- 2.1 MBS 361: Lymantria & Orygia
- 2.2 MBS 362: Assessment of contamination soil as a risk pathway
- 2.4 MBS 364: Rapid identification of target pathogens in imported wood
- 2.5 MBS 365: To develop a blood test for the detection of sheep infected with Echinococcus granulosus
- 2.6 MBS 366: Passage time for weed seeds in digestive tract of herbivorous stock
- 2.7 MBS 367: Use of veterinary practices to define baseline patterns of animal disease for national animal health surveillance
- 2.8 MBS 368: Spread of Salmonella Brandenburg organisms in sheep yards
2. Maintaining Biosecurity
2.1 MBS 361: Lymantria & Orygia
| Programme Title: | Lymantria & Orygia |
| Programme Leader: | Karen Armstrong |
| Institution: | Lincoln |
Additional work is being completed on the final report for this project and a summary is therefore unavailable for inclusion in this report. The results of this project will be included in the next Research Results report.
2.2 MBS 362: Assessment of contamination soil as a risk pathway
| Programme Title: | Assessment of contamination soil as a risk pathway |
| Programme Leader: | Dr John Marshall |
| Institution: | Crop & Food Research |
Additional work is being completed on the final report for this project and a summary is therefore unavailable for inclusion in this report. The results of this project will be included in the next Research Results report.
2.4 MBS 364: Rapid identification of target pathogens in imported wood
| Programme Title: | Rapid identification of target pathogens in imported wood |
| Programme Leader: | Professor Roberta Farrell |
| Institution: | University of Waikato |
Summary
This project was undertaken to assess the range of fungi being imported on solid wood packaging material into New Zealand. Maintaining New Zealand's biosecurity is of acute significance for its inhabitants as a factor in its economic and environmental well being. In order to minimise the threats posed by exotic organisms, sound principles of risk assessment and management need to be developed, based on science and cost-effectiveness in terms of the benefit-risk ratio. Samples of wood from imported wood packaging, collected at different ports over the past two years, were screened. This was done by directly probing wood with target orientated DNA probes against pathogens predetermined as having major potentially detrimental effects both on New Zealand's commercial Agroforestry and its indigenous forests.
Background
The goal of this project is to address Biosecurity concerns by targeting specific fungal pathogens not known to be present in New Zealand but considered as posing a potentially high risk to the Agroforestry sector.
Maintaining New Zealand's biosecurity is of acute significance for its inhabitants as a factor in its economic well being. Today, however, its borders are incessantly tested by organisms having potentially detrimental effects on its Biodiversity, economy, environment and quality of life. In spite of the fact that the MAF Quarantine Service (MQS) inspects a high percentage of containers as compared with other countries (Bulman, 1998; Pasek, 2000), case histories of exotic disease introductions abound. This study followed on from the MBS 364 study (Janson and Farrell, 2000) assessing the general range of fungi and their mode of introduction into New Zealand; however, if offered a more focussed approach. This was achieved by directly probing the wood/fungi with target orientated DNA probes against pathogens determined as having potentially detrimental effects both on New Zealand's commercial Agroforestry and its indigenous forests. In the future it is anticipated gene probes specific to pathogens of consequence will be used to probe wood in situ allowing rapid diagnoses for MQS operations.
Approach & Outcomes
Samples collected over the past two years have been screened for pathogens using probes constructed specifically for this purpose, obtained from colleagues or developed de novo. Additionally, screening was conducted on forest samples collected at different points in the North Island as well as samples sent in from other laboratories.
A list of potential pathogens of consequence to New Zealand Agroforestry was compiled. After screening samples from the 1999-2000 and 2000-2001 samples, we have not positively identified any of these fungal pathogens of concern. Additionally, samples sent to us by Dr. John Marshall were screened with similar negative results. We are presently (July 2001) continuing our work refining the methodology, with funding from Foundation for Research, Science & Technology.
2.5 MBS 365: To develop a blood test for the detection of sheep infected with Echinococcus granulosus
| Programme Title: | To develop a blood test for the detection of sheep infected with Echinococcus granulosus |
| Programme Leader: | Dr Rheinhold Kittelberger |
| Institution: | National Centre for Disease Investigation |
Summary
Animals imported into New Zealand could be infected with E. granulosus and could re-establish hydatid disease in this country. After the recent development of a serological method, a hydatid ELISA with about 50 percent diagnostic sensitivity, it was hoped to increase the diagnostic capability for this disease by developing a test method based on the cell mediated immune response.
Initially the commercially available y-Interferon ELISA was used on a limited
number of bloods from infected and non-infected sheep. The bloods had been stimulated with
various E.granulosus antigens, including semi-purified hydatid cyst fluid proteins,
a protoscolex preparation and a recombinant oncosphere protein. Consequently, an
Interleukin-5 ELISA was also applied to these samples and furthermore, a Western blot
assay was established and used for the detection of IL-1
,
IL-2, IL-6 and IL-8.
None of the test methods for the various cytokines in combination with the various antigen-stimulated blood (plasma) samples, resulted in the specific detection of infected animals. It seems that the cell-mediated immune response to E. granulosus infections in sheep is not a useful means to increase the diagnostic capability for this disease.
Background
The goal of this project was to develop a blood test for the detection of sheep infected with Echinococcus granulosus.
To be able to test imported animals for E. granulosus infections, in order to prevent the re-establishment of hydatid disease in New Zealand, in a previous project (MAFPOL Project MBS 352) and ELISA method was established and validated. Despite good specificity it exhibited limited sensitivity. Therefore it was hypothesised that the y-interterferon test (cellular immune response), which is used as a diagnostic method for other diseases with limited antibody response, such as bovine tuberculosis and Johne's disease, may be of diagnostic value for the detection of animals infected with E. granulosus.
Approach & Outcomes
Various antigens were prepared (semi-pure, concentrated hydatid cyst fluid proteins,
detergent solubilized protoscolex antigen sonicate, recombinant oncosphere protein) and
were used to stimulate bloods obtained from 12 experimentally E. granulosus-infected
and 8 non-infected sheep. The plasmas of these stimulated bloods were tested in the y-interferon
ELISA. In extension of the initial proposal, another commercially available ELISA was used
to screen for the presence of interleukin-5 (IL-5). In addition, a sensitive Western blot
procedure was developed and the plasmas were tested with this method for the presence of
interleukin 1- (IL-1),
interleukin 2 (IL-2), interleukin 6 (IL-6) and interleukin 8 (IL-8).
The y-interferon positive controls showed an average absorbency of 1.800 and the negative controls of 0.083. At the chosen cut-off 0.133, three of the infected and four of the non-infected sheep showed increased gamma Interferon levels. Because of the absence of specific yIF results in the limited number of sheep, it was decided to test for the presence of other cytokines.
A commercially available ELISA for IL-5 was used to screen for the presence of this cytokine. This ELISA was originally developed for mouse IL-5 but it had been shown that it works with sheep IL-5 also. The IL-5 positive controls showed an average absorbance of 1.487 and the average absorbance of non-infected samples was 0.118. At a cut-off of 0.237 three of the infected and one of the non-infected sheep showed increased IL-5.
A panel of four anti-ovine cytokine monoclonal antibodies (Mab) against IL-1, IL-2, IL-6 and IL-8 was commercially available A Western
immunoblot approach, which was using a sensitive anti-mouse immunogold/silver-enhanced
detection system, was applied to detect these cytokines in the antigen-stimulated sheep
plasmas. None of the plasmas showed cytokine-specific staining. The results from this
project cytokine release (cellular immune response) in E. granulosus infected sheep
with the antigens used and for the cytokines tested. While initially only the y-interferon
release was envisaged for detection, the scope of the project was immediately considerably
extended to other cytokines, after it became clear that the y-interferon response
was poor. Nevertheless, test methods for various ovine cytokines were limited by the
availability of specific tests and antibodies for such cytokines.
While these results were disappointing, they have at least shed some light on the little researched field of the cellular immune responses against E. granulosus infections in ruminants.
Publication
Results from this project will be published together with results from the previous project of the development of an ELISA method for the detection of animals infected with E. granulosus. This paper is currently under preparation and will be entitled: Development and evaluation of various immuno-diagnostic methods for the detection of Echinococcus granulosus infections in sheep.
2.6 MBS 366: Passage time for weed seeds in digestive tract of herbivorous stock
| Programme Title: | Passage time for weed seeds in digestive tract of herbivorous stock |
| Programme Leader: | Peter Williams |
| Institution: | Landcare |
Summary
An interpretative literature was prepared on the gut passage times for ruminants to assist in formulating quarantine protocols. There was good information for sheep and cattle, but otherwise the data was patchy. To avoid the importation of most unwanted seeds in the digestive tracts of herbivorous animals destined for New Zealand, they should be fed a seed free diet for at least 10 days prior to their arrival in New Zealand or release from quarantine here. The period for goats could be a little shorter, and for horses a few days longer. Animals that are suspected of carrying seeds should be fed a high quality diet to speed passage time.
Background
The goal of this project was to determine the time taken for weed seeds to pass through the gut of herbivores, their viability after passage, and the factors influencing variation in these factors.
Ruminant animals are imported into New Zealand that may carry viable seeds in their guts. MAF needs to know how long to retain animals in quarantine for any potentially viable seeds to be passed.
Approach & Outcomes
The study is an interpretative literature review. The world literature on gut-passage time and the effects of gut passage on seeds was reviewed and a database constructed.
There is good data for cattle and sheep, fewer data for goats and very little data for horses and deer, and a scattering of data for other species. There is no data for members of the camelidae family (lama, alpaca, etc.).
Cattle and sheep passed about half the seeds ingested by 2.5 days and most of them by 7 days. A few seeds were retained for up to 10 days in sheep, and 1 month in cattle. For goats, the peak passage time was about 2 days, and the maximum time was 5 days. For deer, it was likely to be 10 days for all seeds to be passed. In horses, the peak passage of seed occurred after 3 or 4 days, the passage of half the seeds took 7 days, and the elimination of all seeds was likely to take at least 4 weeks. The wide variation around the mean seed-passage times was attributable to many factors unrelated to seed qualities, such as individual animal effects, whether or not the animal was pregnant, and food intake. The most widely reported factor with potential applicability to quarantine protocol was faster seed-passage time in animals fed a high-quality diet.
There was a wide variation in the passage times, and the effects on seed germination, for different seeds. This was related primarily to seed size and hard-seededness. Most grass species did not pass through cattle or sheep, but there were numerous exceptions. Recovery was generally higher for small seeds that avoided mastication. Recovery of legume seed was proportional to hard seededness amongst the seeds fed. Most studies (91 percent) on cattle showed a decline in germination percentage after seed passage, whereas most studies (81 percent) on sheep showed an increase in germination percentage. This was partly because most studies on sheep used legumes, whereas a higher proportion of cattle studies involved grasses. Because the seeds are scarified in the animal's gut, germination of legume seeds was usually increased by passage. The effects on germination percentage of non-legume broadleaved species, of passage through several mammals, were extremely variable. Some seeds of most species that passed through cattle and sheep were able to germinate, but usually at a lower percentage.
The seeds of most species recorded passing through domestic animals belong to genera that are weeds either in New Zealand or elsewhere in the world.
Publications
Barton, K, Williams, P.A. Passage time for weed seeds in the digestive tract of herbivorous livestock. Landcare Research Contract Report: LC 0001/065.
2.7 MBS 367: Use of veterinary practices to define baseline patterns of animal disease for national animal health surveillance
| Programme Title: | Use of veterinary practices to define baseline patterns of animal disease for national animal health surveillance |
| Programme Leader: | Dr Peter Davies |
| Institution: | Massey University |
Summary
Using a defined population of dairy farms, data on health events obtained from farmer, veterinary and laboratory records were compared. Each source of data has inherent strengths and weaknesses, and veterinary clinical records have valuable potential to complement traditional sources of surveillance data.
Background
The goal of this project was to evaluate the feasibility and reliability of collecting detailed animal disease data directly from clinical veterinarians and compare the resulting data with other sources (farmer record, laboratory submissions).
The comprehensive involvement of veterinary practitioners in New Zealand's livestock industries has yet to be exploited for animal disease surveillance. Uptake of information technology by both the veterinary and livestock industries provides novel opportunities for capturing veterinary clinical data. This project was designed to assess and compare farmer records, veterinary clinic records, and laboratory submissions as indices of animal disease in a defined population of dairy herds.
Approach & Outcomes
Forty dairy farms that were clients of 5 participating veterinary clinics were purposively selected. Animal health events on these farms recorded by farmers (Dairy WIN records), veterinary practitioners (clinic records) and laboratory results were analysed and compared retrospectively. Participants were unaware of this use of the data at the time of data recording. Based on experience gained in examining practice records, a software application, for use on hand held computers, which would allow practitioners to record veterinary events was prototyped. This would simplify and standardise on-farm recording of veterinary visits, to allow uploading to practice records, printing of farmer instructions, and extraction of data of surveillance value without loss of client privacy.
Farmer records yielded the highest rate of recorded animal disease events (14.6 disease events per 1000 cow-months at risk), followed by veterinary clinics (5.1), and laboratory submissions (0.58 for disease records and 2.6 for all records per 1000 cow-months at risk). Features of farm-based data were a focus on farmer-treated disease and low completeness in recording veterinary interventions on many farms, a high proportion of mastitis and lameness events (84 percent of farmer-recorded disease events compare with 28 percent of veterinary events), a low proportion of undiagnosed / unspecified events (0.3 percent vs. 22 percent for veterinarians), and a general failure to specify which diagnoses were made by veterinarians.
For general surveillance purposes, veterinary clinical records currently offer the single best source of dairy animal disease patterns across a spectrum of farms, for types of disease events where veterinary assistance is likely to be sought. It is likely that interest in future surveillance activities will not be confined to national disease control authorities but will command a wider interest allowing a more complete overview of production animal industries and sharing of costs of data collection and analysis.
Furthermore it is likely that a judicious blend of data from multiple sources will prove to be the most useful to meet the range of likely user requirements, and that the development of specific methods for low-cost extraction of veterinary practice records warrants further evaluation.
Publications
McIntyre L, Davies P, Jackson R, Morris R. 2000. A novel approach to endemic disease surveillance in New Zealand. Proceedings, Epidemiology and Animal Health Management Branch, Upper Hutt, 24-25 November, 2000. Veterinary Continuing Education, Massey University Publication 205, pp.19-22.
McIntyre L, Davies P, Jackson R, Morris R. 2002. Towards an epidemiologically sound endemic disease surveillance system using veterinary practitioners. Society for Veterinary Epidemiology and Preventive Medicine (abstract accepted, manuscript in preparation).
Paper in preparation for publication in New Zealand Veterinary Journal.
2.8 MBS 368: Spread of Salmonella Brandenburg organisms in sheep yards
| Programme Title: | Spread of Salmonella Brandenburg organisms in sheep yards |
| Programme Leader: | Gary Clarke |
| Institution: | LABNET Invermay Ltd |
Summary (Introduction)
In recent years, Salmonella Brandenburg has caused widespread sheep abortions in mid and south Canterbury, coastal Otago and Southland (Clark, 2000b). The disease is estimated to have affected between 20 and 25 percent of sheep farms in some areas (Smart and Mavors, pers. comm.). Ewes generally abort from about 80 days gestation, peaking between 100 and 120 days gestation (Clark, 2000b). When ewes abort there are large numbers of bacteria in the placenta and foetus, and this causes considerable environmental contamination. Environment Southland cultured increased numbers of Salmonella organisms in the Mataura and Oreti rivers during August and September 1999, and an isolate was serotyped and found to be S. Brandenburg (Scott Crawford, pers. comm.).
Scavenging birds, such as black-billed gulls, have been shown to carry high numbers of S. Brandenburg (up to 25 million organisms per gram of ingesta) in their gut and they probably play a significant role in spreading the disease within an area during the abortion season (Clark et. al., 1999).
Ewes involved in abortion outbreaks have been shown to excrete the organism in their faeces for at least 6 months and outside the abortion season carrier sheep are probably an important cause of spread between farms (Clark et. al., 2000).
Previous research into enteric salmonellosis has shown that sheep yards are an important source of infection to sheep (Robinson and Royal, 1971; Robinson, 1967).
In a study, involving 32 affected farms where S. Brandenburg caused laboratory confirmed abortion outbreaks in 1999 and 32 control farms where there was no clinical evidence of the disease in 1999, the sheep yard dust was cultured for Salmonella (Clark, 2000a). The results showed that S. Brandenburg was present in sheep yards on 39 percent, 16 percent and 12.5 percent of affected farms in January, March/April and June/July 2000 respectively. The organism was isolated less frequently in the sheep yard dust of farms that had shown no clinical evidence of the disease. The findings indicated that sheep yard dust can be an important source of infection for S. Brandenburg.
The present project was carried out as a continuation of this study, to compare the October 2000 prevalence of S. Brandenburg in the dust of sheep yards of farms where S. Brandenburg abortions have occurred and those where no abortions are thought to have occurred.
Background
The goal of this project was to compare the prevalence of S. Brandenburg in the dust of sheep yeards of farms where S. Brandenburg abortions have occurred and those where no abortions are thought to have occurred.
Previous work has shown an increase in S. Brandenburg isolations from sheep yard dust from farms that have had confirmed S. Brandenburg abortions. The number of farms with positive isolations was greater in January than March/April and June/July. This project was undertaken to determine if numbers of isolations were higher in October close to the abortion season.
Approach & Outcomes
Sheep yard dust samples were collected by AgriQuality New Zealand from 32 S. Brandenburg affected farms and 31 non affected farms as defined by 1999 lambing season. The one missing farm had converted the sheep yards into a calf-rearing unit and covered the area in 30 cm of sawdust. Samples were cultured and Salmonella isolated sent to ESR CDG for serotyping.
Information was also collected on whether yards had been cleaned and disinfected since last sampling, whether S. Brandenburg abortions had occurred this season and, if they had, whether this had been confirmed by laboratory tests, and whether or not ewes had been vaccinated against S. Brandenburg.
S. Brandenburg was isolated from 12 (37.5 percent) of the original 32 S. Brandenburg affected farms and from 8 (26 percent) of the original unaffected control farms.
Four (13 percent) of the original unaffected farms had S. Brandenburg abortions, laboratory confirmed, with one other farm having abortions suspected to be S. Brandenburg, but no laboratory confirmation as to cause. Based on confirmed cases there were 36 affected farms and S. Brandenburg was isolated from sheep yard dust on 15 (43 percent) of these farms. Of the remaining 27 farms with no confirmed S. Brandenburg abortions five farms (18.5 percent) had S. Brandenburg cultured from the sheep yard dust.
There was an increased number of farms with S. Brandenburg cultured from their sheep yard dust in October compared with January, March/April and June/July sampling periods. This is compatible with increase environmental contamination of the organism during the abortion/lambing period and post lambing when the yards are used for handling ewes and lambs.
Six farmers (9.5 percent) cleaned their yards in the period between scanning and October. One of these farms, a 1999 unaffected farm, had S. Brandenburg isolated form the sheep yard dust. No farms used a disinfectant to clean the yards.
One of the S. Brandenburg isolates from a "1999 affected" farm had a different pulse-field electrophoretic DNA pattern, involving a loss of one band and the addition of three bands of lower molecular weight. This is the first evidence of a change in the "S. Brandenburg sheep abortion epidemic strain".
Of 43 farms that had evidence of the organism on the farm 72 percent had vaccinated all or part of their ewe flock using Salvexin + B or Salvexin. Abortions confirmed or thought to have been due to S. Brandenburg occurred to a greater degree (2.56 times odd ratio) on unvaccinated "affected farms" compared with vaccinated "affected farms".
Contact for Enquiries
Farm Monitoring Programme Manager
Monitoring and Evaluation
MAF Policy
PO Box 2526
Wellington
NEW ZEALAND
Phone: +64 4 894 0623
Fax: +64 4 894 0741
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