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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.

This study aimed to evaluate risk factors associated with shedding of pathogenic Leptospira species in urine at animal and herd levels. In total, 200 dairy farms were randomly selected from the DairyNZ database. Urine samples were taken from 20 lactating, clinically normal cows in each herd between January and April 2016 and tested by real-time polymerase chain reaction (PCR) using gyrB as the target gene. Overall, 26.5% of 200 farms had at least one PCR positive cow and 2.4% of 4000 cows were shedding Leptospira in the urine. Using a questionnaire, information about risk factors at cow and farm level was collected via face-to-face interviews with farm owners and managers. Animals on all but one farm had been vaccinated against Hardjo and Pomona and cows on 54 of 200 (27%) farms had also been vaccinated against Copenhageni in at least one age group (calves, heifers and cows). Associations found to be statistically significant in univariate analysis (at P < 0.2) were assessed by multivariable logistic regression. Factors associated with shedding included cattle age (Odds ratio (OR) 0.82, 95% CI 0.71-0.95), keeping sheep (OR 5.57, 95% confidence interval (CI) 1.46-21.25) or dogs (OR 1.45, 95% CI 1.07-1.97) and managing milking cows in a single as opposed to multiple groups (OR 0.45, 95% CI 0.20-0.99). We conclude that younger cattle were more likely to be shedding Leptospira than older cattle and that the presence of sheep and dogs was associated with an increased risk of shedding in cows. Larger herds were at higher risk of having Leptospira shedders. However, none of the environmental risk factors that were assessed (e.g. access to standing water, drinking-water source), or wildlife abundance on-farm, or pasture were associated with shedding, possibly due to low statistical power, given the low overall shedding rate.

Leptospira infection in dairy cattle and leptospirosis in dairy farm workers were common in New Zealand prior to the introduction of dairy cattle vaccination in the 1980s. Despite widespread vaccination within the dairy industry, the long-term effectiveness of vaccination and current Leptospira exposure status remained unknown. A cross-sectional study was conducted from January-April 2016 to investigate the prevalence of pathogenic Leptospira spp. DNA in urine at cow and herd level, and its relationship to five Leptospira serovars known to be endemic. Two hundred dairy farms were randomly selected from the national database. Twenty paired blood and urine samples were collected on each farm from adult cows (n = 4000). Sera were tested using the Microscopic Agglutination Test against serovars Hardjobovis (termed Hardjo), Pomona, Copenhageni, Ballum and Tarassovi with titres ≥48 being considered positive. Urine was tested using quantitative real-time PCR (qPCR) that amplifies the gryB gene. All but one herd had been vaccinated with a bivalent Hardjo/Pomona or trivalent vaccine incorporating Copenhageni. In total, 2.4% of cows were urine qPCR positive and 27% of farms had at least one urine qPCR positive cow. Overall 63% of cows were seropositive to one or more serovars: 44% for Hardjo, 28% for Pomona, 15% for Copenhageni (in vaccinated herds), and for unvaccinated cows: 1% for Copenhageni, and 3% for Ballum and 17% for Tarassovi. Of the 94 qPCR urine-positive cows, 51 were seropositive to Tarassovi, 3 to Ballum, 3 to Copenhageni, 24 to Hardjo, and 17 to Pomona, the latter two presumably reflecting vaccination titres. A strong association was found between shedding and serology for Tarassovi. While there was no evidence that current vaccination programmes were ineffective in protecting against their target serovars, serovar Tarassovi has apparently emerged in NZ dairy cattle. As Tarassovi is currently not included in vaccines and is prevalent in notified leptospirosis cases in dairy workers, we concluded that this serovar poses a public health risk., (Copyright © 2019 Elsevier B.V. All rights reserved.)

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., (© 2019 Blackwell Verlag GmbH.)

Aim: We report a one-health investigation of three cases of leptospirosis on a dairy farm with unvaccinated cattle in New Zealand. The cases are discussed in the context of diagnostics, risk factors, persistence of symptoms and outbreak mitigation measures., Method: Clinical and laboratory records from the human cases were reviewed and serological and molecular investigations were conducted into the Leptospira status of cattle and pigs on the farm., Results: Cases presented early in their illness and all three were confirmed within seven days of onset of symptoms by urine PCR and within 18 days by convalescent MAT (two Hardjo, one Pomona). Cattle and pigs had serological evidence of recent infection with Hardjo/Pomona and Pomona/Copenhageni respectively. Pigs were slaughtered and cattle were vaccinated. Post-exposure prophylaxis was given to staff in-contact with the milking herd until the herd had antibiotic treatment at drying-off (approximately four months after the initial case)., Conclusion: The utility of PCR testing for Leptospira DNA as both an early and rapid test for leptospirosis was demonstrated. Two of three cases reported persistence of symptoms at least six months after the acute episode and one of these remains unable to work. Risk mitigation measures such as post-exposure prophylaxis, animal vaccination, heightened clinical suspicion of leptospirosis and recognition of context specific risk factors (eg, effluent spreading) demonstrate the value of medical and veterinary experts working together., Competing Interests: Nil.

Unlabelled: Vaccines are used in integrated control strategies to protect poultry against H5N1 high-pathogenicity avian influenza (HPAI). H5N1 HPAI was first reported in Indonesia in 2003, and vaccination was initiated in 2004, but reports of vaccine failures began to emerge in mid-2005. This study investigated the role of Indonesian licensed vaccines, specific vaccine seed strains, and emerging variant field viruses as causes of vaccine failures. Eleven of 14 licensed vaccines contained the manufacturer's listed vaccine seed strains, but 3 vaccines contained a seed strain different from that listed on the label. Vaccines containing A/turkey/Wisconsin/1968 (WI/68), A/chicken/Mexico/28159-232/1994 (Mex/94), and A/turkey/England/N28/1973 seed strains had high serological potency in chickens (geometric mean hemagglutination inhibition [HI] titers, ≥ 1:169), but vaccines containing strain A/chicken/Guangdong/1/1996 generated by reverse genetics (rg; rgGD/96), A/chicken/Legok/2003 (Legok/03), A/chicken/Vietnam/C57/2004 generated by rg (rgVN/04), or A/chicken/Legok/2003 generated by rg (rgLegok/03) had lower serological potency (geometric mean HI titers, ≤ 1:95). In challenge studies, chickens immunized with any of the H5 avian influenza vaccines were protected against A/chicken/West Java/SMI-HAMD/2006 (SMI-HAMD/06) and were partially protected against A/chicken/Papua/TA5/2006 (Papua/06) but were not protected against A/chicken/West Java/PWT-WIJ/2006 (PWT/06). Experimental inactivated vaccines made with PWT/06 HPAI virus or rg-generated PWT/06 low-pathogenicity avian influenza (LPAI) virus seed strains protected chickens from lethal challenge, as did a combination of a commercially available live fowl poxvirus vaccine expressing the H5 influenza virus gene and inactivated Legok/03 vaccine. These studies indicate that antigenic variants did emerge in Indonesia following widespread H5 avian influenza vaccine usage, and efficacious inactivated vaccines can be developed using antigenic variant wild-type viruses or rg-generated LPAI virus seed strains containing the hemagglutinin and neuraminidase genes of wild-type viruses., Importance: H5N1 high-pathogenicity avian influenza (HPAI) virus has become endemic in Indonesian poultry, and such poultry are the source of virus for birds and mammals, including humans. Vaccination has become a part of the poultry control strategy, but vaccine failures have occurred in the field. This study identified possible causes of vaccine failure, which included the use of an unlicensed virus seed strain and induction of low levels of protective antibody because of an insufficient quantity of vaccine antigen. However, the most important cause of vaccine failure was the appearance of drift variant field viruses that partially or completely overcame commercial vaccine-induced immunity. Furthermore, experimental vaccines using inactivated wild-type virus or reverse genetics-generated vaccines containing the hemagglutinin and neuraminidase genes of wild-type drift variant field viruses were protective. These studies indicate the need for surveillance to identify drift variant viruses in the field and update licensed vaccines when such variants appear., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Background: The purpose of this study was to determine the association of potential risk factors to the spread and maintenance of the highly pathogenic avian influenza (HPAI) H5N1 virus in poultry and humans at the district level in West Java Province, Indonesia., Methods: The association of demography and environmental risk factors including poultry density, human density, road density, percentage of paddy field, and percentage of swamp, dyke and pond with both HPAI human cases and HPAI outbreaks in poultry were assessed using a descriptive epidemiological design. We also assessed the association of HPAI outbreaks in poultry with HPAI human cases. Poisson regression (generalized linear modeling and generalized estimating equations) was used to analyze the data corrected for over-dispersion., Results: There were 794 HPAI outbreaks in poultry covering 24 of the 25 districts in our study during 2003-2008 and 34 HPAI human cases involving 12 districts during 2005-2008. We found that two risk factors--poultry density and road density--had a statistically significant correlation with the number of HPAI outbreaks in poultry. The number of poultry outbreaks had a negative association with poultry density (29% effect) and a positive association with road density (67% effect). The number of human cases was significantly associated with the number of poultry outbreaks (34% effect), but with none of the other risk factors considered., Conclusions: We conclude that the most effective way to prevent human HPAI cases is to intervene directly in the poultry sector. Our study further suggests that implementing preventive measures in backyard chicken farming and limiting transport of live poultry and their products are promising options to this end., (Copyright © 2010 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)