Journal Articles

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Author: search.filters.author.Marshall JCSubject: search.filters.subject.One Health

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    Investigating animals and environments in contact with leptospirosis patients in Aotearoa New Zealand reveals complex exposure pathways.
    (Taylor and Francis Group, 2025-02-12) Benschop J; Collins-Emerson JM; Vallee E; Prinsen G; Yeung P; Wright J; Littlejohn S; Douwes J; Fayaz A; Marshall JC; Baker MG; Quin T; Nisa S
    CASE HISTORY: Three human leptospirosis cases from a case-control study were recruited for in-contact animal and environment sampling and Leptospira testing between October 2020 and December 2021. These cases were selected because of regular exposure to livestock, pets, and/or wildlife, and sampling was carried out on their farms or lifestyle blocks (sites A-C), with veterinarians overseeing the process for livestock, and cases collecting environmental and wildlife samples. LABORATORY FINDINGS: Across the three sites, a total of 137 cattle, > 40 sheep, 28 possums, six dogs, six rats, three pigs and three rabbits were tested. Herd serology results on Site A, a dairy farm, showed infection with Tarassovi and Pomona; urinary shedding showed Leptospira borgpetersenii str. Pacifica. Animals were vaccinated against Hardjo, Pomona and Copenhageni. The farmer was diagnosed with Ballum. On Site B, a beef and sheep farm, serology showed infection with Pomona; animals were not vaccinated, and the farmer was diagnosed with Hardjo. On Site C, cattle were shedding L. borgpetersenii; animals were not vaccinated, and the case's serovar was indeterminate. Six wild animals associated with Sites A and C and one environmental sample from Site A were positive for pathogenic Leptospira by PCR. CONCLUSION: These findings highlight the complexity of potential exposures and the difficulty in identifying infection sources for human cases. This reinforces the need for multiple preventive measures such as animal vaccination, the use of personal protective equipment, pest control, and general awareness of leptospirosis to reduce infection risk in agricultural settings. CLINICAL RELEVANCE: Farms with unvaccinated livestock had Leptospira infections, highlighting the importance of animal vaccination. Infections amongst stock that were vaccinated emphasise the importance of best practice vaccination recommendations and pest control. Abbreviations: MAT: Microscopic agglutination test; PIC: Person in charge; PPE: Personalprotective equipment
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    Transmission Dynamics of Shiga Toxin-Producing Escherichia coli in New Zealand Cattle from Farm to Slaughter.
    (American Society for Microbiology, 2021-05-11) Browne AS; Midwinter AC; Withers H; Cookson AL; Biggs PJ; Marshall JC; Benschop J; Hathaway S; Rogers L; Nisa S; Hranac CR; Winkleman T; French NP
    Cattle are asymptomatic carriers of Shiga toxin-producing Escherichiacoli (STEC) strains that can cause serious illness or death in humans. In New Zealand, contact with cattle feces and living near cattle populations are known risk factors for human STEC infection. Contamination of fresh meat with STEC strains also leads to the potential for rejection of consignments by importing countries. We used a combination of PCR/matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) and whole-genome sequencing (WGS) to evaluate the presence and transmission of STEC on farms and in processing plants to better understand the potential pathways for human exposure and thus mitigate risk. Animal and environmental samples (n = 2,580) were collected from six farms and three meat processing plants in New Zealand during multiple sampling sessions in spring of 2015 and 2016. PCR/MALDI-TOF analysis revealed that 6.2% were positive for "Top 7" STEC. Top 7 STEC strains were identified in all sample sources (n = 17) tested. A marked increase in Top 7 STEC prevalence was observed between calf hides on farm (6.3% prevalence) and calf hides at processing plants (25.1% prevalence). Whole-genome sequencing was performed on Top 7 STEC bacterial isolates (n = 40). Analysis of STEC O26 (n = 25 isolates) revealed relatively low genetic diversity on individual farms, consistent with the presence of a resident strain disseminated within the farm environment. Public health efforts should focus on minimizing human contact with fecal material on farms and during handling, transport, and slaughter of calves. Meat processing plants should focus on minimizing cross-contamination between the hides of calves in a cohort during transport, lairage, and slaughter. IMPORTANCE Cattle are asymptomatic carriers of Shiga toxin-producing E. coli (STEC) strains, which can cause serious illness or death in humans. Contact with cattle feces and living near cattle are known risk factors for human STEC infection. This study evaluated STEC carriage in young calves and the farm environment with an in-depth evaluation of six farms and three meat processing plants over 2 years. An advanced molecular detection method and whole-genome sequencing were used to provide a detailed evaluation of the transmission of STEC both within and between farms. The study revealed widespread STEC contamination within the farm environment, but no evidence of recent spread between farms. Contamination of young dairy calf hides increased following transport and holding at meat processing plants. The elimination of STEC in farm environments may be very difficult given the multiple transmission routes; interventions should be targeted at decreasing fecal contamination of calf hides during transport, lairage, and processing.