[First isolation of Leptospira borgpetersenii serovar Hardjo type Hardjo Bovis from a clinical case in cattle in Argentina]. / Primer aislamiento de Leptospira borgpetersenii serovar Hardjo tipo Hardjo Bovis a partir de un caso clínico en Argentina.

We here describe the first isolation and molecular typing of Leptospira borgpetersenii serovar Hardjo Bovis in Argentina, obtained from urine of aborted cows from a breeding herd located in Saladillo, Buenos Aires Province. The abortions occurred in coincidence with important floods with many cows presenting suspicious serological titers and subsequent seroconversion. The percentage of abortions was 3.5% of a herd of 1700 cows and the microorganism was isolated from 7 of the 20 urine samples obtained.

Human Hardjo leptospirosis detected in the Slovak Republic by using serum antibody absorption test.

OBJECTIVE: The study was aimed at the discovery of the possible presence of the human Hardjo leptospirosis in Slovakia. BACKGROUND: Throughout the world, there is a considerable number of publications confirming the presence of this zoonotic infection in domestic animals. On the contrary, scarcely more than a dozen of reports dealing with this occupational disease in humans was published till now. Moreover, the results of them are not convincing in all cases. MATERIAL AND METHODS: Patients´ and dairy cattle serum samples with detected antibodies against the Leptospira strains belonging to four different serovars of the serogroup Sejroe known to be present in Slovakia (i. e. Sejroe, Istrica, Saxkoebing, Polonica) and also reacting with serovar Hardjo strains were examined by using the serum-agglutinin absorption tests in order to determine the etiological agent of the illness on serovar level.  RESULTS: The Hardjo infection was unequivocally confirmed approximately in 1/5 of patients´sera and in 3/5 of dairy cattle sera. CONCLUSION: The AATs are useful tools for detection of Hardjo leptospirosis what is a necessary condition for determination of appropriate epidemiological measures related to this occupational disease. As our knowledge, this methodological approach was not used by other authors till now (Tab. 4, Fig. 1, Ref. 19).

Protection of sheep by vaccination against experimental challenge with Leptospira borgpetersenii serovar Hardjo and L. interrogans serovar Pomona.

AIMS: To evaluate a multivalent leptospiral and clostridial vaccine for prevention of renal colonisation and urinary shedding in sheep, following experimental challenge with New Zealand strains of Leptospira borgpetersenii serovar Hardjo type Hardjobovis and L. interrogans serovar Pomona. METHODS: Two separate but similarly designed studies were conducted. In both studies, Romney-cross lambs, aged 9-11 weeks, were randomly allocated to a vaccinated group and a control group. Vaccinated lambs each received two 1.5-mL S/C doses of a multivalent leptospiral and clostridial vaccine, 4 weeks apart, and animals in the control groups received the same dose of saline. Groups of 12 vaccinated and 12 control lambs were randomly selected in each study for challenge with serovars Hardjo or Pomona. Challenge was initiated 16 weeks following the second vaccination with three daily doses of live leptospires by intranasal and conjunctival routes. Following challenge, urine samples were collected weekly for 6 weeks, for dark field microscopy and leptospiral culture; 6 weeks after challenge the lambs were slaughtered and kidneys collected for leptospiral culture. RESULTS: In lambs challenged with serovar Hardjo, 8/12 unvaccinated lambs had ≥1 urine or kidney sample that was positive for leptospires following culture, compared with 0/12 lambs in the vaccinated group (p=0.001). In lambs challenged with serovar Pomona, 9/12 unvaccinated lambs had ≥1 urine or kidney sample that was positive following culture, compared with 0/12 lambs in the vaccinated group (p<0.001). Prevention of renal colonisation and urinary shedding, expressed as the prevented fraction, was 100 (95% CI=61.7-100)% and 100 (95% CI=68.3-100)% against challenge with serovars Hardjo and Pomona, respectively, at 4 months after vaccination. CONCLUSIONS AND CLINICAL RELEVANCE: Use of a multivalent leptospiral and clostridial vaccine demonstrated protection against challenge from New Zealand strains of serovars of Hardjo and Pomona 4 months after vaccination in lambs first vaccinated at 9-11 weeks of age. Further studies are required to assess the duration of immunity against challenge in sheep.

Seroprevalence and herd-level risk factors for seroprevalence of Leptospira spp. in sheep, beef cattle and deer in New Zealand.

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.

Risk of infection and associated influenza-like disease among abattoir workers due to two Leptospira species.

The aims of this study were to determine the annual incidence of infection with Leptospira interrogans serovar Pomona and/or Leptospira borgpetersenii serovar Hardjo and its association with influenza-like illness (ILI) in meat workers in New Zealand. Sera were collected twice, 50-61 weeks apart, from 592 workers at eight abattoirs slaughtering sheep (n = 4), cattle (n = 2) and deer (n = 2), and tested by the microscopic agglutination test for Hardjo and Pomona. Forty-nine (8·3%) participants either seroconverted or had at least a twofold increased serological titre against either serovar. The worker infection risk was higher in sheep abattoirs (11·9%) than in abattoirs processing deer (0%) or cattle (1·2%) (P < 0·01). The annualized risk of mild (ILI) or severe clinical disease attributable to the two Leptospira serovars was 2·7%. This study has demonstrated that meat workers are at substantial risk of infection and clinical disease, suggesting further investigation of infection sources and preventive measures are warranted.

Effect of exposure to Neospora caninum, Salmonella, and Leptospira interrogans serovar Hardjo on the economic performance of Irish dairy herds.

The objective of the current study was to quantify the effects of exposure to Salmonella, Neospora caninum, and Leptospira interrogans serovar Hardjo (L. hardjo) on dairy farm profitability and to simulate the effect of vaccination for Salmonella and L. hardjo on dairy farm profitability. The production effects associated with exposure to each of these pathogens in study herds were defined under 3 categories: (1) milk production effects, (2) reproduction effects (including culling), and (3) mortality effects. The production effects associated with exposure to Salmonella, N. caninum, and L. hardjo were incorporated into the Moorepark Dairy Systems Model. In the analysis, herds negative for exposure to Salmonella, N. caninum, and L. hardjo were assumed baseline herds, with all results presented relative to this base. In simulations examining the effect of vaccination for Salmonella and L. hardjo on farm profitability, vaccinated herds (vaccination costs included) were considered as baseline herds and results were presented relative to this base. Total annual profits in unvaccinated herds were reduced by €77.31, €94.71, and €112.11 per cow at milk prices of €0.24, €0.29, and €0.34/L, respectively, as a result of exposure to Salmonella. In the current study, herds positive for exposure to Salmonella recorded a 316-kg reduction in milk yield, whereas no association was detected between exposure to N. caninum or L. hardjo and milk production. Exposure to both N. caninum and L. hardjo was associated with compromised reproductive performance. Herds positive for exposure to N. caninum and Salmonella had greater rates of adult cow mortality and calf mortality, respectively. Vaccination for both Salmonella and L. hardjo was associated with improved performance in study herds. Exposure to N. caninum resulted in a reduction in annual farm profits of €11.55, €12, and €12.44 per cow at each milk price, whereas exposure to L. hardjo resulted in a reduction in annual farm profits of €13.83, €13.78, and €13.72 per cow at each milk price. Herds that tested positive for exposure to Salmonella and L. hardjo were compared with herds vaccinated for the respective pathogens. Herds vaccinated for Salmonella generated €67.09, €84.48, and €101.89 per cow more profit at each milk price compared with herds positive for exposure. Similarly, herds vaccinated for L. hardjo generated €9.74, €9.69, and €9.63 per cow more profit compared with unvaccinated exposed herds. However, herds that tested negative for exposure to Salmonella and L. hardjo generated additional profits of €10.22 and €4.09 per cow, respectively, compared with vaccinated baseline herds.

Seroprevalence of Coxiella burnetii, Leptospira interrogans serovar hardjo, and Brucella species and associated reproductive disorders in cattle in southwest Ethiopia.

In Ethiopia, Coxiella burnetii, Leptospira Hardjo, and Brucella spp are recognized as the primary factors contributing to cattle reproductive issues. A cross-sectional study was conducted in southwest Ethiopia from October 2020 to October 2021 to assess the risk of reproductive disorders associated with L. Hardjo, Coxiella burnetii, and Brucella spp. Moreover, the study aimed to identify the factors associated with reproductive disorders. Using an indirect ELISA, antibodies against these pathogens were observed in serum samples collected from 461 cattle. We employed multivariable random effect logistic regression analysis to identify potential risk factors associated with reproductive disorders in cattle. The study areas showed a prevalence of 25.16 % (95 % CI: 21.20-29.12) for cattle reproductive disorders. The presence of Leptospira Hardjo (OR = 2.9, 95 % CI: 1.17-4.02) and Coxiella burnetii (OR = 3.0, 1.49-5.94) antibodies was associated to the occurrence of cattle reproductive disorders. Seropositivity to pathogens B. abortus, C. burnetii, and L. Hardjo, along with co-infection of all three, showed association with cattle abortion. The presence of L. Hardjo seropositivity and co-infection with C. burnetii were related to dystocia in cattle. Cattle with retained fetal membranes were associated with co-infection seropositivity to these pathogens. Additionally, B. abortus seropositivity was linked to cases of repeated breeding in cattle. Age, breeding practices, and dog access to cattle showed associations with reproductive disorders, with odds ratios of 2.3 (95 % CI: 2.03-4.69), 2.9 (95 % CI: 1.83-4.82), and 6.5 (95 % CI: 1.04-2.53) respectively. This research indicates that Brucella abortus, Coxiella burnetii, and Leptospira Hardjo, which are responsible for severe zoonotic diseases, have a substantial negative impact on cattle production by causing reproductive disorders. To address the transmission of these diseases, it is essential to implement effective mitigation strategies and enhance public awareness. Additional investigation is necessary to identify and understand the factors contributing to cattle reproductive disorders in the specified area.

Proteomic profiles of Leptospira borgpetersenii serovar Hardjo strains JB197 and HB203 cultured at different temperatures.

Leptospirosis is a global zoonotic disease affecting humans, domestic, and wild animals. Leptospira are typically shed in the urine of reservoir hosts which persist in suitable environments where incidental host transmission occurs after direct contact with infected urine or contaminated environments. Interestingly, serologically identical L. borgpetersenii serovar Hardjo strains JB197 and HB203 show divergent disease severity in the hamster model; JB197 causes severe acute infection while HB203 causes persistent chronic infection. Historically, serovar Hardjo was limited to culture at 29 °C, but utilization of HAN media allows propagation from host tissues at 37 °C. Here, the proteome of strains JB197 and HB203 were characterized after culture from experimentally challenged hamsters at 29 °C and 37 °C. Comparative analyses of JB197 and HB203 samples cultured at 29 °C yielded 425 significantly differentially expressed (DE) proteins, while strains at 37 °C yielded 613 DE proteins including prominent outer membrane proteins and known virulence factors. In agreement, membrane protein GO terms were identified by STRING network analyses along with numerous metabolic KEGG pathways consistent with condition differences. Within strain, JB197 cultured at 29 °C vs 37 °C identified 529 DE proteins, while HB203 identified 524 DE proteins. Investigating differential protein profiles provide insights into strain specific behaviors with implications for better understanding host-pathogen interactions, disease transmission, and response to environmental conditions which can contribute to vaccine development, diagnostic improvement, and ultimately leptospirosis control. SIGNIFICANCE: Leptospirosis is a devastating zoonotic disease affecting humans, wild and domestic animals around the globe. Different species and serovars of Leptospira can affect various animal host species differently; for instance, a serovar that is asymptomatic in the rat may cause severe disease in a dog or human. These differences in host response are not only found at the species and serovar level for Leptospira, but also at the strain level. A prime example comes from strains JB197 and HB203, both species L. borgpetersenii, both serovar Hardjo. Interestingly, JB197 causes a severe acute infection in the hamster while HB203 causes an asymptomatic chronic infection. Understanding these unique relationships between pathogen and host species is important, especially in the context of prevention technologies such as vaccine design, where the strain of Leptospira used as a bacterin might have different efficiencies in different hosts. In this study, proteomic profiles of strains JB197 and HB203 were analyzed, and results revealed diverse protein expression profiles of outer membrane proteins, as well as proteins functioning in motility and growth.

Leptospirosis in the Platypus (Ornithorhynchus anatinus) in Australia: Who Is Infecting Whom?

The platypus (Ornithorhynchus anatinus) is an amphibious, egg-laying mammal of high conservation value that is found only in Australia. The zoonotic bacterium Leptospira interrogans serovar Hardjo was discovered in platypuses in prior studies, but little is known about its epidemiology. Samples in the Platypus Serum Bank were tested in 2023 and the results were combined with historical records. Antibodies against L. interrogans serovar Hardjo were found in 50% of 464 serum samples from 411 platypuses collected from 14 river basins in southeastern Australia between 1981 and 2012; prevalence remained high over three decades in the Shoalhaven River population. Seroprevalence increased with age, suggesting environmental exposure. Individual platypuses had persistent titres, some for six years. Seropositive females lactated, juveniles were recruited into the population, and there were no reports of clinical leptospirosis. Three necropsied platypuses were seropositive and had mild nephritis with leptospires in the renal tubules. The high seroprevalence, persistent titres, lack of disease, mild renal lesions, and renal colonisation suggest the platypus may be a maintenance host. Sympatric cattle had L. interrogans serovar Hardjo titres, but the spatial association with seropositive platypuses was statistically weak. Other mammalian wildlife species and sheep also have L. interrogans serovar Hardjo titres; therefore, a complex ecological network must be considered. A landscape-wide study is recommended to properly assess transmission pathways and confirm who is infecting whom.

Expansion of the in vitro assay for Leptospira potency testing to other serovars: case study with Leptospira Hardjo.

Evaluation of leptospiral vaccines for potency against Leptospira interrogans serovars Pomona, Icterohaemorrhagiae, Canicola, and Grippotyphosa is accomplished using the hamster potency test method described in 9 CFR 113.101-104. Applicability of this method to evaluation of bacterins developed for immunization against infection with L. interrogans serovar Hardjo or Leptospira borgpetersenii serovar Hardjo is complicated by several issues. Information from research on target host animal efficacy studies and evaluation of the immune response elicited using effective whole-cell bacterin formulations have revealed problems in relating these studies to either hamster-based or other potency testing methods. Future work on serovar Hardjo vaccines employing recombinant proteins will require preliminary testing methods in models other than the host animal. These models may also prove applicable to evaluation of potency for protein-based vaccines. Both an acute lethal infection model and a chronic infection model have been developed using two different strains of serovar Hardjo and will be described.

Effectiveness of the Leptospira Hardjo Control Programme and Detection of New Infections in Dairy Cattle in The Netherlands.

Since 2005, a mandatory L. Hardjo control programme (LHCP) has been in place for Dutch dairy herds. Almost 100 percent of dairy farms participate and have an L. Hardjo-free status. In 2020 and 2021, the number of outbreaks seemed to increase as compared to the previous years. In this study, we evaluated the effectiveness of the national LHCP in the Netherlands during 2017-2021. Cases of new infections in herds with an L. Hardjo-free status in the LHCP were described, including the role of risk factors for the introduction. Both the percentage of dairy herds with an L. Hardjo-free status that purchased cattle from herds without a free status and the number of purchased cattle increased over the years. A between-herd cluster evaluation showed that between 2017 and 2021, a suspected infection was detected 144 times in 120 dairy herds. In 26 cases (26 herds, 0.2%) new infections were identified, including within-herd transmission. No infection clusters were identified, indicating that infections never led to local transmission between dairy herds. The introduction of cattle from non-free herds appeared to be the cause of all L. hardjo infections in herds participating in the LHCP. Therefore, the national LHCP seems to be highly effective in the control of infections in dairy herds.

Proteomic dataset comparing strains of Leptospira borgpetersenii serovar Hardjo cultured at different temperatures.

Leptospirosis is a global zoonotic bacterial disease which is a threat for humans and most mammals. Bacterin vaccines for leptospirosis are available however they are severely limited in cross protection between serogroups. Leptospira typically colonize the kidneys of reservoir hosts where they are subsequently shed in the urine and persist in the environment and can thus be indirectly or directly transmitted to incidental hosts. Leptospira borgpetersenii serovar Hardjo is the primary cause of leptospirosis in cattle which can result in abortion, unhealthy calves, and rebreed problems. This dataset comprises proteomic profiles of four strains of L. borgpetersenii serovar Hardjo propagated at the routinely utilized culture temperature of 29 °C, and a newly achieved culture temperature of 37 °C, which more closely emulates the temperature of an infected host. The strains analyzed include JB197 (established strain that causes Hardjo atypical acute disease in the hamster model of leptospirosis), HB203 (established strain, causes typical chronic disease in hamsters), as well as TC129 and TC273 (recently isolated strains from the central United States). Differential expression profiles were detected not only between strains but also within strains between culture temperatures. Mass spectrometry data are available via ProteomeXchange with identifier PXD032831.

Persistence of Leptospira borgpetersenii Serovar Hardjo in Refrigerated Raw Milk: A Transmission Risk of Leptospirosis to Humans.

Leptospira borgpetersenii serovar Hardjo (LH) is an important infectious agent of reproduction pathologies and lactation decline in cattle, with a possible zoonotic role. To figure out the potential zoonotic risk for human raw-milk consumption, the present study aims at assessing the persistence and viability of LH in refrigerated raw milk over a 10-day period, which is set as the maximum time range for raw-milk domestic consumption. A negative sample of fresh raw milk was contaminated with an LH strain (2 × 108 Leptospires/mL) and analyzed by a rrs (16S) gene targeting real-time PCR (rPCR) protocol for LH DNA at days 1, 2, 3, 6, 7, 9, and 10. Seven aliquots of the same sampling time were inoculated into a semisolid EMJH media for bacterial culture. All aliquots tested positive in both rPCR and culture, which demonstrates that raw milk does not alter the detectability and viability of LH, respectively. The analytical sensitivity (LoD, limit of detection) determined for the rPCR (103 Leptospires/mL) was repeatable during the study, whereas it gradually decreased when it came to the bacterial culture. This study demonstrates that bovine raw milk might be a potential vehicle of infection by LH, even when storage conditions are strictly respected.

Genital bovine leptospirosis: A new look for an old disease.

Bovine leptospirosis is often associated with host-adapted leptospires infections, such as strains belonging to the Sejroe serogroup. Although bovine leptospirosis by adapted strains may result in abortions, fetal death, premature births and the birth of weak and/or low-weight calves, this infection is more closely associated with subtler syndromes, such as subfertility and early embryonic death. In this way, this silent disease can go unnoticed and undiagnosed, compromising reproductive efficiency with a consequent decrease in the productivity of herds over long periods. For many years, genital tract infection has been considered a secondary effect of renal infection with the assumption being that leptospires are found in the genital tract due to bacteremia caused by renal colonization. In contrast to this hypothesis, there is some evidence in the literature that suggests that genital leptospirosis should be considered a specific syndrome dissociated from renal/systemic disease. Therefore, this paper aims to gather and critically analyze information about genital leptospirosis in cattle, considering the disease a distinct syndrome, herein denominated bovine genital leptospirosis (BGL), that requires a unique approach to diagnosis and treatment.

Serological evidence of Coxiella burnetii, Leptospira interrogans Hardjo, Neospora caninum and bovine pestivirus infections in a dairy cattle herd from the United Arab Emirates.

The serostatus of five abortigenic agents and the association between abortion history and Coxiella burnetii seropositivity were assessed in 350 dairy cattle from Al Ain, UAE. The bovine sera were ELISA-screened for C. burnetii, Leptospira Hardjo, Neospora caninum, and Brucella abortus antibodies, plus bovine pestivirus (BVDV) antigen. The serology data were collated and the level of significance between the proportions of C. burnetii-seropositive cattle with and without abortion history assessed by the Z test of two proportions. Of the 350 cattle, 41.4%, 1.7%, 1.4%, 0.3%, and 0.0% were seropositive to the above pathogens, respectively. Besides, 61.9%, 2.9%, 1.0%, 0.0%, and 0.0% of the 105 cattle with history of abortion and 32.7%, 1.2%, 1.6%, 0.0% and 0.0% of the 245 seropositive cattle with no history of abortion were also seropositive for the above pathogens respectively. Moreover, the proportion of C. burnetii-seropositive cattle with history of abortion were significantly higher than the C. burnetii-seropositive ones without abortion history (p-value < 0.01). Apparent C. burnetii infections were relatively higher than the other four pathogens suggesting this bacterium contributed to abortion in the herd. Additional research on the public and bovine health implications of C. burnetii and Leptospira in the UAE are urgently needed.

Risk Factors Associated With Seroreactivity Against Leptospira sp. in Horses From Brazilian Amazon.

This study investigated the risk factors associated with seroreactivity to Leptospira sp. in horses from Brazilian Amazon. Blood samples were collected and microscopic agglutination test was performed, and univariate and multivariate analyses were conducted for association with risk factors. General seroprevalence was 32.7% and the most prevalent serogroup observed was Sejroe (5.9%). Seroreactivity was associated with age, sex, activity (work, leisure, or both), feed supplementation, trash accumulation, and presence of felines. Epidemiology of leptospirosis remains poorly understood in Amazon region, particularly in livestock, requiring more studies to improve control and prevention measures.

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.

Herd-level risk factors associated with Leptospira Hardjo infection in dairy herds in the southern Tohoku, Japan.

A cross-sectional study was designed to generate information on the herd level prevalence and the risk factors for Leptospira serovar Hardjo (L. Hardjo) in Yamagata, the southern Tohoku, Japan. Bulk tank milk samples from 109 dairy herds were used to test the herd level sero-prevalence of L. Hardjo using a commercial ELISA kit, which detects both L. interrogans serovar Hardjo and L. borgpetersenii serovar Hardjo. A questionnaire survey was conducted at the sampled farms, and univariable and multivariable analyses were performed. Spatial clustering of L. Hardjo at the herd level was examined using spatial scan statistics. Seventy-one herds were found to be positive for L. Hardjo, and the apparent herd prevalence was 65.1% (95% CI: 56.2-74.1%). The risk factors for sero-positivity were larger herd size (p=0.004) and cows with a history of staying in Hokkaido (p <0.001). The spatial scan statistic detected a most likely cluster (relative risk=1.87, log likelihood ratio=9.93, radius=13.70km, p<0.01) in the southern part of the study area where there are large herd sizes and farm density is high. This study revealed that L. Hardjo is prevalent throughout Yamagata, and large scale herd owners introducing cows from Hokkaido in particular should be aware of the risk of infection.

Effectiveness of a commercial leptospiral vaccine on urinary shedding in naturally exposed sheep in New Zealand.

L. borgpetersenii serovar Hardjo and L. interrogans serovar Pomona are endemic in New Zealand sheep. An effective vaccine and vaccination strategy would protect both humans and livestock. Four to 12 lambs were selected from each of eight farms (total=84, vaccinated group), while four to 16 lambs (total=98) served as unvaccinated controls. A commercial Hardjo/Pomona vaccine was given at 1-6 weeks of age, 5-11 weeks later and 33-67 weeks later on seven farms and at 18 weeks of age and 5 weeks later on the eighth farm. Vaccinates and controls were grazed together. Blood was regularly collected from the control group to assess flock exposure. Urine was collected from both groups 26-82 weeks after the second vaccination and tested by quantitative PCR. Seroprevalence in controls at the time of urine sampling ranged from 2.7 to 98.2% for Hardjo and from 0 to 54.1% for Pomona with seroconversion occurring 13 to 67 weeks after the second vaccination in all but one farm where exposure had happened by the time of vaccination. The shedding prevalence adjusted for clustering in farms was 45.1% [95% CI 17.6-72.7] (for an observed number of 50/98) in the control animals and 1.8% [95% CI 0.0-10.1] (for an observed number of 5/84) in the vaccinated animals. The vaccine was 100% effective on five farms where animals were vaccinated before 12 weeks of age and before natural exposure occurred, but the effectiveness was 80% [0-97] on one farm where the lambs were exposed before vaccination and 65% [9-87] to 80% [0-97] on one farm where the animals were fully vaccinated by 24 weeks of age. The overall vaccine effectiveness was 86.3% [63.6-94.8%] despite maternal antibodies in some flocks at first vaccination. Vaccination timing seemed to be crucial in achieving optimum reduction in shedding in urine in vaccinated sheep.

Effects of rainfall on incidental and host-maintained leptospiral infections in cattle in a tropical region.

This study investigated the effects of rainfall on incidental and host-maintained leptospiral infections in cattle in a tropical region. Serum and urine specimens were collected from 582 bovines in a slaughterhouse. Seropositivity during rainy seasons was 43.6% (158/362) and during dry seasons was 31.8% (70/220; P = 0.0047). Positivity by urine PCR in rainy seasons was 42.3% (153/362) and 33.2% (73/220; P = 0.0296) in dry seasons. Additionally, increases in rainfall rates had different effects on host-adapted (serogroup Sejroe) and incidental (all other serogroups) leptospiral infections. There was a significant increase in the number of cattle shedding Leptospira during the rainy season (CI 1.04-2.09; P = 0.0296), suggesting temporary (transient) urinary shedding of incidental serogroups. Incidental and host-maintained Leptospira infections in cattle require different diagnostic techniques and control strategies.