On-farm risk factors associated withLeptospirashedding in New Zealand dairy cattle

Abstract

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.

Prevalence of Toxoplasma gondii, Leptospira spp., and Coxiella burnetii-associated antibodies in dairy cattle with reproductive disorders

“…Similarly, the transmission of Q fever is mainly through the infected animals, their contaminated body fluids/secretion/aborted materials, contaminated aerosol particles or unpasteurized milk, and animal products; hence, the milk handlers are at high risk. For leptospirosis, young animals shed more bacteria in urine than older ones [ 29 ], causing health hazards to animal handlers.…”

Sero-prevalence and risk factors of leptospirosis in commercial cattle herds of Rupandehi district, Nepal

“…The bigger herd size is the risk factor for leptospirosis, and many of the studies have already proved that [25,29]. The high stocking density in the bigger herd size farms had a higher risk of getting the diseases due to frequent selling or purchasing of animals, and the contact between infectious and susceptible animals takes place more often [50].…”

γδ TCRs Function as Innate-like Receptors in the Bovine γδ T Cell Response against Leptospira

“…This included TRAV33, which has been previously described as a gene expressed in TRD chains (32), and was found to represent 2-3% of the repertoire. Other TRAV genes included members of a large number of TRAV subgroups (TRAV3, 8,9,14,19,22,23,24,25,26,28,29,33,36,38,41, X and Y) -however these were all represented at very low levels (total representation of other TRAV genes ranged from 0.1%-0.2%). In all 4 animals, TRDJ1 and TRDJ3 were the dominant TRDJ genes used, with TRDJ2 under-represented.…”

“…Estimates of global disease burdens in humans are of ~1 million cases and ~58,900 deaths per year, although these figures are likely to represent a significant under-estimate due to the high prevalence of leptospirosis in resourcepoor tropical low-and-middle income countries (2). Leptospirosis can also affect a range of livestock species including cattle where infection can be present at high frequency and cause substantial losses due to reduced fertility and productivity (3)(4)(5)(6). Although a number of Leptospira serovars can cause disease in cattle, those of most concern in many geographical regions are Leptospira borgpetersenii serovar Hardjo and L. interrogans serovar Hardjo (7), which can be transmitted to humans and, thus, bovine leptospirosis is important as both an economically significant veterinary disease and a public health disease.…”

“…Vaccines that are safe and provide effective protection against Leptospira are not currently available for use in humans (8). In contrast, a number of commercially-available vaccines for cattle have been developed and are widely used in high-income countries as a method of controlling the disease (9), although most vaccines do not provide protection against the Leptospira Hardjo serovars (10). Although antibodies have long been considered as the primary mediators of anti-Leptospira immunity and antibody titre remains a parameter used to assess potential vaccine efficacy (8), analysis of the immune responses induced by the bovine vaccines have demonstrated that protection against Leptospira Hardjo serovars is dependent on the induction of a cell-mediated immunity associated with potent interferon-γ producing γδ T cell responses (11,12).…”