TRANSMISSION
• Faecal-oral transmission through direct contact with pets or faeces, or indirect contact with material contaminated by faeces. • Human and animal infection may occur due to exposure to a common source (e.g. pet food or treats). • Reptiles and amphibians are a known source of salmonellosis in people, directly, or potentially indirectly, through intermediate infection of cohabitating dogs and cats.
IN HUMANS
PREVALENCE AND RISK FACTORS • Approximately 14,000 cases of non-typhoidal salmonellosis are reported annually in Australia,
20,000
15,000
however it is estimated there are seven unreported cases for every one report. 11 The most common serovar in humans in Australia is S. enterica ser. Typhimurium. Most infections are foodborne in origin. 2 • A number of host factors are associated with increased susceptibility to salmonellosis (lower initial inoculum required) 12 , more severe infection, more protracted disease course or increased risk of complications: - Gastric acidity – patients on proton pump inhibitors require a lower inoculum. 13 - Age – neonates, children under the age of five and the elderly. 14
10,000
5,000
young, very old, and immunocompromised. 16 The consequences of Salmonella bacteraemia are more serious in adults due to the comorbidities of age, and may include: - Vascular complications – seeding of atherosclerotic plaques leading to infectious endarteritis, including seeding of prosthetic vascular grafts. - Focal infections including endocarditis, meningitis, septic arthritis and osteomyelitis, or pneumonia. - Intrauterine infection may result in abortion in pregnant patients. 17 • Some serovars are more likely to result in invasive extraintestinal disease (e.g. Typhimurium, Dublin, Choleraesuis). 16 Some of these have been reported in dogs and cats, however good serovar prevalence data is lacking. • The presence of multi-drug resistance, including to fluoroquinolones, third generation cephalosporins and more recently carbapenems, is of great concern internationally. Salmonellosis notifications by year in Australia (2010 to 2020) from National Notifiable Diseases Surveillance System, accessed April 2021 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 0
- Decreased cell mediated immunity – e.g. HIV, transplantation, immunosuppressive therapy. 14 - Altered intestinal flora (e.g. antimicrobial therapy).
CLINICAL DISEASE • Uncomplicated cases present with gastroenteritis which begins 6-72 hours after exposure. Diarrhoea and abdominal pain are frequently observed. The condition is typically self-limiting, lasting 3-7 days. Exposure to large inocula can result in a shorter incubation period and more severe disease. 15 Typical shedding period is up to 6 weeks, although longer shedding has been reported. Shedding is longer in pregnant patients, in immune compromised patients and in patients given antimicrobial therapy. 16 • Bacteraemia is reported in approximately 5% of immunocompetent patients, with a higher incidence in the very
CONTENTS
73 Companion Animal Zoonoses Guidelines
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