Carriage of Brachyspira hyodysenteriae on common insect vectors

Blunt, R.; Mellits, K.; Corona-Barrera, E.; Pradal-Roa, P.; McOrist, S.

Abstract

The interactions of likely insect and murine vectors of the causative agent of swine dysentery, Brachyspira hyodysenteriae, were investigated. Insects were collected and analysed from 3 pig farms positive for B hyodysenteriae. Within these farms, several Musca domestica and Orphyra adult fly, Blatta sp. cockroach digestive tracts and hover fly (Eristalis sp) pupal form contents were positive in a standard PCR assay for B hyodysenteriae, whereas all other insect samples on these and case control farms were negative. In challenge exposure studies, B hyodysenteriae DNA was detected in the digestive tract of cockroaches and M domestica flies from day 1 post-inoculation with cultured B hyodysenteriae, for up to 5 days or 10 days respectively, while control non-inoculated insects remained negative. Isolates consistent with B hyodysenteriae were only cultured from frass samples of these inoculated cockroach and flies on days 1–3 post-inoculation. Isolates consistent with B hyodysenteriae were detected by analysis of agar plates exposed to live B hyodysenteriae-inoculated adult flies wandering and feeding on these plates for 20 min per day. In generational challenge inoculation studies, B hyodysenteriae was detected in the adult emergent flies, and internal components of fly pupae on days 1–7 of the pupation period, after being inoculated with B hyodysenteriae as larvae. Five-week-old conventional mice (C3H) that consumed 2 meals of B hyodysenteriae-infected flies remained negative for B hyodysenteriae throughout the next 10 days. The results indicated that pathogenic Brachyspira sp have a limited ability to internally colonise likely insect vectors and do not readily transmit infection to mice. However, the insect vectors analysed were demonstrably capable of mechanical carriage and likely on-farm involvement in consequence.

Citation

Blunt, R., Mellits, K., Corona-Barrera, E., Pradal-Roa, P., & McOrist, S. (2022). Carriage of Brachyspira hyodysenteriae on common insect vectors. Veterinary Microbiology, 269, Article 109417. https://doi.org/10.1016/j.vetmic.2022.109417

• Journal Article Type: Article
• Acceptance Date: Apr 1, 2022
• Online Publication Date: Apr 12, 2022
• Publication Date: Jun 1, 2022
• Deposit Date: Jun 6, 2022
• Publicly Available Date: Apr 13, 2023
• Journal: Veterinary Microbiology
• Print ISSN: 0378-1135
• Electronic ISSN: 1873-2542
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 269
• Article Number: 109417
• DOI: https://doi.org/10.1016/j.vetmic.2022.109417
• Keywords: General Veterinary; General Medicine; Microbiology
• Public URL: https://nottingham-repository.worktribe.com/output/7839923
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0378113522000876
• Additional Information: This article is maintained by: Elsevier; Article Title: Carriage of Brachyspira hyodysenteriae on common insect vectors; Journal Title: Veterinary Microbiology; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.vetmic.2022.109417