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biological and molecular characterizations of toxoplasma gondii strains obtained from southern sea otters (enhydra lutris nereis).toxoplasma gondii was isolated from brain or heart tissue from 15 southern sea otters (enhydra lutris nereis) in cell cultures. these strains were used to infect mice that developed antibodies to t. gondii as detected in the modified direct agglutination test and had t. gondii tissue cysts in their brains at necropsy. mouse brains containing tissue cysts from 4 of the strains were fed to 4 cats. two of the cats excreted t. gondii oocysts in their feces that were infectious for mice. molecular an ...200010864250
evaluation of an indirect fluorescent antibody test (ifat) for demonstration of antibodies to toxoplasma gondii in the sea otter (enhydra lutris).an indirect fluorescent antibody test (ifat) for detection of toxoplasma gondii infection was validated using serum from 77 necropsied southern sea otters (enhydra lutris nereis) whose t. gondii infection status was determined through immunohistochemistry and parasite isolation in cell culture. twenty-eight otters (36%) were positive for t. gondii by immunohistochemistry or parasite isolation or both, whereas 49 (64%) were negative by both tests. at a cutoff of 1:320, combined values for ifat se ...200212099433
clinical pathology and assessment of pathogen exposure in southern and alaskan sea otters.the southern sea otter (enhydra lutris nereis) population in california (usa) and the alaskan sea otter (e. lutris kenyoni) population in the aleutian islands (usa) chain have recently declined. in order to evaluate disease as a contributing factor to the declines, health assessments of these two sea otter populations were conducted by evaluating hematologic and/or serum biochemical values and exposure to six marine and terrestrial pathogens using blood collected during ongoing studies from 1995 ...200314733279
sporulation and survival of toxoplasma gondii oocysts in seawater.we have been collaborating since 1992 in studies on southern sea otters (enhydra lutris nereis) as part of a program to define factors, which may be responsible for limiting the growth of the southern sea otter population. we previously demonstrated toxoplasma gondii in sea otters. we postulated that cat feces containing oocysts could be entering the marine environment through storm run-off or through municipal sewage since cat feces are often disposed down toilets by cat owners. the present stu ...200314736220
an unusual genotype of toxoplasma gondii is common in california sea otters (enhydra lutris nereis) and is a cause of mortality.toxoplasma gondii-associated meningoencephalitis is a significant disease of california sea otters (enhydra lutris nereis), responsible for 16% of total mortality in fresh, beachcast carcasses. toxoplasma gondii isolates were obtained from 35 california otters necropsied between 1998 and 2002. based on multi-locus pcr-restriction fragment length polymorphism and dna sequencing at conserved genes (18s rdna, its-1) and polymorphic genes (b1, sag1, sag3 and gra6), two distinct genotypes were identi ...200415003489
enteric bacterial pathogen detection in southern sea otters (enhydra lutris nereis) is associated with coastal urbanization and freshwater runoff.although protected for nearly a century, california's sea otters have been slow to recover, in part due to exposure to fecally-associated protozoal pathogens like toxoplasma gondii and sarcocystis neurona. however, potential impacts from exposure to fecal bacteria have not been systematically explored. using selective media, we examined feces from live and dead sea otters from california for specific enteric bacterial pathogens (campylobacter, salmonella, clostridium perfringens, c. difficile an ...201019720009
a new pathogen transmission mechanism in the ocean: the case of sea otter exposure to the land-parasite toxoplasma gondii.toxoplasma gondii is a land-derived parasite that infects humans and marine mammals. infections are a significant cause of mortality for endangered southern sea otters (enhydra lutris nereis), but the transmission mechanism is poorly understood. otter exposure to t. gondii has been linked to the consumption of marine turban snails in kelp (macrocystis pyrifera) forests. it is unknown how turban snails acquire oocysts, as snails scrape food particles attached to surfaces, whereas t. gondii oocyst ...201324386100
sea otter health: challenging a pet hypothesis.a recent series of studies on tagged sea otters (enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to toxoplasma gondii in central california. counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of di ...201526155464
limited genetic diversity among sarcocystis neurona strains infecting southern sea otters precludes distinction between marine and terrestrial isolates.sarcocystis neurona is an apicomplexan parasite identified as a cause of fatal neurological disease in the threatened southern sea otter (enhydra lutris nereis). in an effort to characterize virulent s. neurona strains circulating in the marine ecosystem, this study developed a range of markers relevant for molecular genotyping. highly conserved sequences within the 18s ribosomal gene array, the plastid-encoded rna polymerase (rpob) and the cytochrome c oxidase subunit 1 mitochondrial gene (co1) ...201020071081
prey choice and habitat use drive sea otter pathogen exposure in a resource-limited coastal system.the processes promoting disease in wild animal populations are highly complex, yet identifying these processes is critically important for conservation when disease is limiting a population. by combining field studies with epidemiologic tools, we evaluated the relationship between key factors impeding southern sea otter (enhydra lutris nereis) population growth: disease and resource limitation. this threatened population has struggled to recover despite protection, so we followed radio-tagged se ...200919164513
transmission of toxoplasma: clues from the study of sea otters as sentinels of toxoplasma gondii flow into the marine environment.toxoplasma gondii affects a wide variety of hosts including threatened southern sea otters (enhydra lutris nereis) which serve as sentinels for the detection of the parasite's transmission into marine ecosystems. toxoplasmosis is a major cause of mortality and contributor to the slow rate of population recovery for southern sea otters in california. an updated seroprevalence analysis showed that 52% of 305 freshly dead, beachcast sea otters and 38% of 257 live sea otters sampled along the califo ...200516157341
patterns of mortality in southern sea otters (enhydra lutris nereis) from 1998-2001.detailed postmortem examination of southern sea otters (enhydra lutris nereis) found along the california (usa) coast has provided an exceptional opportunity to understand factors influencing survival in this threatened marine mammal species. in order to evaluate recent trends in causes of mortality, the demographic and geographic distribution of causes of death in freshly deceased beachcast sea otters necropsied from 1998-2001 were evaluated. protozoal encephalitis, acanthocephalan-related dise ...200314567210
molecular and bioassay-based detection of toxoplasma gondii oocyst uptake by mussels (mytilus galloprovincialis).toxoplasma gondii is associated with morbidity and mortality in a variety of marine mammals, including fatal meningoencephalitis in the southern sea otter (enhydra lutris nereis). the source(s) of t. gondii infection and routes of transmission in the marine environment are unknown. we hypothesise that filter-feeding marine bivalve shellfish serve as paratenic hosts by assimilation and concentration of infective t. gondii oocysts and their subsequent predation by southern sea otters is a source o ...200313129531
epidemiology and pathology of toxoplasma gondii in free-ranging california sea lions (zalophus californianus).the coccidian parasite toxoplasma gondii infects humans and warm-blooded animals worldwide. the ecology of this parasite in marine systems is poorly understood, although many marine mammals are infected and susceptible to clinical toxoplasmosis. we summarized the lesions associated with t. gondii infection in the california sea lion (zalophus californianus) population and investigated the prevalence of and risk factors associated with t. gondii exposure, as indicated by antibody. five confirmed ...201525588007
biological characterisation of sarcocystis neurona isolated from a southern sea otter (enhydra lutris nereis).sarcocystis neurona was isolated from the brain of a juvenile, male southern sea otter (enhydra lutris nereis) suffering from cns disease. schizonts and merozoites in tissue sections of the otter's brain reacted with anti-s. neurona antiserum immunohistochemically. development in cell culture was by endopolyogeny and mature schizonts were first observed at 3 days postinoculation. pcr of merozoite dna using primer pairs jnb33/jnb54 and restriction enzyme digestion of the 1100 bp product with dra ...200010779575
temporal association between land-based runoff events and california sea otter (enhydra lutris nereis) protozoal mortalities.toxoplasma gondii and sarcocystis neurona have caused significant morbidity and mortality in threatened southern sea otters (enhydra lutris nereis) along the central california coast. because only terrestrial animals are known to serve as definitive hosts for t. gondii and s. neurona, infections in otters suggest a land to sea flow of these protozoan pathogens. to better characterize the role of overland runoff in delivery of terrestrially derived fecal pathogens to the near shore, we assessed t ...201222493114
dual congenital transmission of toxoplasma gondii and sarcocystis neurona in a late-term aborted pup from a chronically infected southern sea otter (enhydra lutris nereis).toxoplasma gondii and sarcocystis neurona are protozoan parasites with terrestrial definitive hosts, and both pathogens can cause fatal disease in a wide range of marine animals. close monitoring of threatened southern sea otters (enhydra lutris nereis) in california allowed for the diagnosis of dual transplacental transmission of t. gondii and s. neurona in a wild female otter that was chronically infected with both parasites. congenital infection resulted in late-term abortion due to dissemina ...201626494610
transplacental toxoplasmosis in a wild southern sea otter (enhydra lutris nereis).in september 2004, a neonatal sea otter pup was found alive on the beach in northern monterey bay, ca. efforts to locate the mother were unsuccessful. due to a poor prognosis for successful rehabilitation, the pup was euthanized. postmortem examination revealed emaciation, systemic lymphadenopathy and a malformation of the left cerebral temporal lobe. on histopathology, free tachyzoites and tissue cysts compatible with toxoplasma gondii were observed in the brain, heart, thymus, liver, lymph nod ...200818304737
coastal freshwater runoff is a risk factor for toxoplasma gondii infection of southern sea otters (enhydra lutris nereis).the association among anthropogenic environmental disturbance, pathogen pollution and the emergence of infectious diseases in wildlife has been postulated, but not always well supported by epidemiologic data. specific evidence of coastal contamination of the marine ecosystem with the zoonotic protozoan parasite, toxoplasma gondii, and extensive infection of southern sea otters (enhydra lutris nereis) along the california coast was documented by this study. to investigate the extent of exposure a ...200212076629
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