Evidence of infectious diseases in harbour porpoises (Phocoena phocoena) hunted in the waters of Greenland and by-caught in the German North Sea and Baltic Sea

The pathological, microbiological and serological findings in harbour porpoises hunted in Greenlandic waters were compared with the findings in animals accidentally caught in fishing gear in the German North Sea and Baltic Sea. The body condition of the Greenlandic animals was good, whereas nine of 23 German harbour porpoises were moderately to markedly emaciated. Both groups were infested with parasites. In the Greenlandic animals parasitism of the aural peribullar cavity with Stenurus minor, of the liver and pancreas with Orthosplanchnus mironovi, of the lungs with Halocercus species and of the subcutaneous and mammary tissue with Crassicauda species was generally associated with a mild inflammatory response. No diseases associated with bacteria were identified in any of the Greenlandic harbour porpoises. In the porpoises from the German North Sea and Baltic Sea, parasites were present in the aural peribullar cavity (S minor), liver (Campula oblonga), first and second gastric compartment (Anisakis simplex) and in the lungs (Pseudalius inflexus and Torynurus convolutus). Moderate to marked pulmonary parasitism and suppurative pneumonia, not observed in the Greenlandic porpoises, were present in 11 and 10, respectively, of the 23 German porpoises. The suppurative pneumonia was attributed to bacterial infection with beta-haemolytic streptococci and Escherichia coil var haemolytica. Four Greenlandic and 10 German porpoises had positive porpoise morbillivirus-specific antibody titres suggesting that the virus was circulating in both populations.

Utilization of stress in the development of an equine model for equine protozoal myeloencephalitis

Neurologic disease in horses caused by Sarcocystis neurona is difficult to diagnose, treat, or prevent, due to the lack of knowledge about the pathogenesis of the disease. This in turn is confounded by the lack of a reliable equine model of equine protozoal myeloencephalitis (EPM). Epidemiologic studies have implicated stress as a risk factor for this disease, thus, the role of transport stress was evaluated for incorporation into an equine model for EPM. Sporocysts from feral opossums were bioassayed in interferon-gamma gene knockout (KO) mice to determine minimum number of viable S. neurona sporocysts in the inoculum. A minimum of 80,000 viable S. neurona sporocysts were fed to each of the nine horses. A total of 12 S. neurona antibody negative horses were divided into four groups (1-4). Three horses (group 1) were fed sporocysts on the day of arrival at the study site, three horses were fed sporocysts 14 days after acclimatization (group 2), three horses were given sporocysts and dexamethasone 14 days after acclimatization (group 3) and three horses were controls (group 4). All horses fed sporocysts in the study developed antibodies to S. neurona in serum and cerebrospinal fluid (CSF) and developed clinical signs of neurologic disease. The most severe clinical signs were in horses in group 1 subjected to transport stress. The least severe neurologic signs were in horses treated with dexamethasone (group 3). Clinical signs improved in four horses from two treatment groups by the time of euthanasia (group 1, day 44; group 3, day 47). Post-mortem examinations, and tissues that were collected for light microscopy, immunohistochemistry, tissue cultures, and bioassay in KO mice, revealed no direct evidence of S. neurona infection. However, there were lesions compatible with S. neurona infection in horses. The results of this investigation suggest that stress can play a role in the pathogenesis of EPM. There is also evidence to suggest that horses in nature may clear the organism routinely, which may explain the relatively high number of normal horses with CSF antibodies to S. neurona compared to the prevalence of EPM.