the renal cortex simulating early neoplasia. Edema of the submucosa of gallbladder, the duodenum, the spiral colon and the fundic stomach as well as the lymph nodes was also observed.

The syndrome which was produced resembled, in many aspects, edema disease although some complicating factors were ob-

     

Differentiation Among Strains of Goat Mycoplasma by Incident Light Immunofluorescence

Antigenic differentiation between strains of goat mycoplasma was studied by direct fluorescent antibody reactions employing incident (vertical) ultraviolet light. Agar colonies of the mycoplasma grown in petri dishes were fixed by alcohol in situ, and stained with conjugated globulin before examination with ultraviolet light.

The fluorescent antibody (FA) conjugate against Vom strain of Mycoplasma mycoides var. capri was Vom strain-specific, no cross reaction with Mexico, Connecticut, or Maryland strains. Similarly, the Mexico strain conjugate was specific for colonies of Mexico, and did not cross with the Vom, strain. Additionally, the conjugate of the PG-2 strain of Mycoplasma agalactiae, which was specific for the colonies of PG-2 was refractory for the strain #99 of M. agalactiae.

It was therefore possible to utilize an immunofluorescent technique (incident ultraviolet light) to demonstrate differences among strains of M. mycoides var. capri and M. agalactiae.

     

Incident Light Immunofluorescence of Alcohol-fixed Colonies of Ruminant Mycoplasma

Two species of ruminant mycoplasma colonies had to be fixed in ethyl alcohol so that incident immunofluorescence method could be applied. In addition, the stain reaction had to be kept for 90 minutes at 37°C.

This fluorescent antibody (FA) method was developed to identify colonies of Vom strain of Mycoplasma mycoides var. capri, V-5 strain of M. mycoides var. mycoides, and PG-2 strain of M. agalactiaeon agar, using fluorescent ultraviolet light. Fluorescence was not demonstrated when heterologous conjugates or normal rabbit serum conjugate were applied but the reaction appeared to be specific for each strain of mycoplasma.

The FA method was able to differentiate specific mycloplasma colonies in mixed cultures.

     

Some Effects of the Source of Bovine Milk Leucocytes and Strain of Staphylococcus on their Interaction in Vitro

A method is described for the quantitative study in vitro of the bovine milk leucocyte: staphylococci interaction which is capable of demonstrating differences between groups of leucocytes, and, to some extent, stains of Staph. aureus.

By means of this method it has been possible to show statistically, that significant differences can occur, between quarters of the same udder, in the numbers of leucocytes competent to ingest staphylococci, and also in the numbers of staphylococci ingested.

Between 4 strains of Staph. aureus significant differences were noted in their ability to multiply in the presence of milk leucocytes; in the production of leucocidal factors; and in the reduction of Resazurin in whole, normal milk.

     

Studies of Escherichia coli in Gnotobiotic Pigs VI. Effects of Feeding Bacteria-Free Filtrates of Broth Cultures

Nine gnotobiotic pigs derived from one gilt were fed bacteria-free filtrates prepared from: 1) cultures of an enteropathogenic strain of Escherichia coli 09:K·:NM (Strain 340), 2) cultures of a nonenteropathogenic strain of E. coli 08.K·.H16 (Strain CDC-1466-56), and 3) uninoculated culture medium.

Diarrhea was observed initially two to four hours after feeding the filtrate prepared from the enteropathogenic E. coli. The duration of diarrhea was five to ten hours. No diarrhea was observed after feeding filtrate prepared from uninoculated medium or cultures of nonenteropathogenic E. coli.

The pH values of the feces increased with the onset of diarrhea and decreased to normal after diarrhea stopped.

No histopathological lesions were found.

     

Wide Distribution of Pasteurella haemolytica Type 1 Over the Nasal Mucosa of Cattle

Studies on the site of proliferation of Pasteurella haemolytica in the bovine nasal cavity have been carried out.

P.haemolytica were isolated from 15 selected major anatomical areas of the nasal cavity in calves with high numbers of P.haemolytica following shipment from Western Canada. When the organisms were present in the nasal cavity of live animals in low numbers, they were isolated from many, but not all, areas. P.haemolytica was isolated post mortem from one or more selected areas of several nasal cavities in spite of negative antemortem cultures.

By the direct fluorescent antibody technique, P.haemolytica was demonstrated at the surface of nasal epithelial cells. Organisms were not seen in or between epithelial cells nor in the ducts nor alveoli of glands. The findings were similar when high and low numbers of P.haemolytica were present in the nasal cavity.

     

Glasser's Disease of Swine Produced by the Intratracheal Inoculation of Haemophilus suis

The intracheal inoculation of pigs with Haemophilus suis led to the production of Glasser's disease at every attempt without significant pulmonary involvement. Isolation of this organism from the experimental animals was possible only in the acute phase of the disease.

The indirect fluorescent antibody technique when applied to frozen sections of tissues obtained from the experimentally infected pigs at autopsy, revealed a few rod forms but mostly “round bodies” of H. suis in animals from which the organism was isolated, and “round bodies” only in the pigs from which the organism was not isolated.

Attention is drawn to the similarities between the lesions caused by H. suis and Mycoplasma hyorhinis, and to the confusion which may result therefrom. It is stressed that the laboratory diagnosis of these two diseases is complicated by the fact that both agents may not be isolated on the media commonly used in diagnostic laboratories. Both organisms necessitate the use of special media where the clinical and autopsy results indicate polyserositis and arthritis.

     

Passage of I131-albumin and I125-gamma globulin into the small intestine of the pig

Metabolism of I¹³¹-albumin and I¹²⁵-gamma globulin was examined simultaneously in 5 pigs (22-30 kg. bodyweight). Total daily catabolism of albumin and gamma globulin was 12-23 per cent/day and 10-13 per cent/day rsp.

The excretion of the two proteins into the small intestine was studied in Thiry-Vella type loops, situated at different levels of the small intestine. Considerable amounts of protein-bound radio-activity could be detected in succus entericus. Perfusions with isotonic magnesium sulphate solution, normal saline and 10 per cent magnesium sulphate solution were followed by increased excretion of both proteins. The increase was very considerable, even when isotonic fluids were used. The excretion of the two proteins was of the same order of magnitude.

Quantitative aspects are discussed with special reference to the difficulties derived from the fact that little is known on secretory variations along the intestine and on the role played by the passage of digesta in the excretion of proteins.

     

Enzootic Pneumonia of Pigs: Complement-Fixation Tests for the Detection of Mycoplasma Antibodies in the Serum of Immunized Rabbits and Infected Swine

The direct, the modified direct and the indirect complement-fixation tests were investigated as methods for the detection of antibodies for the enzootic pneumonia mycoplasma and for Mycoplasma hyorhinis in the serum of infected pigs and of immunized rabbits.

Only the modified direct complement-fixation test in which the guinea-pig complement is supplemented with fresh, normal unheated calf serum was suitable for the detection of mycoplasma antibodies in sera of infected swine. Based on the close correlation between the production of typical lung lesions in experimentally infected pigs and the appearance of significant serum antibody titres, the modified direct complement-fixation test provides for the first time a sensitive, specific in vitro method for the detection of enzootic pneumonia in the live pig. This test also permitted the in vitro differentiation of the mycoplasma causing enzootic pneumonia from M. hyorhinis which causes polyserositis.

Antibodies in the sera of rabbits were demonstrable by the ordinary direct complement-fixation test. However, in contast to the observation made with swine sera, only a slight quantitative antigenic difference between the enzootic pneumonia mycoplasma and M. hyorhinis was seen when the tests were performed with rabbit serum antibodiies.

     

Attempts to Produce Experimental Edema Disease in Swine by Parenterally Injecting Escherichia Coli Serotype 0139:K82:H1

Twenty-two pigs were inoculated parenterally with various E. coli 0139:K82:H1 preparations. Clinical signs of disease in pigs injected with freeze-thaw extract consisted of early listlessness, diarrhea and, later, hyperirritability of varying intensity in some animals.

Hemorrhagic gastroenteritis involving the duodenum, spiral colon and the fundic portion of the stomach, and ulceration of the fundic stomach were observed at post-mortem examination of pigs inoculated parenterallly with living culture or freeze-thaw extract. No significant lesions were observed in pigs inoculated with ultrasonic or hypotonic acid-saline extract.

In pigs injected with living culture or freeze-thaw extract, the histological alterations consisted of moderate perivascular edema of the brain, marked hepatic parenchymal cell degeneration, hepatic subserosal edema and “toxic” lymph nodes, when compared to the control group.

     

The Effect of Edema, Hydrocortisone Acetate, Concurrent Viral Infection and Immunization on the Clearance of Pasteurella hemolytica from the Bovine Lung

The influence of pulmonary edema, hydrocortisone, immunization against Pasteurella hemolytica and concurrent infection with parainfluenza-3 virus upon pulmonary clearance of aerosolized P. hemolytica was studied in 31 calves. Following the various treatments calves were challenged with an aerosol of P. hemolytica. One control calf was killed immediately after the aerosol and the numbers of bacteria in the lung taken as 100%. Two calves were killed four hours after challenge and the numbers of bacteria in the lungs were compared to the 100% of the control calf. The result was the percentage clearance of bacteria at four hours.

Pulmonary edema was induced by three different methods: by an aerosol of histamine, by intravenous injection of endotoxin and by intravenous injection of croton oil emulsion. The edema impaired the clearance of P. hemolytica, which was reflected in high numbers of P. hemolytica present in the lungs at four hours after challenge: 260% after histamine, 300% and 400% after endotoxin and 92% after croton oil.

Six days of treatment of four calves with high doses of hydrocortisone acetate produced inconsistent results: two calves treated with a higher daily dose (36 mg/kg) had normal clearance whereas two calves treated with a lower dose had pulmonary edema and displayed lowered clearance with 111% and 31% respectively of P. hemolytica retained in the lungs four hours after challenge.

Immunization of calves by three different methods, a subcutaneously injected bacterin of P. hemolytica (2 calves), single aerosol (2 calves) and four aerosols (4 calves) of live P. hemolytica was reflected in an accelerated pulmonary clearance of P. hemolytica (with a mean of 1.55% of bacteria retained at four hours).

Concurrent infection with parainfluenza-3 virus did not lower the clearance of P. hemolytica in the lungs of 12 calves over 15 days except on the first day following the exposure to parainfluenza-3 virus. These calves had hemagglutinating antibodies against P. hemolytica before exposure.

     

A Study of Complement-fixation and Serum Agglutination Tests on Vibrio fetus Infected and Immunized Cattle

Complement-fixation (CF) and tube agglutination (TA) tests for demonstration of Vibrio fetus antibodies were conducted on the sera of three groups of ten heifers. One group was vaccinated subcutaneously with a commercial V. fetus var venerealis bacterin and challenged intra-utero, at the external os cervicus one month later; the second was infected only and the third vaccinated only.

The vaccinated cattle developed high CF serum titers, but no such increase was observed in animals infected only. A moderate increase in serum antibody titers was demonstrated by the TA test following either infection or vaccination; although titers observed were not higher than those observed in the sera of some apparently normal uninfected animals. The group receiving both vaccine and challenge was the only one in which significant serum antibody titers were demonstrable by the TA test. The sera of these animals also had significant titers in the CF tests.

The CF and TA tests detected serum antibodies produced by the parenteral inoculation of V. fetus antigen. These two tests were of limited value in detecting serum antibodies from animals with genital V. fetus var venerealis infection, although the formation of local antibodies was demonstrable by the vaginal mucus agglutination test.