Morbidity and Mortality Associated With a New Mycoplasma Species From Captive American Alligators (Alligator Mississippiensis)

Abstract

Nine of 74 American alligators (Alligator mississippiensis) from a captive Florida herd of 3-4-m-long, 200-350-kg, adult males greater than 30 yr of age died within a 10-day period during 1995. Nonspecific clinical signs included anorexia, lethargy, muscle weakness, paraparesis, bilateral white ocular discharge, and various degrees of periocular, facial, cervical, and limb edema. Pneumonia, pericarditis, and arthritis were found on postmortem evaluation of the spontaneously dead and euthanatized alligators. Rapidly growing mycoplasmas were identified by culture, and mycoplasma nucleotide sequences were identified by polymerase chain reaction testing of fresh lung and synovial fluid from an affected alligator. Culture of banked frozen lung from necropsy specimens and fresh lung and fresh synovial fluid from newly affected alligators confirmed the presence of a new mycoplasma species in seven of eight individuals. Oxytetracycline was administered, but related deaths continued for 6 mo until only 14 of the initial alligators remained. An enzyme-linked immunosorbent assay to detect antibody was developed, and the organism was transmitted experimentally to naive juvenile alligators, although the source of the organism, Mycoplasma sp. (ATCC 700619), has not been identified. The alligator isolate is a novel species in the mycoplasma family because its nucleotide sequence does not match those of over 75 characterized mycoplasma species. Such factors as population density, animal age, and mycoplasmal virulence likely contributed to the course of disease.

Galleria mellonella Invertebrate Model Mirrors the Pathogenic Potential of Mycoplasma alligatoris within the Natural Host

“…Mycoplasmal infection usually presents as a chronic, clinically silent disease with high morbidity but low mortality [2, 4-7, 9, 22-26]. In contrast, during the initial 1995 epizootic of captive American alligators, mortality was rapid with >80% of the population dying within a 6-month period [29]. Moreover, histological examinations confirmed that there was multisystem involvement with pneumonia, endocarditis, arthritis, and myocarditis [27].…”

“…In the natural host, the American alligator, we initially used the IT route of infection because that was the original route used in early infection studies [27,29,41]. We also used the results from these studies to inform our choice of infectious doses.…”

“…M. alligatoris ATCC 700619 strain A21JP2 was used for all studies. This is the type strain and was isolated from the joint of one of a group of captive alligators affected by a fatal epizootic disease in St. Johns County, Florida, in 1995 and 1996 [29,87]. SP4 broth and agar [88] were used for cultivation.…”

“…is characterized by low mortality but high morbidity, most commonly presenting as a chronic, and often clinically silent, disease [2, 4-7, 9, 22-26]. Mycoplasma alligatoris is one the few species of Mycoplasma that elicit fulminant disease in their host [27][28][29]. M. alligatoris was first identified in captive American alligators in a Florida zoological park in 1995.…”

Chronic inflammatory systemic diseases – an evolutionary trade-off between acutely beneficial but chronically harmful programs

“…Rainbow trouts can become anorectic under stressful conditions [ 27 ]. Even crocodiles develop anorexia and lethargy during infection [ 28 ], which demonstrates the uniformity of the response. In sum, the immune, endocrine, and nervous systems have evolved over hundreds of millions of years, and to understand diseases in humans, including CIDs, the long evolutionary history of these supersystems has to be taken into account.…”