Wastewater-based epidemiology in hazard forecasting and early-warning systems for global health risks

With the advent of the SARS-CoV-2 pandemic, Wastewater-Based Epidemiology (WBE) has been applied to track community infection in cities worldwide and has proven succesful as an early warning system for identification of hotspots and changingprevalence of infections (both symptomatic and asymptomatic) at a city or sub-city level. Wastewater is only one of environmental compartments that requires consideration. In this manuscript, we have critically evaluated the knowledge-base and preparedness for building early warning systems in a rapidly urbanising world, with particular attention to Africa, which experiences rapid population growth and urbanisation. We have proposed a Digital Urban Environment Fingerprinting Platform (DUEF) - a new approach in hazard forecasting and early-warning systems for global health risks and an extension to the existing concept of smart cities. The urban environment (especially wastewater) contains a complex mixture of substances including toxic chemicals, infectious biological agents and human excretion products. DUEF assumes that these specific endo- and exogenous residues, anonymously pooled by communities' wastewater, are indicative of community-wide exposure and the resulting effects. DUEF postulates that the measurement of the substances continuously and anonymously pooled by the receiving environment (sewage, surface water, soils and air), can provide near real-time dynamic information about the quantity and type of physical, biological or chemical stressors to which the surveyed systems are exposed, and can create a risk profile on the potential effects of these exposures. Successful development and utilisation of a DUEF globally requires a tiered approach including: Stage I: network building, capacity building, stakeholder engagement as well as a conceptual model, followed by Stage II: DUEF development, Stage III: implementation, and Stage IV: management and utilization. We have identified four key pillars required for the establishment of a DUEF framework: (1) Environmental fingerprints, (2) Socioeconomic fingerprints, (3) Statistics and modelling and (4) Information systems. This manuscript critically evaluates the current knowledge base within each pillar and provides recommendations for further developments with an aim of laying grounds for successful development of global DUEF platforms.

Vaccination practices for Leptospira spp. on New Zealand dairy farms

AIMS

To describe leptospiral vaccination practices in dairy herds in New Zealand and evaluate conformity with best practice guidelines issued by the New Zealand Veterinary Association using data from a questionnaire administered by participating veterinary practices.

METHODS

A cross-sectional study of 200 randomly selected dairy farms stratified by herd size and region throughout New Zealand was conducted from January to April 2016 to investigate leptospiral vaccination practices in dairy herds in New Zealand. Using a pre-tested questionnaire administered during a face-to-face interview, vaccination practice details such as vaccine types, time, and age of vaccination and whether vaccines were administered by veterinary or farm staff, were collected.

RESULTS

Leptospiral vaccination programmes had been implemented on 199/200 (99.5 (95% CI = 97.2-99.9)%) farms, and on 178 (89.4%) of those, programmes had been running for ≥5 years. Most farmers used bivalent vaccines containing antigens for leptospiral serovars Pomona and Hardjo (144/179 (80.4%) in calves, 112/167 (60.7%) in heifers, and 112/163 (68.7%) in cows), rather than trivalent vaccines which also include antigens for L. interrogans serovar Copenhageni. In total, 123/200 (61.5%) of farmers purchased only vaccinated animals but 51/199 (25.6%) were unsure of the vaccination status of purchased cattle. Sixty-one percent (105/172) of farmers had other livestock on their farms and of them, 78/186 (42%) vaccinated some or all for Leptospira spp. Leptospiral vaccines were administered always or sometimes with other animal remedies on 30/190 (15.8%) and 91/190 (47.9%) of farms, respectively. Most farmers had not made changes to their vaccination programme in the previous 5 years. Timing of first vaccination of calves ranged from 2 weeks to 10 months of age, with 112/189 (59.3%) vaccinating by 4 months of age. Approximately half of the farms followed the best practice guideline for the timing of vaccinations for calves (high-risk farms; 67/162; 41.4%) heifers (72/165, 43.6%), and cows (171/184; 92.9%).

CONCLUSIONS

The results of this survey suggest that there is almost universal adoption of leptospiral vaccination for dairy cattle in New Zealand. However, there remain areas for improvement regarding the proportion of farmers following best practice guidelines and refinement of vaccination programmes, particularly with respect to timing of vaccination in calves.

Serological study of Leptospira interrogans serovar Copenhageni and L. borgpetersenii serovars Tarassovi and Ballum in beef cattle, sheep and deer in New Zealand

AIMS

To estimate animal-level seroprevalence of Leptospira interrogans serovar Copenhageni and L. borgpetersenii serovars Ballum and Tarassovi, in beef cattle, sheep and deer on New Zealand farms, and herd/flock-level seroprevalence of any serovar when existing same-sera data for serovars Hardjobovis and Pomona were included, and to determine associations between risk factors and animal-level seroprevalence.

METHODS

Banked sera from sheep (n = 82), beef (n = 54) and deer (n = 62) herds/flocks (n = 3,878 animals) from seven regions were analysed using the microscopic agglutination test. Titres of ≥48 were designated positive. Herds/flocks were considered positive if either ≥1, ≥2 or ≥3 animals were positive. Existing same-sera data for serovars Hardjobovis and Pomona were included to establish farm-level any-serovar seropositivity. Factors associated with serological status were analysed using generalised estimating equations.

RESULTS

Animal-level seroprevalence for serovars Ballum, Copenhageni, and Tarassovi, respectively, was 13.7 (95% CI = 11.7-16.0)%, 12.6 (95% CI = 10.6-14.7)% and 18.0 (95% CI = 15.7-20.5)% for beef cattle, 10.5 (95% CI = 9.0-12.1)%, 16.7 (95% CI = 14.9-18.6)% and 14.0 (95% CI = 12.4-15.8)% for sheep and 6.6 (95% CI = 5.3-8.2)%, 15.5 (95% CI = 13.5-17.7)% and 3.6 (95% CI = 2.7-4.8)% for deer, respectively. Herd/flock-level seroprevalence for Ballum was 86.6, 52.4 and 39.0% for sheep, 85.2, 52.7 and 33.3% for beef cattle and 50.8, 27.9 and 21.3% for deer at definitions ≥1, ≥2 and ≥3 seropositive animals per species, respectively. For Copenhageni, corresponding data were 95.1, 73.2 and 56.1% for sheep, 68.5, 48.2 and 29.6% for beef cattle and 73.8, 57.4 and 41.0% for deer, and for Tarassovi, 80.5, 59.7 and 45.1% for sheep, 83.3, 68.5 and 61.1% for beef cattle, and 42.6, 16.4 and 4.9% for deer. Seropositivity to all serovars was observed from all regions, with some differences in seroprevalence observed between species and regions, but not between islands. Combining with Hardjobovis and Pomona data, herd/flock-level seropositivity for all animal species and all five Leptospira serovars was 100% at definition ≥1 animal positive, and 97.5 and 96.3% for sheep flocks, 87.8 and 97.8% for beef cattle herds, and 89.3 and 75% for deer herds at ≥2 and ≥3 animals positive, respectively.

CONCLUSIONS

Seropositivity to serovars Ballum, Copenhageni and Tarassovi is common in sheep, beef cattle and deer New Zealand and most, or all farms have ≥1 livestock species seropositive to ≥1 serovar.

CLINICAL RELEVANCE

Serovars Ballum, Tarassovi and Copenhageni should be considered when clinical or subclinical signs of leptospirosis are observed in sheep, beef cattle or deer. Livestock sector workers are potentially at risk of exposure.

A survey of gastrointestinal nematode species in red deer (Cervus elaphus) farms in New Zealand using PCR

Gastrointestinal nematodes are recognised as an animal health issue for farmed red deer. The aim of this study was to explore the range of species infecting farmed deer herds and their farm-level prevalence in New Zealand. Faecal samples were collected from 12-24-month-old deer (n = 6-26; mean 19) on 59 farms located in the North (n = 25) and South (n = 34) Islands. Sub-samples of faeces were pooled by farm and cultured to recover third stage larvae. Twenty four larvae were randomly selected and identified to species using a multiplex PCR (total = 1217 larvae). At farm-level the most prevalent nematodes were Oesophagostomum venulosum 83% (n = 49) and the deer-specific nematodes in the subfamily Ostertagiinae (=Ostertagia-type) including, Spiculoptera asymmetrica 73% (n = 43), Ostertagia leptospicularis 47% (n = 28), Spiculoptera spiculoptera 47% (n = 28). The recently identified Trichostrongylus askivali was present on 32% (n = 19) of the farms and Oesophagostomum sikae on 17% (n = 10). In the analysis of the total number of larvae identified, the proportion was in similar order, 45% (n = 548) were O. venulosum, 14% (n = 173) S. asymmetrica, 10% (n = 124) S. spiculoptera, 9% (n = 114) O. leptospicularis, T. askivali, 3% (n = 40) and only 2% were O. sikae (n = 20). This study is the first to show the farm-level prevalence of nematode species in deer in New Zealand and the first to use PCR as a diagnostic tool. It provides data consistent with cross-infection from sheep/cattle to deer, and provided tentative insights into the proportions of the main GIN species across the deer population including O. sikae and T. askivali which have only recently been identified in New Zealand.

Investigation of association between bovine viral diarrhoea virus and cervid herpesvirus type-1, and abortion in New Zealand farmed deer

This study tested for association between bovine viral diarrhoea virus (BVDv) and cervid herpesvirus type-1 (CvHV-1) exposure and abortion in New Zealand farmed red deer. Rising two-year-old (R2, n = 22,130) and mixed-age (MA, n = 36,223) hinds from 87 and 71 herds, respectively, throughout New Zealand were pregnancy tested using ultrasound early in gestation (Scan-1) and 55-89 days later (Scan-2) to detect mid-term abortion. Sera from aborted and non-aborted hinds at Scan-2 were tested for BVDv and CvHV-1 using virus neutralisation tests. Available uteri from aborted hinds and from hinds not rearing a calf to weaning were tested by PCR for herpesvirus DNA. In herds with aborted hinds, 10.3% of 639 R2 and 17.2% of 302 MA hinds were sero-positive for BVDv and 18.6% of 613 R2 and 68.5% of 232 MA hinds were sero-positive for CvHV-1. There was no association between BVDv sero-status and abortion at animal level (R2 p = 0.36, MA p = 0.76) whereas CvHV-1 sero-positivity was negatively associated with abortion in MA hinds (p = 0.01) but not in R2 hinds (p = 0.36), MA). Eleven of 108 uteri from aborted R2 hinds but no MA hinds were positive for herpesvirus DNA. Vaginal samples from four R2 and one MA aborted hinds tested were negative for herpesvirus DNA. A Cervid Rhadinovirus type-2 (CRhV-2) was identified in seven PCR positive uteri samples. Findings suggest that BVDv and CvHV-1 may not be associated with abortion in R2 hinds, but association needs to be tested further in MA hinds. The role of CRhV-2 requires clarification.

Meta-analysis of the efficacy of Leptospira serovar Hardjo vaccines to prevent urinary shedding in cattle

Leptospirosis is a zoonosis often associated with occupational exposure from livestock that can be prevented by animal vaccination. Several trials have assessed vaccine efficacy in livestock but there have been no attempts to evaluate these trials jointly. This systematic review and meta-analysis aimed to estimate vaccine efficacy to prevent urinary shedding of Leptospira serovar Hardjo (Hardjo) in cattle. Three databases were used to search for relevant papers published from 1980 to 2015 evaluating commercial vaccines to prevent urinary shedding of leptospires after artificial conjunctival or natural challenge. A total of 1237 articles were initially identified. Eight articles containing information from nine trials that assessed vaccine efficacy to prevent Hardjo urinary shedding, as per bacteriological culture, were included in the meta-analysis. Fixed effects Mantel-Haenszel (MH) and a Bayesian random effects meta-analyses were used to estimate the efficacy of vaccination to prevent Hardjo shedding in urine. Vaccine efficacy against Hardjo challenge was 88.7% (95% CI 81.0%-93.2%) in the MH meta-analysis and 89.9% (95% probability interval 80.6%-94.9%) in the Bayesian random effects meta-analysis. There was no evidence of heterogeneity of study results (p = 0.17). The estimated vaccine efficacy to prevent urinary shedding of Hardjo in cattle may be sufficient to reduce disease incidence in animals and exposure risk of people working in close contact with cattle.

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.

Serological patterns, antibody half-life and shedding in urine of Leptospira spp. in naturally exposed sheep

AIMS

To determine within-farm prevalence, longitudinal pattern of exposure measured by serology, antibody titre longevity and point prevalence of shedding in urine of Leptospira borgpetersenii serovar Hardjo and L. interrogans serovar Pomona in naturally infected sheep on a sample of commercial farms in New Zealand.

METHODS

On eight commercial sheep farms, between September 2011 and January 2014, blood samples were collected from 115-217 ewe lambs on each farm, at intervals of 2-11 months. They were analysed by microscopic agglutination test (MAT) for antibodies to L. borgpetersenii serovar Hardjo and L. interrogans serovar Pomona, using a titre cut-point of 48. Urine from 98 animals was tested by quantitative PCR (qPCR). The half-life of antibodies was estimated in 185 sheep for serovar Hardjo and 21 for Pomona, and the seroprevalence and mean titre of animals lost to follow-up was compared with those remaining in the study.

RESULTS

Within-flock seroprevalence for serovar Hardjo reached a maximum at 17-22 months of age, ranging from 79 to 100%. Seroprevalence for serovar Pomona rose above 10% on three farms and increased to 21-54% by 4-14 months. Seroconversions occurred mainly from late autumn to early summer at 7-15 months of age. Seroprevalences ranging from 3 to 76% for serovar Hardjo and 0.5 to 15% for serovar Pomona were observed up to 3 months of age, likely due to maternally derived immunity. The half-life of antibody in response to infection was estimated to be 6.7 (95% CI=5.8-7.9) months for serovar Hardjo and 6.3 (95% CI=4.8-9.0) months for Pomona. The prevalence of sheep with urine positive for leptospires on qPCR on each farm ranged from 11 to 88%. All but one of the qPCR-positive animals were seropositive for serovar Hardjo. On two farms where Pomona exposure was observed, animals that were lost to follow-up had a higher geometric mean titre for serovar Pomona than those remaining in the study.

CONCLUSIONS

This study demonstrated seasonal exposure from autumn to early summer in young sheep, a wide range of within-flock serological and shedding prevalence, and gives an estimation of the half-life of MAT titres in sheep. More extensive data are needed to fully understand the epidemiology of leptospirosis in sheep flocks across New Zealand and, along with economic analysis, to justify and design cost-effective and efficient control measures to protect human and animal health.

Shedding and seroprevalence of pathogenic Leptospira spp. in sheep and cattle at a New Zealand Abattoir

A cross-sectional study was carried out on sheep and cattle slaughtered at a New Zealand abattoir from September to November 2010 to investigate the supplier-specific shedding rate, renal carriage rate and seroprevalence of leptospires. In the 2008/2009 season, this abattoir experienced three human leptospirosis cases from 20 staff, of which two were hospitalized. Urine, kidney and blood samples were collected from carcasses of 399 sheep (six suppliers, 17 slaughter lines) and 146 cattle (three suppliers, 22 slaughter lines). The urine and kidney samples were tested by quantitative real-time PCR (qPCR), while serum samples (from coagulated blood samples) were tested by microscopic agglutination test (MAT). In total, 27% (73/274; 95% CI: 18-37) of urine samples tested positive by qPCR. Species-specific shedding rates (prevalence of positive urine qPCR) were 31% (95% CI: 17-48) for sheep and 21% (95% CI: 14-30) for cattle. For 545 kidney samples tested, 145 were qPCR positive (27%; 95% CI: 17-39). The average prevalence of kidney qPCR positivity was 29% (95% CI: 17-45) for sheep and 21% (95% CI: 15-28) for cattle. Three hundred and thirty of 542 sampled sheep and cattle had antibodies against Leptospira borgpetersenii serovar Hardjobovis (Hardjobovis) and/or Leptospira interrogans serovar Pomona (Pomona), based on reciprocal MAT titre ≥1 : 48 (overall seroprevalence of 61%; 95% CI: 48-73). Seroprevalence was 57% (95% CI: 40-72) for sheep and 73% (95% CI: 59-83) for cattle. Among the seropositive animals, 41% (70/170; 95% CI: 30-54) were shedding (tested positive by urine qPCR) and 42% (137/330; 95% CI: 30-54) had renal carriage (tested positive by kidney qPCR). Some risk management options for abattoirs or farms to prevent human leptospirosis infections include vaccination of maintenance hosts, the use of personal protective equipment, and the application of urine qPCR to detect shedding status of stock as surveillance and as an alert.

Liver biopsy histopathology for diagnosis of Johne's disease in sheep

Sheep with Johne's disease develop epithelioid macrophage microgranulomas, specific to Mycobacterium avium subsp. paratuberculosis (Map) infection, in the terminal ileum, mesenteric lymph nodes, and organs distant to the alimentary tract such as the liver. The objectives of this study were to determine whether liver pathology was present in ewes affected by Map and whether liver cores provide adequate tissue for this potential diagnostic marker. One hundred and twenty-six adult, low body condition ewes were euthanized, necropsied, and underwent simulated liver biopsy. Ileal lesions typical of Map were found in 60 ewes. Hepatic epithelioid microgranulomas were observed in all ewes with Type 3b (n = 40) and 82% (n = 11) with Type 3c ileal lesions. None were found in ewes unaffected by Map or with Type 1, 2, or 3a ileal lesions. Liver biopsy core samples provided adequate tissue for histopathology with a sensitivity and specificity of 96% (95% confidence interval [CI], 0.87-0.99) and 100% (95% CI, 0.95-1), respectively for detection of types 3b and 3c ileal lesions.

A randomised controlled trial of Silirum vaccine for control of paratuberculosis in farmed red deer

A randomised controlled trial to assess the efficacy of Silirum vaccine in control of paratuberculosis in young farmed deer was carried out in 2008-2009 in six New Zealand herds with a history of clinical disease. Vaccination with Silirum was carried out in four-month-old deer, and vaccinates (n=1671) and controls (n=1664) were weighed at vaccination and at 8 and 12 months old, when faecal samples were collected from 125 vaccinates and 123 controls on five farms. Deer were slaughtered between 11 and 20 months of age, and the incidence of gross visceral lymph node (VLN) pathology typical of paratuberculosis in deer, that is, enlarged and/or granulomatous VLN, was recorded. Clinical disease was confirmed in 18 controls and seven vaccinates, representing a vaccine efficacy estimate of 60 per cent (95% CI 3 per cent to 83 per cent, P=0.04). Forty-seven percent (95% CI 38 per cent to 56 per cent) of faecal samples from vaccinates and 55 per cent (95% CI 46 per cent to 64 per cent) from controls were Mycobacterium avium subspecies paratuberculosis positive (P=0.5). Average daily liveweight gain did not differ between the cohorts. At slaughter, 1.4 per cent of vaccinates and 4.5 per cent of controls had VLN pathology, RR=0.32 (95% CI 0.19 to 0.54, P<0.001). These data indicate that vaccination with Silirum may be useful as an aid to control losses associated with clinical paratuberculosis in young deer.

Prevalence of Mycobacterium avium subsp. paratuberculosis in farmed red deer (Cervus elaphus) with grossly normal mesenteric lymph nodes

AIM

To estimate the prevalence of Mycobacterium avium subsp. paratuberculosis (Map) in farmed deer with no gross post-mortem evidence of Map infection slaughtered in New Zealand, and to assess predictors of infection.

METHODS

Mesenteric lymph node (MLN) samples (n = 251) were collected from 60 lines of deer presented at two slaughterhouses in the North and two in the South Island of New Zealand between October 2008 and January 2009 and cultured for Map. Estimates of individual animal prevalence for each island were adjusted to account for the clustering of individual observations within herds. The national herd prevalence estimate was calculated as a weighted mean, with weights being the proportion of herds from which deer were slaughtered at North and South Island slaughterhouses among all herds slaughtering deer throughout New Zealand. Age, gender, and the presence of other carcasses with enlarged and/or granulomatous MLN in the same line (line status) were assessed as predictors of infection using multivariable logistic regression.

RESULTS

A national cluster-adjusted individual animal prevalence of 45 (95% CI = 30-60)% was estimated, with North and South Island prevalences of 29 (95% CI = 16-45)% and 51 (95% CI = 36-66)%, respectively. Line status was a strong predictor of infection in young deer (OR 7.1, 95% CI = 2.4-21.5), but not in older deer. Herd-level prevalence was 44 (95% CI = 24-64)% in the North Island and 67 (95% CI = 49-85)% in the South Island. Weighted adjustment resulted in a national herd-level prevalence estimate of 59 (95% CI = 41-78)%.

CONCLUSIONS

This study has provided a national baseline prevalence estimate for Map infection at the individual and herd-level, showing a contrast between the North and South Islands. More research to investigate the factors contributing to the difference in infection prevalence seen between the islands may help to identify suitable control measures for Map in deer herds.

The prevalence of disseminated Mycobacterium avium subsp. paratuberculosis infection in tissues of healthy ewes from a New Zealand farm with Johne's disease present

AIM

To determine the prevalence of disseminated Mycobacterium avium subsp. paratuberculosis (Map) infection in healthy ewes in a flock with a history of clinical Johne's disease.

METHODS

Twenty-four healthy ewes, from a large sheep and cattle farm with a history of clinical Johne's disease in the ewe flock, were randomly selected, euthanased, blood sampled, and examined at necropsy. BACTEC™ radiometric culture for Map was performed on samples of faeces, ileum, mesenteric lymph node, biceps femoris muscle and mononuclear cells in peripheral blood. Serum antibody ELISA tests were performed. Histological sections and Ziehl Neelsen (ZN) stains of impression smears of ileum and mesenteric lymph node were examined for pathological lesions characteristic of Johne's disease and acid fast organisms (AFO). Indirect quantification of Map was performed, using BACTEC radiometric growth indices measuring the time taken for the production of (14)CO(2.)

RESULTS

No histological evidence of Johne's disease or AFO was found in the ileum and mesenteric lymph nodes. Twelve of the 24 ewes (50%) had Map cultured from the ileum (n=6) and/or mesenteric lymph nodes (n=8) while none had Map cultured from the faeces, biceps femoris muscle or blood mononuclear cells. One of the 12 Map culture positive ewes was serum ELISA positive. The culture growth rates in liquid medium suggest low numbers of Map were present in the tissues of the culture positive ewes.

CONCLUSION

Fifty per cent of clinically healthy ewes exposed to Map within a Johne's infected flock were Map culture positive in the ileum and/or mesenteric lymph node(s), while the ELISA was positive in 8% of those animals (n=1). There was no faecal shedding of Map and no Map was cultured from skeletal muscle or from blood mononuclear cells suggesting that systemic Map infection, defined as positive culture of Map from skeletal muscle and/or blood, may be uncommon in healthy mixed age ewes without clinical Johne's disease.

CLINICAL RELEVANCE

ELISA serology detected 1 of 12 ewes infected with Map whilst none were detected from faecal BACTEC radiometric culture, suggesting biosecurity measures used to control the spread of Map may be of limited use. Map was not cultured from blood mononuclear cells or skeletal muscle, indicating that meat from healthy ewes, from farms where Johne's disease is present, is an unlikely source of Map exposure for humans. Further research is warranted to establish the prevalence and dissemination of Map in tissues outside the alimentary tract of healthy ewes from farms throughout New Zealand where Map is present.

Alpha and gamma herpesvirus detection in two herds of farmed red deer (Cervus elaphus) in New Zealand

CASE HISTORY

In September 2004 two hinds on Farm 1 were observed with epiphora and keratoconjunctivitis, and corneal scarring. A low pregnancy rate in some hinds had been recorded that year. In the same year six yearling deer were observed on Farm 2 with keratitis, uveitis and corneal scarring.

CLINICAL AND PATHOLOGICAL FINDINGS

On Farm 1, conjunctival swabs and blood samples were collected from the hinds with ocular lesions, and from 24 other hinds. The two affected hinds were immunosuppressed with dexamethasone for 7 days. Conjunctival, nasal and vaginal swabs were collected daily before euthanasia and necropsy on the eighth day. Subsequently, another five non-pregnant hinds were similarly immunosuppressed and necropsied, and the reproductive tracts of 20 non-pregnant hinds were collected following slaughter. Semen samples were collected from four stags implicated with reproductive failure. On Farm 2, conjunctival swabs were collected from six hinds with ocular lesions and from 14 unaffected deer. Viral culture, consensus primer PCR and sequencing for specific herpesviruses was carried out on conjunctival swabs, buffy coat from blood samples, semen and reproductive tracts. Necropsy samples were also examined using gross pathology and histopathology. On Farm 1, a type 2 rhadinovirus (CvRhV) was detected in the conjunctiva of one hind with keratoconjunctivitis using PCR. Following immunosuppression, gross vesicular and histological vaginal lesions typical of infection with alphaherpesvirus were observed in samples of vaginal tissue from the same hind. Buffy coat, vaginal and lumbar spinal nervous tissues were also positive for cervid herpesvirus 1 (CvHV-1) using PCR. Herpesviruses were not detected in reproductive tracts, ocular or semen samples of the other deer. CvRhV was detected in buffy coats from four other hinds and in a conjunctival swab from one hind, all without ocular lesions, using PCR. On Farm 2, conjunctival swabs from two deer with keratitis were culture positive for CvHV-1. Two culture-negative conjunctival samples from deer without ocular lesions were positive for CvHV-1 by PCR. In two other affected animals, presence of CvRhV was confirmed by PCR and sequencing.

DIAGNOSIS

Infection with CvHV-1 associated with keratitis and vulvovaginitis, and CvRhV infection in deer with and without ocular lesions.

CLINICAL RELEVANCE

CvHV-1 is a likely cause of keratoconjunctivitis and possibly reproductive tract pathology in deer. Investigation of ocular lesions and reproductive failure in farmed deer should include CvRhV and CvHV-1.

Growth response and shedding of Leptospira spp. in urine following vaccination for leptospirosis in young farmed deer

AIM

To investigate the effect of vaccination against Leptospira serovars Hardjo-bovis and Pomona on growth rate and shedding of leptospires in urine in rising 1-year-old farmed red deer.

METHODS

In early March 2007, 230 female and 205 male, 3-month-old deer on five farms were treated with streptomycin then were randomly allocated to a control group (n = 218), or were vaccinated (n = 217) with a bivalent whole-cell killed leptospiral vaccine (Leptavoid-2) followed by a booster 4 weeks later. These animals were isolated from other 3-month-old deer on each property until May, when all vaccinated and control deer were combined with deer not treated with streptomycin, for maximum exposure to natural leptospiral challenge. Seroconversion was monitored in control deer against Leptospira borgpetersenii serovar Hardjo-bovis and Leptospira interrogans serovar Pomona using the microscopic agglutination test (MAT). A cut-off of ≥ 1:48 was used to identify a seropositive response to infection, and ≥1:24 to indicate a response to vaccination. Urine was collected from females in all groups and tested for shedding of leptospires using bacterial culture and real-time PCR. Male deer from vaccinated and control groups were weighed every 2-3 months to measure growth rate.

RESULTS

In vaccinated female deer, antibody was present to Hardjo-bovis in 39-73% and to Pomona in 78-100% of animals in May, with titres ranging between 1:24-1:96 and 1:24-1:1536, respectively; control female deer were all serologically negative. In November, female control deer were seropositive to Hardjo-bovis on 4/5 farms (seroprevalence range 4-78%) but seronegative to Pomona on all farms. Between March and November mean growth rate was higher in vaccinated than control deer (26 g/day) on one farm (p = 0.049) that had the highest prevalence of seroconversion (78-88%) and urinary shedding (56%). Between August and November on 4/5 farms, when almost all seroconversions occurred, growth rates were higher in vaccinated than control deer (31 g/day; p = 0.011). Urinary shedding of leptospires was detected by culture and/or PCR in 8/34 (24%) unvaccinated control and 20/38 (53%) animals not treated with streptomycin on 2/5 farms; no shedding was detected in vaccinated deer. The average risk difference for shedding between vaccinated and control deer was -11% (95%CI = -18 to -4) (p = 0.001).

CONCLUSION

Vaccination against Leptospira serovars Hardjo-bovis and Pomona was associated with higher liveweight gain and reduced urinary shedding of leptospires in young deer naturally challenged by Hardjo-bovis. The association with liveweight gain was evident on some but not all farms.

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

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.

Oral rehabilitation with dental implants after cancer treatment

BACKGROUND

Patients who undergo surgical management of oral cancer may greatly benefit from an implant-supported prosthesis. This study reports on the clinical experience of dental implant placement in patients following resection of oral cancer over a 15-year period. Controversies including the use of dental implants in irradiated tissues, and hyperbaric oxygen treatment will also be discussed.

METHODS

Thirty-one patients who had dental implants placed as part of their oral rehabilitation between 1992 and 2007 were investigated. Demographic data and factors including implant survival, type of prosthesis provided, radiotherapy and the hyperbaric oxygen therapy were analysed.

RESULTS

In this retrospective study, there was a retention rate of 110 implants from a total of 115 implants placed. A high rate of implant retention was found, with 5 implant failures from a total of 115 implants placed. The 5 failed implants occurred in free flap bone that had been irradiated.

CONCLUSIONS

Dental implants provide an important role in the oral rehabilitation of oral cancer patients. There may be an increased risk of implant failure in free flap bone that has been irradiated.

Vaccination for leptospirosis improved the weaning percentage of 2-year-old farmed red deer hinds in New Zealand

AIM

To investigate the effect of leptospiral vaccination against serovars Hardjo-bovis and Pomona on fetal loss and weaning percentage in rising 2-year-old farmed red deer hinds.

METHODS

In mid-February 2007, 252 rising 2-year-old hinds on four farms received a single dose of streptomycin (25 mg/kg), to minimise leptospiral infection. They were randomly allocated to vaccinated and control groups. Vaccinated hinds (n=125) received a 2-ml S/C injection of a bivalent whole-cell killed leptospiral vaccine (Leptavoid-2) followed by a booster 4-6 weeks later, and were grazed with control hinds (n=127). These animals were isolated from other hinds on each property, until after mating (June 2007), when all vaccinated and control hinds were combined with hinds not treated with streptomycin, for maximum exposure to natural leptospiral challenge. Evidence of natural challenge by Leptospira spp. was assessed in blood samples from control hinds by serology against L. borgpetersenii serovar Hardjo-bovis and L. interrogans serovar Pomona, using the microscopic agglutination test (MAT), and in hinds not treated with streptomycin by detection of shedding of organisms in urine, using bacterial culture and real-time PCR. Pregnancy diagnosis was carried out in May/June 2007, using transrectal ultrasonography, to determine conception. In late October, prior to calving, the pregnant vaccinated and control hinds were examined by palpation of the abdomen and udder, to determine the percentage of hinds pregnant at term and assess fetal loss. In March 2008, at weaning, vaccinated and control hinds were examined for lactation status, using observation and palpation of the udder. The differences between the groups were evaluated using matched logistic regression analysis.

RESULTS

After mating, pregnancy was diagnosed in 97/125 (77.6%) vaccinated and 106/127 (83.5%) control hinds. All four farms had serological evidence of Hardjo-bovis infection, and a single hind was serologically positive for Pomona between October and March. Real-time PCR confirmed urinary shedding on two farms. The mean percentage of hinds pregnant at term, for those animals confirmed pregnant after mating, in the vaccinated and control groups was 95/97 (98%) (range 95-100%) and 103/106 (97%) (range 94-100%), respectively (p>0.05). The mean weaning percentage for vaccinated and control groups was 86/97 (89%) (range 78-95%) and 88/106 (83%) (range 76-88%), respectively (p=0.015).

CONCLUSION

Vaccination for leptospirosis resulted in no difference in the percentage of hinds pregnant at term, but a higher weaning percentage compared with unvaccinated controls suggesting that vaccination reduced perinatal and/or pre-weaning mortality.

Serosurvey of leptospirosis and investigation of a possible novel serovar Arborea in farmed deer in New Zealand

AIM

To investigate the prevalence of Leptospira spp. and possible novel serovar Arborea infection in farmed deer in New Zealand.

METHODS

In September 2006, five serum samples from a serum bank from each of 70 farms sampled for a previous national prevalence survey were forwarded to the World Health Organisation/Food and Agriculture Organisation/World Organisation for Animal Health (WHO/FAO/OIE) reference laboratory for leptospirosis in Brisbane, Australia, to test for reactivity to a reference panel of 23 serovars, most believed to be exotic to New Zealand, using the microscopic agglutination test (MAT). Eleven farms were seropositive for Arborea, a serovar novel to New Zealand. In July 2007, 126 additional banked serum samples from nine of those 11 farms (n=8-20/farm) were sent to the reference laboratory for similar serology. Two farms in the Southland region were considered positive for serovar Arborea. Tissue from deer kidneys (n=43) from these two farms collected at a deer slaughter premises (DSP) was cultured in November 2007 and November 2008. Sera from those deer were also sent to the laboratory in Brisbane.

RESULTS

From the initial 350 sera, 96 (27.4%) and 19 (5.4%) samples were positive for Leptospira borgpetersenii serovar Hardjo-bovis and Leptospira interrogans serovar Pomona respectively. There were cross-reactions between serovar Hardjo-bovis with serovars Medanensis and Szwajizak. Serological evidence of serovars Tarassovi, Grippotyphosa, Celledoni, Australis, Zanoni, Robinsoni, Canicola, Kremastos, Bulgarica, Cynopteri, Ballum, Bataviae, Djasiman, Javanica, Panama, Shermani and Topaz was negative or sporadic, generally with titres of 1:50 and therefore likely non-specific. Fourteen (4.0%) samples from 11 farms were positive for serovar Arborea, justifying further investigation. The prevalence of serovar Arborea was 15% and 30% on two farms, from the 126 samples. None of 43 kidney and serum samples collected subsequently from those two farms were positive by culture or serology for serovar Arborea.

CONCLUSIONS

While there were samples serologically positive for serovar Arborea in deer, attempts to isolate the organism were unsuccessful. The sample size for the follow-up investigation was insufficient to validate the presence or absence of infection, so further study should be undertaken to verify the status of this serovar of Leptospira spp. in New Zealand, in both deer and other livestock species.

Possible subclinical hepatopathy after copper supplementation in farmed red deer

AIM

To determine the effect of parenteral supplementation with Cu on the activities of hepatic enzymes in deer with adequate concentration(s) of Cu in liver and serum.

METHODS

Male red deer aged 12 months were given either 0.8 or 1.6 mg of Cu/kg of a S/C injectable Cu formulation or no Cu (n=10/group) on 03 December 2007 (Day 0). Concentration of Cu in liver was measured in biopsies taken on Days -13 and 17, and that in serum on Days 0, 1, 3 and 17. Liver enzymes, gamma-glutamyl transferase (GGT) and glutamate dehydrogenase (GDH), were measured in serum on Days 3 and 7. Deer were weighed on Days 0 and 17.

RESULTS

The mean concentration of Cu in liver was 203 (range 50-460) μmol/kg fresh weight (FW) on Day -13 and that in serum was 14.8 (range 7.8-25.0) μmol/mL on Day 0. Concentrations of Cu in liver were adequate (>100 μmol/kg FW) in 25/30 deer. Injection with 0.8 mg of Cu/kg resulted in elevated mean concentrations of Cu in serum to 20.3 (range 14-26) and 17.4 (range 12-26) μmol/mL on Days 1 and 3 respectively, whereas 1.6 mg/kg resulted in mean concentrations of Cu in serum of 26.7 (range 20-42) and 19.3 (range 16-25) μmol/mL on Days 1 and 3 respectively (p<0.05). The mean concentration of Cu in liver on Day 17 was 1,460 (range 1,000-2,300) after injection with 0.8 mg/kg, 1,666 (range 1,100-2,200) after 1.6 mg/kg, and 280 (range 75-420) μmol/kg FW in controls. Injection with 1.6 mg Cu/kg, but not 0.8 mg/kg, resulted in an increase in the activity of GGT (p=0.05), and in 4/10 deer a marked change in the activity of GDH, between Day 3 and Day 7, indicating that injection of copper induced a moderate degree of subclinical hepatopathy. Mean liveweight gain (g/day) to Day 17 was 105.9 (range -176 to 411) in control animals and 64.7 (range -59 to 176) 64.7 and -61.7 (range -294 to 117) in deer given 0.8 and 1.6 mg/Cu/kg respectively (p=0.003).

CONCLUSIONS

S/C administration of 1.6 mg of Cu/kg in deer which had adequate Cu status pre-treatment resulted in elevated activities of GGT and GDH in serum, indicating hepatopathy, and both this dose rate and 0.8 mg/kg resulted in reduced liveweight gain post-treatment compared with untreated controls.

CLINICAL SIGNIFICANCE

Cu supplementation should not be administered when the Cu status of deer is adequate or unknown.

Blood constituents of farmed red deer (Census elaphus). II: biochemical values

Approximately 80 farmed male and female red deer aged three months and over were blood sampled and biochemical parameters measured. The deer were sampled by jugular venepuncture without tranquillization. Mean values recorded were serum gamma-glutamyltransferase (19.5 IU/l), glutamic oxaloacetic transaminase (43.0 IU/l), creatine phosphokinase (197.9 IU/l), plasma pepsinogen (0.91 IU/i), blood urea nitrogen (8.56 mmol/l), serum glucose (6.9 mmol/l), phosphorus (1.75 mmol/l), calcium (2.13 mmol/l), magnesium (0.74 mmol/l), potassium (4.43 mmol/l) and sodium (138.5 mmol/l). There were no significant differences in any parameter between sexes or between age groups 3-8 months, 9-18 months, or older.

Serological responses of farmed red deer to a vaccine againstLeptospira interrogansserovarshardjoandpomona

Six adult, female, red deer were vaccinated with a hardjo-pomona vaccine followed by a second vaccination four weeks later and thereafter, at yearly intervals for two years. Serological responses were determined at intervals using a standard microscopic agglutination test. Increased responses to hardjo were observed in two deer which were seropositive to this serovar before vaccination compared to those which were initially seronegative. Some initially seronegative deer developed titres to hardjo and pomona ranging from 1:24 to 1:48 following the first dose of vaccine, and all deer produced a serological response to both serovars ranging from 124 to 1:96 following the second vaccination except one animal which failed to produce a pomona titre of 124 or greater. Responses to annual revaccinations were more variable both within and between years. Most deer produced titres which ranged from 1:24 to 1:96 for three to live months, although some deer failed to seroconvert following the annual revaccinations. Peak responses were similar to those recorded in cattle following an identical vaccination programme with the same vaccine but titres fell to undetectable levels after three to live months whereas titres reported in cattle generally persisted for at least 12 months.

Observations of a long-acting formulation of oxytetracycline in red deer (Cervus elaphus)

Six nine-month-old red deer were injected intramuscularly with a long-acting injectable solution of oxytetracycline (Terramycin-LA, Pfizer Ltd) at a dose rate of 20 mg/kg. Four similar control deer were injected with saline. There was no significant pain response to injection, and only minor palpable swellings at the injection site were observed in three oxytetracycline-treated and one control animal. No statistically significant changes in white blood cell numbers, blood fibrinogen, creatine phosphokinase or glutamic oxaloacetic transaminase concentrations occurred as a result of oxytetracycline administration up to seven days after injection. Mean plasma oxytetracycline concentration reached a peak (4.68 mg/l) two hours after injection and declined to levels below assay sensitivity (0.3 mg/l) in five deer 72 hours after injection, and in all deer by 96 hours after injection. No gross lesions at the injection site were observed at slaughter 30 days after injection. There were traces of oxytetracycline at the injection site muscle of two deer after 30 days, but residues were not detected in injection site muscle from the other four deer, or in any of the liver, kidney or other muscle specimens.

Chronic malignant catarrhal fever: a case in a sika deer (Cervus nippon)

A condition resembling chronic malignant catarrhal fever was seen in a 9-month-old pet sika hind (Cervus nippon). From an initial acute depression, pyrexia, and anorexia, the condition progressed to include hypopyon, keratitis, lethargy, loss of condition, sloughing of one hoof and eventually death after seven weeks. There were multiple, 5 to 8mm diameter dark-red nodules throughout the mesenteries and mediastinum, along abdominal organ ligaments, and about the uterus and kidneys. Histopathology showed the nodules to be organising vascular thrombi. Concurrent perivascular mononuclear infiltrations and intravascular thrombi in many tissues confirmed that the condition was malignant catarrhal fever.

Blood constituents of farmed red deer (Cervus elaphus): I. Haematological values

Approximately 100 farmed male and female red deer aged three months and over were blood-sampled and haematological parameters were measured. The deer were sampled by jugular venepuncture without tranquilization. Mean values were haemoglobin (16.0 g/dl), packed cell volume (44.6%), mean corpuscular haemoglobin concentration (35.8 g/dl), total plasma protein (66.0 g/l). fibrinogen (4.8 g/l) and white blood-cell numbers (5.80 x 10(9)/l). Differential white blood-cell counts were neutrophils (53.9%), eosinophils (4.8%), basophils (3.0%), lymphocytes (37.2%) and monocytes (1.1%). There were no significant differences in any parameter measured between sexes or between age groups three to eight months, nine to eighteen months, or older.

Sedation and chemical restraint of deer

This review examines the properties of chemical immobilising agents of use or potential use in deer for velvet antler removal. The alpha-2-adrenergic agonist, xylazine, is the most commonly used agent for chemical restraint of stags for this purpose in New Zealand. This compound is often combined with an opioid or ketamine to enhance its effectiveness. Concerns about the carcinogenic potential of a xylazine metabolite have led to a call by the deer industry to limit the use of this drug and stimulated enquiry into alternatives. The potent pure opioid agonists, fentanyl, carfentanil and etorphine, are less effective than xylazine when used alone, and their use presents greater risk to operators and animals and is subject to more stringent legal restrictions. Newer alpha-2-adrenergic agonists, detomidine and medetomidine, are more potent than xylazine and unlikely to result in carcinogenic metabolites. Availability of specific alpha-2-adrenergic antagonists further enhances the usefulness of these drugs. The dissociative agent, ketamine, has proven useful for immobilisation of various domestic and wildlife species and captive species of deer but undesirable side effects and the low concentration, relative to the effective dose, of currently available formulations limit its usefulness. Combination of a dissociative agent with an alpha-2-adrenergic agent reduces the required dose of both and enhances their efficacy. A commercially available combination of the dissociative anaesthetic agent, tiletamine, and the benzodiazepine, zolazepam, is more potent than ketamine and induction times are faster. This combination can be manipulated to varying concentrations by dissolution with alpha-2-adrenergic agents. A long-acting neuroleptic agent, zuclopenthixol, has recently been investigated for calming deer and may be an alternative to classical sedative-immobilising agents. Most chemical immobilisation agents used alone or in combination produce respiratory depression and supplemental oxygen has been recommended. All would likely result in some form of chemical residues in velvet antler.

Trace element metabolism, dietary requirements, diagnosis and prevention of deficiencies in deer

The first deer farms were established in New Zealand about 30 years ago. Extensive studies on trace elements in sheep and cattle have resulted in clarification of the requirements of those species and the development of protocols to diagnose and prevent deficiencies. In contrast, there have been very few studies conducted with deer. This review summarises information available on trace element nutrition of deer and concludes that, in New Zealand, cobalt (Co), vitamin B12, selenium (Se) and iodine (I) deficiencies are of lesser importance than copper (Cu), which can have a significant impact on deer health and performance. However, on individual farms, Se and I deficiency may cause significant production losses if not managed appropriately. There are no reports of production limitations caused by Co deficiency. Copper deficiency manifests itself as clinical disease, namely enzootic ataxia and osteochondrosis. Growth responses to Cu supplementation have only been reported in 2/11 trials and were not predicted from low serum and/or liver Cu concentrations. On the basis of clinical signs of Cu deficiency, the proposed reference ranges used to predict Cu status from serum Cu concentrations (micromol/l) are: 5, deficient; 5-8, marginal and; 8, adequate; and for liver Cu concentrations (micromol/kg fresh tissue) are: 60, deficient; 60-100, marginal and; 100, adequate. Copper supplementation strategies based on Cu-EDTA injections, Cu-oxide needles or the application of Cu to pasture are effective at increasing Cu status for varying periods. More recent research suggests that alternative forage species that have a high Cu content (10 mg/kg dry matter (DM), may play a role in the prevention of Cu deficiency.

Chemical analgesia for velvet antler removal in deer

There is a legal requirement to provide analgesia for velvet antler removal in New Zealand. Currently, this is achieved using local anaesthetic blockade, with or without systemically administered sedative/analgesic agents, or by compression in 1-year-old stags. Lignocaine hydrochloride 2% is most commonly used and is most effective when administered as a high-dose ring block. Combinations of various amino-amide local anaesthetic agents can achieve rapid onset and prolonged duration of analgesia, though concerns about drug residues and carcinogenic potential of a lignocaine metabolite have led to consideration of the amino-ester family of local anaesthetics as alternatives. Systemically administered analgesics, including opioids, alpha-2-adrenergic agents and ketamine provide dose-dependent sedation and analgesia. However, none are sufficient, alone or in combination, to produce surgical analgesia at currently recommended dose rates and when reversal agents are given, analgesic effects are usually reversed as well as sedation. Thus, local anaesthetic blockade is still indicated, though the potential for drug or drug-metabolite residues in velvet antler remains a concern. The need for and effectiveness of non-steroidal anti-inflammatory drugs (NSAIDs) for post-operative analgesia requires investigation. Amitriptyline, locally administered opioid agonists, tramadol and other systemically administered agents may warrant future investigation for surgical and post-operative analgesia for velvet antler removal.

The effect of long-acting injectable selenium formulations on blood and liver selenium concentrations and liveweights of red deer (Cervus elaphus)

AIM

To evaluate the efficacy of a new long acting injectable selenium ( Se ) formulation to increase the Se status and prevent Se deficiency in red deer.

METHODS

Groups of weaned red deer (four stags and six hinds/group) grazing pastures containing <30 mg Se/kg DM were injected subcutaneously with either 0.5, 1.0 or 2.0 mg Se/kg as a new formulation of BaSeO4 (Deposel Multidose), 1.0mgSe/kg of a current formulation (Deposel), or not treated. Blood Se concentrations and liveweight were measured nine times at intervals over 377 and 270 days, respectively.

RESULTS

Both formulations of Se elevated blood Se concentrations from 105 nmol/l pre-injection for at least 377 days with peak levels of 1894, 1395 and 818 nmol/l for high, medium and low doses of Deposel Multidose, respectively, at 73141 days, and 1508 nmol/l at 73-141 days for the medium dose of Deposel, which persisted at similar levels for the duration of the study. Deposel Multidose produced fewer and less severe subcutaneous tissue reactions than Deposel. Pastures contained 10 to 30 mg Se/kg DM. There was no significant difference in growth rate between treated and control deer. There was a significant (p<0. 01) linear relationship (y = 1.25x + 71.6, R2=0.86) between blood (x) and liver (y) Se concentrations in the range of 120 - 2100 nmol/l for blood concentrations, and 200 - 3000 nmol/kg for liver concentrations.

CONCLUSION

Injections of BaSeO4 in both formulations studied were effective in increasing the Se status of deer but the new formulation produced fewer and less-severe tissue reactions. Young growing red deer appear less sensitive to Se deficiency as measured by weight gain, than sheep and cattle, suggesting that reference ranges for those species are not appropriate for deer. There was a linear correlation between blood and liver selenium concentrations.

Welfare of farmed deer in New Zealand. 1. Management practices

This review summarises research of management practices that potentially impact on the welfare of farmed deer. The processes of capture and initial domestication of feral deer caused many welfare problems but are now essentially complete in New Zealand. The health and production status of farmed deer, and readily visible indicators of their welfare are generally good, although preventive medicines and optimum management practices have not been universally adopted. Research into social behaviour, effects of yarding, weaning, mating, calving, shelter, shade and nutrition has identified ways of improving the welfare of farmed deer and has provided recommendations for deer industry quality assurance programmes. Research has identified transport design and practices that minimise the impact of transport on deer welfare and reduce carcass wastage caused by bruising during transport. Time in lairage prior to slaughter should be minimised and electrical stunning is a humane method of slaughter. Ongoing research is needed on management practices and farm environments to further improve the welfare of farmed deer, consistent with the goals of the New Zealand deer industry and its proactive approach to date.

Novel forages for growth and health in farmed deer

AIMS

This paper reviews recent research on the use of new forages in deer farming that may be useful for increasing growth in weaner deer for venison production, increasing the trace element status of deer, and for developing systems less reliant on chemical inputs, notably of anthelmintics used to control internal parasites.

GROWTH

Grazing on pure swards of red clover (Trifolium pratense) or chicory (Chicorium intybus) increased weaner growth during autumn by 26-47% and during spring by 10-14%, relative to red deer (Cervus elaphus) grazed on perennial ryegrass (Lolium perenne) /white clover (Trifolium repens) pasture (0.8/0.2). Pre-weaning growth during lactation was increased by approximately 20%. These increases were due to increased rate of degradation of feed particles in the rumen, leading to higher digestibility and higher voluntary feed intakes (VFI). Red clover and chicory produce a greater proportion of their total dry matter (DM) during late summer and autumn than perennial ryegrass/white clover pastures, and are therefore better aligned with the seasonal feed requirements of deer. Grazing on the legume, sulla (Hedysarum coronarium), in autumn and spring increased the growth of weaner deer by 33% and 10%, respectively, relative to pasture-fed animals.

PARASITES

Plants containing substantial concentrations of secondary compounds such as condensed tannins (CT) show promise for reducing problems caused by internal parasites. CT present in some legumes and the presence of low concentrations of both CT and sesquiterpene lactones in chicory are reviewed. Feeding sulla containing 35g CT /kg DM reduced abomasal nematode establishment and tended to reduce lungworm (Dictyocaulis eckerti) larval counts in faeces. Relative to weaner deer grazing pasture, weaner deer grazing chicory during autumn required fewer anthelmintic treatments without depressing growth rates. CT extracted from a range of legumes, and CT and sesquiterpene lactones extracted from chicory reduced the in vitro motility of both lungworm and gastrointestinal nematode larvae. The beneficial effects of CT-containing forages on the ability of young deer to manage internal parasite infections could be due to: indirect effects of CT resulting in increased amino-acid absorption, better meeting demands of the immune system; direct inhibitory effects of CT on parasite larvae and; taller plant morphology, reducing the ingestion of infective larvae. The effects of CT depend upon both their structure and CT Condensed tannins DM Dry matter L1 First-stage larvae L3 Infective third-stage larvae LWG Liveweight gain ME Metabolisable energy OM Organic matter OMD Organic matter digestibility VFIVoluntary food intake concentration in the plant, which vary between growing conditions, plant varieties and species.

TRACE ELEMENTS

Chicory contained higher concentrations of copper and cobalt than perennial ryegrass/white clover pasture grown on the same farm, and deer grazing chicory had higher liver concentrations of both copper and vitamin B12. These forages may contribute to maintaining adequate trace element status in deer.

CONCLUSIONS

Grazing systems that include legumes and herbs such as sulla, red clover and chicory can be used to substantially increase the growth of weaner deer for venison production whilst maintaining deer health and reducing requirements for chemical inputs. For maximum plant persistence and animal responses, these plants should be grown and managed as special-purpose forages and not used in seed mixtures with perennial grasses.

Regional seroprevalence of leptospirosis on deer farms in New Zealand

AIM

To undertake a seroprevalence survey to estimate the distribution of infection by Leptospira spp. serovars Hardjobovis, Pomona and Copenhageni in farmed deer herds regionally throughout New Zealand.

METHODS

Between March 2003 and February 2005, 111 red and red x wapiti deer herds not using a leptospiral vaccine were selected from nine regions from Northland to Southland. Eighty-three herds were selected for on-farm collection of 12-20 blood samples from hinds predominantly 9-30 months of age, by jugular venepuncture, while similar numbers, predominantly males 9-30 months of age, per farm were collected from 28 herds at sticking at deer slaughter premises (DSP). Serum was stored frozen until analysed using the microscopic agglutination test (MAT). Titre cut-points of 1:24 for serovar Hardjobovis and 1:48 for serovars Pomona and Copenhageni were considered positive at the individual animal level. Herds were considered seropositive if there were at least three animals per herd seropositive to any serovar.

RESULTS

Eighty-one percent of herds were seropositive for Leptospira spp. Hardjobovis was the predominant serovar at the herd (78%) and individual animal (60.8%) levels. The seroprevalence of Pomona was 20% and 8.4% at the herd and animal levels, respectively. Dual seroreactivity to both Hardjobovis and Pomona was observed in 16% of herds and 6.6% of individuals; within-herd seroprevalence for both serovars ranged from 0 to 100%. No herds and 1.2% of animals were seropositive for serovar Copenhageni. There was a regional difference in the prevalence of herds seropositive to both Hardjobovis and Pomona (p=0.02), but no difference between regions in the prevalence of herds seropositive to either Hardjobovis or Pomona alone.

CONCLUSION

The seroprevalence of Leptospira spp. serovars is high, and distributed in farmed deer herds throughout New Zealand.

CLINICAL SIGNIFICANCE

Results confirm the risk of disease and potential loss of production in deer, and exposure of infection to humans and other livestock from deer is widespread, demonstrating that control of the disease needs to be considered at a national rather than regional level.

Histopathology of Grossly Normal Mesenteric Lymph Nodes of New Zealand Farmed Red Deer (Cervus elaphus) Including Identification of Lipopigment

This article describes the histopathology of grossly normal mesenteric lymph nodes (MLNs) of New Zealand farmed red deer ( Cervus elaphus). Eighty MLNs were sourced from 10 deer from 5 North Island herds and 5 South Island herds classified as low risk and high risk of Mycobacterium avium subspecies paratuberculosis (MAP) infection, respectively. Fixed sections were stained with hematoxylin and eosin; Ziehl-Neelsen; and, selectively, periodic acid–Schiff, Perl’s, and Sudan black. Positive Ziehl-Neelsen stain, follicular hyperplasia, capsular eosinophil infiltration, focal granulomas, foci of macrophages containing lipopigment, parasitic granulomas, and calcified foci are described and severity graded where appropriate. Animal age, sex, and herd of origin are variably associated with the presence of one or more features. Trabecular fibrosis and dilated edema-filled sinusoids are described. These observations allow differentiation between likely nonpathologic histologic features in deer MLNs and features possibly attributable to infection with a pathogen such as MAP.

Comparison of concentrations of copper in plasma and serum from farmed red deer (Cervus elaphus)

AIM

To determine the relationship between the concentrations of Cu in plasma and serum in red deer, and to compare this relationship with those previously reported in cattle and sheep.

METHODS

Paired serum and heparinised plasma samples from 114 red deer from 10 herds (n=6-20 per herd) were analysed for concentrations of Cu. Samples were collected either at slaughter (n=84; eight herds) or by jugular venepuncture (n=30; two herds). Thirty-nine of the samples taken at slaughter were from adult hinds from four herds, while other samples were taken from 10-14-month-old males, except for one herd (10 samples) where an equal number of 8-9-month-old males and females were sampled. The effect of age, gender and herd on the relationship between concentrations of Cu in plasma and serum was assessed using univariate ANOVA. The individual results for concentrations of Cu in serum were compared with those in plasma, using limits-of-agreement plotting.

RESULTS

The mean concentration of Cu in plasma was not significantly different from that of serum (0.048; 95% CI=-0.14 to 0.24 micromol/L). There was no effect of age, sex or herd on this relationship.

CONCLUSIONS

In deer, there was no significant difference between concentrations of Cu in plasma and serum regardless of age, sex or herd of origin.

CLINICAL RELEVANCE

In contrast to the situation in cattle and sheep, the concentration of Cu in serum can be used interchangeably with that in plasma for the estimation of concentration of Cu in blood of red deer.

Leptospirosis in farmed deer in New Zealand : a review

Current knowledge of leptospirosis in farmed deer in New Zealand is reviewed. Over the past 25 years, leptospirosis has been reported to occur in individual cases as well as in herd outbreaks in farmed deer and in human cases linked to farmed deer. Serological studies and evidence from bacterial culture suggest infection is widespread. Mixing of young stock from several sources appears to be a significant risk factor for outbreaks. The culture of Leptospira interrogans serovars Hardjobovis, Pomona and Copenhageni has been reported. Infection with serovar Hardjobovis had the highest prevalence, either individually or mixed with serovar Pomona. Infection with serovar Copenhageni appears uncommon and its pathogenicity in deer is unproven. Titres to serovars Australis, Ballum, Balcanica and Tarassovi have been reported. Deer appear to be maintenance hosts for serovar Hardjobovis, incidental or accidental hosts and probably a maintenance population for serovar Pomona, since some infections persist for several months, and accidental hosts for serovar Copenhageni. Serovar Pomona appears to produce clinical and probably subclinical disease, whereas serovar Hardjobovis appears to cause only subclinical disease, although the relative risk of disease causation has not been determined. Clinical disease is usually manifested by haemolysis, jaundice, renal lesions, haemoglobinuria and often by sudden death. Renal lesions are commonly observed at slaughter and many are associated with leptospiral infections. Occupationally, slaughterhouse workers appear to be at greatest risk of contracting the disease from deer. Vaccination produces serological responses, but its effectiveness in protecting against disease, and prevention or reduction of shedding in urine, has not yet been confirmed in deer. More robust knowledge of the epidemiology of leptospiral infections in deer, and the effectiveness of vaccines and vaccination regimes, is needed to assist the deer industry to develop a strategy to manage this disease.

Efficacy, distribution and faecal excretion of copper oxide wire particles in a novel bolus in red deer (Cervus elaphus)

AIM

To determine the efficacy of a novel copper oxide wire particle (COWP) formulation in elevating concentrations of copper (Cu) in the liver and serum of red deer (Cervus elaphus), and to investigate the distribution of particles in the gastrointestinal tract and the rate of their excretion in faeces.

METHODS

Mixed-age red deer hinds were allocated to three groups (n=10 per group) on the basis of pre-treatment liver Cu concentrations. Groups 1 and 2 were treated orally with a 10-g COWP bolus on Days 0 and 30, respectively, while the remaining group served as an untreated control. Animals were slaughtered on Day 60, when blood and liver samples were collected for determination of Cu concentrations. An additional group of 18-month-old red deer hinds (n=20) were treated orally with a 10-g COWP bolus, and four were slaughtered on each of Days 1, 5, 15, 30 and 60 after treatment. The gastrointestinal tract was secured between compartments below the oesophagus and contents rinsed until sedimentation of particles was complete. The sediment was oven-dried and COWP were separated and weighed. Faeces were collected continuously from four additional animals held in metabolism cages for 4 days after treatment, sub-sampled daily, and COWP recovered.

RESULTS

Mean liver Cu concentrations at slaughter were 80, 597 and 447 micromol/kg for controls and hinds treated 30, and 60 days previously, respectively. Corresponding mean serum Cu concentrations were 7.7, 12.9 and 11.9 micromol/L, respectively. Liver and serum Cu concentrations were higher in both treatment groups than in untreated control animals (p<0.001). COWP were found in all compartments of the gastrointestinal tract measured, for at least 15 days, and in the rumen/reticulum and abomasum for at least 60 days post-administration. The highest rate of recovery overall was from the rumen/reticulum. Mean weight of COWP recovered from faeces was 0.09 g during the first 24 h and 0.94 g over the first 4 days following administration.

CONCLUSION

The COWP bolus tested resulted in elevated mean liver Cu concentrations for at least 60 days compared with control animals. The majority of COWP were found in the rumen/ reticulum, where recovery was possible for at least 60 days. About 10% of particle weight was excreted in the faeces within 4 days of administration.

CLINICAL SIGNIFICANCE

The test bolus was efficacious in deer, elevating mean liver and serum Cu concentrations 30 and 60 days after treatment. Variation in faecal excretion may explain between-animal differences in efficacy.