Pulsed-field gel electrophoresis typing of Campylobacter fetus subsp. fetus isolated from sheep abortions in New Zealand

AIMS: To genotype Campylobacter fetus subsp. fetus isolates cultured from sheep abortions submitted to diagnostic laboratories in New Zealand during the year 2000 breeding season. To compare the types found nationally with those found in the Hawke's Bay region in 1999, and strains held in the New Zealand Reference Culture Collection, Medical Section (NZRM) from a study published in 1987. METHODS: Campylobacter fetus subsp. fetus isolates cultured by veterinary diagnostic laboratories in the year 2000 breeding season, from sheep abortions from throughout New Zealand, were typed using pulsed-field gel electrophoresis (PFGE). In addition, seven freeze-dried C. fetus subsp. fetus isolates (strain numbers 2939-2945) from the NZRM, representing restriction types a-g found amongst sheep abortion isolates in a study published in 1987, were typed using PFGE. RESULTS: In total, 293 C. fetus subsp. fetus isolates from 200 farms were obtained from veterinary diagnostic laboratories. Twenty-two distinct PFGE profiles were identified amongst the isolates. PFGE type B1 was predominant in each region of New Zealand and was identified from 66% of farms overall. Of the C. fetus subsp. fetus restriction types a-g lodged with the NZRM, 3/7 had PFGE profiles indistinguishable from profiles found in the current study. The other four restriction types had PFGE profiles that were unique but similar to those found in the current study. CONCLUSIONS: PFGE type B1 was predominant amongst the C. fetus subsp. fetus isolates cultured from sheep abortions in each region of New Zealand in the year 2000, as was found in Hawke's Bay in 1999. The similarity between PFGE profiles of C. fetus subsp. fetus sheep abortion isolates from 1987 and 2000, and the relative prevalence of the PFGE groups, suggests that there has been no major genotypic shift in the population of C. fetus subsp. fetus implicated in sheep abortion in New Zealand during this time.     

Pulsed-field gel electrophoresis of Campylobacter jejuni sheep abortion isolates

Campylobacter species are a significant cause of sheep abortion in most sheep-raising countries. In New Zealand, Campylobacter fetus subsp. fetus is the leading cause of diagnosed sheep abortion and the species C. jejuni and C. coli have also been implicated. To date, strain typing information of C. jejuni sheep abortion isolates is limited. The objective of the present study was to genotype C. jejuni isolates cultured from sheep abortions submitted to diagnostic laboratories in New Zealand during the 2000 breeding season, using pulsed-field gel electrophoresis (PFGE). In this study, C. jejuni isolates were cultured from approximately 10% of farms from which Campylobacter species were isolated from sheep abortions in the year 2000. This equated to 25 C. jejuni isolates from 21 farms. These isolates were obtained from the veterinary diagnostic laboratories and strain typed using the molecular typing technique PFGE. Ten distinct PFGE types were identified amongst the isolates. No particular PFGE type was found most frequently amongst these C. jejuni sheep abortion isolates. However, indistinguishable or similar C. jejuni PFGE types were identified from different aborted foetuses from the same flock, consistent with the role of C. jejuni as an infectious cause of abortion in sheep. These strain types were similar or indistinguishable from C. jejuni sheep abortion isolates obtained in 1999 in a smaller study (Mannering, S.A., Marchant, R.M., Middelberg, A., Perkins, N.R., West, D.M., Fenwick, S.G., 2003. Pulsed-field gel electrophoresis typing of C. fetus subsp. fetus from sheep abortions in the Hawke's Bay region of New Zealand. NZ Vet. J. 51, 33-37).     

Pulsed-field gel electrophoresis typing of Campylobacter fetus subsp. fetus isolated from sheep abortions in New Zealand

AIMS: To genotype Campylobacter fetus subsp. fetus isolates cultured from sheep abortions submitted to diagnostic laboratories in New Zealand during the year 2000 breeding season. To compare the types found nationally with those found in the Hawke' Bay region in 1999, and strains held in the New Zealand Reference Culture Collection, Medical Section (NZRM) from a study published in 1987.

METHODS: Campylobacter fetus subsp. fetus isolates cultured by veterinary diagnostic laboratories in the year 2000 breeding season, from sheep abortions from throughout New Zealand, were typed using pulsed-field gel electrophoresis (PFGE). In addition, seven freeze-dried C. fetus subsp. fetus isolates (strain numbers 2939–2945) from the NZRM, representing restriction types a–g found amongst sheep abortion isolates in a study published in 1987, were typed using PFGE.

RESULTS: In total, 293 C. fetus subsp. fetus isolates from 200 farms were obtained from veterinary diagnostic laboratories. Twenty-two distinct PFGE profiles were identified amongst the isolates. PFGE type B1 was predominant in each region of New Zealand and was identified from 66% of farms overall. Of the C. fetus subsp. fetus restriction types a–g lodged with the NZRM, 3/7 had PFGE profiles indistinguishable from profiles found in the current study. The other four restriction types had PFGE profiles that were unique but similar to those found in the current study.

CONCLUSIONS: PFGE type B1 was predominant amongst the C. fetus subsp. fetus isolates cultured from sheep abortions in each region of New Zealand in the year 2000, as was found in Hawke' Bay in 1999. The similarity between PFGE profiles of C. fetus subsp. fetus sheep abortion isolates from 1987 and 2000, and the relative prevalence of the PFGE groups, suggests that there has been no major genotypic shift in the population of C. fetus subsp. fetus implicated in sheep abortion in New Zealand during this time.     

Campylobacter fetus fetus abortions in vaccinated ewes

AIMS: To investigate the cause of an outbreak of ovine abortion in 1996 in a flock of 300 two-tooth (rising 2-year-old) ewes vaccinated against Campylobacter fetus fetus infection and to subsequently characterise the strain of C. fetus fetus isolated from aborted foetuses. METHODS: Standard bacteriological methods were used to identify C. fetus fetus isolates which were then antigenically typed and subjected to pulsed-field gel electrophoresis (PFGE) and compared to the vaccine strain. RESULTS: C. fetus fetus was identified as the causal agent of the abortions despite the ewes having been vaccinated before ram introduction and at the time of ram removal. Four isolates cultured from aborted material were indistinguishable when compared using antigenic typing and PFGE, but all differed from the vaccine strain. CONCLUSIONS: Within the limitations of the available typing systems, it is proposed that PFGE may be a useful tool to establish the distribution and strain variation of C. fetus fetus. CLINICAL RELEVANCE: This field case indicates the need for further study of non-vaccine C. fetus fetus strains which cause abortion in vaccinated ewes, and of the importance of these strains to the New Zealand sheep industry.     

Campylobacter jejuni abortion in a heifer

Campylobacter jejuni was isolated from the lung and stomach contents of an aborted bovine fetus. The bacterial isolate was classified according to morphologic, biochemical, and thermotolerance characteristics as well as sensitivity to antibiotics and biochemical agents. Serotyping was specific for C jejuni and excluded this isolate from the more common bovine causes of campylobacteriosis, C fetus subsp venerealis or C fetus subsp fetus. This report stresses the need for careful speciation of all Campylobacter isolates from aborted fetuses, especially in conditions where routine vaccination has not reduced abortion rates in the herd. Campylobacter jejuni is much more prevalent in causing human infections than is C fetus subsp venerealis or C fetus subsp fetus. Therefore, from a public health standpoint identification is important.     

Serogroups of Campylobacter fetus and Campylobacter jejuni isolated in cases of ovine abortion

Of 38 aborted ovine fetuses from 23 sheep flocks 29 C. fetus subsp. fetus and 22 C. jejuni were isolated and examined biochemically and serologically for heat-stable antigens. Serologic examinations were carried out by passive haemagglutination test. In case of C. fetus subsp. fetus strains alkaline antigen extraction was used. Antisera to two serogroups of C. fetus and to Penner serotype reference strains 1 to 60 were produced in rabbits. Abortion was caused in 18 (78.3%) flocks by C. fetus subsp. fetus and in 5 (21.7%) flocks by C. jejuni. Six C. fetus subsp. fetus strains grew well at both 43 and 25 degrees C. With one exception all C. fetus subsp. fetus were resistant, whereas all 29 C. fetus subsp. venerealis strains were sensitive to 30 micrograms/ml cefoxitin and cefamandole. These two cephalosporins can be used to differentiate the two subspecies of C. fetus. Passive haemagglutination test using alkaline antigen extraction is a proper method for the examination of heat-stable antigens of both C. fetus subspecies. Out of 24 C. fetus subsp. fetus strains 13 belonged to serogroup A(01), and 11 to serogroup B(02). C. jejuni strains examined belonged to Penner serogroup 1 (6 strains), to serogroup 5 (4 strains) and to serogroup 8 (4 strains).     

Comparison of surface antigens of some Campylobacter fetus subsp. fetus strains of ovine origin by polyacrylamide gel electrophoresis and immunoblotting.

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting were used to identify and to compare the surface antigens of eight C. fetus subsp. fetus strains. Seven strains (one of serogroup A and six of serogroup B) were isolated from aborted ovine fetuses, while one strain (serogroup A) originated from an aborted calf fetus. Saline extracts at 56 degrees C and 100 degrees C were used as antigens. Antisera were produced in rabbits. In saline extracts (56 degrees C) of the strains at least 19 fractions were identified by SDS-PAGE, with molecular masses ranging from approx. 4,800 to 205,000. The major bands appeared at 205,000, 66,000, 31,500, 25,000, 21,000 and 17,500. Despite the fact that the strains were cultured from 4 different sheep flocks and belonged to serogroup A or B, the SDS-PAGE profiles of the strains were very similar. When boiled (100 degrees C) extracts were used, a band migrating at 32,500 in sheep strains and a band at 97,500 in the calf isolate were missing. Most of the bands obtained by SDS-PAGE could be identified also by the immunoblot procedure. A or B type specificity of the ovine isolates was due to an LPS fraction, migrating at approx. 21,000, while the other LPS fractions appearing under this region although reacted with antisera did not influence the type specificity. Using alkaline extracts (pH 12) in SDS-PAGE, LPS fractions gave more pronounced profiles. In two of our C. fetus subsp. fetus isolates, plasmids with a molecular mass of 31,500 were identified.     

Immunohistochemical identification of Campylobacter fetus in natural cases of bovine and ovine abortions

An immunohistochemistry (IHC) procedure for the detection of Campylobacter fetus antigens using an avidin-biotin complex technique was performed on formalin fixed bovine and ovine fetal tissues from 26 natural cases of Campylobacter spp. abortion (four ovine and 22 bovine). The species of Campylobacter isolated included C. fetus ssp. venerealis from 13 bovine fetuses, C. fetus ssp. fetus from two ovine and one bovine fetus, Campylobacter jejuni from seven bovine fetuses, Campylobacter lari from two ovine fetuses and an unspeciated Campylobacter species in one bovine fetus. Histologic lesions identified in the aborted fetuses included placentitis, serositis, pneumonia, gastroenteritis, hepatitis and encephalitis. Campylobacter fetus antigens were identified by IHC in 13 of 13 bovine fetuses from which C. fetus ssp. venerealis was isolated and in two of two ovine fetuses from which C. fetus ssp. fetus was isolated. The IHC stains were negative in tissues from seven bovine fetuses from which C. jejuni was isolated, one bovine fetus infected with C. fetus ssp. fetus, one bovine fetus infected with the unspeciated Campylobacter and two ovine fetuses infected with C. lari. In positive cases, the IHC stain most frequently identified bacteria in the lung and gastrointestinal tract. The C. fetus IHC procedure performed on formalin fixed tissues is a practical tool for the diagnosis of natural cases of ovine and bovine abortion caused by C. fetus.     

An examination of Campylobacter fetus subsp. fetus by restriction endonuclease analysis and serology

Restriction endonuclease analysis was used to examine 70 different strains of Campylobacter fetus subsp. fetus, which were isolated from aborted sheep foetuses. The strains could be divided into seven types based on the DNA fragment patterns obtained by electrophoresis after digestion with the enzyme BstEII. With one exception, digestion with the enzyme XhoI allowed the strains to be grouped identically to that for BstEII. Antisera were made against formalized whole cells representative of each of the seven different restriction types. Analysis of these sera by tube agglutination tests using whole cells revealed five different serogroups. Examination of the 70 strains with absorbed antisera demonstrated a complex relationship between the restriction type and the external antigens of C. fetus subsp. fetus.     

Comparative studies on competitive exclusion of three isolates of Campylobacter fetus subsp. jejuni in chickens by native gut microflora

Resistance of young chicks to Campylobacter fetus subsp. jejuni was substantially increased by early exposure to native gut microflora. Protection was demonstrated against two human isolates and a chicken isolate of C. fetus subsp. jejuni. Significant protection against the chicken isolate was observed throughout a 91-day test period. Infection reached 100% (25/25) in the untreated group at 56 days of age and only 4% (1/25) in the group treated with native gut microflora. Campylobacter fetus subsp. jejuni was isolated from the ceca and less frequently from the gall bladder and liver of chicks that actively shed the bacteria. Cultures of feces from chicks reared on wood-shavings litter were often negative, suggesting that culturing litter as an indicator of infection has limited value.     

Epidemiology of ovine Campylobacter infection determined by numerical analysis of electrophoretic protein profiles

The relationship of 50 Campylobacter strains isolated from aborted ovine foetuses, and the faeces of sheep, cattle and chickens were determined by numerical analysis of electrophoretic (SDS-PAGE) protein profiles. Comparison of protein patterns by numerical methods revealed differences between C. fetus ssp. fetus, C. jejuni, and C. coli strains as well as heterogeneity among isolates from different outbreaks. Isolates from each farm produced a distinct cluster and flocks from different locations were found to be infected with relatively different strains. In most cases, protein patterns of ovine foetal isolates were very similar to those of ovine faecal isolates. Ovine isolates of C. fetus ssp. fetus, C. jejuni and C. coli gave similar protein patterns to the corresponding Campylobacter species isolated from cattle or chicken, on the same farm. Thus, it was concluded that certain protein types of ovine Campylobacter strains were more likely associated with local areas, and Campylobacter strains causing ovine abortions are distributed in the environment more widely than assumed to date.     

Detection of Campylobacter antibodies in sheep sera by a Dot-ELISA using acid extracts from c. fetus ssp. fetus and c. jejuni strains and comparison with a complement fixation test

In this study, a dot-enzyme-linked immunosorbent assay (Dot-ELISA) was evaluated in comparison with a complement fixation test (CFT) for the detection of Campylobacter antibodies in sheep sera. Acid glycine extracts (AGE) of both Campylobacter fetus ssp. fetus and Campylobacter jejuni strains that had been isolated from the gall-bladder of slaughtered sheep was used as antigen in both tests. A total of 153 sheep sera from aborted (74) and slaughtered (79) sheep were examined by both Dot-ELISA and CFT. Twenty-two sera showed anti-complementary activity were not suitable for CFT. Of the 22 sera showing anti-complementary activity, two sera were found to be positive in Dot-ELISA. Eighty-eight (67.2%) of the remaining 131 sera were negative by both Dot-ELISA and CFT using AGE of both Campylobacter strains whereas 43 sera (32.8%) gave different reaction patterns in Dot-ELISA and CFT with the extracts of both Campylobacter strains. Twelve sera were positive by both tests using AGE of C. fetus ssp. fetus but CFT failed to detect antibodies in nine of these sera when AGE of C. jejuni was used. Twelve sera were positive by both tests only when AGE of C. fetus ssp. fetus was used. Eleven sera were positive only by CFT. Seven of these reacted only with the AGE of C. fetus ssp. fetus and four sera were positive by using AGE of both Campylobacter strains. The remaining eight sera were found to be positive only by dot-immunobinding assay either with the AGE of both Campylobacter strains or with the AGE of one of the Campylobacter strains. It is concluded that Dot-ELISA using AGE from C. fetus ssp. fetus could be employed for the detection of Campylobacter antibodies in sheep sera and the additional use of AGE from C. jejuni as antigen appeared not to be profitable for this purpose.     

Phenotypic and molecular characterization of bovine Campylobacter fetus strains isolated in Brazil

The objective of the present study was to characterize the phenotypic and molecular aspects of Campylobacter fetus strains isolated from bovine herds with reproductive problems. Thirty-one Brazilian field isolates, together with one reference strain of each subspecies of C. fetus, were analyzed. The strains were submitted to phenotypic identification followed by subspecies characterization using the polymerase chain reaction (PCR) and numeric evaluation of restriction fragment length polymorphism (RFLP) separated by pulsed-field gel electrophoresis (PFGE). Phenotypically, 4 isolates (12.1%) were classified as C. fetus subsp. fetus, and 29 isolates (87.9%) were classified as C. fetus subsp. venerealis. However, according to molecular analysis, only 1 isolate (3.0%) was classified as C. fetus subsp. fetus (the reference strain), whereas 32 isolates (97.0%) were considered C. fetus subsp. venerealis. SalI digestion of C. fetus genomic DNA, obtained from the 33 strains, yielded 7-10 DNA fragments ranging in size from 40 to 373kb, with 12 distinct patterns. Furthermore, the numeric analysis by neighbor-joining of the DNA from the 33 strains resulted in a dendrogram in which 2 distinct groups were identified. It was concluded that phenotypic characterization of C. fetus subspecies might lead to erroneous classification of field isolates. Although RFLP-PFGE is a powerful and reliable technique to characterize C. fetus, it has the inconvenience of being time consuming and laborious. Whereas PCR, besides providing rapid results, was found to be reliable and convenient for the characterization of field isolates of C. fetus.     

Efficacy of a vaccine to prevent Chlamydia- or Campylobacter-induced abortions in ewes

In a sheep flock, Chlamydia psittaci, Campylobacter fetus, Ca jejuni, and Salmonella dublin caused abortions. A vaccine that contained C psittaci type I from 2 sources: a cow with pneumonia and an aborted ovine fetus, Ca fetus, Ca jejuni, and 4 strains of K99 Escherichia coli was given to 240 ewes before they were bred. All fetuses, placentas, and lambs, that died within 36 hours of birth were examined for infectious agents. Of 55 abortions, 30 (55%) were caused by Chlamydia or Campylobacter spp; 25 of the 30 (83%) abortions took place in the nonvaccinated group (n = 240). Forty-five more lambs survived in the vaccinated group than in the nonvaccinated group. Abortion rates for Chlamydia and Campylobacter spp (2.1 vs 10.4% in vaccinated and nonvaccinated groups, respectively) were significantly different (P = 0.003). Abortion rates for S dublin were not significantly different between groups. The Salmonella epizootic was controlled quickly by sanitation and treatment procedures. The vaccine was at least 80% efficacious against Chlamydia and Campylobacter spp and appeared to be protective.     

Distribution of Campylobacter jejuni isolates from turkey farms and different stages at slaughter using pulsed-field gel electrophoresis and flaA-short variable region sequencing

The aim of this study was to assess the diversity of thermotolerant Campylobacter spp. isolated from turkey flocks at six rearing farms 1-2 weeks prior to slaughter (360 faecal swab samples) and from 11 different stages at the slaughterhouse (636 caecal, environmental, neck skin and meat samples). A total of 121 Campylobacter isolates were identified to species level using a multiplex PCR assay and were typed by pulsed-field gel electrophoresis (PFGE) and flaA-short variable region (SVR) sequencing. All Campylobacter isolates were identified as Campylobacter jejuni. PFGE analysis with KpnI restriction enzyme resulted in 11 PFGE types (I-XI) and flaA SVR typing yielded in nine flaA-SVR alleles. The Campylobacter-positive turkey flocks A, C and E were colonized by a limited number of Campylobacter clones at the farm and slaughter. The present study confirms the traceability of flock-specific strains (PFGE types I, V and IX; flaA types 21, 36 and 161) from the farm along the entire processing line to meat cuts. It seems that stress factors such as high temperature of the defeathering water (54-56 °C), drying of the carcass skin during air chilling (24 h at 2 °C), and oxygen in the air could not eliminate Campylobacter completely. Campylobacter-negative flocks became contaminated during processing by the same subtypes of Campylobacter introduced into the slaughter house by preceeding positive flocks even if they were slaughtered on subsequent days. Proper and efficient cleaning and disinfection of slaughter and processing premises are needed to avoid cross-contamination, especially in countries with a low prevalence of Campylobacter spp. The majority of flaA SVR alleles displayed a distinct association with a specific PFGE type. However, a linear relationship for all strains among both typing methods could not be established. To specify genetic relatedness of strains, a combination of different genotyping methods, is needed.     

Campylobacter fetus subsp. jejuni in poultry reared under different management systems in Nigeria

Cloacal swabs from 487 live birds in 36 flocks and 70 poultry carcasses were cultured for Campylobacter fetus subsp. jejuni. It was isolated from 12.3% of the birds in 19 flocks. Chickens, turkeys, and guinea fowl differed from one another in isolation rates of the organism. Management system affected its occurrence, and only 7.1% of eviscerated carcasses yielded it. It was concluded that bird species, management system, and immersing slaughtered poultry in boiling water before dressing affect recovery of C. fetus subsp. jejuni from live birds and carcasses.     

Genotypic characterisation and cluster analysis of Campylobacter jejuni isolates from domestic pets, human clinical cases and retail food

The genetic similarity of Campylobacter jejuni isolates from pets, compared to human clinical cases and retail food isolates collected in Ireland over 2001-2006 was investigated by cluster analysis of pulsed-field gel electrophoresis (PFGE) fingerprinting profiles. Comparison of the PFGE profiles of 60 pet isolates and 109 human isolates revealed that seven (4.1%) profiles were grouped in clusters including at least one human and one pet C. jejuni isolate. In total six (1.6%) of 60 pet and 310 food profiles were in clusters with at least one food and one pet C. jejuni isolate. The detection of only a small number of genetically indistinguishable isolates by PFGE profile cluster analysis from pets and from humans with enteritis in this study suggests that pets are unlikely to be an important reservoir for human campylobacteriosis in Ireland. However, genetically indistinguishable isolates were detected and C. jejuni from pets may circulate and may contribute to clinical infections in humans. In addition, contaminated food fed to pets may be a potential source of Campylobacter infection in pets, which may subsequently pose a risk to humans.     

Dissemination of antimicrobial resistant strains of Campylobacter coli and Campylobacter jejuni among cattle in Washington State and California

The purpose of this study was to investigate the genetic similarity of Campylobacter jejuni and Campylobacter coli with similar antimicrobial resistance phenotypes, isolated from cattle on different farms and at different times, in order to evaluate the possible existence of disseminated antimicrobial resistant clones. PFGE after SmaI and KpnI restriction identified 23 and 16 distinct PFGE patterns among 29 C. jejuni and 66 C. coli isolates, respectively. In C. coli, 51 (77%) of the resistant isolates demonstrated one of the four indistinguishable PFGE patterns, whereas only 24% doxycycline resistant C. jejuni shared one of the two indistinguishable PFGE patterns. The genetic mechanisms of resistance were homogeneous within and between these clonal types. Genetically indistinguishable (clonal) groups of C. coli accounted for most Campylobacter sp. with multiple antimicrobial resistance observed in this study, consistent with a role for clonal dissemination in the epidemiology of resistance in this species.     

Occurrence and significance of different Campylobacter types in domestic animals in Hungary

Experiences, including results of original experimental work on Campylobacter fetus, C. jejuni and C. coli induced diseases of cattle, sheep, dogs, rabbits poultry and men in Hungary are reviewed. Out of 31 cases of abortion in cows 29 (93.5%) were causes by C. fetus subsp. venerealis and only one case each (3.2%) by C. fetus subsp. fetus and C. jejuni, respectively. Out of the 29 strains of C. fetus subsp. venerealis, 26 belonged to serogroup 01 (A) and only 3 to serogroup 02 (B). Campylobacter abortions in sheep flocks were caused in 18 cases (78.3%) by C. fetus subsp. fetus and in 5 cases (21.7%) by C. jejuni. The latter strains belonged to Penner's serogroup 1 (6 strains), 5 (4 strains) and 8 (5 strains), respectively. In scouring dogs 12.7% of the cases were caused by C. jejuni. The same pathogen caused diarrhoea also in young rabbits. Isolated strains belonged to serogroup 2. In cases of Campylobacter hepatitis of laying hens, egg production has been reduced by 8 to 15% for 2 to 3 weeks. Row poultry meat represents often the source of infection for men. The 32 strains of C. jejuni isolated from faecal samples of men affected with diarrhoea belonged to 12 serogroups.     

Prevalence and clonal diversity of Campylobacter jejuni from dairy farms and urban sources

AIM: To investigate the role of free-living animals such as sparrows, rodents and flies as potential reservoirs of Campylobacter spp on a dairy farm, and to assess the genetic diversity among Campylobacter isolates from the farm and an urban source. METHODS: A total of 290 samples (bovine, passerine and rodent faeces, and whole flies) were collected from a large commercial dairy farm in the Manawatu district in New Zealand, and from faeces from urban sparrows in a nearby city. Other samples collected from the dairy farm included five from silage, two from aprons worn by workers during milking, two from workers' boots and two from water in troughs in a paddock. Isolates of thermophilic Campylobacter spp were identified morphologically and phenotypically and further characterised molecularly using pulsed-field gel electrophoresis (PFGE) and the restriction enzyme SmaI. RESULTS: Campylobacter jejuni was the only Campylobacter species isolated from all samples. The highest prevalence was found in faeces from dairy cows (54%), followed by faeces from sparrows from the urban area (40%) and the farm (38%), and from rodents (11%) and whole flies (9%). Other samples from the farm environment such as silage, trough water, and workers' aprons and boots were also positive for C. jejuni. Of the 22 restriction patterns obtained, seven were common to more than one source. CONCLUSIONS: Cattle, sparrows, rodents and flies are potential reservoirs of C. jejuni on dairy farms. Identical clones of C. jejuni carried by cattle, sparrows, flies and rodents probably indicate a common source of infection. The high level of asymptomatic carriage of C. jejuni by healthy dairy cows could be sufficient to maintain infections within the dairy farm surroundings via environmental contamination.