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In cattle, Ureaplasma diversum has been associated with decreased fertility, granular vulvovaginitis, endometritis, salpingitis and spontaneous abortion in cows and seminal vesiculitis, balanoposthitis and changes in bull sperm. The presence of U. diversum within the Australian cattle population has not been established. One of the aims of this study was to determine if U. diversum was present in Australian cattle, using culture and polymerase chain reaction ( PCR), both of which are considered to be gold standards for bacterial identification. Of 100 samples collected from 66 male and 34 female cattle, 15 were positive for U. diversum. Therefore, Australia can no longer be considered free of U. diversum. Further studies should be conducted to ascertain the effects of U. diversum within Australian cattle herds and, if warranted, to investigate prevention, treatment and eradication protocols. [ABSTRACT FROM AUTHOR]

Salmonella contamination of ground beef has been viewed as originating from the surface of carcasses. Recent studies have identified lymph nodes as a potential source of Salmonella contamination because these tissues play an active role in containment of pathogens in the live animal and because some lymph nodes are unavoidably present in manufacturing beef trimmings or primal cuts that may be incorporated into ground beef. A survey was conducted of the microbiological status of lymph nodes from Australian cattle at the time of slaughter to determine the prevalence of microbiological contamination. Sets of lymph nodes (n = 197), consisting of the superficial cervical (prescapular), prepectoral, axillary, presternal, popliteal, ischiatic, subiliac (precrural), coxalis, and iliofemoralis (deep inguinal), were collected from five geographically separated Australian abattoirs over a period of 14 months. Samples were tested for the presence of Salmonella spp. and Shiga toxin-producing Escherichia coli by BAX PCR assay. Aerobic plate count, E. coli, and coliforms were enumerated with a lower limit of detection of 80 CFU per node. The observed prevalence of Salmonella within peripheral lymph nodes was 0.48% (7 of 1,464). Two of the seven lymph nodes in which Salmonella organisms were detected came from the same animal. Grass-fed, grain-fed, and cull dairy cattle were all found to have detectable Salmonella in lymph nodes. All Salmonella detections occurred during cooler months of the year. No Shiga toxin-producing E. coli were detected. Aerobic microorganisms were detected above the limit of quantification in 3.2% of nodes (median count 2.24 log per node), and E. coli was detected in 0.8% of nodes (median count 3.05 log per node). The low prevalence of Salmonella and low concentration of aerobic microorganisms in Salmonella-positive lymph nodes of Australian cattle at the time of slaughter suggest that the likelihood of lymph nodes contributing significantly to the presence of Salmonella in ground beef is low.

Shiga toxin-producing Escherichia coli (STEC) of serotype O113:H21 have caused severe diseases but are unusual in that they do not produce the intimin protein required for adherence to intestinal epithelial cells. Strains of serogroup O113 are one of the most common STEC found in ground beef and beef products in the United States, but their virulence potential is unknown. We used a microarray to characterize 65 O113 strains isolated in the United States from ground beef, beef trim, cattle feces, and fresh spinach. Most were O113:H21 strains, but there were also nine strains of O113:H4 serotype. Although strains within the same serotype had similar profiles for the genes that were tested on the array, the profiles were distinct between the two serotypes, and the strains belonged to different clonal groups. Analysis by clustered regularly interspaced short palindromic repeat analysis showed that O113:H4 strains are conserved genetically, but the O113:H21 strains showed considerable polymorphism and genetic diversity. In comparison to the O113:H21 strains from Australia that were implicated in severe disease, the U.S. isolates showed similar genetic profiles to the known pathogens from Australia, suggesting that these may also have the potential to cause infections.

This study aims to describe in detail the temporal dynamics of E. coli O157 shedding and risk factors for shedding in a grass-fed beef herd. During a 9-month period, 23 beef cows were sampled twice a week (58 sampling points) and E. coli O157 was enumerated from faecal samples. Isolates were screened by PCR for presence of rfbE, stx 1 and stx 2 . The prevalence per sampling day ranged from 0% to 57%. This study demonstrates that many members of the herd were concurrently shedding E. coli O157. Occurrence of rainfall (P < 0·01), feeding silage (P < 0·01) and lactating (P < 0·01) were found to be predictors of shedding. Moving cattle to a new paddock had a negative effect on shedding. This approach, based on short-interval sampling, confirms the known variability of shedding within a herd and highlights that high shedding events are rare.

Recent reports in North America and Europe of Clostridium difficile being isolated from livestock and retail meats of bovine origin have raised concerns about the risk to public health. To assess the situation in Australia, we investigated the prevalence and genetic diversity of C. difficile in adult cattle and calves at slaughter. Carcass washings, gastrointestinal contents, and feces were collected from abattoirs across five Australian states. Selective culture, toxin profiling, and PCR ribotyping were performed. The prevalence of C. difficile was 56% (203/360 samples) in feces from <7-day-old calves, 3.8% (1/26) in 2- to 6-month-old calves, and 1.8% (5/280) in adult cattle. Three PCR ribotypes (RTs), RT127, RT033, and RT126, predominated in <7-day-old calves and comprised 77.8% (158/203 samples) of isolates. RT056, which has not been reported in cattle before, was found in 16 <7-day-old calves (7.7%). Surprisingly, RT078 strains, which dominate production animal carriage studies in the Northern Hemisphere, were not isolated.

The International Commission on Microbiological Specifications for Foods (ICMSF) classified Arcobacter spp. as emerging pathogens in 2002. Arcobacter spp. have been isolated from numerous food products at retail and from animal carcasses and feces at slaughter. A survey was conducted to determine both the prevalence and concentration of Arcobacter spp. on pre-chill beef carcasses. Surface swab samples were collected from 130 beef carcasses at the end of processing, prior to chilling. The concentration of Arcobacter spp. was determined by a most-probable-number per square centimeter (3 by 3) method with a limit of detection of 0.12 CFU/cm(2). Of the 100 carcasses examined from export abattoirs, 20 (20.0%) were contaminated with Arcobacter spp., and 5 of these had quantifiable levels of contamination ranging from 0.12 to 0.31 CFU/cm(2). Of the 30 carcasses examined at a pet food abattoir, 25 (83.3%) were contaminated with Arcobacter spp., and 10 of these had quantifiable levels of contamination ranging from 0.12 to 0.95 CFU/cm(2). Three species of Arcobacter, A. butzleri, A. cryaerophilus, and A. skirowii, were identified by PCR. Each of the species was present in an approximately equal ratio from export abattoirs. This study demonstrates that slaughter practices at export abattoirs are sufficient to maintain both low prevalence and low levels of contamination of beef carcasses with Arcobacter spp.

Objectives: The main objective of this study was to determine the impact of transport and lairage on the isolation rate and the number of Escherichia coli O157 on cattle., Materials: Ninety animals, divided into three groups (A, B, and C) of 30 animals each, were used in this study. Individual animals were tagged, and samples were collected from the hides and feces of each at a feedlot and again after slaughter. The carcass of each animal was also sampled. Samples were also collected from the feedlot pens, the sides and floors of the transport trucks, and abattoir holding pens. The isolation rate and the number of E. coli O157 were estimated using a combination of immunomagnetic separation and the Most Probable Number technique., Results: Cattle hides were more likely to be contaminated with E. coli O157 at the feedlot (31%) than at the abattoir (4%). E. coli O157 was detected in 18% and 12% of cattle feces collected at the feedlot and after slaughter, respectively. E. coli O157 was isolated from truck floors (26%), truck sides (11%), abattoir pen rails (47%), and pen floors (42%). The mean count of E. coli O157 in positive feces was log(10) 1.17 and 2.37 MPN/g at the feedlot and slaughter, respectively. A 3 log(10) increase in the number of E. coli O157 was observed between the feedlot (2.66 MPN/g) and slaughter (5.66 MPN/g) in the feces of one animal in group B. E. coli O157 was isolated from the hide and carcass of this animal., Conclusions: Transport and lairage did not lead to an increase in the number or isolation rate of E. coli O157 from cattle., Applications: Intervention strategies for reducing E. coli O157 contamination of cattle carcasses should target mechanisms that limit the impact of animals shedding a high number throughout production and processing.

Aims: To determine the prevalence and characteristics of integron-containing bacteria in faeces of cattle from grass-fed, lot-fed, or organically produced cattle., Methods and Results: Faecal samples from grass-fed (n = 125), lot-fed (n = 125) and organic (n = 135) cattle were tested for the presence of class 1 and class 2 integrons by using PCR and colony hybridisation. The prevalence of class 1 and class 2 integrase were higher in lot-fed cattle (71% and 62%) than grass-fed cattle (52% and 30%) which in turn were higher than organic cattle (25% and 11%). Isolation rates of integron-containing bacteria were reflective of PCR prevalence results., Conclusions: The antimicrobial resistance genes harboured by the integrons differed little across the three systems and were typically to antimicrobials that would rarely be used therapeutically or for growth promotion purposes. The differences in prevalence observed between the systems may be a function of the intensiveness of each system., Significance and Impact of the Study: Integron-containing bacteria may be present in all cattle production systems regardless of the amount of antimicrobial use and confirms that the prudent use of antimicrobials is required so that the development of integrons harbouring genes significant to human medicine is avoided.

Australian regulations for microbiological testing of carcasses specify a number of incubation temperatures and media for meat processed at both domestic and export establishments. Accordingly, the effect of incubation temperature and media on aerobic plate counts of samples from beef and sheep carcasses was investigated. For both species, aerobic plate counts on Petrifilm incubated at 35 degrees C were significantly lower than those counts on Petrifilm and pour plates incubated at 25 and 30 degrees C, reflecting the inability of many psychrotrophs to grow at 35 degrees C. When samples were taken from carcasses that had been stored in abattoir chillers for periods between 16 h and 5 days, difference between counts at 35 degrees C versus those incubated at 25 and 30 degrees C became greater as the period of refrigerated storage increased. For export beef carcasses, the effect of this difference is minimal, since the vast majority of counts incubated at 35 degrees C are done on carcasses that have been chilled for less than 24 h and will not have a large proportion of psychrotrophs.

In Australian export-registered abattoirs microbiological monitoring is carried out within the E. coli and Salmonella Monitoring (ESAM) program. During the calendar year 2003, the ESAM database indicated a national prevalence of Escherichia coli of around 3.0% for steers/heifers and 7.1% for cows/bulls. An investigation was carried out to attempt to elucidate why some establishments had E. coli prevalence markedly higher or markedly lower than the national average. The investigation was based on a questionnaire completed by fifteen export establishments which provided data on livestock, processing, operator training and management. The responses were verified by site visits and then evaluated for their relationship with ESAM data on E. coli in two stages. In stage 1, E. coli prevalence for each abattoir was plotted against each variable recorded by the questionnaire; no single variable was a reasonable predictor for prevalence of E. coli on carcases. In stage 2, variables influencing contamination were grouped under two categories: contamination on incoming livestock (Problem variables) together with the ability of the plant's process to deal with such contamination (Process variables). The analysis prompted two main conclusions. Firstly, plants with a large incoming problem with livestock (long haul, high tag score and proportion of cows/bulls slaughtered) plus "poor" processes had higher than average E. coli prevalence. Secondly, plants with hot water decontamination systems had low E. coli prevalence even when there was a substantial incoming problem with livestock, such as a relatively high proportion of cows/bulls.

Typeability, reproducibility, and discriminatory power of ERIC-PCR and Apal-PFGE to establish the genetic relation of P. multocida strains were determined. Forty-nine strains of different source, biotype, capsular group, somatic serotype, and resistance to antimicrobials were studied. By ERIC-PCR, 31 patterns were defined with 10 to 14 bands in a rank of 0.2 and 1.2 kb. By Apal-PFGE, 37 restriction patterns were established with 7 to 15 bands of 34 to 450 kb. Typeability was 100% (T=1) for ERIC-PCR, and 94% (T = 0.94) for Apal-PFGE. Reproducibility of both techniques was 100% (R=1). Discriminatory power was 93% (D = 0.93) for ERIC-PCR, and 98% (D = 0.98) for Apal-PFGE. By using both techniques, epidemiologically related strains were grouped, and unrelated strains were clearly differentiated. The value of ERIC-PCR and Apal-PFGE as complements to epidemiologic studies was demonstrated, especially when both techniques were used to analyze the strains.

The third national baseline microbiological survey of Australian beef carcasses and frozen boneless beef was conducted in 2004. Carcasses (n=1155) sampled at 27 slaughter establishments had a mean aerobic plate count (at 25 degrees C) of 1.3 log CFU/cm2. Escherichia coli was isolated from 8.0% of the cacasses, with a mean count of -0.8 log CFU/cm2 for positive samples. On samples from 24 boning (fabrication) plants (n=1082), the mean aerobic plate count for frozen boneless beef was 1.3 log CFU/g, and the mean count for the 1.8% of samples with detectable E. coli was 1.5 log CFU/g. E. coli O157: H7 was isolated from 1 of 1,143 carcasses and from 0 of 1082 boneless samples. Salmonella was isolated from 0 of 1155 carcasses and from 1 of 1082 samples of boneless product. No Campylobacter spp. were isolated from carcasses or boneless beef. Coagulase-positive staphylococci were isolated from 28.7% of beef carcasses and 20.3% of boneless beef samples, and positive samples had a mean count of 0.3 log CFU/cm2 and 0.8 log CFU/g, respectively.

During the 1990s, there was radical change in regulation of meat and poultry hygiene in Australia, and Australian Standards were developed for each sector of the meat industry. Systems for industry/government co-regulation and company-employed meat inspection were introduced based on company HACCP programs approved and audited by the Controlling Authority. However, in the 5 years since regulatory changes took full effect, rates of salmonellosis have not decreased (surveillance and reporting systems have remained unchanged). Using statistics gathered by the National Enteric Pathogens Surveillance Scheme, an attempt was made to link Salmonella serovars isolated from meat and poultry with those causing salmonellosis. Two periods were studied, 1993/1994, before regulations were introduced, and 2000/2001, when regulations should be having an effect. For red meat, the same serovars were prominent among the top 10 isolates both before and after regulation, and there was little linkage with salmonelloses. For poultry, frequently isolated serovars differed pre- and post-regulation, however, in both periods there was some linkage between serovars isolated from poultry and those causing salmonelloses. Using published and unpublished survey data, it was concluded that there had been improvements in microbiological quality of red meat and poultry over the same timeframe as regulatory changes. That these improvements apparently have not carried through to reduced case-rates for salmonellosis may be due to numerous causes, including lack of control in the food processing, food service and home sectors. The present paper illustrates difficulties faced by governments in measuring public health outcomes of changes to food hygiene regulation.

A total of 523 chilled beef and lamb carcases were sampled from four abattoirs and 13 very small plants (VSPs) in South Australia during March 2002 in order to develop a microbiological profile of meat produced for domestic consumption within the State. Aerobic viable counts (AVCs) and Escherichia coli counts were obtained from samples taken by sponge-sampling the muscle-adipose tissue at sites designated for each species in the Microbiological Guidelines to the Australian Standard for Hygienic Production of Meat for Human Consumption (identical with those of the USA Pathogen Reduction: hazard analysis and critical control point (HACCP) systems: final rule). On beef carcases (n=159) mean log AVC/cm(2) was 1.82 and E. coli was detected on 18.8% of carcases (area sampled 200 cm(2)) for which the mean log of the positives was -0.34; for lamb carcases, on which 75 cm(2) was sampled (n=364), corresponding values were 2.59, 36.2% and log(10) 0.27, respectively. There was little difference in mean log AVC/cm(2) of carcases produced at abattoirs and VSPs, 1.72 versus 1.81, respectively, for beef, and 2.80 versus 2.44, respectively, for sheep. Prevalence of E. coli was lower at VSPs, however, with abattoirs having 28.4% for beef and 61.5% for sheep, compared with corresponding values of 4.7% and 18.5% at VSPs. In VSPs, the range of mean log AVC/cm(2) was 0.47-3.16 for beef and 1.63-3.65 for sheep carcases, data which will allow the Controlling Authority to assist plants to improve performance of slaughter and dressing techniques. The present survey is part of an assessment by the State meat authority of the effectiveness of co-regulation of meat hygiene between government and industry.

This report summarises the range of Salmonella serovars and phage types found in humans in Australia during the years 1987 to 1992 inclusive, and compares them with serovars from food animals and raw meats for the same period. It also compares the major serovars found from different animal sources with their frequency from humans. The common serovars from animal feeds are compared with their frequency from animals.

Ruminant production is a major focus of Australian agriculture. The ability of ruminant animals such as sheep and cattle to make productive use of low quality plant materials depends on the activity and efficiency of the anaerobic microbial population that resides in the rumen. Factors that affect ruminant production include the ability of cellulolytic microorganisms to digest plant structural polysaccharides (primarily cellulose and hemicellulose), the capacity of microorganisms to metabolise and detoxify otherwise inhibitory plant products and the efficiency of nitrogen utilisation by ruminal organisms. This review will consider some current Australian research programs aimed at improving ruminant production efficiency by genetic engineering of ruminal bacteria.

A new member of the Simbu group of arboviruses, for which the name Peaton virus is proposed, has been isolated from midges and cattle in Australia. Nine isolates were obtained from 101 pools of the biting midge Culicoides brevitarsis collected at Peachester, Qld, (26.51 degrees S., 152.53 degrees E.) between 30 November and 8 December 1976. Three isolations of the same virus were made from the blood of sentinel cattle collected at Grafton and Tamworth, N.S.W., on 20 January and 13 April 1977, respectively. Peaton virus was shown to be a member of the Simbu group of arboviruses by complement-fixation tests using antisera prepared against Australian strains of Akabane and Aino viruses. It was readily distinguishable from these viruses in cross-neutralization tests in tissue cultures and mice. A serological survey of sentinel cattle showed that neutralizing antibody was detectable only in cattle within the recorded limits of the suspected vector C. brevitarsis. Neutralizing antibody in blood serum was detected in 22 of 157 sheep, 21 of 137 horses, 7 of 18 buffaloes, 7 of 20 goats and 3 of 62 pigs, but not in 22 camels, 34 dogs, 3 cats, 76 human beings, 240 marsupials, 19 reptiles or 31 wild birds. The pathogenecity of Peaton virus has yet to be determined. The Yale Arbovirus Research Unit and the Center for Disease Control, Fort Collins, U.S.A., found that Peaton virus was distinguishable from all other Simbu group viruses and thus is a new virus.

Results of the typing of Brucella cultures received at the WHO Brucellosis Centre, CSL, Melbourne, from 1968-1976 are presented. The distribution of the biotypes of cultures recovered throughout Australia is shown on a host and State basis and atypical cultures are discussed. Cultures identified from Australia were Br. abortus, biotypes 1, 2 and 4 and Strain 19; Br. suis, biotype 1 and Br. ovis. Br. melitensis biotypes 1, 2 and 3 were recorded only as exotic human infections from the Mediterranean area and from laboratory infections. Br. abortus, biotype 1 was the most common bovine and human isolate and was found in horses, a goat and a sheep. There was a low incidence of Br. abortus, biotype 2 in cattle and it was found in 1 horse. Br. abortus, biotype 3 was not found in Australia but was submitted from Tanzania. Br. abortus, biotype 4 was rare in cattle and was found once in a horse. Br. abortus, Strain 19 was found occasionally in cattle and once from a test guinea pig. Br. suis, biotype 1 was found in both man and pigs in Queensland and New South Wales whereas biotype 3 was isolated only in New Guinea from pigs and cattle. Br. ovis was submitted from 3 States. Br. canis has not been found in Australia.

An epidemiological study of Q fever infection in a Brisbane meatworks was undertaken. A retrospective 10-year study (1968 to 1977) revealed an average annual incidence of 1% for the nine years excluding 1969, while an outbreak with a 7.9% incidence occurred in 1969. No seasonal distribution was found. Results indicated that cattle form the major source of Coxiella burneti (infectious agent of Q fever) in the meatworks and that the highest risk of infection exists on the cattle slaughter floor. The 1969 outbreak showed a departure from the average pattern of infection in that the highest incidences were recorded in small stock (sheep and swine) workers and non-meat handlers rather than in cattle slaughtermen. This suggested the importance of sheep and/or swine forming a source of the infection. Investigations into the factors contributing to the 1969 outbreak in this meatworks failed to reveal an; conclusive data. Inhalation of infectious dust and aerosols proved to be the major channel of transmission of infection rather than direct inoculation. A serological survey of 139 employees revealed 15.8% prevalence of complement-fixing antibodies to C. burneti, 0% to brucellosis, 0.7% to leptospirosis, and 0.7% to Toxoplasma gondii. Of those with positive titres for Q fever, nine of the 22 subjects did not recall any clinical illness.

In the 200 years that cattle and sheep have been present in Australia no evidence of bluetongue (BT) disease has ever been reported. The discovery in 1977 that a virus isolated from Culicoides species collected in 1975 was bluetongue virus (BTV) triggered a search for BT viruses and their vectors throughout the country. Between 1975 and 1983, 46 strains of 5 serotypes of BTV were isolated by various workers from the blood of subclinically infected sentinel cattle or from Culicoides species. The serotypes are 1, 20, 21 and 2 others not yet fully characterized. By testing stored sera from cattle and buffaloes, antibodies to serotype 21 were found in sera collected in 1958, but antibodies to serotypes 20 and 1 were not found earlier than 1973 and 1969 respectively. Discrepancies between the results of BTV group antibody and neutralizing antibody surveys indicate that other serotypes may yet be found. Neutralizing antibodies to BTV have been found in cattle, buffaloes, deer, goats and sheep, but mammals indigenous to Australia are apparently not being infected. In the course of the search, Ibaraki virus and 4 other viruses of the epizootic haemorrhagic disease (EHD) group were found. Infection with EHD viruses has produced heterotypic antibodies detected in tests for BT group antibodies. The prevalence of antibodies to BT and EHD viruses in cattle is greater in the northern 1/3 of the continent than the middle 1/3 while the southernmost 1/3 is free. By the sequential sampling of sentinel cattle it has been determined that infection with BT and EHD viruses occurs mainly in the latter part of summer, and autumn. The seasons of the year, and the locations from which BT and EHD viruses originated were consistent with the serological findings. Isolations of BT and EHD viruses have also been made from insect vectors, BTV serotype 1 from C. fulvus and C. brevitarsis, plus serotype 20 from a mixed pool of Culicoides species and 2 different EHD viruses from C. brevitarsis. The susceptibility of other Culicoides species to experimental infection with BT and EHD viruses suggests that they may be involved in the natural spread of these viruses. BT and EHD viruses appear to be non-pathogenic for cattle under experimental conditions, but mildly or moderately pathogenic for sheep. The clinical signs produced are consistent with those produced experimentally in other countries.

A virus isolated from the blood of a healthy steer and designated DPP53 was shown to have rhabdovirus morphology. Although DPP53 virus was antigenically related to Tibrogargan virus by reciprocal immunofluorescence and neutralization tests, the viruses were distinguishable by neutralization tests. DPP53 virus contained RNA and was sensitive to both ether and chloroform. The geographical distribution of neutralizing antibody to DPP53 virus in Australian cattle corresponded to the distribution of Culicoides brevitarsis indicating that this virus may be arthropod-borne with this midge as a possible vector. Antibody to DPP53 virus was detected in serum from cattle, buffalo, dogs and one horse, but not in serum from deer, pigs, humans or wallabies. Highest virus titres were obtained by growth in Vero and BHK21 cell cultures, but the virus could also be grown in Aedes albopictus cell cultures. Higher virus titres were obtained when the multiplicity of infection was low. The name advanced for DPP53 virus is 'Coastal Plains' virus.

CSIRO 368 virus was isolated from blood collected in the Northern Territory from a healthy cow and electron microscope studies showed that the isolate had rhabdovirus morphology. Fluorescent antibody studies and complement fixation tests related the virus to bovine ephemeral fever (BEF) virus. Neutralization tests in both suckling mice and Vero cells showed that the virus was not BEF virus. Antibodies to CSIRO 368 virus were found in cattle sera from northern and eastern Australia and Papua New Guinea. Antibodies were found in 16 out of 45 buffalo, some of which also had antibodies to BEF virus. In contrast, none of the 419 deer tested had antibodies to CSIRO 368 virus, although 142 of the same deer had antibodies to BEF virus. No antibodies to CSIRO 368 virus were detected in 16 goats, 54 horses, 10 pigs, 31 sheep, 25 kangaroos, or 14 human beings. Both CSIRO 368 and BEF viruses were found to be sensitive to ether and chloroform, but were not affected by the DNA inhibitor 5-bromo-2'-deoxyuridine, showing that they probably had the same type of nucleic acid--namely RNA. CSIRO 368 was also shown to grow to higher titres in BHK21 cells than in Vero cells. Temperature sensitivity studies at -20, 4 and 37 degrees C showed that the presence of foetal calf serum increased the survival time markedly at -20 degrees C, but only slightly at 4 and 37 degrees C. The virus survived the longest at -20 degrees C in the presence of foetal calf serum.

Cattle and goats in Australia lack the ability to totally degrade 3-hydroxy-4(1H)-pyridone, also known as 3,4-dihydroxy pyridine (3,4 DHP), the ruminal metabolite of mimosine, a toxic aminoacid present in the leguminous shrub Leucaena leucocephala. Ruminants in Hawaii have this capacity due to the presence of micro-organisms able to rapidly degrade the DHP. A mixed bacterial population capable of rapidly degrading DHP in vitro was isolated from a goat on the island of Maui. Cultures were grown anaerobically, without added sugars, in Medium 98-5 containing DHP. Cultures at a dilution of 10(-12) from the original rumen fluid were introduced into Townsville and further sub-cultured and multiplied in vitro in strict isolation at the Oonoonba Veterinary Laboratory, Townsville. Infusion of the culture into a goat and a steer fed a 100% leucaena diet resulted in cessation of DHP excretion in the urine. After 60 days the serum thyroxine levels and thyroid size were normal and there were no clinical signs of disease. The ability of the rumen fluid to degrade DHP in vitro showed that the bacteria had become established in the rumen. In the absence of any disease in the animals, clearance has been given for the wider use of these cultures in areas where leucaena is grown. The limited evidence suggests that the leucaena toxicity problem can be solved by the use of these introduced bacteria.

An Australian bovine parvovirus isolate (BPV 267) was found to haemagglutinate human, guinea-pig, rat and dog erythrocytes, out of a range of 16 species of erythrocyte tested. The haemagglutinating activity was generally found to be both pH and temperature dependent. The virus was found to replicate best in intestinal epithelium, macrophage and lung cells, out of 9 bovine cell types tested. Highest yields of virus were obtained by the use of selected cell strains at low-passage levels which were maintained near neutral pH under conditions of high rates of cell growth. Studies of the rates of thermal inactivation with time showed the virus to be relatively stable at 37 degrees C, 56 degrees C and 70 degrees C, the incorporation of serum proteins, 1 M MgCl2 and 2 M NaCl in the medium having no influence on stability at 56 degrees C. The virus was resistant to the action of CHCl3, ether and 1% trypsin, and its replication was inhibited by BUDR, this effect being reversed by thymidine. Actinomycin D was found to inhibit virus replication, but only when applied during the first 8 h post-infection. Density gradient studies showed infective virus to have a density of 1.41 g cm-3; haemagglutinating non-infective virus with defective morphology having a density of 1.31 g cm-3. In addition, a proportion of morphologically-complete haemagglutinating, but non-infective virus particles was found at a density of 1.36 g cm-3. The virus proved to have a mean diameter of 22 nm.

Ruminants became established in Australia after European settlement which commenced in the late 18th century. Bluetongue (BT) disease has never been suspected in cattle or sheep in this country. The species of ruminants found to have antibodies to BT and epizootic haemorrhagic disease (EHD) viruses are cattle, buffaloes, deer, goats and sheep. No antibodies have been found in pigs, horses, marsupials (kangaroos and wallabies) or humans, even in areas of high prevalence of BT and EHD infection. The serological and historical evidence suggests that Indonesia, where ruminants have been indigenous for a very long period, is a more likely source of infection for the Australian BT and EHD viruses than Papua-New Guinea though the method of their entry to Australia is unknown. It is unlikely that all the BT viruses entered from there in ruminants as there has been no importation of ruminants from Indonesia this century. Antibody surveys of cattle have shown that 2 of the 5 Australian BTV serotypes, DPP90 and DPP192 (Gard GP: unpublished data), are restricted to a limited area of the northern part of the Northern Territory of Australia, 1 (serotype 20) to the north of the 18th parallel of south latitude and the remaining 2 (serotypes 1, 21) to the north of the southern limit of the distribution of the suspected vector Culicoides brevitarsis. The prevalence of antibodies to BT and EHD viruses is highest in the far north of the Australian continent and declines rapidly in the middle 3rd. In the southern 3rd, the cattle and sheep are free of BT and EHD antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Of 1,791 tissues submitted from 1975 to 1978 for histological examination for tuberculosis, 78.5% were classified as tuberculosis, 8.1% as club-forming granulomas, 3.3% as hydatid cysts, 3.4% as other granulomas and 2.4% as squamous cell carcinomas. Cultural examination of 2,682 tissues for mycobacteria yielded Mycobacterium bovis from 42.88%, other mycobacteria from 7.64% and 0.89% Rhodococcus (Corynebacterium) equi. Of 1,478 tissues on which both examinations were performed, culture and histology results were in agreement on 94.1%. M. Bovis was isolated on one or more occasions from 564 herds with the highest herd prevalence being recorded in western areas of the state. Culture of 1,024 tissues from no visible lesion (NVL) reactors yielded 0.59% M. bovis, 15.04% other mycobacteria and 0.19% R. equi. Of 120 isolates of other mycobacteria from tissues of NVL reactors, 39 were Runyon Group III (20 M.avium complex) and 61 Runyon Group IV. Approximately half of the herds from which NVL tissues were collected were confirmed M. bovis infected properties.

Counts of Salmonella were performed by the most probable number technique on 16 articles of abattoir equipment having direct contact with the carcase. Forty samples were collected from each article over 21 months. The contamination rate of these articles with salmonellae varied from nil % for a saw used to quarter the sides to 47.5% for stainless steel tables and hooks. Mesh gloves were also highly contaminated, salmonellae being isolated from 32.5% of gloves on the slaughter floor and 40% of those in the boning room. Salmonella counts ranged from 1.0 to 3,663 organisms per article. Mesh gloves, cutting boards and stainless steel tables were found to have counts that were at times greater than 1,000 salmonellae per article.