bovis - Articles
Salmonellosis
Synonym(s): Diarrhoea, Diarrhea, Abortion, Septicemia, Enterobacteriaceae
Introduction
- Signs: enteric, septicemic and reproductive diseases are all possible manifestations of salmonella infection in cattle.
- Diagnosis: clinical signs consistent with disease, bacterial culture, serology.
- Treatment: fluid therapy, non-steroidal anti-inflammatories and antimicrobials as necessitated based on culture and sensitivity results.
- Prognosis: guarded.
Geographic incidence
- Worldwide.
Public health considerations
- Many salmonellae are Zoonotic Zoonotic; indeed, salmonellosis is the second most common cause of bacterial food poisoning in people worldwide.
- In the EU and UK legislation is in place to protect people from exposure to salmonella spp.
- In the UK this is achieved through the Zoonoses order 1989.
Pathogenesis
Etiology
- Salmonella Salmonella spp is a genus of Gram-negative, facultative anaerobic bacteria that belong to the family of Enterobacteriaceae.
- The genus Salmonella comprises more than 2600 serovars:
- S Dublin is the host adapted serovar in cattle.
- S Typhimurium, S Mbandaka and S Newport are the most common serovars isolated from cattle in the UK.
Predisposing factors
General
- UK disease outbreaks occur most commonly in winter and spring, often associated with periods of housing, lambing and calving.
Specific
- Fecal contamination of food and water sources.
- Carrier status is an important factor in the maintenance of endemic herd infection.
- Physiological stress.
- High stocking density.
- Increased herd size.
- Concurrent Fasciola hepatica Fasciola hepatica infection.
- Concurrent immunosuppressive disease, eg BVDV BVDV.
Pathophysiology
- Most salmonellae are acquired via fecal oral contamination from other livestock, wildlife or birds.
- More rarely via the conjunctival or respiratory system.
- Upon ingestion, salmonella are capable of attaching to mucosal cells and causing enterocyte destruction.
- From here they invade through M-cells, enterocytes and tonsillar lymphoid tissue. Stimulating an inflammatory response, or are engulfed by macrophages and neutrophils. Upon entry to these mononuclear cells, they can then be disseminated throughout the body.
- The virulence mechanisms of Salmonella spp include the ability to invade the intestinal mucosa, to multiply in lymphoid tissues, and to evade host defence systems, leading to systemic disease.
Timecourse
- Calves may be infected and exhibit clinical signs associated with a diverse array of salmonella serotypes within hours of birth.
Epidemiology
- Calves between 14 days and three months and animals in the first 14 days of lactation are most susceptible to Salmonella Dublin infection.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed Papers
- Recent references from PubMed and VetMedResource.
- Holschbach C L & Peek S F (2018) Salmonella in dairy cattle. Vet Clin Food Anim (34), 133–154.
- Hateley G & Carson A (2017) Salmonella investigations in ruminants. Vet Rec (181), 366-367.
- Henderson K & Mason C (2017) Diagnosis and control of salmonella dublin in dairy herds. In Practice (39), 158-168.
- Pecoraro H L, Thompson B & Duhamel G E (2017) Histopathology case definition of naturally acquired Salmonella enterica serovar Dublin infection in young Holstein cattle in the northeastern United States. J Vet Diagn Invest 29 (6), 860–864.
- Mohler V L, Izzon M & House J K (2009) Salmonella in calves. Vet Clin Food Anim (25), 37–54.