Detection of Mycobacterium avium subsp. paratuberculosis in skeletal muscle and blood of ewes from a sheep farm in New Zealand

Abstract

AIM: To determine whether viable Mycobacterium avium subsp. paratuberculosis (Map) is present in skeletal muscle and blood in ewes with and without Johne's disease confirmed histologically.

METHODS: A total of 51 mixed-aged ewes in poor body condition from a farm with a history of clinical Johne's disease were culled and examined at necropsy. BACTEC radiometric culture was performed on samples of skeletal muscle from the biceps femoris, mononuclear cells in peripheral blood (hereafter referred to as blood), and ileum. Histological sections and Ziehl-Neelsen (ZN)-stained impression smears of terminal ileum and mesenteric lymph nodes were examined. Ewes were defined as having confirmed Johne's disease if there was histopathological evidence typical of the disease within the ileum and adjacent lymph nodes.

RESULTS: Eighteen of 21 (86%) ewes with confirmed clinical Johne's disease were culture-positive for Map from sites peripheral to the alimentary tract, comprising 15 from skeletal muscle and 13 from blood. Five of 30 (17%) ewes that did not have Johne's disease were culture-positive, with four from skeletal muscle and one from blood. The likelihood that ewes with confirmed Johne's disease had systemic Map infection compared with ewes without was determined as OR=30 (95% CI=6.3–142.0; p<0.001).

CONCLUSION: The prevalence of Map infection of skeletal muscle and blood in ewes with confirmed Johne's disease was 71% and 62% respectively, and in unaffected ewes was 13% for muscle and 3% for blood.

CLINICAL RELEVANCE: Skeletal muscle and blood are potential sources of exposure of humans to Map, and the risk appears higher from sheep with Johne's disease.     

Development and spatial distribution of the free-living stages of Teladorsagia circumcincta and Trichostrongylus colubriformis on pasture: A pilot study

Abstract

AIMS: To measure the development of Teladorsagia (=Ostertagia) circumcincta and Trichostrongylus colubriformis eggs to third-stage infective larvae (L3) at different times of the year. Also, to measure the spatial distribution of L3 across herbage, soil and faeces, in order to assess whether spatial issues could be important in larval dynamics on pasture.

METHODS: Field plots were contaminated with sheep faeces containing approximately 20,000 eggs of each of T. circumcincta and T. colubriformis on five separate occasions, viz 01 December 1996 (summer), 18 March 1998 (autumn), 17 June 1998 (winter), 15 October 1998 (spring), and 23 July 1999 (winter). Replicate plots (n=10) were harvested at intervals for up to 12 months after deposition of faeces, and the number and distribution of L3 were measured. Larvae were sampled from faeces (where these remained), herbage, and three soil zones to a depth of 145 mm.

RESULTS: There were large differences between contamination dates in the percentage of eggs that developed to L3. For both species the highest percentage development was for eggs deposited in December (7.8% and 25.9% for T. circumcincta and T. colubriformis, respectively) and the lowest for June (0.4% and 0.03% T. circumcincta and T. colubriformis, respectively). Development in winter was often delayed, and this was always associated with a low yield of larvae, probably due to compounding mortalities associated with long periods of exposure to low temperatures.

The relative distribution of L3 present on herbage, in faeces or in the soil varied between sampling times. However, overall the most L3 were recovered from soil (74% and 66% for T.circumcincta and T. colubriformis, respectively, averaged over all samples), and the lowest recoveries were from the herbage.

CONCLUSIONS: Although the data are limited, the results indicated that the highest percentage of eggs developed to infective larvae in summer and only minimal development occurred in winter. The data do not support the view that substantial contamination of pastures with sheep parasites occurs over winter. Large numbers of larvae were recovered from soil, which indicates that, assuming they can subsequently migrate onto herbage, soil is a potentially important reservoir ofinfective larvae in New Zealand. Therefore, the spatial distribution of L3 on pasture may affect both the dynamics and transmission of parasite populations. Further work on both these issues is warranted.     

BILATERAL ELBOW MALFORMATION IN A CAT CAUSED BY RADIO-ULNAR SYNOSTOSIS

A 9-month-old neutered male cat was referred because of left forelimb lameness. Physical examination, laboratory analysis, and radiographic examination of the entire skeleton were performed. The radiographic diagnosis was bilateral radio-ulnar synostosis with secondary elbow malformation. A comparison between clinical and radiographic findings of the cat and those described in children affected by radio-ulnar synostosis is reported. Correlations and differences are discussed.     

Pathology of cutaneous trombidiosis caused by larval trombiculid mites in a wild Lesueur's tree frog (Litoria wilcoxii)

Cutaneous trombidiosis caused by larvae of trombiculid mites (Vercammenia gloriosa and V. zweifelorum) in the skin of a wild tree frog, Litoria wilcoxii, in northern Queensland, Australia manifested as small, domed vesicular lesions on the dorsal and lateral surfaces posterior to the eyes. The lesions contained small, orange trombiculid mites, with a surrounding minimal inflammatory reaction. The general health and behaviour of the frog appeared unaffected. Provisional diagnosis of cutaneous trombidiosis can be made from its distinctive clinical appearance and confirmed by biopsy with direct microscopic examination of mites. This case report represents a new host record.     

GIS‐based rapid assessment of erosion risk in a small catchment in the wet/dry tropics of Australia

Assessing the impact of various land uses on catchment erosion processes commonly requires in‐depth research, monitoring and field data collection, as well as the implementation of sophisticated modelling techniques. This paper describes the evaluation of a geographic information system (GIS)‐based rapid erosion assessment method, which allows the user to quickly acquire and evaluate existing data to assist in the planning of more detailed monitoring and modelling programmes. The rapid erosion assessment method is based on a simplified version of the revised universal soil loss equation (RUSLE), and allows the rapid parameterization of the model from widely available land unit and elevation datasets. The rapid erosion assessment method is evaluated through the investigation of the effects of elevation data resolution on erosion predictions and field data validation. The use of raster digital elevation model (DEM)‐derived data, as opposed to vector land unit relief data, was found to greatly improve the validity of the rapid erosion assessment method. Field validation of the approach, involving the comparison of predicted soil loss ratios with adjusted in‐stream sediment yields on a subcatchment basis, indicated that with decreasing data resolution, the results are increasingly overestimated for larger catchments and underestimated for smaller catchments. However, the rapid erosion assessment method proved to be a valuable tool that is highly useful as an initial step in the planning of more detailed erosion assessments. Copyright © 2001 Commonwealth of Australia.     

Presence and diversity of mixed avian Plasmodium spp. infections in introduced birds whose distribution overlapped with threatened New Zealand endemic birds

ABSTRACT

Aims: To determine the presence of infection and co-infection of Plasmodium lineages in introduced birds at translocation sites for the North Island saddleback (Philesturnus rufusater), to investigate their role as Plasmodium spp. reservoirs.

Methods: Blood samples were collected from introduced bird species, with a special focus on blackbirds (Turdus merula) and song thrushes (Turdus philomelos), at six locations in the North Island of New Zealand that were the origin, or translocation sites, for North Island saddleback. Where available, blood smears were examined, and blood samples were tested using nested PCR with subsequent sequence analysis, for the presence of Plasmodium spp.

Results: Of the 55 samples tested using PCR analysis, 39 (71%) were positive for Plasmodium spp., and 28/40 (62%) blood smears were positive for Plasmodium spp. Overall, 31 blood samples were from blackbirds with 28/31 (90%) samples positive for Plasmodium spp. Six distinct avian Plasmodium lineages were identified, including three cosmopolitan lineages; Plasmodium vaughani SYAT05 was detected in 16 samples, Plasmodium matutinum Linn1 in 10 samples and Plasmodium elongatum GRW6 in eight samples. Mixed infections with more than one lineage were detected in 12 samples. Samples from two Australian magpies (Gymnorhina tibicen) were positive for Plasmodium. sp. lineage MYNA02, previously not identified in New Zealand.

Conclusions and clinical relevance: This is the first report from New Zealand in which specific Plasmodium spp. mixed infections have been found in introduced birds. Co-infections with several cosmopolitan Plasmodium lineages were identified, as well as the first report in New Zealand of an exotic avian Plasmodium sp. lineage, in Australian magpies. Whilst the role of introduced birds in maintaining and spreading pathogenic avian malaria in New Zealand is unclear, there is a potential infection risk to native birds, especially where distributions overlap.     

Solar wind outflow and the chromospheric magnetic network

Observations of outflow velocities in coronal holes (regions of open coronal magnetic field) have recently been obtained with the Solar and Heliospheric Observatory (SOHO) spacecraft. Velocity maps of Ne7+ from its bright resonance line at 770 angstroms, formed at the base of the corona, show a relationship between outflow velocity and chromospheric magnetic network structure, suggesting that the solar wind is rooted at its base to this structure, emanating from localized regions along boundaries and boundary intersections of magnetic network cells. This apparent relation to the chromospheric magnetic network and the relatively large outflow velocity signatures will improve understanding of the complex structure and dynamics at the base of the corona and the source region of the solar wind.     

Is GRO J1744-28 a strange star?

The unusual hard x-ray burster GRO J1744-28 recently discovered by the Compton Gamma-Ray Observatory can be modeled as a strange star with a dipolar magnetic field of 相似文献