Erysipelothrix rhusiopathiae occurrence, epidemiology and vaccine reactions in cetaceans: a thirty-year retrospective based on two global surveys.

Erysipelas, an infection caused by Erysipelothrix rhusiopathiae, has always been a threat to marine mammal collections. A first global survey (1989-2000) about erysipelas occurrences, covering 1384 animals, reported 69 cases of erysipelas (5%). To better understand the disease epidemiology and vaccine-related reactions, a second survey (2001-2020) was conducted, reaching a 68.6% response rate (140/204 facilities) and including 2267 cetaceans. It reported 108 cases (4.8%), with more than 5 cases annually and a 50% fatality rate. At least 1 case was reported in 40% of responding facilities, all involving non-vaccinated animals or those vaccinated only once or twice. Most facilities began vaccinating after experiencing a case, while fear of adverse fatal anaphylaxis reaction remains the primary reason for avoiding it. Notably, only 1 fatal vaccine reaction was reported in 1989, though procaine penicillin had been co-administered. Adverse reactions were rare and mostly resembled expected inflammatory reactions post vaccination such as anorexia, local swelling or blood changes. These were more frequent with oil-adjuvanted vaccines containing alpha-tocopherol or Amphigen®, and minimal to absent with aluminum hydroxide-based vaccines. Three facilities using the Amphigen®-adjuvanted ER Bac® Plus vaccine (Zoetis) observed transient lethargy and irregular breathing in 8 animals after several vaccinations, of which 1 had been treated. Regional differences in vaccine availability were observed. This 30 yr retrospective study highlights that cetaceans in human care face a greater risk of dying from erysipelas than from vaccine side effects. Furthermore, regular vaccination appears to offer effective protection against this preventable disease.