Yersiniosis in sheep due to Yersinia enterocolitica.

An outbreak of acute yersiniosis occurred amongst sheep transported from Inner Mongolia to Hunan Province in southern China. Morbidity was 41% and mortality of affected sheep was 34%. Eleven apparently identical isolates of Yersinia enterocolitica were obtained from liver, lung and skin lesions of affected sheep and all were biotype 3. Isolates could not be serotyped with available antisera. Lesions were observed in the skin, intestine, liver and lungs. The causative bacterium is apparently different from isolates previously identified as causing disease in sheep and goats in Australia, New Zealand, Norway and Great Britain. The source of infection could not be determined.

Serological response of sheep to plasmid-encoded proteins of Yersinia species following natural infection with Y. enterocolitica and Y. pseudotuberculosis.

A prospective study of the serological response to natural infection with Yersinia enterocolitica and Y. pseudotuberculosis was performed in an experimental flock of sheep. A preliminary investigation with immunoblotting techniques showed that lambs infected with virulent Yersinia spp. produced antibodies to several yersinia outer-membrane proteins (yops) encoded by a virulence plasmid (pYV) of Y. enterocolitica or Y. pseudotuberculosis. Thereafter, an enzyme immunoassay (EIA) was developed to measure antibodies to yops. Criteria for interpreting the EIA were established by examining sera from a negative control population of lambs which had not been infected with Yersinia spp. since birth. Test samples comprised 25 pairs of pre- and post-infection sera from animals with bacteriologically proven infections with Yersinia spp. The results showed that infection of lambs with pYV-bearing strains of Y. enterocolitica or Y. pseudotuberculosis invariably evoked a significant antibody response to yops, even though all the infections were subclinical. No animal infected with so-called "environmental", pYV-negative Yersinia spp. seroconverted to yops. EIA with yops as antigen provided a sensitive and specific means to diagnose subclinical infection of lambs with virulent Yersinia spp.

Epidemiology of Yersinia pseudotuberculosis and Y. enterocolitica infections in sheep in Australia.

Infections with Yersinia pseudotuberculosis serotype III and Y. enterocolitica serotype O2,3 were found to be common in Australian sheep flocks. Transmission of Y. pseudotuberculosis occurred in late winter and early spring, while Y. enterocolitica transmission occurred from midwinter to early summer. Excretion of Y. pseudotuberculosis was limited to the winter and spring period and was particularly common in 1- and 2-year-old sheep. Infection persisted for up to 14 weeks. Y. pseudotuberculosis infection did not confer immunity to natural infection with Y. enterocolitica. Y. enterocolitica excretion occurred year-round, with the greatest prevalence being in summer and autumn. Infection persisted for up to 29 weeks. Sheep less than 1 year old were most commonly infected with Y. enterocolitica. Infection with either Y. pseudotuberculosis or Y. enterocolitica was rare in aged sheep. Restriction endonuclease analysis of Y. pseudotuberculosis serotype III from sheep, cattle, deer, and pigs showed that the bacterial isolates were genetically indistinguishable. Similarly, Y. enterocolitica isolates from sheep were indistinguishable from those isolated from goats and cattle.

Enteritis in sheep and goats due to Yersinia enterocolitica infection.

Yersinia enterocolitica biotype 5, serotype 02,3 was isolated from the intestine of 38 sheep and 8 goats submitted to the laboratory for disease diagnosis. Infected animals were usually young, had diarrhoea and were in poor condition or emaciated. A number were moribund or dead when submitted. Characteristic microabscesses were demonstrated in the intestine of 5 of 38 sheep and 3 of 8 goats and no alternative cause of morbidity or mortality was established in these animals. Of the 33 sheep and 5 goats infected with Y. enterocolitica in which microabscesses were not demonstrated, a number of other diagnoses were made, including internal parasitism (18), selenium deficiency or white muscle disease (6) and cobalt deficiency (2), so that morbidity and mortality were possibly unrelated to Y. enterocolitica infection. Five of 6 sheep exposed experimentally by mouth to Y. enterocolitica biotype 5, serotype 02,3 developed an intestinal infection. Although infected sheep showed no clinical evidence of disease and haematological and biochemical indices remained normal, multiple intestinal microabscesses typical of yersiniosis were demonstrated in 3 of 5 infected sheep. It is concluded that Y. enterocolitica biotype 5, serotype 02,3 is an enteropathogen of sheep and goats. Since sheep and goats may be the specific hosts of this bacterium, its virulence for these species is apparently low. Morbidity and mortality may, therefore, be unusual manifestations of infection.

Enteritis in sheep, goats and pigs due to Yersinia pseudotuberculosis infection.

The features of naturally occurring Yersinia pseudotuberculosis serotype III infections in 16 sheep, one goat and 3 pigs, and Y. pseudotuberculosis serotype I infections in 3 goats, are described. Affected animals usually had diarrhoea and were in poor condition or emaciated. A number were moribund or dead when submitted for necropsy. Thickening of the caecal and colonic mucosa was the only gross lesion attributable to Y. pseudotuberculosis infection, with liver or other visceral abscesses not being seen. Characteristic microabscesses were demonstrated in the intestinal mucosa of 10 sheep, one goat and one pig infected with Y. pseudotuberculosis serotype III and one goat infected with Y. pseudotuberculosis serotype I. Sheep, goats and pigs dosed orally with Y. pseudotuberculosis serotype III, the serotype isolated most commonly from these species, developed intestinal infection. In sheep and pigs, infection was accompanied by diarrhoea. Haematological changes and specific antibodies were elicited in all 3 species in response to infection. Microabscesses were seen in the intestinal mucosa of all experimentally exposed animals. The occurrence of field cases and the results of experimental exposure confirm that Y. pseudotuberculosis serotype III is an enteropathogen of sheep, goats and pigs. The association of Y. pseudotuberculosis serotype I with lesions in a goat, indicates that this bacterium may also be a pathogen of this species. It is concluded that Y. pseudotuberculosis serotype III is an enteric pathogen of a wide range of ungulate species including cattle, buffalo, deer, antelopes, sheep, goats and pigs. Serotypes I and II, while having a more restricted host range, are probably also pathogens of ungulates and, in particular, deer, antelopes and goats.

Yersiniosis in farmed deer.

Samples from 77 chital (Axis axis), 42 fallow (Dama dama), 26 red (Cervus elaphus), 7 rusa (Cervus timorensis) and 1 sambar deer (Cervus unicolor) were examined. Yersinia pseudotuberculosis infection was diagnosed as the cause of death in 6 (23%) of the red and 23 (30%) of the chital deer. Yersiniosis was the most common infectious cause of death diagnosed. Affected deer were usually found moribund or dead, often with faecal staining of the perineum. Gross pathology in chital included a fibrinous enterocolitis, enlarged congested mesenteric lymph nodes and multiple pale foci through the liver. Gross changes in red deer were limited to intense congestion of the intestinal mucosa and enlargement and congestion of mesenteric lymph nodes. Microscopic intestinal changes in both species consisted of microabscessation or diffuse suppurative inflammation of the intestinal mucosa with numerous bacterial colonies in the lamina propria. Multifocal suppurative mesenteric lymphadenitis was a common finding. Multifocal suppurative or non-suppurative hepatitis was frequently present in the liver of chital but was uncommon in the red deer. Yersiniosis occurred during the cooler months from June to November, with younger age classes most commonly affected. Y. pseudotuberculosis serotypes I, II and III were isolated in the ratio 17:3:0 in the chital deer and 1:1:2 in red deer. The clinical, epidemiological and bacteriological features are similar to those documented previously by New Zealand workers. The increased susceptibility to disease of red deer and chital compared to fallow deer and perhaps other species has not previously been documented.

Enteritis in cattle due to Yersinia pseudotuberculosis infection.

A selective medium was used to isolate Yersinia sp from the intestinal tract of 222 scouring cattle in Gippsland during 1985 and 1986. Intestinal infection with Y. pseudotuberculosis, particularly of serotype III, was found to be especially prevalent in weaned calves, yearlings and young adult cattle. Clinically affected cattle had a profuse liquid diarrhoea and many were systemically ill. Haematological changes suggestive of infection were present in 38 of 49 of these cattle. At least 35 cattle died and characteristic microabscesses were demonstrated in the intestinal mucosa of 20 of 26 examined histologically. Y. pseudotuberculosis was sensitive to tetracyclines in vitro and this drug produced a rapid bacteriological cure. Yersiniosis occurred during the winter, spring and early summer. Challenge of adult cattle with Y. pseudotuberculosis serotype III did not result in intestinal colonisation or clinical disease. Intestinal infection was, however, established in 4 weaned calves and haematological changes and antibody production were demonstrated in them. Intestinal microabscesses were seen in three calves killed on days 8, 14 and 18 after challenge. The fourth calf eliminated infection by day 18 and no lesions were demonstrated when it was killed on day 72. There is a very high prevalence of antibodies reacting with Y. pseudotuberculosis serotype III in adult cattle. It is concluded that cattle are a common host for this bacterium, infection being frequent, with clinical and fatal disease occurring occasionally. The factors leading to clinical disease are unknown.

Metronidazole for the treatment of bovine pyometra.

Metronidazole, an antibiotic with specific activity against anaerobic bacteria, was assessed as a treatment for bovine pyometra. A preliminary experiment with metronidazole-neomycin was followed by an experiment in which metronidazole-ampicillin was compared with povidone iodine. Each treatment was given as a single intrauterine infusion. The success of therapy was judged by clinical examination, bacteriological examination before and after treatment and, in the second experiment, by post treatment reproductive performance. Before treatment 45 of the 84 cows in both experiments were infected with a mixture of anaerobic and aerobic bacteria, 23 cows were infected with aerobes alone and significant bacteria were not isolated from 16 cows. Complete bacteriological and clinical cures were achieved in 23 of 32 cows treated with metronidazole-neomycin, 15 of 32 cows treated with metronidazole-ampicillin and 1 of 20 cows treated with iodine. When only those cows with mixed anaerobe/aerobe infections were considered, complete cures occurred in 12 of 17 cows treated with metronidazole-neomycin, and 11 of 16 cows treated with metronidazole-ampicillin, but none of the 12 cows treated with iodine. Twenty-two of 29 cows treated with metronidazole-ampicillin conceived after treatment (mean 51.4 days), while 9 of 18 cows treated with iodine conceived (mean 58.7 days). Statistically, metronidazole-ampicillin treatment produced significantly better clinical and bacteriological cure rates than iodine treatment (P less than 0.05), but the differences in reproductive parameters were not significant.

Mycotic abortion in cattle.

Placentas and foetuses from 1107 bovine abortions were examined and a fungal infection was diagnosed in 131 instances. Fungi seen in silver impregnated sections of tissues could be placed into 3 categories designated aspergillus, phycomycete and atypical. Culture indicated that the first 2 of these categories were due to Aspergillus sp and Mortierella wolfii respectively. The infections in the atypical category are probably also due to Aspergillus sp. Gross or microscopic examination or culture of the placenta were valuable diagnostically but examination of the foetus was seldom of value as infection in most instances did not involve foetal tissues. Questionnaires indicated that many M. wolfii abortions were associated with the feeding of poorly prepared or stored grass silage. As the majority of cattle are fed hay or silage, no association could be demonstrated between Aspergillus sp abortion and these feeds. Fertility following fungal abortion was apparently unimpaired.

Investigation of purulent vaginal discharge in cows, with particular reference to Haemophilus somnus.

The relationship between vaginal discharge, site of inflammation in the reproductive tract and species of bacteria isolated was examined in cows that were either normal, subfertile, or had had an abnormal parturition. Microbiological and cytological examinations were performed on uterine swabs from 221 cows and cervical swabs from 107 cows. There were 167 subferitle cows, 144 of which had failed to conceive to 3 or more services (FTC) and 23 of which had not had a visible oestrus since calving (NVO). Metritis was diagnosed in 22% of the FTC cows, 48% of the NVO cows, and 12% of the cows with abnormal parturition. Fifty percent of cows with metritis had purulent vaginal discharge. However, only 25% of a total of 91 cows with vaginal discharge had metritis; the remainder had cervicitis. Fifty-four percent of subfertile cows had cervicitis without metritis. Mixed infection with aerobes and anaerobes was significantly correlated with uterine inflammation and was found in 20% of cows with metritis. The rate of isolation of H.somnus from inflamed uteruses (22%) and inflamed cervixes (39%) was significantly greater than the isolation rate from normal uteruses (8%) and cervixes (10%). No bacteria were isolated from 50% of inflamed uteruses and 37% of inflamed cervixes. The number of subfertile cows with or without metritis that subsequently conceived was not significantly different.

A microaerophilic coccus in pyogenic infections of ruminants.

Pyogenic infections of cattle, sheep and goats were examined for the presence of a Gram positive bacterium that has been designated "microaerophilic coccus" by other workers. The bacterium was found to be involved in a range of disease processes, including foot and soft tissue abscesses, mastitis, pericarditis and pyometra in cattle, joint and foot abscesses in sheep and foot abscesses in goats. The characteristic feature of the bacterium was its satellitic growth around colonies of other organisms. The microaerophilic coccus was usually part of a mixed flora, which included Corynebacterium pyogenes, Fusobacterium necrophorum, Peptostreptococcus indolicus and Bacteroides sp.

Selective medium for isolation of Haemophilus somnus from cattle and sheep.

Incorporation of vancomycin (5 micrograms/ml), neomycin (5 micrograms/ml), sodium azide (50 micrograms/ml), nystatin (100 iu/ml) and cyclohexamide (100 micrograms/ml) into 5 per cent horse blood agar results in a selective medium for the primary isolation of Haemophilus somnus from cattle and sheep. Addition of thiamine monophosphate (1 microgram/ml) to the medium enhanced growth of this bacterium. Gram-positive bacteria did not grow on the medium and colonies of many Gram-negative bacteria were eliminated or reduced in numbers and size. Colonies of H somnus were larger on the selective medium than on sheep blood agar but retained typical morphology. Recovery of 18 laboratory strains was 73 to 166 per cent (mean 112) on selective medium compared to sheep blood agar. H somnus was isolated from the vagina of a total of 136 (28.6 per cent) of 476 cows surveyed, 79 (16.6 per cent) on sheep blood agar and 129 (27.1 per cent) on selective medium. The selective agents and thiamine were stable indefinitely as a freeze dried mixture while prepared plates were stable for two weeks.

Skin ulcers caused by Mycobacterium ulcerans in koalas near Bairnsdale, Australia.

Skin ulcers were found in 7 koalas from Raymond Island in the Gippsland Lakes of southeastern Australia. Ulcers in 4 koalas showed loss and underrunning of cutaneous tissue, with coagulative necrosis of subcutaneous tissue. These lesions contained large numbers of acid-fast bacilli, and areas of granulation tissue formation and superficial inflammation were present. Mycobacterium ulcerans was isolated from 2 of these animals. The ulcers from the other 3 koalas contained both M. ulcerans and M. scrofulaceum, and in these the necrotic tissue was surrounded by a granulomatous reaction which, in one case, extended into bone. Four of the koalas had more than one ulcer. The possible origin of the infections is discussed.

Colitis in sheep due to a Campylobacter-like bacterium.

Epidemic diarrhoea was observed in approximately 2,000 of 6,700 sheep on 9 farms. The disease, called weaner colitis, caused mortality of 1%, while morbidity varied from 20 to 75%. Colon contents from affected sheep were inoculated into 17 sheep, 13 of which developed diarrhoea 5 to 7 days after inoculation. Naturally and experimentally infected sheep had mild, erosive typhlitis and colitis. Microscopic examination of washed scrapings of colonic mucosa from all affected sheep revealed masses of curved bacteria that were not seen in controls. Electron microscopic examination showed similar bacteria adherent to colonic epithelium of an experimentally infected sheep. Curved, motile bacteria were isolated from 2 naturally occurring cases. One isolate was inoculated into 9 sheep, 2 of which developed diarrhoea. The other isolate was given to 4 sheep without observable effect. The curved bacteria grew only on media containing blood, in an atmosphere of approximately 10% air, 10% CO2 and 80% H2. They were Gram-negative, with a polar flagellum at one or both ends, they did not ferment glucose or give a positive catalase reaction. It is suggested that these bacteria are a new Campylobacter species and that they play a major role in the aetiology of weaner colitis.

Multiple apparent Sarcocystis abortion in four bovine herds.

Foetuses recovered from multiple abortions in four dairy herds had multifocal nonsuppurative encephalitis, myocarditis and hepatitis. Focal placentitis was usually present. Sarcocystis-like protozoa were found in the brains of foetuses from two of the outbreaks. Apart from excess salivation in a few cows in one herd, farmers reported no clinical abnormalities prior to the abortions, and all cows remained normal after the abortions. Dogs and cats fed an affected foetus and neonatal calves from the affected herds failed to excrete protozoa in their faeces. The identity of the protozoa in the foetal brain was not confirmed.

Bovine abortion associated with Leptospira interrogans serovar hardjo infection.

During 1981, 265 bovine abortions were investigated by serological and histological methods for evidence of leptospiral infection. Leptospires were demonstrated in the tissues of 10 foetuses by a Levaditi silver impregnation technique. Serological testing of maternal sera indicated that Leptospira interrogans serovar hardjo was associated with 5 of the abortions while the remaining 5 were due to L. interrogans serovar pomona infection. In cases of abortion associated with L. interrogans serovar hardjo leptospires were readily demonstrated in foetal liver, kidney, intestine and heart. They were demonstrated less often in lung and placenta and could not be found in foetal brain. Autolysis did not appear to interfere with the demonstration of leptospires by silver impregnation. No lesions attributable to leptospiral infection were seen in placentas but mild interstitial nephritis was found in some of the foetuses. Fourteen other cows had serological evidence of recent leptospiral infection but leptospires were not detected in foetal tissues. Histological examination of silver impregnated foetal tissues in combination with the microscopic agglutination test was shown to be an effective method for diagnosing abortion associated with L. interrogans serovar hardjo in cattle.