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.

Jamides wananga, a new species from Papua New Guinea and Australia (Lepidoptera: Lycaenidae)

Jamides wananga sp. n. is described and illustrated from Madang Province of Papua New Guinea and Dauan Island in the Torres Strait (Queensland, Australia). The new species is similar in appearance to several other Jamides Hübner species in the bochus-group. DNA sequence data and morphology were used to distinguish the nominotypical subspecies found on the New Guinea mainland from J. w. roxina subsp. n. on Dauan Island. Notes on the habitat and behaviour are also provided.

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.

Age-related reproductive performance of the Adélie penguin, a long-lived seabird exhibiting similar outcomes regardless of individual life-history strategy

Age-related variation in reproductive performance in long-lived iteroparous vertebrate species is common, with performance being influenced by within-individual processes, such as improvement and senescence, in combination with among-individual processes, such as selective appearance and disappearance. Few studies of age-related reproductive performance have compared the role of these drivers within a metapopulation, subject to varying degrees of resource competition. We accounted for within- and among-individual changes among known-aged Adélie penguins Pygoscelis adeliae during 17 years (1997-2013), at three clustered colonies of disparate size, to understand patterns in age-related reproductive success during early and late adulthood. Age at first reproduction (AFR) was lowest, and number of breeding attempts highest, at the largest colony. Regardless of AFR, success improved with early post-recruitment experience. For both oldest and youngest recruitment groups, peak performance occurred at the end of their reproductive life span indicating a possible cost of reproduction. Intermediate recruitment groups reached peak performance in their mid-reproductive life span and with intermediate breeding experience, before decreasing. Breeding success was lowest for the initial breeding attempt regardless of AFR, but we observed subsequent variation relative to recruitment age. Gaining experience by delaying recruitment positively influenced reproductive performance early in the reproductive life span and was most evident for the youngest breeders. Oldest recruits had the highest initial and peak breeding success. Differences in AFR resulted in trade-offs in reproductive life span or timing of senescence but not in the overall number of breeding attempts. Patterns differed as a function of colony size, and thus competition for resources. Early life improvement in performance at the larger colonies was primarily due to within-individual factors and at the largest colony, AFR. Regardless of colony size late-life performance was positively related to the age at last reproduction, indicating selective disappearance of lower performing individuals. These results highlight that different life-history strategies were equally successful, indicating that individuals can overcome potential trade-offs associated with early- and late-life performance. These results have important implications for understanding the evolution of life-history strategies responsible for driving population change.

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.

Interlayer Hybridization of Virgin Carbon, Recycled Carbon and Natural Fiber Laminates

To meet sustainability objectives in the transport sector, natural fiber (NF) and recycled carbon fiber (RCF) have been developed, although they have been typically limited to low to medium performance components. This work has considered the effect of interlayer hybridization of woven NF and non-woven RCF with woven virgin carbon fibers (VCF) on the mechanical and damping performance of hybrid laminates, produced using double bag vacuum infusion (DBVI). The mean damping ratio of the pure laminates showed a trend of NF>RCF>VCF, which was inversely proportional to their modulus. The tensile, flexural and damping properties of hybrid laminates were dominated by the outermost ply. The VCF-RCF and VCF-NF hybrid laminates showed a comparatively greater mean damping ratio. The results of this work demonstrate a method for the uptake of alternative materials with a minimal impact on the mechanical properties and improved damping performance.

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.

Estimation of the burden of leptospirosis in New Zealand

BACKGROUND

Human leptospirosis mainly affects people in close occupational contact with domestic livestock and their products in New Zealand. The disease has an unquantified impact on both human health and animal production in the country. This study aimed to estimate the burden of leptospirosis in terms of disability-adjusted life years (DALYs) and cost associated with loss due to absence from work, treatment of disease, animal production loss and cost of vaccination.

METHODS

Previously published studies of abattoir workers farmers, and veterinarians, reporting annual risks of influenza-like illness attributable to Leptospira infection, were used to estimate the expected number of cases in a year. The cost of lost animal production was based on results of observational studies in beef cattle, sheep and deer conducted in New Zealand.

RESULTS

Expected median annual number of severe and mild cases of human leptospirosis was 2,025 (95% probability interval [95% PI] 1,138-3,422). Median annual DALYs were 0.42 (95% PI: 0.06-2.40) per 100,000 people for the entire population, and 15.82 (95% PI: 2.09-90.80) per 100,000 people working in at-risk occupations (i.e. abattoir workers, farmers and veterinarians). Human infection resulted in a median cost of 4.42 (95% PI: 2.04-8.62) million US dollars (USD) due to absence from work and disease treatment. Median production loss cost in beef cattle, sheep and deer was USD 7.92 (95% PI: 3.75-15.48) million, while median vaccination cost in cattle, (including dairy), sheep and deer was USD 6.15 (95% PI: 5.30-7.03) million. Total annual cost of leptospirosis plus vaccination was USD 18.80 (95% PI: 13.47-27.15) million, equivalent to USD 440,000 (95% PI: 320,000-640,000) per 100,000 people.

CONCLUSION

This study provides an estimate of the disease burden and cost of leptospirosis in New Zealand that could support occupational health authorities and livestock industries in assessing interventions for this disease.

Epidemiological investigation of Leptospira spp. in a dairy farming enterprise after the occurrence of three human leptospirosis cases

An epidemiological investigation was conducted in an unvaccinated dairy farming enterprise in which three workers on one of the milking herds (Herd 1) were diagnosed with leptospirosis due to serovars Hardjo (H) (n = 2) and Pomona (P) (n = 1) between January and March 2015. Blood and urine samples were collected from milking cows in Herd 1 (N = 230) and Herd 2 (N = 400), rising one- (R1, N = 125) and rising two-year-old (R2, N = 130) replacement heifers, and four pigs associated with Herd 1, in March 2015. Sera were tested using the MAT for serovars H, P, Copenhageni (C), Ballum (B) and Tarassovi (T), and urine samples were tested by qPCR. Seventy-five per cent of 109 cows in Herd 1 and 36% of 121 in Herd 2 were seropositive (≥48), predominantly to H and P, and 23% of 74 cows in Herd 1 and 1% of 90 cows in Herd 2 were qPCR positive. Fifty-five per cent of 42 R2 heifers were seropositive to T. No R1 and 17% of 42 R2 heifers were qPCR positive. Subsequently, all cattle were vaccinated for H and P, and Herds 1 and 2 were given amoxicillin. After the booster vaccination, 7% of 91 in Herd 1, 2% of 82 in Herd 2 and 11% of 38 R1 heifers (sampled as R2) were PCR positive. After the amoxicillin treatment, no cows in Herd 1 and 5% of 62 cows in Herd 2 were urine PCR positive. Calves and pigs were seropositive to H, P, C and B. Vaccination and antibiotic treatment appeared effective in reducing the risk of exposure of workers to vaccine serovars. However, evidence of non-vaccine serovars indicated that workers likely remain at risk of exposure to Leptospira.

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.

Effects of natural infection by L. borgpetersenii serovar Hardjo type Hardjo-bovis, L. interrogans serovar Pomona and leptospiral vaccination on sheep reproduction

Most New Zealand sheep flocks are seropositive to Leptospira serovars Hardjo and/or Pomona, yet vaccination is rare. This study evaluated the impact of exposure to these serovars and of vaccination, on primiparous one- (P1) and two-year-old (P2) sheep reproduction outcomes. The study was designed as a split-flock vaccination trial, with a third of the animals vaccinated starting at one month of age. Reproduction outcomes were the proportion of bred P1 (7 months old) and as P2 (19 months old) scanned pregnant, the proportion of pregnant ewes rearing a lamb to tail docking and the proportion of docked lambs that were weaned. Odds ratios and their 95% confidence intervals were calculated to compare reproductive performance between vaccinated and control sheep, and within the control group, between seropositive and seronegative sheep. Odds ratios (OR) were also calculated to assess the relationship between vaccination and loss to follow-up. There was no difference in pregnancy and docking rates between vaccinated and control sheep, or between seropositive and seronegative sheep. P1 with a Hardjo titre ≥1536 were significantly less likely (OR = 0.41, 95%CI = 0.19-0.93) to keep a lamb between docking and weaning than P1 with both Hardjo and Pomona titres <1536, for an observed difference in weaning rate of up to 22.6% points on one farm. A reduction of weaning rates in 2-tooths seropositive for Pomona alone and both Hardjo and Pomona was observed but this was non-significant, possibly because of a lack of power. No difference in weaning rate was observed between vaccinated and control P1 or P2. On one farm vaccinated P1 were less likely to be lost to follow-up (OR = 0.27, 95% CI 0.08 to 0.95) between breeding and weaning. Comparing reproductive performance of vaccinated and control sheep revealed no significant difference. However, comparing exposed and non-exposed ewes revealed a possible adverse effect of Leptospira on weaning rates. This suggests that a full vaccination program may result in an improvement of reproductive outcomes, possibly by providing herd immunity.

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.

Interlaboratory and between-specimen comparisons of diagnostic tests for leptospirosis in sheep and cattle

A study was performed to investigate interlaboratory test agreement between a research and a commercial veterinary diagnostic laboratory on blood and urine samples, and to investigate test agreement between blood, urine, and kidney samples (research laboratory) for leptospirosis diagnosis. Samples were sourced from 399 sheep and 146 beef cattle from a local abattoir. Interlaboratory agreement for real-time quantitative polymerase chain reaction (qPCR) results on urine samples was almost perfect (kappa = 0.90), despite the use of different amplification targets (DNA gyrase subunit B gene vs. 16s ribosomal RNA gene), chemistries (SYTO9 vs. TaqMan probe), and pre-PCR processing. Interlaboratory agreement for microscopic agglutination test (MAT) positivity was almost perfect (kappa = 0.93) for Leptospira borgpetersenii serovar Hardjo subtype Hardjobovis (Hardjobovis) but moderate (kappa = 0.53) for Leptospira interrogans serovar Pomona (Pomona). Among animals that had different titers recorded, higher Hardjobovis and lower Pomona titers were reported by the commercial laboratory than by the research laboratory (P < 0.005). These interlaboratory comparisons can assist researchers and diagnosticians in interpreting the sometimes discrepant test results. Within the research laboratory, the comparison of qPCR results on urine and kidney showed almost perfect agreement (kappa = 0.84), suggesting that the qPCR on these 2 specimens can be used interchangeably. The agreement between MAT positivity and urine and kidney qPCR results was fair (kappa = 0.32 and kappa = 0.33, respectively). However, the prevalence ratio of urine and kidney qPCR positivity in Hardjobovis-seropositive versus Hardjobovis-seronegative sheep indicated that Hardjobovis seropositivity found in sheep may be able to predict shedding or renal carriage.

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.

Bayesian estimation of the sensitivity and specificity of individual fecal culture and Paralisa to detect Mycobacterium avium subspecies paratuberculosis infection in young farmed 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.

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.

Paraspinal abscess complicated by endocarditis following a facet joint injection⋆

Infectious complications secondary to lumbar facet injections are exceedingly rare, follow an indolent course, and local sequelae include abscess spread or infections of the central nervous system. We present the case of the development of a facet abscess and infective endocarditis, which developed shortly after a lumbar facet injection. With the increase in interventional pain procedures, physicians must be aware of potential infectious complications.

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.