| 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 ... | 2000 | 10779575 |
| 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 ... | 2000 | 10864250 |
| dual sarcocystis neurona and toxoplasma gondii infection in a northern sea otter from washington state, usa. | dual sarcocystis neurona and toxoplasma gondii infection was observed in a northern sea otter from washington, usa. the animal was found stranded, convulsed, and died shortly thereafter. encephalitis caused by both s. neurona and t. gondii was demonstrated in histological sections of brain. immunohistochemical examination of sections with s. neurona specific antisera demonstrated developmental stages that divided by endopolygeny and produced numerous merozoites. pcr of brain tissue from the sea ... | 2001 | 11390085 |
| 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 ... | 2002 | 12076629 |
| 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 ... | 2002 | 12099433 |
| 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 ... | 2003 | 13129531 |
| 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 ... | 2003 | 14567210 |
| toxoplasma gondii, neospora caninum, sarcocystis neurona, and sarcocystis canis-like infections in marine mammals. | toxoplasma gondii, neospora caninum, sarcocystis neurona, and s. canis are related protozoans that can cause mortality in many species of domestic and wild animals. recently, t. gondii and s. neurona were recognized to cause encephalitis in marine mammals. as yet, there is no report of natural exposure of n. caninum in marine mammals. in the present study, antibodies to t. gondii and n. caninum were assayed in sera of several species of marine mammals. for t. gondii, sera were diluted 1:25, 1:50 ... | 2003 | 14580799 |
| 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 ... | 2003 | 14733279 |
| 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 ... | 2003 | 14736220 |
| 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 ... | 2004 | 15003489 |
| 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 ... | 2005 | 16157341 |
| biology and epidemiology of toxoplasma gondii in man and animals. | toxoplasma gondii is a coccidian parasite which utilizes felids as definitive hosts, and which has an unusually wide intermediate host range. the parasite was initially described by nicolle and manceaux in 1908 from the rodent, ctenodactylus gundi. infection with t. gondii is one of the most common parasitic infections of man and other warm-blooded animals. it has been found worldwide from alaska to australia. nearly one-third of humanity has been exposed to this parasite; serologic surveys indi ... | 2005 | 16164008 |
| clinical sarcocystis neurona, sarcocystis canis, toxoplasma gondii, and neospora caninum infections in dogs. | sarcocystis neurona, sarcocystis canis, toxoplasma gondii, and neospora caninum are related apicomplexans that can cause systemic illness in many species of animals, including dogs. we investigated one breeder's 25 basset hounds for these infections. in addition, tissues from dogs and other non-canine hosts previously reported as s. canis infections were studied retrospectively. schizonts resembling those of s. neurona, and recognized by polyclonal rabbit anti-s. neurona antibodies, were found i ... | 2006 | 16458431 |
| a genetically diverse but distinct north american population of sarcocystis neurona includes an overrepresented clone described by 12 microsatellite alleles. | the population genetics and systematics of most coccidians remain poorly defined despite their impact on human and veterinary health. non-recombinant parasite clones characterized by distinct transmission and pathogenesis traits persist in the coccidian toxoplasma gondii despite opportunities for sexual recombination. in order to determine whether this may be generally true for tissue-cyst forming coccidia, and to address evolutionary and taxonomic problems within the genus sarcocystis, we chara ... | 2006 | 16488197 |
| protozoal meningoencephalitis in sea otters (enhydra lutris): a histopathological and immunohistochemical study of naturally occurring cases. | protozoal meningoencephalitis is considered to be an important cause of mortality in the california sea otter (enhydra lutris). thirty nine of 344 (11.3%) california (ca) and washington state (wa) sea otters examined from 1985 to 2004 had histopathological evidence of significant protozoal meningoencephalitis. the aetiological agents and histopathological changes associated with these protozoal infections are described. the morphology of the actively multiplicative life stages of the organisms ( ... | 2007 | 17692867 |
| evaluation of two toxoplasma gondii serologic tests used in a serosurvey of domestic cats in california. | we evaluated the sensitivity (se) and specificity (sp) of an igg enzyme-linked immunosorbent assay (elisa) and igg indirect fluorescent antibody test (ifat) for detection of toxoplasma gondii-specific antibodies in sera from 2 cat populations using a bayesian approach. accounting for test covariance, the se and sp of the igg elisa were estimated to be 92.6% and 96.5%, and those of the igg ifat were 81.0% and 93.8%, respectively. both tests performed poorly in cats experimentally coinfected with ... | 2007 | 17918359 |
| genetic diversity among sea otter isolates of toxoplasma gondii. | sea otters (enhydra lutris) have been reported to become infected with toxoplasma gondii and at times succumb to clinical disease. here, we determined genotypes of 39 t. gondii isolates from 37 sea otters in two geographically distant locations (25 from california and 12 from washington). six genotypes were identified using 10 pcr-rflp genetic markers including sag1, sag2, sag3, btub, gra6, c22-8, c29-2, l358, pk1, and apico, and by dna sequencing of loci sag1 and gra6 in 13 isolates. of these 3 ... | 2008 | 18155841 |
| atypical toxoplasma gondii strain from a free-living jaguar (panthera onca) in french guiana. | like domestic cats, wild felids are involved in the complete infective cycle of toxoplasma gondii because they can host in their gastrointestinal tract sexually mature parasites and shed infective oocysts in their feces. we report, to our knowledge, the first isolation and molecular characterization of a t. gondii strain from the heart tissue of a free-living jaguar (panthera onca) in french guiana. sequencing at six polymorphic markers indicated that the jaguar isolate had an atypical genotype, ... | 2008 | 18256411 |
| 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 ... | 2008 | 18304737 |
| experimental infection of peromyscus californicus with toxoplasma gondii. | eight female peromyscus californicus were infected with 10(2) or 10(4) toxoplasma gondii culture-derived tachyzoites (type ii or x) isolated from southern sea otters. all but 2 mice survived infection and developed antibodies to t. gondii. the 2 fatally infected mice were inoculated with 10(4) tachyzoites of the type x strain. parasite detection by immunohistochemistry (ihc) and dna amplification with 2 polymerase chain reaction (pcr) methods was compared for brain, heart, lung, liver, spleen, b ... | 2007 | 18314680 |
| type x toxoplasma gondii in a wild mussel and terrestrial carnivores from coastal california: new linkages between terrestrial mammals, runoff and toxoplasmosis of sea otters. | sea otters in california are commonly infected with toxoplasma gondii. a unique type x strain is responsible for 72% of otter infections, but its prevalence in terrestrial animals and marine invertebrates inhabiting the same area was unknown. between 2000 and 2005, 45 terrestrial carnivores (lions, bobcats, domestic cats and foxes) and 1396 invertebrates (mussels, clams and worms) were screened for t. gondii using pcr and dna sequencing to determine the phylogeographic distribution of t. gondii ... | 2008 | 18452923 |
| the history of toxoplasma gondii--the first 100 years. | in this paper the history of toxoplasma gondii and toxoplasmosis is reviewed. this protozoan parasite was first discovered in 1908 and named a year later. its medical importance remained unknown until 1939 when t. gondii was identified in tissues of a congenitally infected infant, and veterinary importance became known when it was found to cause abortion storms in sheep in 1957. the discovery of a t. gondii specific antibody test, sabin-feldman dye test in 1948 led to the recognition that t. gon ... | 2008 | 19120791 |
| 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 ... | 2009 | 19164513 |
| 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 ... | 2010 | 19720009 |
| 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) ... | 2010 | 20071081 |
| uptake and transmission of toxoplasma gondii oocysts by migratory, filter-feeding fish. | from bottlenose dolphins, to walruses, to sea otters, the parasitic protozoan toxoplasma gondii is infecting marine mammals around the world. whereas the terrestrial transmission pathways of t. gondii are well-described, the transmission pathway by which marine mammals are being infected is unknown. we hypothesize that migratory filter feeders, specifically northern anchovies (engraulis mordax) and pacific sardines (sardinops sagax), are serving as biotic vectors for t. gondii within the marine ... | 2010 | 20097009 |
| effect of estuarine wetland degradation on transport of toxoplasma gondii surrogates from land to sea. | the flux of terrestrially derived pathogens to coastal waters presents a significant health risk to marine wildlife, as well as to humans who utilize the nearshore for recreation and seafood harvest. anthropogenic changes in natural habitats may result in increased transmission of zoonotic pathogens to coastal waters. the objective of our work was to evaluate how human-caused alterations of coastal landscapes in california affect the transport of toxoplasma gondii to estuarine waters. toxoplasma ... | 2010 | 20802072 |
| self-mating in the definitive host potentiates clonal outbreaks of the apicomplexan parasites sarcocystis neurona and toxoplasma gondii. | tissue-encysting coccidia, including toxoplasma gondii and sarcocystis neurona, are heterogamous parasites with sexual and asexual life stages in definitive and intermediate hosts, respectively. during its sexual life stage, t. gondii reproduces either by genetic out-crossing or via clonal amplification of a single strain through self-mating. out-crossing has been experimentally verified as a potent mechanism capable of producing offspring possessing a range of adaptive and virulence potentials. ... | 2010 | 21203443 |
| genetic analyses of atypical toxoplasma gondii strains reveal a fourth clonal lineage in north america. | toxoplasma gondii is a widespread parasite of animals that causes zoonotic infections in humans. previous studies have revealed a strongly clonal population structure in north america and europe, while strains from south america are genetically separate and more diverse. however, the composition within north america has been questioned by recent descriptions of genetically more variable strains from this region. here, we examined an expanded set of isolates using sequenced-based phylogenetic and ... | 2011 | 21320505 |
| genetic characterisation of toxoplasma gondii in wildlife from north america revealed widespread and high prevalence of the fourth clonal type. | little is known of the genetic diversity of toxoplasma gondii circulating in wildlife. in the present study wild animals, including dolphins, from the usa were examined for t. gondii infection. tissues of naturally exposed animals were bioassayed in mice for isolation of viable parasites. viable t. gondii was isolated from 31 animals including, to our knowledge for the first time, from a bald eagle (haliaeetus leucocephalus), five gray wolves (canis lupus), a woodrat (neotoma micropus), and five ... | 2011 | 21802422 |
| assessment of clinical pathology and pathogen exposure in sea otters (enhydra lutris) bordering the threatened population in alaska. | northern sea otter (enhydra lutris kenyoni) abundance has decreased dramatically over portions of southwest alaska, usa, since the mid-1980s, and this stock is currently listed as threatened under the endangered species act. in contrast, adjacent populations in south central alaska, usa, and russia have been stable to increasing during the same period. sea otters bordering the area classified in the recent decline were live-captured during 2004-2006 at bering island, russia, and the kodiak archi ... | 2011 | 21719822 |
| serological evidence of toxoplasma gondii infection in captive marine mammals in mexico. | toxoplasma gondii infection in marine mammals is important because they are considered as a sentinel for contamination of seas with t. gondii oocysts, and toxoplasmosis causes mortality in these animals, particularly sea otters. serological evidence of t. gondii infection was determined in 75 captive marine mammals from four facilities in southern and central geographical regions in mexico using the modified agglutination test (mat). antibodies (mat, 1:25 or higher) to t. gondii were found in 55 ... | 2011 | 21944844 |
| a systematic review of changes in marine mammal health in north america, 1972-2012: the need for a novel integrated approach. | marine mammals are often cited as "sentinels of ocean health" yet accessible, synthesized data on their health changes that could effectively warn of ocean health changes are rare. the objectives of this study were to 1) perform a systematic review of published cases of marine mammal disease to determine spatial and temporal trends in disease from 1972-2012, including changes in regions and taxa affected and specific causes; and 2) compare numbers of published cases of neoplasia with known, hosp ... | 2015 | 26579715 |
| pathogen exposure and blood chemistry in the washington, usa population of northern sea otters (enhydra lutris kenyoni). | northern sea otters (enhydra lutris kenyoni) from washington state, united states were evaluated in 2011 to determine health status and pathogen exposure. antibodies to brucella spp. (10%) and influenza a virus (23%) were detected for the first time in this population in 2011. changes in clinical pathology values (serum chemistries), exposure to pathogens, and overall health of the population over the last decade were assessed by comparing 2011 data to the data collected on this population in 20 ... | 2013 | 24502716 |
| 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 ... | 2016 | 26494610 |
| 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 ... | 2012 | 22493114 |
| concentration and retention of toxoplasma gondii surrogates from seawater by red abalone (haliotis rufescens). | small marine snails and abalone have been identified as high- and low-risk prey items, respectively, for exposure of threatened southern sea otters to toxoplasma gondii, a zoonotic parasite that can cause fatal encephalitis in animals and humans. while recent work has characterized snails as paratenic hosts for t. gondii, the ability of abalone to vector the parasite has not been evaluated. to further elucidate why abalone predation may be protective against t. gondii exposure, this study aimed ... | 2016 | 27573192 |
| 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 ... | 2015 | 26155464 |
| concentration and retention of toxoplasma gondii oocysts by marine snails demonstrate a novel mechanism for transmission of terrestrial zoonotic pathogens in coastal ecosystems. | the parasite toxoplasma gondii is an environmentally persistent pathogen that can cause fatal disease in humans, terrestrial warm-blooded animals and aquatic mammals. although an association between t. gondii exposure and prey specialization on marine snails was identified in threatened california sea otters, the ability of kelp-dwelling snails to transmit terrestrially derived pathogens has not been previously investigated. the objective of this study was to measure concentration and retention ... | 2015 | 26033089 |
| 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 ... | 2015 | 25588007 |
| aquatic polymers can drive pathogen transmission in coastal ecosystems. | gelatinous polymers including extracellular polymeric substances (epss) are fundamental to biophysical processes in aquatic habitats, including mediating aggregation processes and functioning as the matrix of biofilms. yet insight into the impact of these sticky molecules on the environmental transmission of pathogens in the ocean is limited. we used the zoonotic parasite toxoplasma gondii as a model to evaluate polymer-mediated mechanisms that promote transmission of terrestrially derived patho ... | 2014 | 25297861 |
| using molecular epidemiology to track toxoplasma gondii from terrestrial carnivores to marine hosts: implications for public health and conservation. | environmental transmission of the zoonotic parasite toxoplasma gondii, which is shed only by felids, poses risks to human and animal health in temperate and tropical ecosystems. atypical t. gondii genotypes have been linked to severe disease in people and the threatened population of california sea otters. to investigate land-to-sea parasite transmission, we screened 373 carnivores (feral domestic cats, mountain lions, bobcats, foxes, and coyotes) for t. gondii infection and examined the distrib ... | 2014 | 24874796 |
| 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 ... | 2013 | 24386100 |
| toxoplasma gondii, source to sea: higher contribution of domestic felids to terrestrial parasite loading despite lower infection prevalence. | environmental transmission of toxoplasma gondii, a global zoonotic parasite, adversely impacts human and animal health. toxoplasma is a significant cause of mortality in threatened southern sea otters, which serve as sentinels for disease threats to people and animals in coastal environments. as wild and domestic felids are the only recognized hosts capable of shedding toxoplasma oocysts into the environment, otter infection suggests land-to-sea pathogen transmission. to assess relative contribu ... | 2013 | 24048652 |