SARCOCYSTIS NEURONA INFECTIONS IN SEA OTTER (ENHYDRA LUTRIS): EVIDENCE FOR NATURAL INFECTIONS WITH SARCOCYSTS AND TRANSMISSION OF INFECTION TO OPOSSUMS (DIDELPHIS VIRGINIANA)

Although Sarcocystis neurona has been identified in an array of terrestrial vertebrates, recent recognition of its capacity to infect marine mammals was unexpected. Here, sarcocysts from 2 naturally infected sea otters (Enhydra lutris) were characterized biologically, ultrastructurally, and genetically. DNA was extracted from frozen muscle of the first of these sea otters and was characterized as S. neurona by polymerase chain reation (PCR) amplification followed by restriction fragment length polymorphism analysis and sequencing. Sarcocysts from sea otter no. 1 were up to 350 μm long, and the villar protrusions on the sarcocyst wall were up to 1.3 μm long and up to 0.25 μm wide. The villar protrusions were tapered towards the villar tip. Ultrastructurally, sarcocysts were similar to S. neurona sarcocysts from the muscles of cats experimentally infected with S. neurona sporocysts. Skeletal muscles from a second sea otter failed to support PCR amplification of markers considered diagnostic for S. neurona b...