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Grönthal TSC, Lehto AK, Aarnio SS, Eskola EK, Aimo-Koivisto EM, Karlsson T, Koskinen HI, Barkoff AM, He Q, Lienemann T, Rimhanen-Finne R, Mykkänen A. Pastern dermatitis outbreak associated with toxigenic and non-toxigenic Corynebacterium diphtheriae and non-toxigenic Corynebacterium ulcerans at a horse stable in Finland, 2021. Zoonoses Public Health 2024; 71:127-135. [PMID: 37926867 DOI: 10.1111/zph.13090] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 10/13/2023] [Accepted: 10/21/2023] [Indexed: 11/07/2023]
Abstract
AIMS Corynebacterium diphtheriae and Corynebacterium ulcerans, when producing toxin, are the cause of diphtheria, a potentially life-threatening illness in humans. Horses (Equus ferus caballus) are known to be susceptible to infection that may manifest clinically on rare occasions. In late 2021 and early 2022, specimens from five horses suffering from pastern dermatitis were cultured at the Laboratory of Clinical Microbiology at the Faculty of Veterinary Medicine, University of Helsinki, Finland. C. diphtheriae and/or C. ulcerans were recovered from all of these. This study aimed to (1) analyse the bacterial isolates and (2) describe the outbreak and identify possible sources of the infection and infection routes in the stable. METHODS AND RESULTS Susceptibility testing, PCR for the tox gene, and Elek test for toxin production in PCR-positive isolates were performed. Whole genome sequencing was also conducted to achieve high-resolution strain typing. An epidemiological survey was done by means of a semi-structured interview of horses' caretaker, and contact tracing was done among people at the stable. Two tox gene-positive, toxin-producing C. diphtheriae belonged to sequence type (ST) 822. Other C. diphtheriae (n = 2, ST828) and C. ulcerans (n = 2, ST325 and ST838) isolates did not carry the tox gene. The epidemiological investigation explored numerous possible routes of transmission, but the definite source of infection was not identified. All established human contacts tested negative for diphtheriae. All horses recovered after antimicrobial treatment. CONCLUSIONS Our study shows that C. diphtheriae and C. ulcerans may readily spread among horses at the same stable and complicate pastern dermatitis infections. These potentially zoonotic bacteria can cause outbreaks even in a country with a very low prevalence. Caretakers should be encouraged to wear gloves and practice good hand hygiene when treating infected skin lesions in horses.
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Affiliation(s)
- Thomas Sven Christer Grönthal
- Animal Health Diagnostics Unit, Finnish Food Authority, Helsinki, Finland
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Anna Karoliina Lehto
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Sanna Sofia Aarnio
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Eva Katarina Eskola
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Elina Marjaana Aimo-Koivisto
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Teemu Karlsson
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Heli Irmeli Koskinen
- Infectious Disease Control and Vaccinations Unit, Department of Health Security, Finnish Institute of Health and Welfare, Helsinki, Finland
| | - Alex-Mikael Barkoff
- Institute of Biomedicine, Research Center for Infections and Immunity, University of Turku, Turku, Finland
| | - Qiushui He
- Institute of Biomedicine, Research Center for Infections and Immunity, University of Turku, Turku, Finland
| | - Taru Lienemann
- Animal Health Diagnostics Unit, Finnish Food Authority, Helsinki, Finland
| | - Ruska Rimhanen-Finne
- Infectious Disease Control and Vaccinations Unit, Department of Health Security, Finnish Institute of Health and Welfare, Helsinki, Finland
| | - Anna Mykkänen
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
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Virtanen J, Hautala K, Utriainen M, Dutra L, Eskola K, Airas N, Uusitalo R, Ahvenainen E, Smura T, Sironen T, Vapalahti O, Kant R, Virtala AMK, Kinnunen PM. Equine dermatitis outbreak associated with parapoxvirus. J Gen Virol 2023; 104. [PMID: 38117290 DOI: 10.1099/jgv.0.001940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023] Open
Abstract
Parapoxviruses (PPV) cause skin and mucous membrane lesions in several animal species, and of the five recognized PPVs, at least three are zoonotic. Equine PPV (EqPPV) is the sixth one initially described in humans in the United States and later in a severely sick horse in Finland in 2013-2015. In 2021-2022, a large-scale pustulo-vesicular pastern dermatitis outbreak occurred in horses all over Finland. This study aimed at analysing the outbreak, identifying and describing the causative agent, describing clinical signs, and searching for risk factors. EqPPV was identified as a probable causative agent and co-infections with several potentially pathogenic and zoonotic bacteria were observed. Histopathologically, suppurative and ulcerative dermatitis was diagnosed. Due to the lack of specific tests for this virus, we developed a novel diagnostic EqPPV-PCR with sensitivity of 10 copies/reaction. Based on a large proportion of the genome sequenced directly from clinical samples, very little variation was detected between the sequences of the case from 2013 and the cases from 2021 to 2022. Based on an epidemiological survey, the main risk factor for pastern dermatitis was having racehorses. Approximately one third of the horses at each affected stable got clinical dermatitis, manifesting as severe skin lesions. Skin lesions were also occasionally reported in humans, indicating potential zoonotic transmission. Case stables commonly reported attendance at race events before acquiring the disease. Survey also identified differences in practises between case and control stables. Taken together, these results enable a better preparedness, diagnostics, and guidelines for future outbreaks.
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Affiliation(s)
- Jenni Virtanen
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Katja Hautala
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Mira Utriainen
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Lara Dutra
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Katarina Eskola
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
- Animal Health and Welfare Department, Finnish Food Authority, Helsinki, Finland
| | - Niina Airas
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Ruut Uusitalo
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Geosciences and Geography, Faculty of Science, University of Helsinki, Helsinki, Finland
| | - Ella Ahvenainen
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Teemu Smura
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Tarja Sironen
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Olli Vapalahti
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Ravi Kant
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Anna-Maija K Virtala
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Paula M Kinnunen
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
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