Monitoring for atrophic rhinitis: five years' experience with a pilot control scheme

A pilot control scheme for atrophic rhinitis was initiated in Britain by the Pig Health Control Association in January 1977. To qualify, herds must have maintained a low degree of turbinate damage and not shown clinical signs of atrophic rhinitis over a period of at least two years. Qualifying herds can import pigs only from other qualifying herds or via hysterectomy/hysterotomy methods. During the first five years, 45 herds qualified at some stage, and at the end of 1982, 34 herds (comprising about 7200 sows) were still listed. Although the scheme is not related to particular infectious agents, atrophic rhinitis has not appeared within it or in herds established entirely from listed herds, despite the fact that 31 of the 45 qualifying herds had imported stock from 15 other qualifying herds.     

Eight years' experience with a register of pig herds monitored for Aujeszky's disease

The Pig Health Control Association launched a control scheme for Aujeszky's disease in Britain in January 1978. Participating herds must not show clinical signs suggestive of Aujeszky's disease and must be serum-sampled every six months for the absence of antibodies. Importations are allowed only from listed herds, or through hysterectomy or hysterotomy, embryo transfer, or artificial insemination (the donor animals in each case having been serologically screened beforehand). During the subsequent eight years, 103 herds have qualified, and at the end of 1985, 49 herds (average size 249 sows) were listed. Despite a high degree of inter-herd stock movements, no clinical or serological evidence of Aujeszky's disease has occurred, and the disease has not arisen in any herd established from the listed herds. During the same period, Aujeszky's disease was spreading in Britain and an eradication programme began in March 1983. By the end of 1985, 502 herds not on the Pig Health Control Association's scheme comprising 421,825 pigs had been slaughtered, together with 259 serologically positive animals in 69 other herds. The Pig Health Control Association's register has provided a safe source of stock.     

Swine dysentery control in the German Democratic Republic and the suitability of injections of tiamulin for the programme

In 1977 swine dysentery was made a notifiable disease in the German Democratic Republic, with the intention of eradicating it by the systematic treatment of clinically affected herds using intensive medication and hygiene control programmes. On individual farms the scheme appeared to be successful, but the national incidence of the disease did not decline, owing to the continuous presence of latently infected herds and the movement of carrier pigs to uninfected farms. In 1981 the scheme was re-appraised and a new scheme was introduced in one region where all the breeding herds were screened for the presence of Treponema hyodysenteriae; all positive herds were treated with either metronidazole or tylosin, and the movement of pigs into the region was controlled. This programme effectively eradicated the disease from the region and is being introduced to the rest of the country. Owing to concern about the safety of metronidazole and the development of resistance to tylosin, alternative antimicrobials were examined and tiamulin was selected to assess its suitability for inclusion in the programme. A 560 sow breeding herd and progeny were treated for five days with tiamulin at 10 mg/kg bodyweight. This was coupled with extensive cleaning, disinfection and rodent control programmes. The results of the trial showed that the clinical disease stopped in two days and that no further clinical signs were seen in the subsequent two-and-a-half years. Bacterial monitoring of faeces samples and colonic scrapings from dead pigs failed to identify viable T hyodysenteriae. There was a significant increase of 0.6 piglets weaned per litter and improvements in weaning weights and growth rates. It was concluded that tiamulin was suitable for inclusion in the swine dysentery eradication programme in the GDR.     

Swine dysentery: inoculation of gnotobiotic pigs with Treponema hyodysenteriae and Vibrio coli and a Peptostreptococcus.

Pure cultures of Treponema hyodysenteriae given orally to conventional pigs resulted in the development of swine dysentery, whereas identical cultures given to gnotobiotic pigs did not produce the disease. Oral inoculation of gnotobiotic pigs with Vibrio coli and/or a peptostreptococcus in addition to T. hyodysenteriae did not result in dysentery. Neutralization of gastric secretions with NaHCO3 immediately prior to inoculation with T. hyodysenteriae increased the period during which treponemes were evident in the feces, as did the inoculation of this organism via the intracecal route. None of the gnotobiotic pigs with a persistent fecal Treponema population developed signs of dysentery. Factors other than those investigated in this work must play a part in the etiology of swine dysentery.     

Investigations on Brachyspira--diagnostic and therapeutic strategies in swine dysentery

The infectious agent of swine dysentery, Brachyspira (Br.) hyodysenteriae, seems to be widespread in German pig herds. Due to different reasons the eradication is increasingly difficult. Not only the success of therapeutic procedures but also the possibilities of diagnostics are unsatisfactory. Although only the bacteriological investigation of faeces or intestinal probes by culture techniques allows the typing of Brachyspira strains and the testing of drug resistance, however, the rate of false negative results is relatively high. In comparison with the cultural method an easy, prompt and cheap immunofluorescent test (IFT) resulted in a good sensitivity (90%). The higher rate of negative results by culture techniques can not be attributed to a lower specificity of the IFT, but to an insufficient transport of samples to the laboratory. The IFT therefore has to be considered as a valuable supplement to the cultural diagnostic of Br. hyodysenteriae. It is absolutely necessary to establish strategies in eradication of swine dysentery which result in pig breeding herds free of Br. hyodysenteriae. Only weaner pigs which are reliable free of this germ guarantee a fattening period sufficiently free of swine dysentery. The principles of different measures in effective eradication are described.     

Vesicular stomatitis.

Vesicular stomatitis is an infrequent yet important vesicular disease of cattle, horses, and swine. Periodic outbreaks of this disease in the United States have caused economic losses in cattle herds because of decreased production, movement restrictions, and trade embargoes. Vesicular stomatitis causes clinical signs indistinguishable from those of foot-and-mouth disease. It is of utmost importance that appropriate samples are collected from clinical cases of vesicular disease in cattle and swine so a rapid laboratory diagnosis can be made.     

Comparison of the microtitration agglutination test and the enzyme-linked immunosorbent assay for the detection of herds affected with swine dysentery

A method was designed to evaluate and compare the microtitration agglutination test (MAT) and the enzyme-linked immunosorbent assay (ELISA) to detect antibodies in swine sera to Treponema hyodysenteriae and thereby establish a method for determining the prevalence of swine dysentery (SD) in herds. According to sampling criteria based on the hypergeometric distribution, sera were collected from 3 age groups of swine from farms having a history of SD on the premises (SD+) recently or being free of the disease (SD-). The highest degree of test sensitivity was obtained when sera from market age swine were evaluated with the ELISA. Of 14 SD+ herds from which sera were obtained from market-age swine, 13 were positive with the ELISA (93%); none of the 8 SD- herds was positive. The detection rates of individual swine in the SD+ herds for the 2 tests by age group were as follows: MAT--adult swine 1.4%, market-age swine 6%, and weaned pigs 0.8%; ELISA--adult swine 16%, market swine 31%, and weaned pigs 0.5%.     

Screening pig herds for toxigenic Pasteurella multocida and turbinate damage in a health scheme for atrophic rhinitis

The Pig Health Control Association launched a health scheme for atrophic rhinitis in 1978. For several years pig herds were monitored by scoring the degree of turbinate damage and by clinical inspections. When laboratory facilities became available for detecting toxigenic Pasteurella multocida, nasal swabs were taken from pigs in Association herds during 1988 and 1989 to determine whether the organism was present. Sows were screened routinely and in the worst affected herds, sucklers and weaners were also swabbed. In 12 of 19 herds with consistently low snout scores toxigenic P multocida were not isolated, and in 15 herds which developed higher snout scores with time toxigenic P multocida were also not found. Eleven herds had never been listed by the Association, either because their snout scores were consistently high or because they had received importations of stock from herds with high snout scores; of six of these herds with the most persistently high snout scores five showed varying degrees of the clinical signs of atrophic rhinitis, but none of the six showed evidence of infection with toxigenic P multocida, and the organism was not found in the other five herds in the group. There seems to be an overlap between the clinical and gross pathological signs of atrophic rhinitis seen in some herds not infected with toxigenic P multocida and the mild and spasmodic signs of atrophic rhinitis seen in some herds which are substantially infected with the organism.     

Financial benefit from the eradication of swine dysentery

Swine dysentery was eradicated from a 270 sow herd by using medication in conjunction with cleaning and disinfection, without reducing the herd size. The feed conversion efficiency, cost per kg liveweight gain and veterinary costs in the herd were compared with similar Meat and Livestock Commission recorded herds before swine dysentery entered the farm, while it was present and after its eradication. During the four years when the disease was endemic in the herd the feed conversion efficiency deteriorated by 0.58, equivalent to 7.31 pounds per pig, the cost per kg liveweight gain was 15 per cent higher and the costs of veterinary care and medicines were 1.38 pounds per pig greater. Although there were pigs with clinical swine dysentery in the herd during the four year period, the poor production figures were attributed mainly to subclinical disease. The cost of eradicating the disease was more than 20,000 pounds but this sum was recouped within 12 months by the improved production and reduced drug usage. The chances of success of such a programme have been estimated to be between 54 and 90 per cent.     

Pathogenicity of Vibrio Coli for Swine I. Experimental Infection of gnotobiotic Pigs with Vibrio Coli

Fifteen gnotobiotic pigs varying in age from three to eight weeks were exposed to 23 strains of V. coli isolated from swine with clinical and/or pathological signs of swine dysentery and also from clinically healthy pigs. Clinical or pathological signs of swine dysentery were not produced, although the organism was readly established in the sedimentary tract. Culture of feces, alimentary tract and environment revealed V. coli in large numbers, but no bacterial growth was obtained from other organs. The histopathology and serology are discussed.     

Apparent reinfection of enzootic-pneumonia-free pig herds: early signs and incubation period

Since 1959, the Pig Health Control Association (PHCA) has run a national health-control scheme for pig herds believed to be free from enzootic pneumonia. During this time, many herds developed this disease without a simple explanation. From 1968, 55 such unexplained breakdowns have been studied in detail. The first signs in 50 breakdowns were either coughing in growing pigs (52 per cent of outbreaks), illness in adult stock (34 per cent of outbreaks) or pneumonia in routinely slaughtered pigs (14 per cent of outbreaks). In some outbreaks, enzootic pneumonia appeared to grow out of a pre-existing respiratory infection, which was not identified as enzootic pneumonia, in suckling pigs, suggesting that either Mycoplasma hyopneumoniae was already present in a latent state, or it more readily seeded damaged respiratory tracts from outside. In three outbreaks of this type, where pathological material was collected during the transition period, no laboratory evidence was obtained for the presence of M hyopneumoniae in the primary respiratory disease. Analysis of breakdowns in two national testing stations indicated that clinical/pathological signs might not develop until three to five months after the introduction of an infected group of weaners. It is possible, therefore, that a pig herd might not show obvious signs of the disease until up to six months or more after initial infection. There was little evidence to indicate that unexplained breakdowns arose from long term latent infection in other herds from which stock had been imported. There was considerable evidence, however, to suggest that breakdowns arose from extraneous sources.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serological comparison of French WD-42 enterovirus isolate with bovine winter dysentery in New York State.

Forty-eight acute and convalescent paired serums from 10 dairy cattle herds naturally infected with winter dysentery and 10 paired serums from laboratory infected heifers were tested for antibody to bovine enterovirus WD-42 which reportedly reproduced the disease syndrome in France. Only 3 naturally infected and 1 experimentally infected animals had 2-fold antibody responses. No clinical symptoms were observed in 2 steers inoculated with WD-42. Each had a 4-fold or greater antibody response to the virus. Results indicate that the winter dysentery syndrome observed in New York is produced by an agent other than WD-42 virus and that it is produced by an agent other than an enterovirus.     

Comparison of the suitability of phase-contrast and immunofluorescence technics in the laboratory diagnosis of porcine dysentery]

Immunofluorescence technique, compared with the method of phase contrast, does not appear to be better for laboratory diagnostics of swine dysentery because neither of these methods can be used for distinguishing between pathogenic and nonpathogenic strains of treponemas. The number of treponemas contained in faeces should still be considered to be the main criterion in laboratory diagnostics. In clinically healthy pigs from stocks which never suffered from dysentery treponemas were found only in few cases and always in small numbers. The numbers of treponemas contained in the faeces of dysenteric pigs were several times higher. Antigenic relationship of one nonpathogenic and three pathogenic strains of Treponema hyodysenteriae was proved by the agglutination and fluoresence methods.     

Swine dysentery: studies of gnotobiotic pigs inoculated with Treponema hyodysenteriae, Bacteroides vulgatus, and Fusobacterium necrophorum

Transmission experiments were carried out in gnotobiotic pigs to determine whether lesions typical of swine dysentery could be produced by oral inoculation of Treponema hyodysenteriae in combination with Bacteroides vulgatus or Fusobacterium necrophorum, or both. Each of the organisms had been isolated from swine with early lesions of the disease. Lesions were not found in 6 pigs inoculated with T hyodysenteriae alone, in 4 pigs given F necrophorum and T hyodysenteriae, or in 4 pigs given B vulgatus and F necrophorum. Lesions typical of swine dysentery developed in 8 pigs given B vulgatus, F necrophorum, and T hyodysenteriae as well as in 3 of 4 pigs given B vulgatus and T hyodysenteriae. In both of these groups, the inoculated bacteria were recovered from the colon, and T hyodysenteriae was demonstrated in the colonic crypts, epithelium, and lamina propria. The pathogenicity of the T hyodysenteriae was shown by the development of characteristic signs and lesions of swine dysentery in 12 of 14 naturally farrowed pigs inoculated with T hyodysenteriae alone.     

A serological survey to determine the prevalence of infection with Treponema hyodysenteriae in Western Australia

A serological survey to detect antibody titres against Treponema hyodysenteriae was conducted on pigs from 106 herds in Western Australia. Titres indicating a positive result in the tests were determined by examining 400 sera from 4 herds known to be free of swine dysentery, and sera from immunised or experimentally infected pigs. Samples of serum from 40 bacon-weight pigs from each of the 106 herds were then collected at 2 abattoirs. Each serum was tested in enzyme-linked immunosorbent assays (ELISA) against the lipopolysaccharide of T hyodysenteriae of serogroups A, B and E, respectively. To assist in evaluating the test, 19 herds were resampled and retested, and faecal samples from 17 herds were cultured for T hyodysenteriae. Thirty-five of the 106 herds (33%) had serological evidence of infection when only one batch of sera from each herd was tested. The ELISA to detect T hyodysenteriae infection in herds using 40 sera was estimated as having a sensitivity of 77.3% and a specificity of 81.8% based on the owners' opinion of their herds disease status. Prevalence of infection within herds ranged from 2.5% to 47.5%, with a mean of 18%.     

Detectability and prevalence of Brachyspira species in herds rearing health class feeder pigs in Finland

Faeces samples were taken three times at two-week intervals, from the farrowing units of four herds of known Brachyspira (formerly Serpulina) status and one of unknown Brachyspira status. Brachyspira hyodysenteriae, Brachyspira pilosicoli, Brachyspira intermedia and Brachyspira group III were isolated from the faecal samples from the weaners in the herds using either a maximum of 50 ppm of olaquindox or no feed additives. The detection rates were relatively consistent. However, B hyodysenteriae was not detected at one sampling in a known positive herd. The prevalence of Brachyspira species was also studied in feeder pigs originating from LSO 2000 health class farrowing units, comparable with specific pathogen-free herds. These farms were free from swine dysentery, sarcoptic mange, swine enzootic pneumonia and progressive atrophic rhinitis. Fifty of 428 herds were sampled once. B hyodysenteriae was not isolated from any of them, but B intermedia, B pilosicoli and Brachyspira group III were isolated from five, 14 and 37 of the herds, respectively. The detection of Brachyspira species did not relate to the prevalence of diarrhoea in the herds, as judged by the farmers. The herds using carbadox (40 to 50 ppm) had a lower prevalence of Brachyspira species than those using olaquindox (40 to 50 ppm).     

Prevention of swine dysentery with a combination of lincomycin and spectinomycin and resistance of swine dysentery to tylosin and sodium arsanilate.

The addition of a combination of lincomycin and spectinomycin to feed at the total concentrations of 44 and 77 mg/kg, beginning at the time of exposure and continuing for 8 weeks, prevented experimentally induced swine dysentery in swine. The disease did not develop after the medication was withdrawn. In contrast, swine dysentery, similar to that seen in the nonmedicated swine, did develop in simultaneously exposed swine treated with feed containing either 44 mg of tylosin or 99 mg sodium arsanilate/kg. The swine fed sodium arsanilate and which developed hemorrhagic diarrhea had a more severe form of this type of diarrhea than did the nonmedicated swine. After reexposure to inefective inoculum of swine dysentery 86 days after initial exposure, all remaining swine previously medicated with either tylosin or sodium arsanilate and all nonmedicated swine were immune; whereas 17 of the 24 swine fed the combination of lincomycin and spectinomycin were susceptible to swine dysentery and developed diarrhea.     

A novel method for isolation of Brachyspira (Serpulina) hyodysenteriae from pigs with swine dysentery in Italy

Brachyspira (Serpulina) hyodysenteriae was isolated from 10 of 11 pigs with clinically suspected swine dysentery in six herds in northern Italy. All strains were successfully isolated in the selective blood agar modified medium with spectinomycin and rifampin (BAM-SR) currently used in our laboratory to isolate B. (S.) pilosicoli of human origin, after pre-treatment of intestinal material with spectinomycin and rifampin in foetal calf serum. Isolates had phenotypic characteristics typical of B. (S.) hyodysenteriae.     

Feeding sodium arsanilate for exciting diarrhea and identifying carriers of swine dysentery.

Sodium arsanilate was fed to nondiarrhetic swine, previously exposed to and treated for swine dysentery, for the purpose of inducing them into developing a swine dysentery diarrhea. From 40 to 100% of these swine in each pen had previously had a swine dysentery diarrhea. The isolate of Treponema hyodysenteriae in the diced colon which was used to expose the swine was resistant to sodium arsanilate. After an interim of no treatment for swine dysentery, sodium arsanilate was fed at a level of 220 parts per million for 21 days. Of the 14 pens containing swine fed sodium arsanilate, ten pens had one or more swine that developed a swine dysentery diarrhea while being fed sodium arsanilate. This was significantly (P less than 0.05) greater than the three pens that each had one pig that developed a swine dysentery diarrhea of 13 pens containing similar swine not fed sodium arsanilate during a comparable period. In the 14 pens containing swine fed sodium arsanilate, 14 swine were the first to develop a swine dysentery diarrhea since in four pens, two swine in each pen developed diarrhea within 24 hours of each other. This also was significantly (P less than 0.01) greater than the three swine in the ten pens not fed sodium arsanilate. From these results, it was theorized that sodium arsanilate excited the nondiarrhetic carrier into developing a swine dysentery diarrhea and that this phenomenon may have potential in identifying the carrier state.     

An epidemiological study of winter dysentery in fifteen herds in France

Winter dysentery is a highly contagious disease of cattle seen most often during the winter months. In the course of an epidemiological study, the management, production, hygiene and previous diseases in 15 herds were characterized by 32 variables. Each herd was then visited twice a week for 8 weeks and 8 to 10 cows were clinically examined during each visit. Winter dysentery occurred in half of the herds during the survey.All data were analysed by classical statistical methods and by multivariate analysis.Mild or severe disease provoked nasal discharge and was associated with significant economic loss. Winter dysentery outbreaks appeared to be associated with small farms in which the area available per cow is either too small or too large, the presence of coronavirus in the faeces and variations in the temperature of the stable and of the drinking water.