Salmonellosis is a zoonotic disease that affects many vertebrate species. It has been described for the first time as a pathogen in elephants in 1940 (Matzek 1940). The symptoms of salmonellosis can range from mild depression, colic, diarrhea, ventral edema, weight loss, cachexia to death. Subclinical infections do also occur (Scharling 2021). One case of abortion in an African elephant has been described (Emanuelson 2000). Salmonellosis can manifest itself as an acute illness as well as a chronic disease. Different serotypes have been associated with intestinal disease and death (S. typhimurium, S. blockley) (Matzke 1940, Windsor 1972 and 1976, Chooi 1988). S. saintpaul was associated with septicemia in an adult Asian elephant (Molenaar 2021). The source of the infection is not always found, but can be contaminated food, infected conspecifics, care takers and other species sharing the exhibit with the elephant.
Diagnosis of salmonellosis
Detection of Salmonella spp. in feces is by culture or PCR the most common way to demonstrate the presence in an elephant. However, shedding of the pathogen is intermittent, which means that multiple fecal samples taken in a period of at least 3 days are required. Salmonella spp. are more likely to be detected in elephants with abnormal feces. Selective media like selenite cystine broth and MacConkey agar are part of the routine culture method for Salmonella spp. (FAO 1992). To detect Salmonella in food samples in general, molecular testing in addition to conventional culture-based methods can be used. Multiplex quantitative PCR (qPCR) has proven to be a fast, easy to perform, and sensitive molecular technique for the detection of Salmonella species and various Salmonella serovars (Heymans 2018).
Treatment of salmonellosis
The decision to treat an elephant for salmonellosis depends on the clinical situation. Subclinical infections may be hard to clear. If attempted, treatment should be based on an antibiogram. In humans, common first-line oral antibiotics for susceptible Salmonella infections are fluoroquinolones (for adults) and azithromycin (for children). Ceftriaxone is an alternative first-line treatment agent (CDC 2018). In order to reduce the risk of antibiotic resistance to these antibiotics, their use in elephants should be considered only after the antibiogram has demonstrated that other antibiotics (e.g. sulfonamides) are not effective.
Information on dosage and administration of antibiotics can be found on:
Chooi K.F., and Z. Z. Zahari. 1988. Salmonellosis in a Captive Asian Elephant. The Journal of Zoo Animal Medicine, Vol. 19, No. 1/2 (1988), pp. 48-50Matzke, M. 1940. Salmonella typhimurium Infection in Elephants. Tierarztliche Rundschau 1940 Vol.46 pp.521-522
Emanuelson K.A., Kinzley C.E. 2000. Salmonellosis and subsequent abortion in two African Elephants (Loxodonta africana). IAAAM 2000.
Heymans R, Vila A, van Heerwaarden C.A.M., Jansen C.C.C., Castelijn G.A.A.,van der Voort, Biesta-Peters E.G. (2018). Rapid detection and differentiation of Salmonella species, Salmonella Typhimurium and Salmonella Enteritidis by multiplex quantitative PCR. PLOS ONE 13(10)
Molenaar, F.M and Silvestre S. 2021. Clinical approach to colic and collapse in an Asian elephant (Elephas maximus) with Salmonella saintpaul septicaemia and subsequent ileus. Vet Rec Case Rep. 2021;e214. https://doi.org/10.1002/vrc2.214.
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