Adenovirus precipitating antibodies in the sera of brush-tailed possums in New Zealand

Sera collected from the Australian brush-tailed possum Trichosurus vulpeculu in New Zealand in 1975 and 1989 were tested for the presence of antibodies to adenovirus. Of the 231 sera tested in an agar gel diffusion test, eight (3.5%) had precipitating antibodies to the group specific antigen of mammalian adenoviruses. Available data allowed 99/231 sera to be classified as being obtained from either adult (total 62) or sexually immature (total 37) possums. From the adult animals, 4/62 (6.5%) sera were positive, while no reactive sera were detected among the 37 immature animals. The results provide evidence that natural infection by an adenovirus occurs in possums in New Zealand. Further work needs to be carried out to isolate this adenovirus to enable detailed serological and epidemiological studies to be performed. A species-specific “possum adenovirus” could have potential in the biological control of this species.     

Endoparasites of brushtail possums (Trichosurus vulpecula) from the South Island,New Zealand

As part of a study to assess whether endoparasites could assist in the biological control of brushtail possums in New Zealand, we investigated the composition and distribution of possum endoparasites in the South Island. Possums were collected near five of the original release areas in the South Island: Banks Peninsula, Hokitika, Nelson, Dunedin and Invercargill.

Among the nematodes, those most frequently encountered were Trichostrongylus spp., which were present in possums from all five study areas. Trichostrongylus species from possums in the Invercargill area comprised 4.5% T. colubriformis, 0.9% T. vitrinus and 11.3% T. retortaeformis. Paraustrostrongylus trichosuri and Parastrongyloides trichosuri were found only in the Invercargill area, where they infected 1.4% and 14% of possums respectively. The cestode Bertiella trichosuri was present in possums from all locations except Dunedin. The protozoan Eimeria spp. occurred in all areas.

These are the first records of Parastrongyloides trichosuri, Paraustrostrongylus trichosuri, T. vitrinus, T. retortaeformis and Eimeria spp. in South Island possums.

The prevalence of endoparasites and the intensity of infection was very low compared to the lower North Island of New Zealand. Endoparasites at the existing levels in the South Island probably have very little effect on possum populations.     

Mycobacterium bovis infections in wild ferrets

Extract

Bovine tuberculosis is one of the more important animal health problems in New Zealand. In contrast to a number of other countries, the classical test and slaughter methods in New Zealand have not led to the eradication of bovine tuberculosis. The failure to eradicate bovine tuberculosis is due to the continual spread of Mycobacterium bovis from wildlife to cattle and farmed deer. Although the Australian brushtail possum Trichosurus vulpecula is the most important wildlife reservoir of infection in New Zealand, M. bovis has also been isolated from wild deer, feral pigs, feral goats, feral cats and feral cattle. In this letter we wish to report the finding of M. bovis-infected wild ferrets (Mustela putorius furo) in seven geographically distinct areas of New Zealand (Figure 1). While there are reports from overseas of M. bovis being isolated from domesticated ferrets, there are no reports of its isolation from wild ferrets or polecats (Mustela putorius)⁽¹⁾.     

Mycobacterium bovis infection in the brush-tailed possum (Trichosurus vulpecula): II. Comparison of experimental infections with an Australian cattle strain and a New Zealand possum strain

Experimentally induced M. bovis infection in brush-tailed possums (Trichosurus vulpecula) with a possum-adapted strain from New Zealand, produced a more rapidly progressive, severe disease than did that induced by an Australian cattle strain. Possums infected with either strain excreted large numbers of mycobacteria in urine, faeces and discharges from abscesses. Aerosol transmission of infection occurred only with the New Zealand possum strain. The infectious aerosol most probably was of respiratory origin but urine may have been the source.All possums had focal interstitial nephritis consistent with Leptospira infection. Histopathological evidence of severe stress was observed in only one possum; the remainder had either mild or no stress-associated lesions.     

A selection of naturally occurring pathological phenomena in the brush-tail possum,Trichosurus vulpecula

During a study of the brush-tail possum, Trichosurus vulpecula, from three different sites in New Zealand, two of which are endemic for bovine tuberculosis, several pathological entities were encountered. Some of these are differential diagnoses for tuberculosis. The list included: bite abscess, foreign body granulomas, calcification of the caudal aorta, lymphoid nodules in the lung, pulmonary lipid plaques, lipid pneumonia, pneumoconiosis, focal fibrosing alveolitis, adiaspiromy-cosis, collagenous hamartoma, focal dystrophic calcification in the lung, mineralised casts in renal tubules, hyaline nephrosis with proteinuria, focal interstitial nephritis, pyelonephritis, renal and hepatic amyloidosis, lymphoid nodules around sublobular veins in the liver, multi-focal non-suppurative hepatitis, multi-focal bacterial hepatitis, bile ductular hyperplasia and peri-portal fibrosis, hepatocellular fatty change, intranuclear inclusions and cytoplasmic invaginations in hepato-cytes, hepatocellular lipopigmentation and gastrointestinal parasitism.     

Accidental Mycobacterium bovis infection in a veterinarian

CASE: A veterinarian developed tenosynovitis and secondary carpal tunnel syndrome following accidental inoculation of Mycobacterium bovis during the necropsy of a tuberculous possum from Westland, New Zealand.

CLINICAL RELEVANCE: M. bovis infection is a zoonotic disease, and occupational exposure to tuberculous animals places people at risk of contracting the disease.

CONCLUSIONS: Adhering to safe work practices reviewed in this article is important to minimise the risk of infection to people handling tuberculous animals.     

Routine blood values for New Zealand brushtail possums at capture

Abstract

Extract

Thank you for the opportunity to reply to Dr Clark's and Ms Cooke's recent letters. As stated in our original letter “Routine blood values for New Zealand brushtail possums (Trichosurus vulpecula) at capture”, the brushtail possum is the subject of intense and diverse study throughout the country (Lynch, 1997 Lynch, R, ed. 1997. “Biological Control of Possums”. In Workshop Report. The Royal Society of New Zealand, Miscellaneous Series 45, Wellington: Royal Society of New Zealand.  [Google Scholar]). Part of this study focuses on finding disease agents that may be useful in biological control. At present there are no publications detailing the blood values one might expect to find in a non-diseased, wild New Zealand possum at capture. As noted in our letter, we have not set out to find absolute normal values, rather those blood values an investigator might expect to find in a healthy possum presented with little or no history by a member of the public immediately following capture (hence the use of the word “routine” in the title rather than “normal”).     

Development of an indirect ELISA for detection of antibody to wobbly possum disease virus in archival sera of Australian brushtail possums (Trichosurus vulpecula) in New Zealand

AIMS: To develop an indirect ELISA based on recombinant nucleocapsid (rN) protein of wobbly possum disease (WPD) virus for investigation of the presence of WPD virus in Australian brushtail possums (Trichosurus vulpecula) in New Zealand.

METHODS: Pre- and post-infection sera (n=15 and 16, respectively) obtained from a previous experimental challenge study were used for ELISA development. Sera were characterised as positive or negative for antibody to WPD virus based on western-blot using WPD virus rN protein as antigen. An additional 215 archival serum samples, collected between 2000–2016 from five different regions of New Zealand, were also tested using the ELISA. Bayesian modelling of corrected optical density at 450?nm (OD₄₅₀) results from the ELISA was used to obtain estimates of receiver operating characteristic (ROC) curves to establish cut-off values for the ELISA, and to estimate the prevalence of antibody to WPD virus.

RESULTS: Western blot analysis showed 5/14 (36%) pre-infection sera and 11/11 (100%) post-infection sera from experimentally infected possums were positive for antibodies to WPD virus. Bayesian estimates of the ROC curves established cut-off values of OD₄₅₀≥0.41 for samples positive, and OD₄₅₀<0.28 for samples negative for antibody to WPD virus, for sera diluted 1:100 for the ELISA. Based on the model, the estimated proportion of samples with antibodies to WPD virus was 0.30 (95% probability interval=0.196–0.418). Of the 230 archival serum samples tested using the ELISA, 48 (20.9%) were positive for antibody to WPD virus, 155 (67.4%) were negative and 27 (11.7%) equivocal, using the established cut-off values. The proportion of samples positive for WPD virus antibody differed between geographical regions (p<0.001).

CONCLUSION: The results suggested that WPD virus or a related virus has circulated among possums in New Zealand with differences in the proportion of antibody-positive samples from different geographical regions. Antibodies to WPD virus did not seem to protect possums from disease following experimental infection, as one third of possums from the previous challenge study showed evidence of pre-existing antibody at the time of challenge. These results provide further support for existence of different pathotypes of WPD virus, but the exact determinants of protection against WPD and epidemiology of infection in various regions of New Zealand remain to be established.

CLINICAL RELEVANCE: Availability of the indirect ELISA for detection of WPD virus antibody will facilitate prospective epidemiological investigation of WPD virus circulation in wild possum populations in New Zealand.     

A behaviour study on the potential for direct transmission of tuberculosis from possums (Trichosura vulpecula) to alpacas (Lama pacos), and the converse from alpacas to possums

Aims. To evaluate the potential for the direct transmission of tuberculosis from possums to alpacas, and vice versa.

Methods. A field study was conducted on an alpaca farm in Northland, New Zealand on 7 January 1999. Observations were recorded on the interaction of one group of male alpacas with a simulated dead possum, one male and one female alpaca group with a simulated terminally tuberculous possum, and one group of male alpacas with a normal possum in an enclosure from which the animals could not escape. The possum was sedated with ketamine as hydrochloride to simulate death (inactive; no movement), and terminal illness (active, into-ordinated movement around the paddock). The observations were based on the focal animal sampling technique, they were un-replicated, and recorded visually and manually with intermittent still photography.

Results. Both male and female alpacas showed strongly inquisitive interaction with the possum. They clustered around the possum (focal animal) very soon after it was observed by the first member of the group. The interest of the majority of both sex groups remained high for the observation periods of approximately 30 minutes, and most individuals remained within 5 metres of the possum for that time. Approximately 50% of the alpacas were within possible aerosol transmission distance of 2 metres from the sedated, erratically mobile possum with their heads towards it for approximately 50% of the two observation periods. Aggressive behaviour was recorded for a young male with stamping on the moving possum. Similar, but more vigorous and prolonged stamping behaviour was recorded for a female with a young (<1 week) offspring (cria).The stamping behaviour was accompanied by very close nose to nose contact of the alpaca and possum. At one point the female threw the possum approximately 1.5 metres in the air with her teeth. The group of male alpacas placed in an enclosure with an unsedated normal possum generally moved away from the possum during its rapid active attempts to escape. When it became inactive their approaches were cautious and only once elicited a defence reaction from the possum, from which they recoiled. One male made one attempt to stamp on the active possum. Soon after the possum became inactive in a small loose hay pile, the alpacas lost interest in it.

Conclusions. The alpaca / possum behavioural interactions show there is potential for direct aerosol transmission of tuberculosis from possums to alpacas, but probably not from alpacas to possums.     

Adenovirus precipitating antibodies in the sera of brush-tailed possums in New Zealand

Sera collected from the Australian brush-tailed possum Trichosurus vulpecula in New Zealand in 1975 and 1989 were tested for the presence of antibodies to adenovirus. Of the 231 sera tested in an agar gel diffusion test, eight (3.5%) had precipitating antibodies to the group specific antigen of mammalian adenoviruses. Available data allowed 99/231 sera to be classified as being obtained from either adult (total 62) or sexually immature (total 37) possums. From the adult animals, 4/62 (6.5%) sera were positive, while no reactive sera were detected among the 37 immature animals. The results provide evidence that natural infection by an adenovirus occurs in possums in New Zealand. Further work needs to be carried out to isolate this adenovirus to enable detailed serological and epidemiological studies to be performed. A species-specific possum adenovirus could have potential in the biological control of this species.     

Longevity of Mycobacterium bovis in brushtail possum (Trichosurus vulpecula) carcasses,and contact rates between possums and carcasses

Abstract

AIM: To determine, for a variety of environmental conditions, how long Mycobacterium bovis might remain viable inside the carcass of a brushtail possum (Trichosurus vulpecula) that died of bovine tuberculosis (Tb), and to measure the rate of contact between free-ranging possums and possum carcasses.

METHODS: Lesions of M. bovis were simulated by inoculating excised spleens weighing 0.5–1 g with 0.2 mL liquid culture containing approximately 5 x 10⁷ cfu M. bovis/mL. Simulated lesions were inserted into possum carcasses (n=48) at the peripheral lymph nodes. Carcasses were placed in the field at two sites (a tussock grassland and a podocarp-broadleaved forest site) and in two seasons (summer and winter) for up to 62 days. Survival rates of M. bovis were estimated by sampling the simulated lesions over time, and culturing the recovered lesion to determine if any viable M. bovis bacteria were present.

The time taken for a free-ranging possum to first encounter a dead possum in its home range was estimated by live-trapping possums and fitting them with proximity loggers (n=13). A ‘contact’ was recorded if these possums came within 40–50 cm of proximity loggers fitted to possum carcasses.

RESULTS: There were strong seasonal and site effects in the survival rate of M. bovis in possum carcasses. In the grassland habitat, no viable bacilli were cultured from any carcass after 3 days in summer, whereas in winter all samples were culture-positive for the first 20 days, and some were still positive after 27 days. The survival rates for forest habitat were intermediate between the results for grassland, and there were no culture-positive carcasses after 9 days in summer or 27 days in winter.

In summer, infected carcasses (n=6) were first encountered by possums a mean 1.9 (range 0.4–6.7) days after placement.

CONCLUSIONS: Possum carcasses were contacted by free-ranging possums within the period that viable M. bovis were shown to survive in a carcass. The risk of such infection is likely to be most significant in winter or in areas with microhabitats where the survival of M. bovis is high. However, the generally low survival rate of M. bovis in possum carcasses and the low frequency of possum-to-carcass contacts indicate this route of transmission alone could not maintain Tb in a possum population.     

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.     

Vertebrate pesticide risk assessment by indigenous communities in New Zealand

In New Zealand, the vertebrate pesticide sodium fluoroacetate (Compound 1080) is aerially applied in baits for control of the brush-tailed possum Trichosurus vulpecula (Kerr, 1792). Maori, the indigenous people of New Zealand, have raised concerns about 1080 impacts on culturally-important species. Here, we outline two steps taken to help Maori assess 1080 risk. First, field research was undertaken to determine if naturally-occurring plants utilized by a Maori community for food and medicine would take up 1080 from baits. Single baits were placed at the base of individual plants of two species, pikopiko (Asplenium bulbiferum) and karamuramu (Coprosma robusta). Plants were sampled at various times up to 56 days, and samples were analyzed for 1080 content. No 1080 was detected in any of the pikopiko samples, whereas 1080 was detected in karamuramu, at a maximum concentration of 5 ppb after seven days, and 2.5 ppb after 14 days. This concentration decreased to 0 at 28 days, indicating that 1080 was not persistent. The results of the present study suggest there is negligible risk of humans being poisoned by consuming plants that have taken up 1080 from baits. To allay community concerns that minute concentrations of 1080 might influence the medicinal properties of plants, it is suggested that a withholding period of 30 days after 1080 control operations could be adopted. Second, after further consultation we undertook a review of the scientific literature relating to 1080 impacts on additional non-target species of cultural importance to Maori. The information was presented on an interactive foodweb database that allowed the collection and presentation of a large volume of complex information about 1080 in a holistic and pictorial fashion. This database was presented to many Maori communities throughout New Zealand, and feedback was overwhelmingly positive. The database is likely to play a key role in informing these communities about 1080, and is seen as an important new tool to help these communities make their own risk assessments.     

Seroprevalence and Risk Factors for Leptospira Seropositivity in Beef Cattle,Sheep and Deer Farmers in New Zealand

Leptospirosis is a global zoonosis that in New Zealand affects primarily people occupationally exposed to livestock. The objective of this study was to estimate the seroprevalence of five Leptospira serovars in farmers working on cattle, sheep and deer farms that had the serological status of animals previously assessed and to identify risk factors for farmer seropositivity. A total of 178 farmers from 127 properties participated in the study. Blood samples were tested using the microscopic agglutination test (MAT) for the presence of antibodies to Leptospira. Samples with a MAT titre ≥48 were considered seropositive. Using Bayesian statistical analysis, the median seroprevalence of Leptospira, all serovars combined, was estimated to be 6.6% (95% probability interval (PI) 3.6–10.9%). Risk factors associated with seropositivity were assisting deer or cattle calving, farming deer, having ≥25% of flat terrain and high abundance of wild deer on farm, while high possum abundance on farm was negatively associated with seropositivity. No association was observed between farmer serostatus and previously recorded livestock serology. Leptospira seropositivity was associated with influenza‐like illness of farmers (RR = 1.7; 95% PI 1.0–2.5). Assuming a causal relationship, this suggested an annual risk of 1.3% (95% PI 0.0–3.0%) of influenza‐like illnesses due to Leptospira infection in the population of farmers. The association between seropositivity and disease can be used to estimate the public health burden of leptospirosis in New Zealand. Identifying and understanding risk factors for Leptospira seropositivity can inform preventive measures, hence contributing to the reduction of leptospirosis incidence in farmers.     

Adiaspiromycosis in suspected cases of pulmonary tuberculosis in the common brushtail possum Trichosurus vulpecula)

Pulmonary adiaspiromycosis was diagnosed in 15 of 17 common brushtail possums (Trichosurus vulpecula) examined for bovine tuberculosis. Emmonsia crescens was isolated from two of the affected animals. This is the first reported isolation of this dimorphic fungus in New Zealand. The infections varied from light to heavy with sparsely distributed, focal, 1–2 mm diameter, grey-white spherical granulomas in the lightly infected cases to innumerable foci throughout the lungs in the heavily infected cases. Histologically, the lesions were characterised by a central fungal adiaspore consistent in morphology with E. crescens located in alveolar spaces or bronchioles. These were surrounded by a cuff of granulomatous inflammation which varied in density and extent in proportion to the degree of degeneration exhibited by the organism.

The lesions in most cases of adiaspiromycosis in the possum are sufficiently distinctive to allow their differentiation from tuberculosis by gross examination, but where any doubt exists over the possibility of dual infection by Emmonsia and Mycobacterium species differentiation should be made on the basis of a histological examination of the tissue and culture for mycobacterial organisms.     

A serological survey of cattle in the Thames-Coromandel district of New Zealand for antibodies to Ross River virus

AIM: To determine if cattle exposed to the southern saltmarsh mosquito (SSM), Aedes camptorhynchus, in the Thames-Coromandel district of New Zealand had been exposed to Ross River virus (RRV).

METHODS: A purposive sampling design was used to test cattle from seven farms located in close proximity to four sites infested with A. camptorhynchus in the Thames-Coromandel district. Sera from 207 cattle were tested for antibodies to RRV, using an ELISA and confi rmatory virus neutralisation test (VNT) as the gold standard.

RESULTS: All 207 cattle tested negative for antibodies to RRV using the ELISA and VNT.

CONCLUSIONS: This study found no evidence of exposure to RRV in cattle in locations in the Thames-Coromandel district of New Zealand where populations of SSM were present.     

Influence of contact heterogeneity on TB reproduction ratio R0 in a free-living brushtail possum Trichosurus vulpecula population

Social network analyses were used to investigate contact patterns in a free-living possum Trichosurus vulpecula population and to estimate the influence of contact on R(0) for bovine tuberculosis (TB). Using data collected during a five-year capture-mark-recapture study of a free-living possum population, observed estimates of R(0) were computed and compared with R(0) computed from random networks of similar size that approximated a random mixing process. All networks displayed a heterogeneous pattern of contact with the average number of contacts per possum ranging from 20 to 26 per year. The networks consistently showed small-world and single-scale features. The mean estimates of R(0) for TB using the observed contact networks were 1.78, 1.53, 1.53, 1.51, and 1.52 times greater than the corresponding random networks (P <0.05). We estimate that TB would spread if an average of between 1.94 and 1.97 infective contacts occurred per year per infected possum, which is approximately half of that expected from a random network. These results have implications for the management of TB in New Zealand where the possum is the principal wildlife reservoir host of Mycobacterium bovis, the causal agent of bovine TB. This study argues the relevance of refining epidemiological models used to inform disease management policy to account for contact heterogeneity.     

Isolation of Mycobacterium bovis from brushtail possums with non-visible lesions

AIM: To determine the prevalence of Mycobacterium bovis infection in brushtail possums (Trichosurus vulpecula) that did not have macroscopic lesions of bovine tuberculosis, and to evaluate culture of pooled tissues from multiple possums as a method for determining the M. bovis-infection status of wildlife populations in New Zealand.

METHODS: Pools of selected tissues were collected from possums from four different populations known to be infected with M. bovis. Tissue pools from individual animals, and combined pools from multiple animals, were cultured for M. bovis.

RESULTS: In the four populations investigated, the prevalence of possums with macroscopic lesions confirmed by culture to be infected with M. bovis ranged from 1 to 19 (mean 31/283; 10.9)%. The prevalence of possums with non-visible lesions that were culture positive for M. bovis in the same populations ranged from 4 to 10 (mean 24/283; 8.5)%. The mean of the log10 cfu of M. bovis of the macroscopic lesions and of the culture-positive samples that did not have visible lesions was 3.85 (SE 0.26) and 1.46 (SE 0.26) log₁₀ cfu, respectively (p<0.01). Mycobacterium bovis was cultured from pools of 30–50 animals in the four populations studied.

CONCLUSIONS: The finding of M. bovis infection in possums with non-visible lesions identified a potential deficiency of declaring possum populations free of M. bovis on the basis of absence of macroscopic lesions. The culturing of pools of selected tissues from multiple animals without visible lesions can be used to reduce laboratory costs of possum surveys without a major reduction in the ability to detect M. bovis infection.     

A behaviour study on the potential for direct transmission of tuberculosis from possums (Trichosurus vulpecula) to alpacas (Lama pacos), and the converse from alpacas to possums

AIMS: To evaluate the potential for the direct transmission of tuberculosis from possums to alpacas, and vice versa. METHODS: A field study was conducted on an alpaca farm in Northland, New Zealand on 7 January 1999. Observations were recorded on the interaction of one group of male alpacas with a simulated dead possum, one male and one female alpaca group with a simulated terminally tuberculous possum, and one group of male alpacas with a normal possum in an enclosure from which the animals could not escape. The possum was sedated with ketamine as hydrochloride to simulate death (inactive; no movement), and terminal illness (active, inco-ordinated movement around the paddock). The observations were based on the focal animal sampling technique, they were un-replicated, and recorded visually and manually with intermittent still photography. RESULTS: Both male and female alpacas showed strongly inquisitive interaction with the possum. They clustered around the possum (focal animal) very soon after it was observed by the first member of the group. The interest of the majority of both sex groups remained high for the observation periods of approximately 30 minutes, and most individuals remained within 5 metres of the possum for that time. Approximately 50% of the alpacas were within possible aerosol transmission distance of 2 metres from the sedated, erratically mobile possum with their heads towards it for approximately 50% of the two observation periods. Aggressive behaviour was recorded for a young male with stamping on the moving possum. Similar, but more vigorous and prolonged stamping behaviour was recorded for a female with a young (<1 week) offspring (cria). The stamping behaviour was accompanied by very close nose to nose contact of the alpaca and possum. At one point the female threw the possum approximately 1.5 metres in the air with her teeth. The group of male alpacas placed in an enclosure with an unsedated normal possum generally moved away from the possum during its rapid active attempts to escape. When it became inactive their approaches were cautious and only once elicited a defence reaction from the possum, from which they recoiled. One male made one attempt to stamp on the active possum. Soon after the possum became inactive in a small loose hay pile, the alpacas lost interest in it. CONCLUSIONS: The alpaca / possum behavioural interactions show there is potential for direct aerosol transmission of tuberculosis from possums to alpacas, but probably not from alpacas to possums.     

Endoparasites of brushtail possums (Trichosurus vulpecula) from the South Island, New Zealand

As part of a study to assess whether endoparasites could assist in the biological control of brushtail possums in New Zealand, we investigated the composition and distribution of possum endoparasites in the South Island. Possums were collected near five of the original release areas in the South Island : Banks Peninsula, Hokitika, Nelson, Dunedin and Invercargill. Among the nematodes, those most frequently encountered were Trichostrongylus spp., which were present in possums from all five study areas. Trichostrongylus species from possums in the Invercargill area comprised 4.5% T. colubriformis, 0.9% T. vitrinus and 11.3% T. retortaeformis. Paraustrostnmgylus trichosuri and Parastrongyloides trichosuri were found only in the Invercargill area, where they infected 1.4% and 14% of possums respectively. The cestode Bertiella trichosuri was present in possums from all locations except Dunedin. The protozoan Eimeria spp. occurred in all areas. These are the first records of Parastrongyloides trichosuri, Paraustrostrongylus trichosuri, T. vitrinus, T. retortaeformis and Eimeria spp. in South Island possums. The prevalence of endoparasites and the intensity of infection was very low compared to the lower North Island of New Zealand. Endoparasites at the existing levels in the South Island probably have very little effect on possum populations.