Abstract

Erysipelothrix rhusiopathiae is a small, gram-positive, non-sporulating, facultative anaerobic rod that is responsible for dermal infections and acute fatal septicemia in cetaceans.¹ The disease erysipelas is commonly found in domestic swine and poultry and is the causative agent of cutaneous erysipeloid and endocarditis in humans.^4,5 An eight year-old male intact wild-caught Russian beluga whale (Delphinapterus leucas) had a history of mild leukocytosis occurring one month after his arrival; this was approximately three months prior to a clinical infection with E. rhusiopathiae). One month prior to his onset of anorexia, the beluga received the first of a series of vaccines for E. rhusiopathiae with the Pfizer ERBAC® PLUS bacterin. The beluga was diagnosed with acute Erysipelothrix rhusiopathiae septicemia after a five day history of inappetance, anorexia, and lethargy.

Physical examination revealed no significant abnormalities, including no skin lesions. Hematologic and biochemical abnormalities early in the disease included a marked leukocytosis, a mild increase in serum protein and globulin, mild thrombocytopenia, and anemia beginning 14 days after presentation (see Tables 1, 2). These abnormalities were consistent with infection with E. rhusiopathiae. Blood culture confirmed the presence of the bacteria, supporting the diagnosis of acute Erysipelothrix rhusiopathiae septicemia.

The treatment protocol for the case was complex and evolving based on the severity of the disease, accessibility to the whale for treatments, intermittent anorexia, and the development of a secondary bacterial infection. Initial treatment was administered based on suspicion of bacterial disease prior to blood culture confirmation of septicemia. Early in the disease and intermittently through the 3.5 months of treatment, the beluga was anorexic. On days when his condition was poor or he would not accept oral medications, intramuscular injections of the following drugs were administered: penicillin G benzathine and penicillin G procaine (Longicil 9000 IU/kg), flunixin meglumine (0.5 mg/kg as needed), and amikacin (15 mg/kg). On days when oral treatment was practical, the following drugs were administered: diazepam (0.02 mg/kg) for appetite stimulation, cephalexin (10 mg/kg BID), esomeprazole (Nexium 0.08 mg/kg), and dexamethasone (0.05 mg/kg). The oral antibiotic was changed to amoxicillin-clavulanic acid (Apo-brand 15.5 mg/kg BID) and the herbal remedy Yunnan Paiyao (1 tablet QID) was administered orally. One month into treatment, oral itraconazole (Sporanox 1.2 mg/kg BID), vitamin K1 (0.1 mg/kg) and aspirin (0.16 mg/kg BID) were added to the regiment. After two months of treatment, the oral antibiotic was changed from amoxicillin-clavulanic acid to oxytetracycline (Liquamycin LA-200 brand 4 mg/kg). For the final month of treatment, oral supplements were given: iron (0.1 mg/kg BID) and folic acid (0.01 mg/kg BID). Approximately 3.5 months after the onset of disease, the beluga was clinically stable and his blood values were all within normal limits.

Despite alternating periods of improvement and deteriorating condition, the beluga recovered from his septicemic infection with Erysipelothrix rhusiopathiae and did not display any obvious signs of renal failure. One and a half years later, the beluga continues to be free of clinical disease. The success in this case is attributed to the early and aggressive initiation of antibiotic therapy, the choice of antibiotics, and prior vaccination. Limiting zoonotic Erysipelothrix rhusiopathiae at the marine park has particular public health significance because visitors interact with the beluga whales. In order to prevent the recurrence of the disease in the collection, it is important to monitor the bacterial content of feed fish by bacterial culture and to consider adding a low concentration chlorine solution to fish thawing sinks.^2,3 Other animals in the collection can be screened and diagnosed with blood culture and paired antibody titers.

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	Table 1. CBC results for leukocyte count of an 8 year-old male beluga (Delphinapterus leucas) infected with Erysipelothrix rhusiopathiae. The normal range for white blood cells is 5-9.5 *109/L. The date 10/18/05 marks the onset of clinical signs.
	Table 2. CBC results for platelet count of an 8 year-old male beluga (Delphinapterus leucas) infected with Erysipelothrix rhusiopathiae. The normal range for platelet count is 60-130 *109/L. The date 10/18/05 marks the onset of clinical signs.

Acknowledgements

Thank you to June Mergl, DVM for her encouragement and mentorship, and to the dedicated marine mammal staff at Marineland Canada.

References

1.  Dunn JL, Buck JD, Robeck T. Bacterial Diseases of Cetaceans and Pinnipeds. In: Dierauf LA, Gulland F.,eds CRC Handbook of Marine Mammal Medicine. 2nd ed. New York, 2001; 309-328.

2.  Greenwell MG, Boehm JR, Harris B. A One-year Surveillance Program for Erysipelothrix rhusiopathiae: Methodology, Findings, and Recommendations, in Proceedings, Annu Meet IAAAM.

3.  Harris B, Boehm JR. A Pilot Surveillance Program for Erysipelothrix rhusiopathiae, in Proceedings, Annu Meet IAAAM.

4.  Mazaheri A, Lierz M, Hafez M. Investigations on the Pathogenicity of Erysipelothrix rhusiopathiae in Laying Hens. Avian Diseases 2005:49:574-576.

5.  Ruiz ME, Richards JS, Kerr GS, et al. Erysipelothrix rhusiopathiae Septic Arthritis. Arthritis and Rheumatism 2003:48:1156-1157.