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This study tested for association between Toxoplasma gondii and pregnancy and abortion to investigate sub-optimal reproduction in farmed red deer (Cervus elaphus). Sera from a sub-sample (n = 2304) of pregnant and non-pregnant hinds in early gestation at first pregnancy scan (scan 1) and approximately at the end of second trimester at second pregnancy scan (scan 2) were tested for T. gondii antibodies using a validated ELISA. Foetuses and/or uteri from pregnant, non-pregnant, and aborting hinds at scan 1, scan 2, or weaning were tested for T. gondii DNA by nested PCR. At scan 1, 31.1% of 861 rising two-year-old (R2) and 28.3% of 357 mixed-aged (MA, ≥ 2 years) hinds were sero-positive. There was no association between scan 1 serology and non-pregnancy at animal (R2, p = 0.05 and MA, p = 0.43) or herd level (R2, p = 0.37). Toxoplasma gondii DNA was detected in 3/18 placenta and 4/18 foetal brains from aborting R2 hinds and 15/157 R2 and 3/21 MA uteri from non-pregnant hinds at scan 1. At scan 2, sero-prevalence was higher (odds ratio = 1.6, 95% CI = 1.04-2.48) in aborted (34.3% of 268) than in non-aborted (23.5% of 446) R2 hinds (p = 0.03) and 7.9% of abortions between scans were attributable to T. gondii exposure. Within-herd sero-prevalence at scan 2 was positively associated with daily abortion rate in R2 herds with aborted hinds (p < 0.001) but not in MA herds (p = 0.07). Toxoplasma gondii DNA was detected in 27/169 uteri, 2/20 cotyledons, and 1/5 foetal brains from aborted hinds at scan 2 and in uteri from 5/33 hinds not rearing a calf to weaning. Toxoplasma gondii RFLP genotyping of five loci revealed a unique type I/III genotype pattern, TgRDNZ1, in a foetal brain sample, not been previously reported in deer. These findings provide serological and molecular evidence that T. gondii infection is associated with abortion in red deer, possibly in all three trimesters.

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., (Copyright © 2018 Elsevier B.V. All rights reserved.)

AIMS To determine seroprevalence of Leptospira borgpetersenii serovar Hardjo and L. interrogans serovar Pomona in beef cattle, sheep and deer in New Zealand and the association between farm-level risk factors and seroprevalence. METHODS Between June 2009 and July 2010, 20 serum samples per flock or herd were collected from 162 sheep flocks, and 116 beef cattle and 99 deer herds from 238 farms, along with farm data by interview. Samples were tested for antibodies to serovars Hardjo and Pomona by microscopic agglutination testing, with a titre ≥48 being positive. Species-specific associations between herd-level seroprevalence (number of seropositive animals, for each serovar, divided by the number of animals tested) and herd-level risk factors were determined by multivariable logistic regression analysis. Vaccinated animals were excluded from seroprevalence estimates but included in multivariable analyses. RESULTS For sheep (n=3,339), animal-level seroprevalence was 43.6 (95% CI=41.9-45.3)% for serovar Hardjo and 14.1 (95% CI=12.9-15.3)% for serovar Pomona; for beef cattle(n=1,886), it was 45.6 (95% CI=43.3-47.9)% for Hardjo and 19.6 (95% CI=17.9-21.5)% for Pomona; and for deer (n=1,870), it was 26.3 (95% CI=24.3-28.4)% for Hardjo, 8.8 (95% CI=7.6-10.2)% for Pomona. In sheep flocks (n=161), flock-level prevalence for Hardjo varied from 77.9-91.3%, and for Pomona from 40.4-73.9%, when ≥1, ≥2 or ≥3 animals were seropositive. In beef herds (n=95), herd-level prevalence for Hardjo varied from 79.0-90.5%, and for Pomona from 42.1-68.4%. In deer herds (n=93), herd-level prevalence for Hardjo varied from 45.2-59.1%, and for Pomona from 22.6-48.4%. For sheep flocks, herd-level seroprevalence for Hardjo was associated with flock size (OR=1.56) and number of dogs (OR=0.75), and for Pomona, seroprevalence varied with region. For beef cattle, herd-level seroprevalence for Hardjo was associated with herd size (OR=1.4), presence of dams (OR=0.6) and vaccination (OR=2.9), and for Pomona, co-grazing with deer (OR=0.4), vaccination (OR=3.22), presence of dams (OR=0.2) and streams (OR=2.7). For deer herds, seroprevalence for Hardjo or Pomona was associated with herd size (OR=1.6 and 1.8) and varied with region, and for Pomona seroprevalence varied with season (summer vs. winter: OR=4.8). CONCLUSIONS Serovars Hardjo and Pomona were highly prevalent at herd and animal levels, with serovar Hardjo highest in all species. Larger herd size was the common risk factor for seroprevalence in all livestock species.

This paper describes pregnancy and mid-term abortion rate data from an investigation of sub-optimal reproductive performance in New Zealand farmed red deer. For 2 years, 87 yearling (YL) and 71 mixed-age adult (MA) herds from 85 farms were observed with 15 YL and seven MA herds observed both years. Hinds were pregnancy diagnosed using ultrasonography in the late autumn-early winter (PD1) and again late winter-early spring (PD2) and mid-term daily abortion rates (DAR) were calculated. Overall, 85.8% of 22,130YL (range, 7.0%-100% between herds) and 93.3% of 36,223 MA hinds (range, 39.8%-100% between herds) were pregnant at PD1. The mean interval between ultrasonic assessments was 90 and 87 days in YL and MA herds, respectively. Mid-term abortions occurred in 305 (2.8%) hinds from 60 (73%) YL herds and 92 (1.2%) hinds from 36 (61%) MA herds. The mean mid-term DAR, was greater (P = 0.009) in YL (mean 0.043%, range 0.005%-0.213%, 95% CI = 0.034-0.053) than MA herds (mean 0.025%, range 0.007%-0.101%, 95% CI = 0.018-0.032). In herds with hinds that aborted, the mean DAR was greater in small than large YL herds (0.055% compared with 0.033%, P = 0.023), but not MA herds. At PD1, 46 YL and 12 MA hinds had ultrasonographic evidence of abortions from 22 herds. This, combined with the 1.2% to 7.1% foetal loss in three herds pregnancy diagnosed earlier than the usual PD1 date as a pilot to test for earlier abortion, supports that abortion can occur prior to normal pregnancy assessment dates, contributing to sub-optimal pregnancy rates. Abortion rates were not consistent within herd between years for either YL or MA herds. Thus, early and mid-term abortion is prevalent in New Zealand farmed deer constituting a significant production cost, warranting further investigation into causation., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This paper investigates Leptospira borgpeterseni serovar Hardjobovis and L. interrogans serovar Pomona as potential causes of sub-optimum pregnancy rates and mid-term abortion in 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 ultrasound scanned early in gestation (Scan-1) and a sub-sample re-scanned (Scan-2) 55-89 days later and mid-term daily abortion rate calculated. A sub-sample of sera from pregnant and non-pregnant hinds at both scans, both with (case herds) and without aborted hinds was tested for Leptospira using the microscopic agglutination test with titre cut-point ≥1:48 as positive. At Scan-1, 44.3% of 661 and 4.6% of 647 hinds were sero-positive for Hardjobovis and Pomona, respectively. The geometric mean titre (GMT) for Pomona was higher in pregnant than non-pregnant MA hinds (p = 0.015) but not in R2 hinds. At Scan-2 in case herds, 40.3% of 2242 and 7.1% of 2243 hinds were sero-positive for Hardjobovis and Pomona, respectively. There was no association between Hardjobovis or Pomona serology and non-pregnancy (Scan-1) or mid-term abortion (Scan-2) at animal or herd level. In case herds, GMT was higher in non-aborted than aborted hinds for Hardjobovis (p = 0.018) in MA herds and for Pomona in R2 herds (p = 0.006). No uteri from hinds not pregnant or aborting at either scan, or not rearing a calf to weaning, and fetuses as available, were positive on PCR. Evidence is insufficient to confirm that Leptospira Hardjobovis and Pomona play a significant role in sup-optimum early pregnancy or mid-term abortion rates in deer., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This review summarises current control measures for clinical paratuberculosis (Johne's disease; JD) in New Zealand pastoral livestock. Most New Zealand sheep, deer, beef and dairy cattle herds and flocks are infected by Mycobacterium avium ssp. paratuberculosis (Map). Dairy cattle and deer are mostly infected with bovine (Type II), and sheep and beef cattle with ovine (Type I) strains. Control in all industries is voluntary. While control in sheep and beef cattle is ad hoc, the dairy and deer industries have developed resources to assist development of farm-specific programmes. The primary target for all livestock is reduction of the incidence rate of clinical disease rather than bacterial eradication per se. For dairy farms, a nationally instituted JD-specific programme provides guidelines for risk management, monitoring and testing clinically suspect animals. While there is no formal programme for sheep farms, for those with annual prevalences of clinical disease >2%, especially fine wool breeds, vaccination may be a cost effective control option. The deer industry proactively monitors infection by a national abattoir surveillance programme and farmers with an apparent high disease incidence are encouraged to engage with a national network of trained consultants for management and control advice. Evaluation of the biological and economic effectiveness of control in all industries remains to be undertaken. Nevertheless, opportunities exist for farmers, who perceive significant JD problems in their herds/flocks, to participate in systematic best-practice activities that are likely to reduce the number of clinical infections with Map on their farms, and therefore the overall prevalence of JD in New Zealand's farming industries.

Abortion due to Toxoplasma gondii has been suspected in New Zealand farmed red deer. However, knowledge around the epidemiology and prevalence of T. gondii in farmed red deer is limited. The aim of this study was to firstly, assess the sensitivity and specificity of two commercially available assays, ELISA and latex agglutination test (LAT), for use in deer and secondly, to estimate the sero-prevalence of T. gondii in red deer. A total of 252 sera from rising 2-year-old and adult hinds from 17 New Zealand red deer herds at early and late pregnancy scanning and from known aborted and/or non-aborted hinds were tested for the presence of T. gondii antibodies. Each assays' sensitivity and specificity was evaluated by both the Western Blot (WB) as a gold standard method and Bayesian latent class (BLC) analysis in the absence of a gold standard. The sensitivity and specificity for WB were 95.8% (95% credible interval: 89.5-99.2%) and 95.1% (95% credible interval: 90.6-98.1%), respectively. For the LAT at the manufacturer's recommended ≥1:32 cut-off titre, the sensitivity (88.7%, 95% credible interval: 80.8-94.7%) and specificity (74.3%, 95% credible interval: 67.5-80.5%) were lower and higher than the sensitivity (76.2%, 95% credible interval: 66.7-84.5%) and specificity (89.7%, 95% credible interval: 84.5-93.9%) at a ≥1:64 cut-off, using (BLC) analysis. Sensitivity and specificity of the LAT at cut-off titre of 1:32 were estimated to be 84.4% (95% CI: 74.9-90.9%) and 73.5% (95% CI: 65.8-79.9%) against WB. The LAT had better agreement with WB at cut-off titre of ≥1:64 than ≥1:32 (Kappa=0.63 vs 0.54). At optimised cut-off S/P of 15.5%, the sensitivity (98.8%, 95% credible interval 96.1-99.8%) and specificity (92.8%, 95% credible interval 88.9-95.7%) of the ELISA were higher and lower, respectively, than the sensitivity (85.1%, 95% credible interval 76.2-91.9%) and specificity (98.5%, 95% credible interval 96.9-99.4%) at manufacturer's cut-off S/P of 30%, from BLC analysis. The sensitivity and specificity of ELISA at S/P cut-off of 15.5% was 91.1% (95% CI: 83.2-96.1%) and 90.7% (95% CI: 85.2-94.7%), respectively, when assessed against WB. The sero-prevalence from ELISA and LAT, at cut-off of S/P 15.5% and ≥1:64, respectively, was not significantly different to that from WB (McNemar's Chi-square p=0.21 for ELISA and p=0.28 for LAT)., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The present study aimed to describe the molecular diversity of Mycobacterium avium subsp. paratuberculosis (MAP) isolates obtained from sheep, cattle (beef and dairy) and deer farms in New Zealand. A total of 206 independent MAP isolates (15 beef cattle, 89 dairy cattle, 35 deer, 67 sheep) were sourced from 172 species-mobs (15 beef cattle, 66 dairy cattle, 31 deer, 60 sheep). Seventeen subtypes were identified, using a combination of variable number of tandem repeats (VNTR) and short sequence repeat (SSR) methods. Rarefaction analysis, analysis of molecular variance (AMOVA), Fst pairwise comparisons and proportional similarity index (PSI) were used to describe subtype population richness, genetic structure and potential associations between livestock sectors and New Zealand two main islands (North and South). The rarefaction analysis suggests a significantly higher subtype richness in dairy cattle herds when compared to the other livestock sectors. AMOVA results indicate that the main source of subtype variation is attributable to the livestock sector from which samples were sourced suggesting that subtypes are generally sector-specific. The pairwise Fst results were similar, with low Fst values for island differences within a livestock sector when compared to between sector analyses, representing a low subtype differentiation between islands. However, for a given island, potential associations were seen between dominant subtypes and specific livestock sectors. Three subtypes accounted for 76% of the isolates. The most common of these was isolated from sheep and beef cattle in the North Island, the second most frequent subtype was mainly isolated from dairy cattle (either island), while the third most common subtype was associated with deer farmed in the South Island. The PSI analysis suggests similarities in subtypes sourced from sheep and beef cattle. This contrasted with the isolates sourced from other livestock sectors, which tended to present sector-specific subtypes. Sheep and beef cattle were mainly infected with MAP Type I, while dairy cattle and deer were almost exclusively infected with MAP Type II. However, when beef cattle and deer were both present at farm level, they harboured similar subtypes. This study indicates that cross-species transmission of MAP occurs on New Zealand farms although close contact between species appears to be required, as in the case of sheep and beef cattle which are commonly grazed together in New Zealand., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The study aimed to estimate the national- and island-level flock/herd true prevalence (HTP) of Mycobacterium avium subsp. paratuberculosis (MAP) infection in pastoral farmed sheep, beef cattle and deer in New Zealand. A random sample of 238 single- or multi-species farms was selected from a postal surveyed population of 1940 farms. The sample included 162 sheep flocks, 116 beef cattle and 99 deer herds from seven of 16 geographical regions. Twenty animals from each species present on farm were randomly selected for blood and faecal sampling. Pooled faecal culture testing was conducted using a single pool (sheep flocks) or two pools (beef cattle/deer herds) of 20 and 10 samples per pool, respectively. To increase flock/herd-level sensitivity, sera from all 20 animals from culture negative flocks/herds were individually tested by Pourquier(®) ELISA (sheep and cattle) or Paralisa™ (deer). Results were adjusted for sensitivity and specificity of diagnostic tests using a novel Bayesian latent class model. Outcomes were adjusted by their sampling fractions to obtain HTP estimates at national level. For each species, the posterior probability (POPR) of HTP differences between New Zealand North (NI) and South (SI) Islands was obtained. Across all species, 69% of farms had at least one species test positive. Sheep flocks had the highest HTP estimate (76%, posterior probability interval (PPI) 70-81%), followed by deer (46%, PPI 38-55%) and beef herds (42%, PPI 35-50%). Differences were observed between the two main islands of New Zealand, with higher HTP in sheep and beef cattle flocks/herds in the NI. Sheep flock HTP was 80% in the NI compared with 70% (POPR=0.96) in the SI, while the HTP for beef cattle was 44% in the NI and 38% in the SI (POPR=0.80). Conversely, deer HTP was higher in the SI (54%) than the NI (33%, POPR=0.99). Infection with MAP is endemic at high prevalence in sheep, beef cattle and deer flocks/herds across New Zealand., (Copyright © 2014 Elsevier B.V. All rights reserved.)

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.

A Bayesian latent class model was used to estimate the sensitivity and specificity of an immunoglobulin G1 serum enzyme-linked immunosorbent assay (Paralisa) and individual fecal culture to detect young deer infected with Mycobacterium avium subsp. paratuberculosis. Paired fecal and serum samples were collected, between July 2009 and April 2010, from 20 individual yearling (12-24-month-old) deer in each of 20 South Island and 18 North Island herds in New Zealand and subjected to culture and Paralisa, respectively. Two fecal samples and 16 serum samples from 356 North Island deer, and 55 fecal and 37 serum samples from 401 South Island deer, were positive. The estimate of individual fecal culture sensitivity was 77% (95% credible interval [CI] = 61-92%) with specificity of 99% (95% CI = 98-99.7%). The Paralisa sensitivity estimate was 19% (95% CI = 10-30%), with specificity of 94% (95% CI = 93-96%). All estimates were robust to variation of priors and assumptions tested in a sensitivity analysis. The data informs the use of the tests in determining infection status at the individual and herd level.

Aims: To develop and validate criteria for identification of abnormal lymph nodes (LN) at commercial slaughter, for the purpose of national surveillance for Mycobacterium avium subspecies paratuberculosis (Map) in New Zealand farmed deer. This included estimation of the predictive value of abnormal LN for Map infection; a standard circumference cut-point for measurement of abnormal LN; and identification of risk factors associated with increasing LN circumference., Methods: In Study 1, official assessors sampled 129 LN with macroscopically visible abnormalities (abnormal LN) from 76 deer herds between May and November 2007. LN samples were cultured for Map, with culture-negative LN further examined for typical histopathological changes. The predictive value of abnormal LN for Map infection was calculated and significance of herd location (North or South Island) assessed. In Study 2, the circumferences of 412 mesenteric LN (MLN) from 79 herds were measured between October 2007 and January 2009, with samples cultured for Map and examined for eight histopathological features. The minimum circumference of an abnormal MLN was defined, based on an arbitrary >95% specificity of a culture-positive Map diagnosis. Associations between the predictor variables Map culture status, carcase weight, animal age and gender, and histopathological features, and increasing MLN circumference were assessed using a linear mixed-effects model., Results: Based solely on culture, the predictive value of abnormal LN for Map infection was 92.2 (95% CI: 86.2-96.2)% with no difference between the North and South Islands (p = 0.09). Inclusion of three culture-negative LN with histopathological changes typical of Map infection increased the predictive value estimate to 94.6 (95% CI: 89.2-97.3)%. The minimum circumference of an abnormal MLN was defined as 55 mm, with a sensitivity of Map detection at this cut-point of approximately 12%. Increasing MLN circumference was positively associated with the presence of moderate follicular hyperplasia (p < 0.01), focal granulomas (p < 0.01) and a synergistic interaction between focal granulomas and Map status (p = 0.03)., Conclusions: Deer MLN with macroscopically visible abnormalities and/or a circumference of >55 mm have >95% likelihood of Map infection. However, sensitivity of Map diagnosis in MLN with circumference of >55 mm was 12%, indicating use of abnormal LN as a sole criterion in national surveillance for Map in slaughtered deer will underestimate animal-level prevalence.

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.

This study aimed to develop a mathematical model describing the dynamics of paratuberculosis (PTB) in red deer (Cervus elaphus) under pastoral farming conditions in New Zealand. The model examined infectivity differences between ovine and bovine strains of Mycobacterium avium subspecies paratuberculosis (MAP) and seasonality of MAP survival. We also evaluate variable use of pasture and the effect of management interventions on the infection prevalence and annual clinical incidence of PTB. A state-transition model was developed and calibrated to observed data on both prevalence of infection and incidence of clinical PTB. To accommodate specific PTB features for deer, the model included a fast and a slow track for progression of infection to disease. MAP on pasture was the source for horizontal transmission and infected dams for vertical transmission. In the presence of a single strain, an infectivity reduction of up to 80% allowed MAP to persist in the herd (R(0)>1). For mixed infection by two strains however, a 30% reduction in infectivity of one strain was sufficient to outcompete a strain with lower infectivity, suggesting that mixed infection of MAP strains with different infectivity may not be common in deer. The model showed that seasonal variation of MAP survival on pasture had little impact on transmission dynamics, and that rotational grazing with pasture spelling vs. permanent grazing of the same paddock reduced both infection prevalence and clinical PTB by about 50%. Based on model outputs, early detection of young deer in a high-shedding state was the most effective means of controlling PTB among the tested scenarios., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Aim: To investigate the seroprevalence of Leptospira spp. serovars Hardjo-bovis and Pomona on deer and mixed deer, sheep and/or beef cattle farms in the lower North Island of New Zealand and to examine associations between putative risk factors for seropositive deer herds., Methods: Serological screening was conducted on 19 commercial deer farms, 16 with sheep and/or beef cattle, between August and October each year between 2006 and 2008. No leptospiral vaccination had been conducted on the farms. On each farm every year, serum samples were collected from a random sample of 20 or more rising 2-year-old replacement animals from each species. The microscopic agglutination test (MAT) was used to detect leptospiral antibodies against Leptospira borgpetersenii serovar Hardjo-bovis and Leptospira interrogans serovar Pomona. For both serovars, a titre of ≥1:48 was considered positive and a herd was considered seropositive if >3 of 20 serum samples were positive. Information on potential herd-level risk factors for deer herds being seropositive was obtained from a questionnaire completed by the farm owner or manager., Results: The mean percentage of deer, cattle and sheep herds seropositive for Hardjo-bovis alone over 3 years was 42%, 53% and 54%, respectively, and for serovar Pomona was 7%, 5% and 0%, respectively. Antibodies to both serovars were found in 23%, 16% and 10% of deer, cattle and sheep herds, respectively. At the individual animal level, 228/1,107 (21%) deer, 308/767 (40%) cattle and 369/1,244 (30%) sheep were seropositive for Hardjo-bovis, 102 (9%) deer, 51 (7%) cattle and 23 (2%) sheep were seropositive for Pomona, and 49 (4%) deer, 28 (4%) cattle and 18 (1%) sheep were seropositive for both serovars. Deer herds were more likely to be seropositive for Hardjo-bovis in 2006 than 2008 (p=0.008), when seropositive in the preceding year (p=0.016) and on hilly compared with flat topography (p<0.001). Deer herds were more likely to be seropositive for Pomona when seropositive in the preceding year (p=0.016), when co-grazing with sheep flocks that were seropositive for Pomona (p<0.001), and when herds had a closed- compared with open-herd replacement policy (p<0.001)., Conclusions: Exposure to Leptospira spp. was widely distributed in deer, sheep and beef cattle in the lower North Island of New Zealand. Co-grazing of deer with sheep that were seropositive was a potential risk factor for deer herds to be seropositive.

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.

Aim: To assess the effect of vaccination against paratuberculosis (Johne's disease) on reactivity to diagnostic tests for bovine tuberculosis (Tb) in deer exposed to natural challenge with Mycobacterium avium subsp. paratuberculosis (Map), and to investigate Map infection as a factor in Tb test cross-reactivity at the herd level., Methods: In Study 1, yearling deer (n=180 vaccinates and n=181 controls) were randomly selected from three commercial deer herds participating in a trial of a commercial vaccine against paratuberculosis. The deer were subjected to the comparative cervical skin test (CCT) for Tb at 44 weeks post-vaccination. Interpretation as a mid-cervical tuberculin skin test (MCT) was also recorded. Serum from deer positive to the CCT was collected 3-4 weeks after tuberculin injection and tested using the ELISA Tb test (ETB), with both standard and the modified-ETB interpretations. In Study 2, 102 herds were categorised as infected or uninfected with Map based on results of pooled faecal culture, and positive to MCT if one or more deer gave a positive reaction to the MCT following testing in 2005. Information on other potential risk factors for MCT reactivity was collected using a standardised questionnaire conducted on each farm. The data were analysed using a multivariable logistic regression model., Results: In Study 1, 79/180 (44%) vaccinates and 42/181 (23%) controls were positive to the MCT (p<0.001). Two vaccinates (1.1%) that were CCT-positive were both positive to the standard ETB and negative to the modified ETB. One of three CCT-positive controls was negative to the standard ETB, and the other two were positive; both controls were modified ETB-positive. In Study 2, significantly more MCT-positive (41/58; 71%) than MCT-negative (18/44; 41%) herds were infected with Map (p=0.003). The OR for a positive MCT for herds infected with Map was 3.1 (95% CI=1.3-7.5), compared with uninfected herds. Herd size was positively associated with a positive MCT result (p=0.004)., Conclusions: Infection with Map and vaccination increased the risk of non-specificity of the MCT in deer herds. The CCT and ancillary testing of CCT-positive animals using the modified ETB are effective tools to address the reduced specificity of the MCT. However, where use of these tests is not permitted, non-specificity related to infection and vaccination will be more difficult to resolve.

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.

A SYTO9 real-time polymerase chain reaction assay for detection of pathogenic Leptospira spp. based on amplification of DNA gyrase subunit B (gyrB) gene has been optimized and evaluated for sensitivity and specificity on kidney and urine samples of New Zealand farmed deer. The detection limit was 10(3) cells/ml (2-10 copies/reaction). Comparison of the assay on deer kidneys (n = 268) with culture as the gold standard revealed a sensitivity and specificity of 85% and 99.2%, respectively. For deer urine (n = 113), the assay was compared with known inoculated samples and revealed a sensitivity and specificity of 96.7% and 100%, respectively. The assay was applied for quantifying pathogenic leptospires shed naturally in deer urine and revealed a detectable concentration of 3.7 × 10(3) to 1.7 × 10(6) cells/ml. To assess the assay's capability for identifying pathogenic Leptospira spp., 14 field isolates of L. borgpetersenii serovar Hardjo-bovis and L. interrogans serovar Pomona were amplified for polymerase chain reaction (PCR) product, purified, and sequenced. When compared with the National Center for Biotechnology Information database, sequence data matched with L. borgpetersenii serovar Hardjo-bovis in 13 samples and L. interrogans serovar Pomona in 1 sample, which was consistent with the microscopic agglutination test (MAT). Sequence analysis of purified PCR product amplified directly from kidney and urine samples also yielded serovar-comparable MAT results. Results suggest that the assay is rapid, sensitive, and specific for detection of pathogenic leptospires in deer clinical samples. The developed assay can also be used for estimating the concentration of leptospires and identifying Leptospira spp. in combination with DNA sequencing.

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.

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.

Aim: To find evidence for localisation in the uterus, and fetal infection, of Leptospira spp. in farmed deer in the lower North Island of New Zealand during and shortly after the breeding season., Methods: Between February and July 2008, 116 blood samples, 120 kidneys, 120 uteri and 27 fetuses were collected from 120 mixed-age hinds from lines from nine farms, at a deer slaughter premises. Serum samples were tested for antibodies against Leptospira borgpetersenii serovar Hardjo-bovis and Leptospira interrogans serovar Pomona, using the microscopic agglutination test (MAT). For both serovars, a titre of ≥1:48 was considered positive. Samples from kidneys, uteri and fetal tissue were subjected to bacterial culture, using Ellinghausen-McCullough-Johnson-Harris (EMJH) medium, and real-time PCR, using DNA gyrase subunit B gene primers., Results: Thirty-four of 116 (29.3%) serum samples were positive for serovar Hardjo-bovis, and 13 (11.2%) for serovar Pomona. Seven of 120 kidneys were positive for serovar Hardjo-bovis by culture, and five of these, but no others, were positive by real-time PCR. Of 120 uteri, none was culture- or PCR-positive. None of 27 fetal samples was culture-positive but one was positive by real-time PCR. The dam of the PCR-positive fetus was culture-negative from the kidney, but had an MAT titre of 1:192 for Hardjo-bovis., Conclusions: Attempts to isolate Leptospira spp. from the genital tracts and early fetuses of farmed deer were unsuccessful. However, molecular evidence suggested fetal infection in one case. This finding justifies further study of the role of leptospires in the genital tract and fetus and its association with reproductive loss in farmed deer.

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.

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.

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. 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. 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. 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. 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. [ABSTRACT FROM AUTHOR]

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 fourmonth-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. [ABSTRACT FROM AUTHOR]