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Brucella ovis is recognized worldwide as an important pathogen of sheep, and has also been identified in farmed deer in New Zealand. Previously, only one strain type of B. ovis has been identified. The objective of this paper was to perform pulsed-field gel electrophoresis (PFGE) on field isolates of B. ovis to determine whether strain variations exist, whether sheep and deer are affected by the same strains, and to compare the performance of the rare-cutting restriction enzymes XbaI and SwaI. Ten B. ovis isolates from sheep and two from deer in New Zealand, as well as the type strain, were subjected to PFGE analysis using both XbaI and SwaI. PFGE of XbaI restriction fragments produced two banding patterns consisting of 27-28 bands, which were found to be 98% similar by cluster analysis, and were named X1 and X1a. PFGE of SwaI restriction fragments resulted in three banding patterns consisting of 13-15 bands each. Ten of the isolates had identical banding patterns and were named S1. One isolate differed by one band, representing a subtype named S1a. Two isolates differed by six bands, representing a different strain type of B. ovis and this was named S2. Cluster analysis showed S2 to be 78% similar to the S1/S1a cluster. Both strain types were isolated from both sheep and deer. Thus, two distinct strain types of B. ovis were identified in New Zealand, which is the first report of more than one strain type being identified worldwide. Neither strain was species-specific for sheep or deer. The restriction endonuclease SwaI was found to be more discriminatory than the enzyme XbaI, which has been used in previous studies.

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.

Prevotella oralis, an obligate Gram-negative anaerobe, was shown to be the cause of meningitis in a two-year-old crossbreed dog. The dog had a six-week history of lethargy and neck pain. On presentation, the animal was reluctant to walk, had a stiff gait and neck pain on flexion. Analysis of cerebrospinal fluid documented a neutrophilic pleocytosis (7488 cells/microl) and the presence of occasional intracellular bacterial coccobacilli. The aetiological diagnosis was confirmed by routine aerobic and anaerobic culture, and identification of the isolates. This report also reviews the literature of the documented cases of bacterial meningitis in dogs.

The Salmonella serotypes S. Cerro and S. Newport were isolated from New Zealand sea lions (Phocarctos hookeri) and feral pigs on the Auckland Islands in the New Zealand subantarctic region. The isolates were typed by pulsed-field gel electrophoresis using Xba1 as the restriction enzyme. The isolates were indistinguishable, which suggests that Salmonella infection cycles between sea lions and pigs in this environment. Apart from a previous isolation from a single New Zealand fur seal (Arctocephalus forsteri), S. Newport has not been recorded in any animals from New Zealand, but it is associated with gastroenteritis in humans. Contamination of the marine environment by human waste is a possible source of infection for marine mammals and warrants further investigation.

The duration of infection and pulsed-field gel electrophoresis (PFGE) types of bovine intramammary Streptococcus uberis isolates were examined. Milk samples were collected in duplicate from all 4 glands of 503 cows from 5 herds within 1 to 3 d of parturition and from 113 cows with clinical mastitis in the same herds throughout lactation. Glands from which S. uberis was isolated were resampled at 28-d intervals.The prevalence of S. uberis was 12% for cows around parturition, and the median duration of infection was 16 d. Cows >2 yr old had a longer duration of infection than 2 yr old cows, and duration varied among herds. A total of 173 different PFGE types were identified from a total of 234 S. uberis isolates. Each farm had a unique set of PFGE types. Only 3 PFGE types were common to each of 3 pairs of cows, and these occurred on the same farm. Where S. uberis was isolated on more than one occasion from a gland, only 55% of the PFGE types were the same across time. For cows with multiple glands infected, only one-half (9 of 18) had the same PFGE type in more than one gland. No predominant PFGE type was identified in any herd. It is concluded that there was wide heterogeneity of PFGE types, that the environment rather than other cows was the likely source of S. uberis infections, and that glands may be infected with multiple S. uberis PFGE types over a lactation.

Aims: The aim of the study was to determine Campylobacter jejuni contamination and prevalence on fomites moving between broiler farms and the processing plant in the period after cleaning and before departure to harvest chickens. In addition, changes in the proportion of contaminated fomites in the course of a day were assessed., Methods and Results: Pooled swab samples were obtained from pallets, crates, wheels of trucks, tractors and forklifts, truck beds, and from drivers' and catchers' boots. After enrichment in Bolton's broth Campylobacter were recovered on modified blood-free Campylobacter selective agar (mCCDA). Isolates were identified using tests for phenotypic and biochemical characteristics. Of the 209 samples collected, 53% were positive for C. jejuni, with all fomites positive except tractor wheels. Pallets had the highest contamination rate at 75%. More than 50% of catchers' boots, drivers' boots, crates and truck wheels were positive. Forty-seven per cent and 31% of truck beds and forklift wheels, respectively, were contaminated. The proportion of contaminated fomites did not change significantly during the day., Conclusions: This study has identified trucks, forklifts, pallets, crates, drivers' and catchers' boots as potential sources of C. jejuni for broilers., Significance and Impact of the Study: Campylobacter jejuni contamination of broiler processing plant fomites was found to be extensive ranging from 31% for truck beds to 75% for pallets. The proportion of contaminated fomites was observed to be similar throughout the day. The impact of contaminated fomites as sources of colonization of broilers with C. jejuni is discussed.

Free available chlorine (FAC) concentrations in drinking water supplied to broiler chickens grown commercially in New Zealand were monitored for 11 farms in two companies. Different sites within a growout house were examined at different times of the day to determine spatial and temporal differences in FAC concentrations. Taps provided water with significantly higher FAC concentrations than did drinkers. There were no significant differences between the concentrations of FAC taken from various drinkers around the growout house. There were differences in the variations of measurements taken from the same drinker within a growout house at different times of the day, with variations increasing in the afternoon. No growout houses provided an average FAC content of 2 ppm, the suggested standard in one company. Three growout houses consistently met the chlorine concentration of 0.2 ppm suggested by the New Zealand Drinking Water Standards.

Aim: This study reports an outbreak of salmonellosis due to S. Typhimurium DT160 which caused extensive mortality in wild birds and enteric disease in humans in New Zealand during the winter and spring months of the year 2000., Methods: Necropsies were performed and microbiological examinations undertaken on wild birds from populations in which mass mortality was reported, and on captive indigenous birds which died suddenly during the winter and spring of 2000. Affected tissues were examined histologically and isolates of S. Typhimurium were phage typed and examined using pulsedfield gel electrophoresis (PFGE). Isolates of S. Typhimurium obtained from cases of human enteric disease which occurred during these months were phage typed, examined using PFGE and compared with the bird isolates., Results: Central and northern areas of the South Island and the southern North Island were worst affected with die-offs of several hundreds of sparrows and other birds reported in rural areas. Mortalities reached a peak in winter (July-August) 2000 and decreased to small numbers during the spring and early summer. The birds usually died of an acute septicaemia with multifocal necrotising lesions in the liver and spleen. Human cases throughout the country increased gradually over the same period. Isolates from birds, livestock and humans examined using PFGE were indistinguishable from one another., Conclusion: This strain of Salmonellahas emerged as a major cause of septicaemia in wild birds in New Zealand. Because of the close association between house sparrows (Passer domesticus) and humans, the organism also poses a serious zoonotic risk. The possibility that the infection may spread to involve indigenous species needs investigation.

Aims: To compare three culture methods to detect Yersinia enterocolitica from oral or rectal swabs from experimentally infected pigs., Methods and Results: The three methods used were: direct plating on Cefsulodin-Irgasan-Novobiocin (CIN) agar, cold enrichment in phosphate buffered saline (PBS) followed by plating on CIN agar and selective enrichment with Luria-Bertani-Bile Salts Irgasan (LB-BSI) followed by plating on CIN agar. Selective enrichment with LB-BSI produced the highest recovery rate (63%), when compared with cold enrichment (52%) and plating on CIN agar alone (43%). Selective enrichment with LB-BSI was significantly (P < 0.02) more sensitive than direct plating on CIN agar and more sensitive than cold enrichment (P < 0.1)., Conclusions, Significance and Impact of the Study: Selective enrichment with LB-BSI was more sensitive than the widely accepted method of cold enrichment and it reduced the time required for detection of Y. enterocolitica by three weeks. Selective enrichment with LB-BSI was also compatible with a multiplex PCR technique.

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.

Aim: To determine whether Brucella ovis can be transmitted from stag to stag by successive grazing of infected and noninfected stags in the same paddock, or by grazing infected and non-infected stags in adjacent paddocks., Methods: Six red deer stags (Cervus elaphus) were artificially infected with B. ovis and 5 were confirmed to be shedding the organism in their semen. Infected stags alternated paddocks, and therefore grazing and wallows (successive grazing), once or twice weekly with 6 non-infected stags from 3 March to 18 August, 1999. Direct contact between the 2 groups of animals was prevented. The 2 groups alternated paddocks 32 times. Six other non-infected stags were grazed in a paddock adjacent to the infected stags throughout this period, separated by a standard deer fence. Non-infected stags were blood sampled at 2to 6-week intervals to test for B. ovis antibodies using a complement fixation test and an enzyme linked immunosorbent assay., Results: No stag from either non-infected group became infected with B. ovis., Conclusions: The risk of stags becoming infected with B. ovis by successive grazing of the same paddock as, or by grazing in paddocks adjacent to, infected stags appears to be low. We conclude from this result, and similar experimental evidence and experience of this disease in sheep, that transmission of B. ovis requires animals to be grazed or confined together in a way that allows direct contact between animals., Clinical Relevance: It is likely that infected and non-infected stags can be managed on the same property without transmission occurring between the groups, provided that they do not come into direct contact with one another.

Three hundred and forty-two Streptococcus uberis isolates were cultured from milk samples from subclinical and clinical cases of dairy cattle mastitis. The samples were collected from 15 different New Zealand farming regions, including eight specific farms, during field research trials and veterinary diagnostic investigations. Pulsed-field gel electrophoresis was used to determine and compare the degree of genetic dissimilarity between the restriction endonuclease fragment pattern of the 342 New Zealand and a single United States S. uberis isolate. The 343 isolates exhibited 330 different restriction endonuclease fragment patterns. The United States isolate had a pattern unlike any of the New Zealand isolates. Most of the isolates were genetically different strains (pattern deferred by at least 33%), but identical patterns were noted within the same or different quarters of an individual cow, different cows within the same farm, and from different cows from the same or different districts, farming regions or islands. Seven of the eight selected farms had at most only one pair of isolates with banding patterns, which differed by less than 33%. A high degree of dissimilarity was noted in individual herds in which all the samples were collected on the same day or over a 2-year period. The high degree of dissimilar isolates is an indication that S. uberis infections in New Zealand dairy cattle are largely due to the opportunistic nature of the organism in the cows' environment. Prevention and treatment of S. uberis mastitis will therefore need to be directed at a multitude of different strains present throughout the country as well as in individual herds.

Aims: To determine the prevalence by isolation of Bordetella bronchiseptica infection in healthy cats and in cats showing signs of upper respiratory tract (URT) disease attended by a veterinary practice in the Manawatu region., Methods: The nasal cavity and oropharynx of 100 cats of mixed sex and age were swabbed and the swabs cultured for B. bronchiseptica. The population of cats surveyed was that attended by the Massey University Veterinary Teaching Hospital, and included healthy cats, cats with clinical signs of URT disease, cats with a recent history of URT disease, cats from single cat households, cats from multiple-cat households, and cats from a colony., Results: Bordetella bronchiseptica was recovered from 7 cats (5 from pharyngeal samples and 2 from nasal samples). Five of the 7 cats appeared to be healthy at the time of sampling, whilst 2 showed clinical signs of URT disease. Six of the 7 culture-positive cats were from a cat colony. The prevalence of B. bronchiseptica in healthy cats sampled was 7% and in cats with URT disease was 8%., Conclusion: This study confirms that B. bronchiseptica infection is present, but the prevalence of infection is low, in both healthy cats and in cats with URT disease attended by the Massey University Veterinary Teaching Hospital. It is unlikely that B. bronchiseptica infection is a frequent cause of feline URT disease of cats in this region.

Aim: To describe the clinical course of a dog infected with Mycobacterium bovis causing a granulomatous pneumonia., Clinical Findings: The dog initially presented with a persistent cough, inappetence and weight loss. Clinical findings included a fever, dyspnoea and tachypnoea, with haematological evidence of a mild neutrophilia and hypoalbuminaemia. Radiographs of the chest demonstrated a concomitant pneumothorax, pleural effusion, and a consolidated area within the left caudal lung lobe. An exploratory thoracotomy revealed this to be a ruptured granulomatous lesion. Subsequent histopathological, microbiological and genetic studies identified M. bovis as the causal agent., Clinical Significance: Mycobacterium bovis infections should be included in the differential diagnosis of pulmonary disease and pleural effusions in dogs living in regions of New Zealand known to have a high incidence of mycobacterial infection in wildlife and farm animals.

Aim: To determine whether B. ovis will transmit from infected rams to non-infected red deer stags (Cervus elaphus) grazing together in the same paddock., Methods: Six rams artificially infected with B. ovis were grazed with six non-infected 14-month-old red deer stags for a four and a half month period from March 4 to July 20, 1999. Stags were blood sampled at one- to six-weekly intervals to test for B. ovis antibodies using a complement fixation test. Stags that seroconverted were semen sampled to test for B. ovis infection by bacteriological culture., Results: Between day 92 and day 124 of grazing together (June 4 and July 6), sera from five of the six stags became positive in the B. ovis complement fixation test. B. ovis was cultured from semen samples from four of the seropositive stags., Conclusions: Brucella ovis can be transmitted from infected rams to non-infected stags grazing in the same paddock, suggesting that B. ovis infection in farmed deer in New Zealand initially came from infected rams. Whether transmission occurs from direct contact between rams or stags, or indirectly by environmental contamination needs to be established.

The ability of a newly identified probiotic lactic acid bacterial strain, Bifidobacterium lactis (HN019), to confer protection against Salmonella typhimurium was investigated in BALB/c mice. Feeding mice with B. lactis conferred a significant degree of protection against single or multiple oral challenge with virulent S. typhimurium, in comparison to control mice that did not receive B. lactis. Protection included a ten-fold increase in survival rate, significantly higher post-challenge food intake and weight gain, and reduced pathogen translocation to visceral tissues (spleen and liver). Furthermore, the degree of pathogen translocation showed a significant inverse correlation with splenic lymphocyte proliferative responses to mitogens, blood and peritoneal cell phagocytic activity and intestinal mucosal anti-S. typhimurium antibody titers in infected mice; all of these immune parameters were enhanced in mice fed B. lactis. Together, these results suggest that dietary B. lactis can provide a significant degree of protection against Salmonella infection by enhancing various parameters of immune function that are relevant to the immunological control of salmonellosis. Thus dietary supplementation with B. lactis provides a unique opportunity for developing immune-enhancing probiotic dairy food products with proven health benefits.

One of the risks for contamination of edible product in the pre-inspection area of processing lines in meat plants is cross contamination. This can occur directly as a result of carcass-to-carcass contact or indirectly via knives or the hands of butchers. Standard procedures require that operators rinse their hands and knives to remove any visible contamination. In New Zealand, protective gloves are not allowed in the pre-inspection area because they are considered a potential risk for cross contamination until the carcasses have passed the final meat inspection. However, the risk of injury to the bare hands is as high in this area as in other parts of the plant, where such gloves are permitted. There is therefore a need to evaluate the risk of bacterial cross contamination via bare hands and via protective gloves. The present study compared bacterial adherence to bare hands and to gloves after rinsing for 5 s in a shower of water at 40 degrees C and after rinsing gloves in hotter water (60 degrees C) following simulated contact with the hide of a recently slaughtered animal. Under laboratory conditions there were no statistically significant differences between bacterial adherence to bare hands or to gloves rinsed in water at 40 degrees C or 60 degrees C.

The size and distribution of histological lesions was studied in 14 cases of avian pseudotuberculosis using a combination of serotype-specific immunohistochemistry and image analysis. The material was derived from recent and archival cases in six canaries (Serinus canaria), two zebra finches (Poephila guttata), three psittaciformes (a kaka, Nestor meriondalis, one rainbow lorikeet, Trichoglossus mollucanus, and one budgerigar, Melopsittacus undulatus), and three New Zealand wood pigeons (Hemiphaga novaeseelandiae). The disease observed in the passerine species appeared to have an acute clinical course and the bacterial lesions were predominately enteric. In the pigeons and the psittaciformes examined, the clinical course of the disease was more chronic in nature and involved the liver and spleen. A correlation was found between the amount of stainable iron in the liver of affected birds and the area of bacterial lesions. All of the 11 strains of Yersinia pseudotuberculosis isolated from fresh necropsy material were serotype II, as determined using a standard serum agglutination test. Immunohistochemistry indicated the presence of antigen(s) common to serotype II in histological material from confirmed cases and in another three cases where the organism had been cultured but the serotype not specified. The in vitro virulence characteristics and plasmid profiles of Y. pseudotuberculosis isolates were also determined.

Thirty cohort pigs were followed from birth to slaughter to study epidemiological patterns of porcine pleuropneumonia caused by Actinobacillus pleuropneumoniae. The study was conducted within a larger 380-animal study of vaccination against Mycoplasma hyopneumoniae and A. pleuropneumoniae in a 340-sow farrow-to-finish piggery with 4-month weaning, operating a continuous system of intensive production in the North Island of New Zealand. The cohort pigs were randomly allocated into two equal groups: vaccinated and control. Pigs in the first group were vaccinated at 2 and 4 weeks of age with both M. hyopneumoniae vaccine and A. pleuropneumoniae vaccine at separate vaccination sites. A series of nasal swabs was taken at 4, 8, 10, 11, 12, 14, 16 and 18 weeks of age. Each swab was streaked onto the surface of a selective medium on the farm and the plates were immediately transported to a laboratory and incubated at 37 degrees C for 5 days. After the trial, pigs were slaughtered at an average of 132 days of age, lungs were examined and samples taken for bacteriological culture and isolation. Thirty-five out of 256 samples produced haemolytic colonies which were Gram-negative, V-factor-dependent and positive to the CAMP test. A. pleuropneumoniae was first isolated at 4 weeks of age from one vaccinated pig. This finding suggests that piglets became infected in the farrowing pen and the source of infection might be a carrier sow. The interval-specific cumulative incidence of A. pleuropneumoniae infection reached a maximum of 54% and 40% at 11 weeks of age in the vaccinated and control groups, respectively. Infection status of the litter is considered to be a factor influencing morbidity in infected herds during weaner and grower periods. Our results suggest that simultaneous vaccination with M. hyopneumoniae and A. pleuropneumoniae vaccines at 2 and 4 weeks of age might lessen the prevalence but cannot absolutely prevent A. pleuropneumoniae infection during the weaner or grower-finisher periods.

The development of disease following oral challenge with Yersinia pseudotuberculosis (serotype II) was compared in four groups of five chickens treated with a combination of 10 mg parenteral iron-dextran, 10 mg of the chelating agent desferrioxamine or 10 mg of dextran, 2 days before infection. The chickens pretreated with iron-dextran, with or without desferrioxamine, developed diarrhoea and were lethargic 2 days following bacterial challenge. Chickens not given iron-dextran showed no clinical signs of disease. Histological examination of selected tissues indicated that chickens pre-treated with iron-dextran had significantly more intestinal lesions, but fewer lesions in the spleen, than chickens in groups not treated with iron-dextran. In contrast to control chickens given iron dextran, but not challenged with bacteria, there was no stainable iron in the livers of chickens challenged with Y. pseudotuberculosis 10 days after an injection of 10 mg of iron-dextran. This suggests that chickens challenged with Y. pseudotuberculosis utilised exogenously administered iron during infection.

Twenty five isolates of Yersinia recovered from the faeces of cattle, sheep, goats and people in New Zealand were characterised biochemically and serologically and were found to be unrelated to any known Yersinia species. Two phenotypes were identified biochemically. Testing against all known O-factors of Yersinia showed that the isolates were serologically unique and two new serotypes were proposed, O:77 and O:78. Deoxyribonucleic acid relatedness studies indicated that the strains formed a homogeneous group, closely related to Yersinia enterocolitica. The definitive status of the isolates has not yet been decided.

The level of non-specific reactions found in the brucellosis serology of ruminants in New Zealand was very low until July 1992. This changed when, in an export consignment of 1071 deer, 35% reacted in the Brucella abortus tube agglutination test with titres varying from 50 to 200 IU. The reactors were also positive in the Rose-Bengal agglutination test and most of them reacted in the complement fixation test with titres varying from 10 to 80 IU. Yersinia enterocolitica 0:9 was later isolated from one deer of this consignment. It was the first isolate of this serotype recovered in New Zealand from an animal. Shortly after, false reactors occurred more frequently than before in sera from Brucella abortus accredited free cattle herds. As the involvement of Yersinia enterocolitica 0:9 was suspected in these cases, faecal samples from reactors and in-contact animals were cultured for this organism. Yersinia enterocolitica 0:9 was isolated from nine of 19 herds showing one or more false Brucella abortus seroreactions. Prior to 1990, Yersinia enterocolitica serotype 0:9 had not been isolated in New Zealand, despite the recovery of a number of other bio- or serotypes of the organism from humans and animals. From 1990 onward, serotype 0:9 began to be isolated from human faecal samples with increasing frequency. Since the first isolations from deer and cattle in 1992, it has now also been recovered from a cat and an alpaca and from cattle without any association with false positive Brucella abortus reactions. All serotype 0:9 isolates were of biotype 2.

A survey was carried out to determine the prevalence of Yersiniae in wild passerines in the lower half of the North island of New Zealand over a period of 12 months. Samples of soil, water and foliage were also collected. Out of a total of 1370 avian samples, only two strains of Y. pseudotuberculosis were isolated and a total of 98 strains of environmental yersiniae were identified, including Y. enterocolitica biotype 1a, Y. frederiksenii, Y. kristensenii and Y. intermedia. No strains of Y. pseudotuberculosis were isolated from 1032 non-avian samples collected, which included 100 samples taken from wild mammals. From the non-avian samples, 51 strains of environmental Yersiniae were identified, of which the relative prevalence of Yersinia enterocolitica, biotype 1a, Y. frederiksenii, Y. kristensenii and Y. intermedia was similar to that in the rural passerines. The prevalence of Yersiniae in soil samples was greater in rural areas than in urban areas of the survey region. In both rural and urban passerine populations, the prevalence of Yersiniae was greater in the winter and early summer than at other times of the year.

Aims: Infections with Yersinia enterocolitica are a significant cause of gastroenteritis in many countries, However, little information is available on the incidence of human disease in New Zealand. A study was performed between January 1988 and December 1993 to investigate aspects of the epidemiology of yersiniosis in the Auckland region including prevalence, age and sex distribution, strain definition and seasonal occurrence., Methods: Culture of 231 128 faecal samples for enteric pathogens was performed at Diagnostic Laboratory, a community laboratory in Auckland, between January 1988 and December 1993. All yersinia isolates recovered were sent to the department of veterinary pathology and public health, Massey University for further typing. Relevant data were entered into a database and reviewed at the end of the study period., Results: 1469 of the samples, representing 941 cases, were positive for strains of yersinia during the study period, a crude isolation rate of 0.6%. A single strain from each of the cases was further typed and yersinia enterocolitica was found to constitute the majority of the isolates (918), making it the third most common enteric pathogen isolated after campylobacter and salmonella. Of the strains isolated, 98% were recognised human pathogens, with biotype 4, serotype 0:3 being the most frequently recovered, as it is worldwide. No clear seasonal pattern emerged although most isolations were made in the autumn-winter period. The age distribution showed two peaks, 0-4 (17.6%) and 25-29 year olds (13%). Infections in males outnumbered those in females (56:44)., Conclusion: The results of this study show that Y enterocolitica is an important enteric pathogen in the Auckland region, particularly in children and young adults and it has identified a need for a case-control study to assess the relevant risk factors for acquisition of Y enterocolitica infections in New Zealand.

Newborn, colostrum-deprived Large White piglets infected with a human isolate of Yersinia enterocolitica biotype 4 serotype 0:3 were used as an animal model of yersiniosis. Within 3 hours of birth and before being fed, 14 piglets were inoculated orogastrically with 10 ml of bacterial suspension containing about 3 x 10(10) colony forming units of Y. enterocolitica, followed by 10 ml of 10% NaHCO3 solution. A further 14 litter mates acted as controls. The animals were reared on an artificial milk formula and humanely killed at 3 or 5 days after infection. Of the 14 infected piglets, 11 became anorexic, five vomited and 13 developed diarrhoea. Yersinia enterocolitica was isolated from their faeces and small intestinal contents. Body weight gains and the plasma glucose concentrations were significantly lower in the infected piglets than in the controls. Damage to the mucosa was observed in the whole gastro-intestinal tract, but was more severe in the small intestine and caecum. Micro-abscesses surrounding bacteria were present at the base of the villi in all parts of the small intestine, particularly in the distal ileum. Lesions were present in the small intestine in all infected piglets by day 3 and were more extensive by day 5. The liver was damaged by day 5, but not day 3. Similar lesions were seen in the mucosa of the stomach in one of six piglets at 3 days and in two of eight piglets at 5 days. It is hypothesised that the hypoacidity in the newborn stomach, as well as the administration of the NaHCO3 solution, may have produced favourable conditions for bacterial invasion.

Thirteen isolates of Yersinia spp., regarded as environmental strains, were recovered from 70 sausages containing venison which were presented for sale through retail outlets. It is not possible to incriminate venison as the source of these strains because the sausages contained other food ingredients. The pathogenic potential of such environmental strains remains unclear.

Human infections with pathogenic strains of Yersinia enterocolitica have been linked to contact with dogs excreting these microorganisms. This study examines the carriage and transmission of Y. enterocolitica biotype 4, serotype 03 in dogs. Fourteen 6-month-old cross-bred dogs were separated into 5 groups, 2 containing 4 dogs (I and II) and the others 2 dogs (III-V). Each of the 4 dogs in Group I and 2 of the dogs in Group II were inoculated orally with the test strain. Bacteriological examination of faecal samples showed that dogs can be readily infected and can carry the organism for up to 23 days. The two in-contact dogs in Group II started to shed the test organism after 5 days. Subsequent transfer of these dogs to Group III and those in Group III to Group IV showed that Y. enterocolitica biotype 4, serotype 03 can be readily transmitted between dogs. At no time did any of the dogs show clinical signs of infection. Group V served as a negative control for the trial. These findings suggest that dogs can carry Y. enterocolitica biotype 4, serotype 03 asymptomatically and hence might act as a potential source of infection for people.

Abstract The development of disease following oral challenge with Yersinia pseudotuberculosis (serotype 11) was compared in four groups of five birds treated with a parenteral dose of 10 mg iron dextran (Imferon), 10 mg of iron dextran plus 10 mg of the chelating agent desferrioxamine (Desferal), 10 mg of desferrioxamine or 10 mg of dextran 2 days before the experiment. Four groups of two birds received the above treatment regimens but no bacterial challenge. In iron dextran treated birds, oral challenge resulted in faecal shedding for the 10 day duration of the experiment, whereas in those birds which received dextran or desferrioxamine alone, the duration of faecal shedding was significantly less. Serological titres to the lipopolysaccharide antigen of the challenge bacteria were also lower in the groups not pretreated with iron dextran. The birds pretreated with iron dextran had diarrhoea and were clinically unwell 2 days following the initial oral challenge. Birds not given iron dextran showed no clinical signs of disease. Histological examination of five selected areas in the liver, spleen and intestine of each bird indicated that birds in the groups treated with iron dextran prior to bacterial challenge had significantly more intestinal lesions than birds in the groups not treated with iron. In contrast, there were significantly more lesions in the spleens of birds not pretreated with iron dextran. There was no evidence of stainable iron in the livers of birds challenged with Y pseudotuberculosis 10 days after an injection of 10 mg of iron dextran. This is in contrast to birds given iron dextran and no bacteria. It was concluded that pretreatment of birds with iron dextran resulted in more severe clinical disease, prolonged faecal shedding with associated intestinal lesions and higher serological titres to bacterial antigen. The number of lesions in the spleen and liver was not necessarily correlated with the severity of clinical disease, and in all infected birds the hepatic iron levels were significantly lower than in the non-infected control birds 10 days after oral challenge. It seems probable that the chicken has a high requirement for iron during infection with Y pseudotuberculosis and mobilises stored and exogenously supplied iron for tissue repair and immunological function.