Swine dysentery: aetiology, pathogenicity, determinants of transmission and the fight against the disease.

Swine Dysentery (SD) is a severe mucohaemorhagic enteric disease of pigs caused by Brachyspira hyodysenteriae, which has a large impact on pig production and causes important losses due to mortality and sub-optimal performance. Although B. hyodysenteriae has been traditionally considered a pathogen mainly transmitted by direct contact, through the introduction of subclinically infected animals into a previously uninfected herd, recent findings position B. hyodysenteriae as a potential threat for indirect transmission between farms. This article summarizes the knowledge available on the etiological agent of SD and its virulence traits, and reviews the determinants of SD transmission. The between-herds and within-herd transmission routes are addressed. The factors affecting disease transmission are thoroughly discussed, i.e., environmental survival of the pathogen, husbandry factors (production system, production stage, farm management), role of vectors, diet influence and interaction of the microorganism with gut microbiota. Finally, prophylactic and therapeutic approaches to fight against the disease are briefly described.

A novel enteropathogenic, strongly haemolytic spirochaete isolated from pig and mallard, provisionally designated 'Brachyspira suanatina' sp. nov.

Atypical, strongly haemolytic porcine isolates of intestinal spirochaetes differing genetically from Brachyspira hyodysenteriae were identified and characterized. The isolates were subjected to culture and biochemical tests, antimicrobial susceptibility testing and molecular analyses. None of four species-specific polymerase chain reaction systems targeting genes of B. hyodysenteriae gave a positive reaction. All the atypical porcine isolates were identical in their partial 16S rRNA and nox gene sequences with a previously described isolate from a mallard (Anas platyrhynchos), and differed only slightly from another mallard isolate. All these isolates were distinctly different from all currently recognized Brachyspira species. A challenge study was carried out using recently weaned pigs. Clinical signs and macroscopic changes consistent with swine dysentery were seen both in pigs given the atypical porcine isolate and in control pigs given the reference strain of B. hyodysenteriae (B204(R)). Pigs given the genetically similar isolate from a mallard became colonized and diarrhoea was observed. This is the first study indicating that Brachyspira isolates from mallard can infect pigs and induce diarrhoea. We propose that this atypical spirochaete genotype should be regarded as a new species within the genus Brachyspira, and be provisionally designated 'Brachyspira suanatina' sp. nov.

Colonic spirochetosis in animals and humans.

Colonic spirochetosis is a disease caused by the gram-negative bacteria Brachyspira aalborgi and Brachyspira pilosicoli. B. pilosicoli induces disease in both humans and animals, whereas B. aalborgi affects only humans and higher primates. Symptoms in humans include diarrhea, rectal bleeding, and abdominal cramps. Colonic spirochetosis is common in third world countries; however, in developed countries, the disease is observed mainly in homosexual males. Terminally ill patients infected with Brachyspira are particularly at risk for developing spirochetemia. Diarrhea, poor growth performance, and decreased feed-to-gain efficiency is seen in pigs with colonic spirochetosis. The disease in chickens is characterized by delayed and/or reduced egg production, diarrhea, poor feed conversion, and retarded growth. Thus, colonic spirochetosis can represent a serious economic loss in the swine and poultry industries. The organisms are transmitted by the fecal-oral route, and several studies have demonstrated that human, primate, pig, dog, or bird strains of B. pilosicoli can be transmitted to pigs, chickens, and mice. B. pilosicoli may be a zoonotic pathogen, and although it has not been demonstrated, there is a possibility that both B. pilosicoli and B. aalborgi can be transferred to humans via contact with the feces of infected animals, meat from infected animals, or food contaminated by food handlers. Neither B. pilosicoli nor B. aalborgi has been well characterized in terms of basic cellular functions, pathogenicity, or genetics. Studies are needed to more thoroughly understand these Brachyspira species and their disease mechanisms.

[Human intestinal spirochetosis]. / Intestinální spirochetóza cloveka.

A characteristic feature of human intestinal spirochetosis (IS) is the colonization of the mucosa of the large intestine with intestinal spirochetes of the genus Brachyspira. The joining of the brachyspirae with the apical cellular membrane of enterocytes resembles in histological slides a false brush border of the intestinal mucosa. Various symptoms related to the involvement of the large gut were found with invasive IS. From the cultures of these cases were isolated Brachyspira aalborgii and B. pilosicoli. The frequency of the incidence of brachyspirae depended on the socio-economic living conditions of people. Colonization of the mucosa of the large gut was found more often in human populations in the developing countries; it was fairly rare in countries with high hygienic standards. An exception were men of homosexual orienation and patients presenting with a HIV infection. Isolation of brachyspirae from the faeces and biopsy of the mucosa of the large gut are fairly demanding jobs, especially with B. aalborgii. Most documented IS cases of this aetiology were diagnosed using immunohistochemical methods and amplification of the genus-specific region of the gene 16S rRNA. Isolation of B. pilosicoli tends to be simpler, it requires anaerobic incubation on selective blood agars for a period of 3-6 days at 37 degrees C. When manual haemoculture systems were used, patients in a critical state presented a translocation of brachyspirae into blood circulation, while automatic systems don't necessarily diagnose spirochetaemia. In the management of described cases of invasive IS particularly successful proved metronidazole and beta-lactam antibiotics. In isolated B. pilosicoli, in vitro tests confirmed sensitivity to metronidazole, ceftriaxone, meropenem, tetracycline, moxifloxacine and chloramphenicol. A varying frequency of resistance was found with clindamycin and amoxicillin, which how ever was efficacious in combination with clavulanic acid.

Experimental infection of layer hens with a human isolate of Brachyspira pilosicoli.

The anaerobic intestinal spirochaete Brachyspira pilosicoli commonly colonizes the large intestine of a number of species, including chickens and human beings. The purpose of the current study was to determine whether an isolate of B. pilosicoli recovered from an HIV-infected patient with diarrhoea could infect and cause disease in adult chickens. Over a 4-week period following experimental infection, a group of eight inoculated chickens showed a persistent and significant increase in faecal water content ( approximately 6-7 %). The faeces of three of the eight birds became culture-positive, and remained so. At post-mortem examination, no specific pathological changes were found, and no spirochaetal attachment to the caecal epithelium was observed. These findings confirm that B. pilosicoli strains can infect across species barriers and cause chronic mild diarrhoea in intact adult chickens.

[Toxicity of the combination of salinomycin and tiamulin in swine]. / Zur Toxizität der Kombination von Salinomycin und Tiamulin beim Schwein.

The toxicity of the combination of salinomycin (sal.) and tiamulin (tia.) was investigated in dependence upon dosage and feeding method. In addition the efficacy of a safe dose for prophylactic treatment of dysentery was controlled. Following feed medications were tested for toxic effects in pigs: a) 3 mg sal. + 5 mg tia./kg BW, b) 3 mg sal. + 3 mg tia./kg BW, c) 3 mg sal. + 1 mg tia./kg BW, d) 3 mg sal./kg BW, e) 10 mg tia./kg BW, f) 30 mg tia./kg BW. The daily dose was given for 2 weeks by restricted feeding (twice a day) either as bolus or mixed in the whole ration or by feeding ad libitum. Animals were controlled for clinical symptoms and activities of creatine phosphokinase (CK) and aspartate aminotransferase (ASAT) were evaluated daily. Main clinical signs of poisoning were loss of appetite and locomotor disturbances and could be noticed for dosages of 8, 6 and 4 mg sal. + tia./kg BW. Activities of CK and ASAT were increased dose-related, the feeding method also had an influence on the degree of intoxication. Some animals showed locomotor disturbances without any corresponding changes of CK and ASAT levels. Single pigs remaining without any symptoms even at high dosage pointed to differences in individual susceptibility. Toxicity was not found to be age dependent. Feed medication with 60 ppm sal. + 20 ppm tia. (feeding ad libitum) did not result in any signs of toxicity, however, the transmission of Serpulina hyodysenteriae from infected pigs to healthy, treated control animals could not be inhibited efficiently. Therefore the simultaneous application of salinomycin and tiamulin should be avoided generally, because the risk of intoxication is high and subtherapeutical dosage has an insufficient effectiveness against Serpulina hyodysenteriae.

The prevalence of Serpulina pilosicoli in humans and domestic animals in the Eastern Highlands of Papua New Guinea.

In a survey of five villages in the Eastern Highlands of Papua New Guinea, Serpulina pilosicoli was isolated from rectal swabs from 113 of 496 individuals (22.8%). Colonization rates ranged from 22.6-30.1% in four of the villages but was only 8.6% in the other village. In comparison colonization was demonstrated in only 5 of 54 indigenous people (9.3%) and none of 76 non-indigenous people living in an urban environment in the same region. Colonization did not relate to reported occurrence of diarrhoea, age, sex, or length of time resident in a village. A second set of 94 faecal specimens was collected from 1 village 6 weeks after the first set. S. pilosicoli was isolated from 27 of 29 individuals (93.1%) who were positive on the first sampling and from 7 of 65 individuals (10.8%) who previously were negative. In this case, isolates were significantly more common in watery stools than in normal stools. The annual incidence of infection in the village was calculated as 93.6%, with an average duration of infection of 117 days. S. pilosicoli could not be isolated from any village pig (n = 126) despite its confirmed presence in 17 of 50 commercial pigs (34.0%) sampled at a local piggery. Four of 76 village dogs (5.3%) and 1 of 2 village ducks were colonized with S. pilosicoli, suggesting the possibility of cross transmission between humans and animals.

[Diagnosis and treatment of infections in a neonatal unit--viral infections, spirochete infections and toxoplasma infections]. / Diagnostikk og behandling av infeksjoner i en neonatalavdeling--virus-, spiroket- og toxoplasmainfeksjoner.

Viral and protozoal infections are often suspected as causes of neonatal illness or congenital anomalies. The TORCH titer has traditionally been the foremost diagnostic tool in this context, but it is now becoming increasingly clear that this tool is inadequate, partly for conceptual reasons, but also because of the often uncritical way in which it is used. During a recent critical review of our routines and practices for diagnosis and treatment of neonatal infections we also revised our approach to the diagnosis and treatment of suspected pre- or perinatally acquired viral, spirochetal, and protozoal illnesses. The resulting guidelines, originally intended for our house staff, are presented here.

Epidemiology and clinical similarities of human spirochetal diseases.

Lyme disease, first identified in 1975, is the most recently recognized of the seven human spirochetal diseases; the evolving clinical picture of Lyme disease indicates it shares many features with the other diseases. These similarities are striking in view of the diverse epidemiology of the seven diseases, which are caused by Treponema species (spread by human-to-human contact) or Leptospira or Borrelia species (zoonoses). These similarities include the following: (1) skin or mucous membrane as portal of entry; (2) spirochetemia early in the course of disease, with wide dissemination through tissue and body fluid; and (3) one or more subsequent stages of disease, often with intervening latent periods. Lyme disease shares with many spirochetal diseases a tropism for skin and neurologic and cardiovascular manifestations, whereas chronic arthritis is unique to Lyme disease. These similarities and dissimilarities offer opportunities to discover which properties unique to the pathogenic spirochetes are responsible for clinical manifestations and suggest that certain clinical features of patients with spirochetal diseases other than Lyme disease may someday be recognized in patients with Lyme disease.

The enlarging spectrum of tick-borne spirochetoses: R. R. Parker Memorial Address.

The author reviews his changing interest in tick-borne spirochetoses during his career (1951-1985) as a medical entomologist at the U.S. Public Health Service's Rocky Mountain Laboratory. The discoveries of relapsing fevers in the western United States in the 1930s and 1940s led to well-supported epidemiologic research, including studies on the relationships between vectors and spirochetes. When tick-borne relapsing fever in the United States was shown to be a relatively rare and readily treatable disease, financial support was withdrawn, and ongoing research was limited or terminated. Interest in relapsing fever spirochetes, particularly the relation to the relapse phenomenon in animal hosts, resurfaced in the 1960s and 1970s with the introduction of immunofluorescence assays and with the development of Kelly's medium for continuous cultivation of certain spirochetes. This interest increased significantly in 1981 when the author discovered a tick-borne spirochete to be the causative agent of Lyme disease and of several clinically related disorders in Europe. The discovery of this agent, now known as Borrelia burgdorferi, has led not only to intensive clinical, epidemiologic, and ecologic investigations in the United States and abroad but also to the identification of molecular and immunochemical techniques necessary for the study of the complex biology of tick-borne spirochetes. Reference is also made to a new species of Borrelia that may be the etiologic agent of epizootic bovine abortion in the western United States.

[Enlarged spectrum of tick transmitted spirochaetoses]. / Zum erweiterten Spektrum zeckenübertragener Spirochätosen.

After the successful identification of Borrelia burgdorferi as the cause of Lyme disease, a new tick-borne infection occurring in the United States, almost identical spirochaetes have been isolated from the tick Ixodes ricinus in Europe. As a result, the spirochaetal aetiology of skin diseases, which had long been recognized as tick-borne infections, namely erythema chronicum migrans with its neurological complications of the tick-borne meningopolyneuritis of Garin-Bujadoux-Bannwarth, acrodermatitis chronica atrophicans and lymphadenosis cutis benigna, could be confirmed by means of microbiological, histological and serological methods. On the basis of case histories it had already been assumed for some time that anetodermia maculosa and the localised sclerodermas might also be caused by a tick-borne agent. The results of serological investigations have now strengthened this assumption, although microbiological confirmation is still lacking.

Erythema chronicum migrans in Sweden: clinical manifestations and antibodies to Ixodes ricinus spirochete measured by indirect immunofluorescence and enzyme-linked immunosorbent assay.

26 Swedish patients with erythema chronicum migrans (ECM) were studied regarding associated clinical symptoms and antibodies to Swedish Ixodes ricinus spirochete. 11/26 (42%) of the patients had associated symptoms, compared to more than 90% of 314 American patients with ECM, as described by Steere et al. Only 2/26 (8%) had multiple skin lesions, compared to 48% of the American patients. Elevated erythrocyte sedimentation rate and circulating immune complexes were demonstrated in 6/25 (24%) and 8/25 patients (32%), respectively, as against in 53% and 84%, respectively, of the American patients. The antibody response to Ixodes ricinus spirochete was measured by indirect immunofluorescence (IFA) and enzyme-linked immunosorbent assay (ELISA). Compared to the 95% percentile of controls, significantly high antibody titers were demonstrated in 3/25 (12%) by IFA, and 7/25 (28%) by ELISA. The ELISA antibody titers differed significantly (p less than 0.05) between ECM-patients and controls. The spirochetal antibody response in ECM was also compared with that in spirochete-associated disease of the central nervous system.

Successful cultivation of spirochetes from skin lesions of patients with erythema chronicum migrans Afzelius and acrodermatitis chronica atrophicans.

Spirochetes could be cultivated from 9 out of 13 skin biopsies from patients with erythema chronicum migrans Afzelius (ECMA) and from 2 out of 5 biopsies from patients with acrodermatitis chronica atrophicans (ACA) by using a newly modified serumless Kelly's medium. The different spirochete strains grew best at a low oxygen tension. Attempts to grow spirochetes from blood and cerebrospinal fluid failed. The cultivation of spirochetes from secondary ECMA lesions favours the presumption that a spirochetemia may occur in ECMA. The isolation of spirochetes from an ACA patient who had a disease duration of greater than 10 years proves that the spirochetes may survive in the human body for a considerable time.

Infections acquired in the fields and forests of the United States.

Sportsmen, backpackers, and outdoor workers may present with unusual infections acquired in the fields and forests of the United States. Infections to be considered in such persons with a febrile illness include Rocky Mountain spotted fever, Colorado spotted tick fever, babesiosis, borreliosis, and Lyme disease. The differential diagnoses for clinical presentations of pulmonary and gastrointestinal disease are also discussed.