No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Survey of Toxoplasma gondii Exposure in Muskrats in a Relatively Pristine Ecosystem
Abstract
Waterborne transmission of Toxoplasma gondii is assumed to be enhanced in areas with human-altered landscapes (e.g., urbanization, agriculture) and increased populations of non-native domestic and feral cats (Felis catus). However, little is known concerning T. gondii exposure risks in more natural watersheds (e.g., reduced human footprint, no domestic or feral cats) to establish a baseline for comparisons. In this study, muskrats (Ondatra zibethicus) were used as sentinels to assess baseline T. gondii exposure in a relatively pristine watershed in the Greater Voyageurs Ecosystem, northern Minnesota during the summers of 2018-2019. Toxoplasma gondii antibodies were assayed in sera of live-trapped muskrats (n = 70) using a modified agglutination test. None of our samples were positive for T. gondii antibodies (p = 0.00, 95% Wald Score Interval Confidence Interval = 0.00 - 0.05). This study establishes a baseline to compare T. gondii waterborne transmission risks in other human-modified watersheds.
... Both have been used as sentinel species in serologic studies for T. gondii. Factors such as proximity to cities, agricultural land, or the amount of municipal waste in waterbodies have been assumed to play an important role for infection (Hejlícek et al. 1997;Ahlers et al. 2015Ahlers et al. , 2020Zanzani et al. 2016). Given that beavers are mainly distributed along the water bodies of the Swiss Plateau, they are often located close to settlements and agricultural land and thus in potentially oocystcontaminated areas. ...
... Modified drainage systems used in agriculture and urbanized areas have been associated with facilitating transport of T. gondii into freshwater ecosystems (Ahlers et al. 2015). In comparison, in a study in Minnesota, far away from most human influences, no antibodies against T. gondii were detected in various populations of muskrats (Ahlers et al. 2020). To accurately estimate the risk of oocyst ingestion, additional research on the environmental contamination burden is necessary. ...
Toxoplasma gondii is a coccidian parasite able to infect all warm-blooded animals and humans. Rodents are one of the most important intermediate hosts for T. gondii, but little is known about infection in beavers and its clinical relevance. Toxoplasmosis was not considered an important waterborne disease until recently, but with increased outbreaks in humans and animals this perspective has changed. Serum samples from 247 Eurasian beavers (Castor fiber) collected from 2002 to 2022 were tested for antibodies to T. gondii by a commercial ELISA. Antibodies to T. gondii were found in 113 (45.8%) beavers. Higher weight and proximity to urban areas were found to be significant predictors for seropositivity. Additionally, T. gondii DNA was detected in 23/41 brain tissue samples by real-time PCR. Histopathologic examination of brain sections revealed inflammatory changes in 26/40 beavers, mainly characterized by encephalitis, meningitis, choroid plexitis, or a combination of them. In six of these cases the lesions were in direct association with parasitic stages. With an adapted nested PCR multilocus sequence typing and in silico restriction fragment length polymorphism analysis approach, three different T. gondii genotypes were detected in brain samples: the clonal Type II strain (ToxoDB 1), a Type II variant (ToxoDB 3), and a novel genotype exhibiting both Type II and I alleles in a further animal. Toxoplasma gondii infections in beavers have epidemiologic and clinical significance. The high seroprevalence indicates frequent contact with the parasite, and as competent intermediate hosts they may play an important role, contributing to maintaining the life cycle of T. gondii in semiaquatic habitats. In addition, although most beavers appear to develop subclinical to chronic disease courses, acute and fatal outcomes, mainly characterized by encephalitis and generalized infection, do also occur.
... In the Great Lakes region of North America, T. gondii has been reported in a variety of wildlife species (Table 6), with prevalence ranging from 0% in muskrats (Ahlers et al. 2020) to 84.4% in red fox (Vulpes vulpes; Tizard et al. 1976). In our study, prevalence of T. gondii in river otters (28%; 20-39%) was significantly lower than terrestrial species in the region (58%; 55-62%; v 2 ¼14.249; df¼1). ...
Toxoplasma gondii is a ubiquitous parasitic protozoan that poses a health threat to wildlife and human health worldwide. Oocysts shed into the environment in felid host feces may persist for several years. Runoff from rainfall and snowmelt may carry the oocysts into waterways. Semiaquatic mammals such as the Northern American river otter (Lontra canadensis) are particularly at risk of exposure, as they may encounter infective stages in both terrestrial and aquatic environments. Despite this risk, only a small number of studies have examined the prevalence of T. gondii in US river otter populations. Tongue tissue was sampled from 124 otters from the Upper Peninsula of Michigan submitted by trappers to the Michigan Department of Natural Resources in the 2018-19 harvest season. Following DNA extraction, a portion of the B1 T. gondii gene was amplified with PCR. A subset of positive samples was genotyped for comparison with known T. gondii sequences. Of the 124 tongue samples, 35 (28%) were positive for T. gondii. Prevalence did not differ significantly between sexes or age classes across the entire study area. Most (69%) of the genotyped samples were type 4 (type 12), a genotype commonly found in North American wildlife. Genotypes 127 and 197 were also found. Three clusters of T. gondii prevalence were identified through SaTScan analysis, although they were not significant. When modeling prevalence of T. gondii with covariates at individual otter locations, the top three models included the presence of Sarcocystis, area of exotic plants, area of agriculture, and sex of the otter. Our results suggest that T. gondii is widespread in otter populations in the Upper Peninsula of Michigan.
... We detected a high prevalence of antibodies to T. gondii (38%) in the first screen of trapper-harvested muskrats; however, only 1/28 of the secondary PCR screened muskrats was positive for T. gondii, although infections can be missed by PCR testing of a single tissue and sample. Our prevalence is intermediate to two recent studies on T. gondii exposure in Illinois (18/30; 60%) and Minnesota (0/70, 0%) [40,41]. The difference in prevalence could be ...
Using diagnostic data and contemporary sampling efforts, we conducted surveillance for a diversity of pathogens, toxicants, and diseases of muskrats (Ondatra zibethicus). Between 1977 and 2019, 26 diagnostic cases were examined from Kansas and throughout the Southeast and Mid-Atlantic, USA. We identified multiple causes of mortality in muskrats, but trauma (8/26), Tyzzer’s disease (5/6), and cysticercosis (5/26) were the most common. We also conducted necropsies, during November 2018—January 2019 Pennsylvania muskrat trapping season, on 380 trapper-harvested muskrat carcasses after the pelt was removed. Tissue samples and exudate were tested for presence of or exposure to a suite of pathogens and contaminants. Gastrointestinal tracts were examined for helminths. Intestinal helminths were present in 39.2% of necropsied muskrats, with Hymenolepis spp. (62%) and echinostome spp. (44%) being the most common Molecular testing identified a low prevalence of infection with Clostridium piliforme in the feces and Sarcocystis spp. in the heart. We detected a low seroprevalence to Toxoplasma gondii (1/380). No muskrats were positive for Francisella tularensis or Babesia spp. Cysticercosis was detected in 20% (5/26) of diagnostic cases and 15% (57/380) of our trapper-harvested muskrats. Toxic concentrations of arsenic, cadmium, lead, or mercury were not detected in tested liver samples. Copper, molybdenum, and zinc concentrations were detected at acceptable levels comparative to previous studies. Parasite intensity and abundance were typical of historic reports; however, younger muskrats had higher intensity of infection than older muskrats which is contradictory to what has been previously reported. A diversity of pathogens and contaminants have been reported from muskrats, but the associated disease impacts are poorly understood. Our data are consistent with historic reports and highlight the wide range of parasites, pathogens and contaminants harbored by muskrats in Pennsylvania. The data collected are a critical component in assessing overall muskrat health and serve as a basis for understanding the impacts of disease on recent muskrat population declines.
... Studies of California sea otters (Enhydra lutris) [60] and beluga whales (Delphinapterus leucas) [61] reported increased T. gondii prevalence under conditions of higher terrestrial runoff. Further evidence of anthropogenic oocyst loading of freshwater comes from the higher prevalence of T. gondii in muskrats (Ondatra zibethicus) exposed to wastewater [62] or watersheds subject to larger amounts of terrestrial runoff [63], compared to the absence of seropositive muskrats in pristine watersheds [64]. Compared to terrestrial ecosystems, there may also be increased oocyst accumulation and persistence within aquatic ecosystems due to oocyst adherence to biofilms on aquatic vegetation [65] and bioaccumulation within aquatic microorganisms [66] and larger-bodied filter-feeding transport hosts [67]. ...
Macroecological approaches can provide valuable insight into the epidemiology
of globally distributed, multi-host pathogens. Toxoplasma gondii is
a zoonotic protozoan that infects any warm-blooded animal, including
humans, in almost every ecosystem worldwide. There is substantial geographical
variation in T. gondii prevalence in wildlife populations and the
mechanisms driving this variation are poorly understood. We implemented
Bayesian phylogenetic mixed models to determine the association between
species’ ecology, phylogeny and climatic and anthropogenic factors on
T. gondii prevalence. Toxoplasma gondii prevalence data were compiled for
free-ranging wild mammal species from 202 published studies, encompassing
45 079 individuals from 54 taxonomic families and 238 species.We found
that T. gondii prevalence was positively associated with human population
density and warmer temperatures at the sampling location. Terrestrial
species had a lower overall prevalence, but there were no consistent patterns
between trophic level and prevalence. The relationship between human
density and T. gondii prevalence is probably mediated by higher domestic
cat abundance and landscape degradation leading to increased environmental
oocyst contamination. Landscape restoration and limiting freeroaming
in domestic cats could synergistically increase the resiliency of
wildlife populations and reduce wildlife and human infection risks from
one of the world’s most common parasitic infections.
... Previous literature reported 60% seroprevalence to Toxoplasma gondii in the muskrat population from a human-dominated ecosystem, 2 while we observed no evidence of T. gondii exposure in our muskrat population. 4 Collectively, these findings suggest that reference values produced from this study may be an optimal baseline for comparison of future muskrat studies. The difference in WBC and platelet estimates versus counts is likely related to methodology. ...
Muskrat (Ondatra zibethicus) populations show long-term and widespread declines across North America, necessitating research into potential mechanistic explanations, including population health. Previous research established reference hematology values, a proxy of individual health, of muskrats occurring in highly modified ecosystems. However, our knowledge of hematology metrics in muskrat populations occurring in more natural ecosystems is limited. We measured several hematological parameters of wild-caught muskrats (n = 73) in the Greater Voyageurs Ecosystem in northern Minnesota in 2018-2019 to establish baseline muskrat health in a relatively intact, near-pristine ecosystem. Additionally, we measured rectal temperature and heart and respiratory rates and collected whole blood for complete blood cell count assessment. We established baseline physiologic and hematologic reference ranges for the population and describe variations between total white blood cells, nucleated cell differentials, and basic erythron and platelet estimates and demonstrate methods of estimation to be poor proxies for more standardized counting methods. Our results establish a baseline to compare muskrat health assessments for populations affected by landscape change or in decline.
... On the other hand, a low income and poor sanitation were not the determining factors for low seropositivity to T. gondii in cats in Durango, Mexico 24 . Since a high density of felines (specially domestic cats) increases the risk of infection and T. gondii prevalence in intermediate hosts, a gradient of prevalence rate of infection has been demonstrated depending on the anthropization degree of the environment 25,26 . ...
Felidae as definitive hosts for Toxoplasma gondii play a major role in transmission to all warm-blooded animals trough oocysts dissemination. Therefore the current comprehensive study was performed to determine the global status of T. gondii infection in domestic and wild felids aiming to provide comprehensive data of interest for further intervention approaching the One Health perspective. Different databases were searched by utilizing particular key words for publications related to T. gondii infecting domestic and wild feline host species, worldwide, from 1970 to 2020. The review of 337 reports showed that the seroprevalence of T. gondii in domestic cats and wild felids was estimated in 37.5% (95% CI 34.7–40.3) (I² = 98.3%, P < 0.001) and 64% (95% CI 60–67.9) (I² = 88%, P < 0.0001), respectively. The global pooled prevalence of oocysts in the fecal examined specimens from domestic cats was estimated in 2.6% (95% CI 1.9–3.3) (I² = 96.1%, P < 0.0001), and that in fecal samples from wild felids was estimated in 2.4% (95% CI 1.1–4.2) (I² = 86.4%, P < 0.0001). In addition, from 13,252 examined soil samples in 14 reviewed studies, the pooled occurrence of T. gondii oocysts was determined in 16.2% (95% CI 7.66–27.03%). The observed high rates of anti-T. gondii antibodies seroprevalence levels and oocyst excretion frequency in the felids, along with soil (environmental) contamination with oocysts may constitute a potential threat to animal and public health, and data will result of interest in further prophylaxis programs.
... We marked individuals with passive integrated transponder tags (Ahlers et al. 2010a) and individual ear-tags. Prior to recovery, we collected 1.5 ml blood from individuals' cranial vena cava using a 25-ga needle attached to a 3-ml syringe (Ahlers et al. 2011(Ahlers et al. , 2020. Additionally, we recorded four morphometric tail measurements from each individual (length, base-width, mid-width and end-width). ...
Muskrats Ondatra zibethicus are semiaquatic herbivores experiencing long-term and widespread population declines across North America. Translocation may be a viable tool to bolster or reestablish local populations; however, subsequent effects of translocation on muskrats are unknown. We live-trapped and translocated radiomarked muskrats (n = 65) during the summers of 2018–2019 in Voyageurs National Park, MN, USA and assessed post-translocation effects on weekly survival probabilities and space-use patterns. We did not observe homing behavior, though individuals moved an average of 2.2 km (SE = 0.30 km) from release sites and established home ranges within ∼8 days (SE = 1.16 days) post-translocation. Weekly post-translocation survival probabilities (0.95, SE = 0.001) and average home-range sizes (2.52 ha, SE = 0.44 ha) were similar to other studies of non-translocated muskrats. Our most-supported known-fate survival model revealed muskrats using beaver Castor canadensis lodges had greater weekly survival probabilities. Additionally, weekly muskrat survival varied between years suggesting a positive response to a novel soft-release technique applied in 2019. Our study provides the first empirical assessment of translocation effects on muskrats and suggests translocation may be effective for establishing or enhancing local muskrat populations. Additionally, our study suggests beaver lodges may confer fitness benefits to sympatric muskrats particularly during dispersal.
Macroecological approaches can provide valuable insight into the epidemiology of globally distributed, multi-host pathogens. Toxoplasma gondii is a protozoan that infects any warm-blooded animal, including humans, in almost every habitat worldwide. Toxoplasma gondii infects its hosts through oocysts in the environment, carnivory of tissue cysts within intermediate host prey and vertical transmission. These routes of infection enable specific predictions regarding the ecological and life history traits that should predispose specific taxa to higher exposure and, thus infection rates of T. gondii. Using T. gondii prevalence data compiled from 485 studies representing 533 free-ranging wild mammalian species, we examined how ecological (habitat type, trophic level) and life history (longevity, vagility, gestation duration and torpor) traits influence T. gondii infection globally. We also compared T. gondii prevalence between wild and domesticated species from the same taxonomic families using data compiled from 540 studies of domestic cattle, sheep, and pigs. Across free-ranging wildlife, we found the average T. gondii prevalence was 22%, which is comparable to the global human estimate. Among ecological guilds, terrestrial species had lower T. gondii prevalence than aquatic species, with freshwater aquatic taxa having an increased prevalence compared to marine aquatic species. Dietary niches were also influential, with carnivores having an increased risk compared to other trophic feeding groups that have reduced tissue cyst exposure in their diet. With respect to influential life history traits, we found that more vagile wildlife species had higher T. gondii infection rates, perhaps because of the higher cumulative risk of infection during movement through areas with varying T. gondii environmental loads. Domestic farmed species had a higher T. gondii prevalence compared to free-ranging confamilial wildlife species. Through a macroecological approach, we determined the relative significance of transmission routes of a generalist pathogen, demonstrating an increased infection risk for aquatic and carnivorous species and highlighting the importance of preventing pathogen pollution into aquatic environments. Toxoplasma gondii is increasingly understood to be primarily an anthropogenically-associated pathogen whose dissemination is enhanced by ecosystem degradation and human subsidisation of free-roaming domestic cats. Adopting an ecosystem restoration approach to reduce one of the world’s most common parasites would synergistically contribute to other initiatives in conservation, feline and wildlife welfare, climate change, food security and public health.
This is the only book to cover toxoplasmosis of animals and humans thoroughly in one single source. Found worldwide from Alaska to Australasia, Toxoplasma gondii is the cause of one of the most common parasitic infections in humans, livestock, companion animals, and wildlife, and is included on the list of potential bioterrorism microbes. Furthermore, T. gondii has been and continues to be used extensively as a model for the cell biology of apicomplexan parasites. In the decade since the second edition of this book was published, there has been an explosion of knowledge concerning the parasite Toxoplasma gondii and toxoplasmosis. This update provides unique information on all known host types for this parasite, with an additional chapter on history, substantial updates throughout, and a detailed focus on the biology of the parasite in Chapter 2. The third edition is compiled by author JP Dubey, an authority on T. gondii who has worked with virtually all hosts of the protozoan during the last 55 years, including humans, all livestock species, wildlife, and zoo animals. The book distills the voluminous and potentially confusing scientific literature, that has grown geometrically in the 30+ years since the publication of the first edition, into a comprehensive resource for all professionals, graduate students and researchers working in this field.
Toxoplasma gondii infections are common in humans and animals worldwide. Rodents are one of the most important intermediate hosts for T. gondii because they are preyed on by cats, who in turn excrete the environmentally resistant oocysts in their feces and thus spread the infection. Information on T. gondii infections is spread in numerous reports and is not easily accessible to readers. Here, we review prevalence, persistence of infection, clinical disease, epidemiology, and genetic diversity of T. gondii infections in wild rodents worldwide. Data are tabulated by country, by each rodent species alphabetically, and chronologically. Recent genetic diversity of T. gondii strains in rodents is critically evaluated.
Toxoplasma gondii is a zoonotic protozoan parasite that can cause morbidity and mortality in humans, domestic animals, and terrestrial and aquatic wildlife. The environmentally robust oocyst stage of T. gondii is fundamentally critical to the parasite's success, both in terms of its worldwide distribution as well as the extensive range of infected intermediate hosts. Despite the limited definitive host species (domestic and wild felids), infections have been reported on every continent, and in terrestrial as well as aquatic environments. The remarkable resistance of the oocyst wall enables dissemination of T. gondii through watersheds and ecosystems, and long-term persistence in diverse foods such as shellfish and fresh produce. Here, we review the key attributes of oocyst biophysical properties that confer their ability to disseminate and survive in the environment, as well as the epidemiological dynamics of oocyst sources including domestic and wild felids. This manuscript further provides a comprehensive review of the pathways by which T. gondii oocysts can infect animals and people through the environment, including in contaminated foods, water or soil. We conclude by identifying critical control points for reducing risk of exposure to oocysts as well as opportunities for future synergies and new directions for research aimed at reducing the burden of oocyst-borne toxoplasmosis in humans, domestic animals, and wildlife.
Toxoplasmosis is caused by the globally distributed protozoan parasite Toxoplasma gondii (phylum Apicomplexa); the disease can be clinically important for almost all homeothermic animals, including birds and humans. Toxoplasmosis course involves general clinical signs, such as fever, anorexia, or dyspnea, and more specific signs with neural, respiratory, cutaneous, or ocular involvement. Because of the wide range of clinical signs, the diagnosis in domestic and pet animals can be complicated. Hence, this review aims to provide a comprehensive analysis of some scarcely discussed aspects of toxoplasmosis, such as ocular and cutaneous manifestations, congenital infections, influence of T. gondii genotype on clinical toxoplasmosis, and recent findings regarding differential diagnosis. This review could be of special interest to clinicians and researchers.
Introduction: Toxoplasmosis is a parasitic zoonosis and an important cause of abortions, mental retardation, encephalitis, blindness, and death worldwide. Few studies have quantified toxoplasmosis mortality and associated medical conditions in Sub-Saharan Africa. This retrospective hospital-based study aimed to determine the mortality patterns of toxoplasmosis and its comorbidities among in-patients in Tanzania.
Methods: Data on causes of death were collected using customized paper-based collection tools. Sources of data included death registers, inpatient registers, and International Classification of Diseases report forms. All death events from January 2006 to December 2015 were collected. Data used in this study is a subset of deaths where the underlying cause of death was toxoplasmosis. Data was analyzed by STATA programme version 13.
Results: Thirty-seven public hospitals were involved in the study. A total of 188 deaths due to toxoplasmosis were reported during the 10-years period. Toxoplasmosis deaths accounted for 0.08% (188/247,976) of the total deaths recorded. The age-standardized mortality rate per 100,000 population increased from 0.11 in 2006 to 0.79 in 2015. Most deaths due to toxoplasmosis affected the adult age category. Of the 188 deaths, males accounted for 51.1% while females for 48.9% of the deaths. Dar es Salaam, Mbeya, Pwani, Tanga, and Mwanza contributed to over half (59.05%) of all deaths due to Toxoplasmosis. Of the total deaths due to toxoplasmosis, 70.7% were associated with other medical conditions; which included HIV/AIDS (52.6%), HIV/AIDS+Cryptococcal meningitis (18.8%) and HIV+Pneumocystis pneumonia (6.8%).
Conclusion: The age-standardized mortality rate due to toxoplasmosis has been increasing substantially between 2006 and 2015. Most deaths due to toxoplasmosis affected the adult age category and were highly associated with HIV/AIDS. Appropriate interventions are needed to alleviate the burden of toxoplasmosis in Tanzania.
Landscape disturbances such as forest harvest, blowdowns, fire, and development activities create patches on the landscape that modify the structure and function of ecosystems and watersheds. Understanding the timing, location, size and intensity of these disturbances can assist resource managers while making decisions regarding management options. In an effort to provide information regarding these metrics, the Great Lakes Inventory and Monitoring Network implemented a long-term monitoring project to quantify landscape dynamics inside and surrounding Voyageurs National Park using an automated satellite-based change detection program called LandTrendr (Landsat-based detection of trends in disturbance and recovery). This is the second report for Voyageurs and varies slightly from the original report published in 2009 in terms of analysis area and the time period analyzed. We have doubled the analysis area outside the park and have increased the number of years analyzed from 2002–2007 (6 years) to 1995–2013(19 years). Inside the park, disturbances due to beaver affected the largest percent of land (0.44%, 0.02% per yr), followed closely by forest pathogen (0.41%, 0.02% per year) and fire (0.36%, 0.02% per yr). Lands adjacent the park experienced far greater levels of disturbance, with forest harvest accounting for 90% of the land disturbed outside the park (13.63%, 0.71% per yr). The second most prevalent disturbance agent outside the park was forest pathogen with only 0.66% (0.03% per yr) of the land disturbed outside the park during the 19-year analysis period. Continual long-term monitoring of this analysis area will contribute to our understanding of how these disturbances can and will affect the movement of wildlife through corridors through the park.
Voyageurs National Park (VOYA) is located in far northern Minnesota on the border with
Canada and at the southern range of numerous plant and animal communities of the boreal
ecosystem. Disturbances, or distinct changes in vegetative cover, are an important part of how
this ecosystem functions at the southern edge of its range. Monitoring these disturbances through
time will provide information regarding historic disturbance regimes compared to present and
future conditions and trends. For this analysis, disturbances in and around VOYA were
delineated for six years, 2002-2007, using a combination of Landsat satellite imagery and high
resolution aerial photos. We employed a set of computer algorithms, collectively known as
LandTrendr, in conjunction with a dense time series of Landsat imagery to track vegetation
changes in and around the park. Disturbance agents such as fire, forest harvest, development,
flooding due to beaver activity, and blowdowns were attributed to each disturbance, in addition
to the year of occurrence, and starting and ending vegetation classes. LandTrendr was used to
identify apparent disturbances, after which high resolution imagery (e.g., airphotos, Quickbird)
was used for photo interpretation to substantiate evidence of a disturbance, and hence, validate
whether the disturbance occurred. Summary analyses showed that disturbances outside the park
were dominated by forest harvest, while inside the park disturbances were most often caused by
beaver, blowdowns, or fire. After relativizing the data, the areas adjacent to VOYA in Canada
and MN experienced 10 and six times more disturbance, respectively, than inside the park.
Little is known of the epidemiology of toxoplasmosis in Minnesota. Here, we evaluated Toxoplasma gondii infection in 50 wild bobcats (Lynx rufus) and 75 other animals on/near 10 cattle farms. Antibodies to T. gondii were assayed in serum samples or tissue fluids by the modified agglutination test (MAT, cut-off 1:25). Twenty nine of 50 bobcats and 15 of 41 wildlife trapped on the vicinity of 10 farms and 9 of 16 adult domestic cats (Felis catus) and 6 of 14 domestic dogs resident on farms were seropositive. Toxoplasma gondii oocysts were not found in feces of any felid. Tissues of all seropositive wild animals trapped on the farm were bioassayed in mice and viable T. gondii was isolated from 2 badgers (Taxidea taxus), 2 raccoons (Procyon lotor), 1 coyote (Canis latrans), and 1 opossum (Didelphis virginiana). All 6 T. gondii isolates were further propagated in cell culture. Multi-locus PCR-RFLP genotyping using 10 markers (SAG1, SAG2 (5'- 3'SAG2, and alt.SAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) of DNA from cell culture derived tachyzoites revealed three genotypes; #5 ToxoDataBase (1 coyote, 1 raccoon), #1 (1 badger, 1 raccoon, 1 opossum), and #2 (1 badger). This is the first report of T. gondii prevalence in domestic cats and in bobcats from Minnesota, and the first isolation of viable T. gondii from badger. This article is protected by copyright. All rights reserved.
Climate change is predicted to increase the frequency of droughts and intensity of seasonal precipitation in many regions. Semiaquatic mammals should be vulnerable to this increased variability in precipitation, especially in human-modified landscapes where dispersal to suitable habitat or temporary refugia may be limited. Using six years of presence-absence data (2007-2012) spanning years of record-breaking drought and flood conditions, we evaluated regional occupancy dynamics of American mink (Neovison vison) and muskrats (Ondatra zibethicus) in a highly altered agroecosystem in Illinois, USA. We used noninvasive sign surveys and a multiseason occupancy modeling approach to estimate annual occupancy rates for both species and related these rates to summer precipitation. We also tracked radiomarked individuals to assess mortality risk for both species when moving in terrestrial areas. Annual model-averaged estimates of occupancy for mink and muskrat were correlated positively to summer precipitation. Mink and muskrats were widespread during a year (2008) with above-average precipitation. However, estimates of site occupancy declined substantially for mink (0.56) and especially muskrats (0.09) during the severe drought of 2012. Mink are generalist predators that probably use terrestrial habitat during droughts. However, mink had substantially greater risk of mortality away from streams. In comparison, muskrats are more restricted to aquatic habitats and likely suffered high mortality during the drought. Our patterns are striking, but a more mechanistic understanding is needed of how semiaquatic species in human-modified ecosystems will respond ecologically in situ to extreme weather events predicted by climate-change models.
Guidelines for use of wild mammal species are updated from the American Society of Mammalogists (ASM) 2007 publication. These revised guidelines cover current professional techniques and regulations involving mammals used in research and teaching. They incorporate additional resources, summaries of procedures, and reporting requirements not contained in earlier publications. Included are details on marking, housing, trapping, and collecting mammals. It is recommended that institutional animal care and use committees (IACUCs), regulatory agencies, and investigators use these guidelines as a resource for protocols involving wild mammals. These guidelines were prepared and approved by the ASM, working with experienced professional veterinarians and IACUCs, whose collective expertise provides a broad and comprehensive understanding of the biology of nondomesticated mammals in their natural environments. The most current version of these guidelines and any subsequent modifications are available at the ASM Animal Care and Use Committee page of the ASM Web site (http://mammalsociety.org/committees/index.asp).
The parasitic protozoan Toxoplasma gondii infects about one-third of the population of developed countries. The life-long presence of dormant stages of this parasite in the brain and muscular tissues of infected humans is usually considered asymptomatic from the clinical point of view. In the past 20 years, research performed mostly on military personnel, university students, pregnant women and blood donors has shown that this 'asymptomatic' disease has a large influence on various aspects of human life. Toxoplasma-infected subjects differ from uninfected controls in the personality profile estimated with two versions of Cattell's 16PF, Cloninger's TCI and Big Five questionnaires. Most of these differences increase with the length of time since the onset of infection, suggesting that Toxoplasma influences human personality rather than human personality influencing the probability of infection. Toxoplasmosis increases the reaction time of infected subjects, which can explain the increased probability of traffic accidents in infected subjects reported in three retrospective and one very large prospective case-control study. Latent toxoplasmosis is associated with immunosuppression, which might explain the increased probability of giving birth to a boy in Toxoplasma-infected women and also the extremely high prevalence of toxoplasmosis in mothers of children with Down syndrome. Toxoplasma-infected male students are about 3 cm taller than Toxoplasma-free subjects and their faces are rated by women as more masculine and dominant. These differences may be caused by an increased concentration of testosterone. Toxoplasma also appears to be involved in the initiation of more severe forms of schizophrenia. At least 40 studies confirmed an increased prevalence of toxoplasmosis among schizophrenic patients. Toxoplasma-infected schizophrenic patients differ from Toxoplasma-free schizophrenic patients by brain anatomy and by a higher intensity of the positive symptoms of the disease. Finally, five independent studies performed in blood donors, pregnant women and military personnel showed that RhD blood group positivity, especially in RhD heterozygotes, protects infected subjects against various effects of latent toxoplasmosis, such as the prolongation of reaction times, an increased risk of traffic accidents and excessive pregnancy weight gain. The modern human is not a natural host of Toxoplasma. Therefore, it can only be speculated which of the observed effects of latent toxoplasmosis are the result of the manipulation activity of the Toxoplasma aimed to increase the probability of its transmission from a natural intermediate to the definitive host by predation, and which are just side effects of chronic infection.
Modern farming practices in the midwestern United States have drastically altered the landscape. Most wetlands have been drained, and small streams are channelized to transport excess water away from tile-drained agricultural fields. Loss of critical wetland habitat has shifted the distribution of muskrats Ondatra zibethicus, an economically important furbearer in the region, to highly altered riparian habitats with unstable flow regimes. However, information regarding home-range size and space use for muskrats occurring in these linear habitats is lacking. We used location data from 26 radio-marked muskrats to estimate home-range size and space use in riparian habitats in an agroecosystem in east-central Illinois, USA. Home ranges were highly linear and confined to stream bank edges. Contrary to our prediction, muskrats did not freely move to upland habitat (e.g. row-crop agriculture) adjacent to stream edges to forage. Linear home ranges were longer for adults than for juveniles. Home-range size also was related positively to number of burrows used by individuals. As expected, muskrats used space non-randomly within linear home ranges with most movements aggregated around established bank burrows. Muskrats in riparian habitat are multiple central-place foragers. Our study provides insight into how muskrats, a semi-aquatic species affected by large-scale landscape change, use space within highly restricted linear habitats.
Baseline hematologic and serum chemistry values are used by veterinarians and wildlife biologists to identify abnormally high or low levels of particular blood parameters in a target species. This vital information can assist animal care providers in making informed decisions on the care of wildlife and help to determine diagnoses for certain illnesses. Published blood parameter values are not available for wild-caught muskrats (Ondatra zibethicus). We measured 27 blood parameter values from 29 free-ranging, riparian muskrats caught from June-November 2008 in east-central Illinois, USA, and compared mean values between adults and juveniles. Adult muskrats had higher levels of globulins (F(1,27)=6.394, P ≤ 0.018) and eosinophils (F(1,25)=6.883, P ≤ 0.015) than did juvenile muskrats, possibly because of increased exposure to parasites and allergens over time.
We conducted a cross-sectional study from 2008 to 2009 to evaluate the occurrence of feral and wild cats and the risk of Toxoplasma gondii infection in terrestrial wildlife in a natural area in Illinois, USA. Felids are definitive hosts for T. gondii and cats are a key component of rural and urban transmission of T. gondii. We selected four forest sites within the interior of the park and four edge sites within 300 m of human buildings. Feline and wildlife occurrence in the natural area was determined with the use of scent stations, motion-detection cameras, and overnight live trapping. Based on scent stations and trapping, feral cats used building sites more than forest sites (scent stations: P=0.010; trapping: P=0.083). Prevalence of T. gondii antibodies was determined with the use of the indirect immunofluorescent antibody test (IFAT) with a titer of 1:25 considered positive; T. gondii antibodies were detected in wildlife at all sites. Wildlife species were classified as having a large home range (LHR) or a small home range (SHR), based on published estimates and using a cutoff of 100 ha. Small-home-range mammals had a higher prevalence of antibody to T. gondii (odds ratio [OR]=4.2; P=0.018) at sites with a high frequency of cat occurrence (defined as ≥ 9 cat occurrences across three detection methods); this finding indicates that feral cats are the most likely source of environmental contamination. Overall, the prevalence of antibody to T. gondii among LHR mammals was significantly higher than the prevalence among SHR mammals (OR=7.1; P<0.001). Small-home-range mammals are an essential part of T. gondii-antibody prevalence studies and can be used as sentinels for risk of disease exposure to humans and wildlife in natural areas. This study improves our understanding of ecologic drivers behind the occurrence of spatial variation of T. gondii within a natural area.
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 gondii is a protozoan parasite that is excreted in the feces of infected felids and is thought to reach coastal waters in contaminated
runoff. This zoonotic pathogen causes waterborne toxoplasmosis in humans and is a significant cause of death in threatened
California sea otters. Surrogate particles that mimic the behavior of T. gondii oocysts in water were released in transport studies to evaluate if the loss of estuarine wetlands is contributing to an increased
flux of oocysts into coastal waters. Compared to vegetated sites, more surrogates were recovered from unvegetated mudflat
habitats, which represent degraded wetlands. Specifically, in Elkhorn Slough, where a large proportion of otters are infected
with T. gondii, erosion of 36% of vegetated wetlands to mudflats may increase the flux of oocysts by more than 2 orders of magnitude. Total
degradation of wetlands may result in increased Toxoplasma transport of 6 orders of magnitude or more. Destruction of wetland habitats along central coastal California may thus facilitate
pathogen pollution in coastal waters with detrimental health impacts to wildlife and humans.
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 disease, shark attack, and cardiac disease were identified as common causes of death in sea otters examined. While infection with acanthocephalan parasites was more likely to cause death in juvenile otters, Toxoplasma gondii encephalitis, shark attack, and cardiac disease were more common in prime-aged adult otters. Cardiac disease is a newly recognized cause of mortality in sea otters and T. gondii encephalitis was significantly associated with this condition. Otters with fatal shark bites were over three times more likely to have pre-existing T. gondii encephalitis suggesting that shark attack, which is a long-recognized source of mortality in otters, may be coupled with a recently recognized disease in otters. Spatial clusters of cause-specific mortality were detected for T. gondii encephalitis (in Estero Bay), acanthocephalan peritonitis (in southern Monterey Bay), and shark attack (from Santa Cruz to Point Año Nuevo). Diseases caused by parasites, bacteria, or fungi and diseases without a specified etiology were the primary cause of death in 63.8% of otters examined. Parasitic disease alone caused death in 38.1% of otters examined. This pattern of mortality, observed predominantly in juvenile and prime-aged adult southern sea otters, has negative implications for the overall health and recovery of this population.
Water was the suspected vehicle of Toxoplasma gondii dissemination in a toxoplasmosis outbreak in Brazil. A case-control study and geographic mapping of cases were performed. T. gondii was isolated directly from the implicated water and genotyped as SAG 2 type I.
Three separate mortality events affecting wild eastern fox squirrels ( Sciurus niger) were investigated in suburban areas within southeastern Michigan over a 3-yr period from the summer of 2015 through the winter of 2017. A total of seven squirrels were submitted for investigation. The squirrels were generally in fair to good body condition with moderate fat deposits. The tissues that most commonly exhibited gross or histologic lesions included the lungs, liver, and heart, whereas spleen and brain exhibited lesions less frequently. Lung lesions in all seven squirrels consisted of moderate interstitial pneumonia with necrosis and moderate to high numbers of protozoal organisms. Livers in four out of seven squirrels had multifocal necrosis associated with low to moderate numbers of protozoal organisms. Three out of seven brains examined had mild nonsuppurative meningoencephalitis with widely scattered protozoal cysts. Protozoal organisms observed in various tissues were strongly immunoreactive to Toxoplasma gondii antibody by immunohistochemical staining. Other primary disease conditions tested for included West Nile virus infection, pesticides, and anticoagulants. Toxoplasma gondii can cause disease and mortality in a variety of wild squirrel species, especially near human settlements, and would merit more attention.
Found worldwide from Alaska to Australasia, Toxoplasma gondii knows no geographic boundaries. The protozoan is the source of one of the most common parasitic infections in humans, livestock, companion animals, and wildlife, and has gained notoriety with its inclusion on the list of potential bioterrorism microbes. In the two decades since the publication of the first edition of Toxoplasmosis of Animals and Humans there has been an explosion of knowledge concerning T. gondii and toxoplasmosis. Still used extensively as a cell model, its genome has recently been published making it a subject of even greater scientific interest. Keeping the organizational style that made the previous edition so popular and usable, this second edition has been completely revised and updated. New in the Second Edition: Expanded information on the cultivation, maintenance, and preservation of T. gondii Expanded information on the cell biology and molecular biology of the parasite Reviews all literature from the past 20 years for each domestic animal Summarizes information on the worldwide prevalence of toxoplasmosis in pregnant women and the devastating disease it can cause in newborn Written by one of the pioneers of the field, the book provides unique information on all known host types for this parasite. It distills the voluminous and potentially confusing scientific literature that has grown geometrically in the 20 years since the publication of the first edition into a comprehensive resource. The single author approach ensures a strong foundation in the biology and a seamless integration of topics. The new edition of this groundbreaking work is the only volume to cover toxoplasmosis of animals and humans thoroughly in one source. It supplies an entry point to further research by cutting through the morass of literature to identify the most relevant references.
Abstract We assessed risk factors for Toxoplasma gondii exposure in semiaquatic mammals in east-central Illinois, USA. This agricultural region has extensive drainage systems that could potentially transport T. gondii oocysts into the watershed. We used muskrats (Ondatra zibethicus) and American mink (Neovison vison) as sentinels of watershed contamination. We predicted individuals from larger subwatersheds would more likely be antibody-positive for T. gondii, as they were exposed to drainage from larger areas. We also evaluated amount of urban land cover within the subwatershed, proximity to farmsteads, and age of individuals in competing models of T. gondii infection. Antibodies to T. gondii were assayed in animal sera by modified agglutination tests (titer 25 or higher) and detected in 18 (60%) of 30 muskrats and 20 (77%) of 26 mink. Infection rates were ≥1.7 times higher than those typical for mammals in upland habitats in this region. Subwatershed size and age class were important predictors of T. gondii infection in muskrats (R(2) = 0.35). Models incorporating urban land cover and proximity to farmsteads had little support. None of our models of antibody prevalence in mink were well supported, possibly because mink are less strictly associated with riparian habitats. Because ∼91% of our study area is devoted to agricultural production and urbanization, transport of T. gondii into freshwater ecosystems is likely facilitated by modified drainage practices common in these areas.
Waterborne outbreaks of Toxoplasma gondii have focused attention on the importance of oocysts shed in the feces of infected cats. Cat feces deposited annually into the environment in the United States total approximately 1.2 million metric tons. The annual oocyst burden measured in community surveys is 3 to 434 oocysts per square foot and is greater in areas where cats selectively defecate. Because a single oocyst can possibly cause infection, this oocyst burden represents a major potential public health problem. The proper disposal of cat litter, keeping cats indoors, reducing the feral cat population, and protecting the play areas of children might potentially reduce the oocyst burden.
We examine the role of the protozoan Toxoplasma gondii as a manipulatory parasite and question what role study of infections in its natural intermediate rodent hosts and other secondary hosts, including humans, may elucidate in terms of the epidemiology, evolution and clinical applications of infection. In particular, we focus on the potential association between T. gondii and schizophrenia. We introduce the novel term 'T. gondii-rat manipulation-schizophrenia model' and propose how future behavioural research on this model should be performed from a biological, clinical and ethically appropriate perspective.
Toxoplasmosis, caused by Toxoplasma gondii, is one of the most common parasitic infections of humans and other warmblooded animals. It has been found worldwide and nearly one-third of humans have been exposed to the parasite. Congenital infection occurs when a woman becomes infected during pregnancy and transmits the parasite to the fetus. Besides congenital infection, humans become infected by ingesting food or water contaminated with sporulated oocysts from infected cat feces or through ingestion of tissue cysts in undercooked or uncooked meat. Food animals (pigs, chickens, lambs and goats) become infected by the same routes, resulting in meat products containing tissue cysts, which can then infect consumers. Toxoplasma infection is common in food animals in the United States. Implementation of management factors such as biosecure confinement housing are important in reducing the levels of infection in animals destined for human consumption.
Alzheimer disease (AD), a chronic progressive neurodegenerative disorder, has a mainly unknown multifactorial etiology. Neuroinflammatory mechanisms might contribute to the cascade of events leading to neuronal degeneration. Central nervous system infections have been previously suggested as possible etiological agents in the development of sporadic AD. Toxoplasmosis can be associated with various neuropsychiatric disorders. In this study, we aimed to investigate the possible association between toxoplasma infection and AD.
This study evaluated the serum anti-Toxoplasma gondii IgG levels. It included an age-matched and sex-matched study and control groups that consisted of 34 patients with AD and 37 healthy individuals, respectively. There were no difference between the socio economic states of the patients and control subjects. serecm anti-I-gondi IgG levels were measured by using ELISA.
According to the statistical analysis, there were no significant differences among the patients and the control participants with respect to age (68.05±15.98, 62.91±5.89 y, P=0.072; respectively) and sex. The seropositivity rate for anti-T. gondii IgG antibodies among AD patients and control groups were 44.1% and 24.3%, respectively, and there was significant difference between the serum anti-T. gondii IgG levels (P=0.005).
Our findings suggest that toxoplasma infection may be involved in the pathogenetic mechanisms of AD. If confirmed, a positive correlation between toxoplasmosis and AD may lead to new approaches for the management of AD.
The availability of accurate diagnostic tests is essential for the detection and control of Toxoplasma gondii infections in both definitive and intermediate hosts. Sensitivity, specificity and the area under the receiver-operating characteristic (ROC) curve are commonly used measures of test accuracy for infectious diseases such as toxoplasmosis. These test performance characteristics are important considerations when selecting from among a group of tests for a specific testing purpose. In this study, we reviewed statistical approaches to evaluation of tests for toxoplasmosis with and without a gold-standard (reference) test, including use of ROC analysis and likelihood ratios which retain the diagnostic information inherent in a quantitative test result. We use previously published data from a comparison of the accuracy of serological tests for swine toxoplasmosis to demonstrate suggested methods of data analysis. We make recommendations for statistical analysis and reporting of test evaluation studies for T. gondii in food animals based on our own experiences and those of others.
Humans become infected with Toxoplasma gondii mainly by ingesting uncooked meat containing viable tissue cysts or by ingesting food or water contaminated with oocysts from the feces of infected cats. Circumstantial evidence suggests that oocyst-induced infections in humans are clinically more severe than tissue cyst-acquired infections. Until recently, waterborne transmission of T. gondii was considered uncommon, but a large human outbreak linked to contamination of a municipal water reservoir in Canada by wild felids and the widespread infection of marine mammals in the USA provided reasons to question this view. The present paper examines the possible importance of T. gondii transmission by water.
Sera from 273 wild mammals from Missouri and Kansas (USA), collected between December 1974 and December 1987, were tested for the presence of antibodies to Toxoplasma gondii using the Sabin-Feldman dye test. Sixty-five (24%) had antibodies at titers of > or = 1:8, including 38 (66%) of 58 carnivores, 14 (15%) of 94 omnivores, 13 (11%) of 117 herbivores, and none of four insectivores. The prevalence of antibodies in mice (Mus musculus and Peromyscus spp.) and rats (Rattus norvegicus and Sigmodon hispidus) was low (3%), while medium sized herbivores such as squirrels (Sciurus spp.), rabbits (Sylvilagus floridanus), and muskrats (Ondatra zibethicus) had prevalences of about 18%. Red foxes (Vulpes fulva) and mink (Mustela vison) had the highest prevalence of antibodies with frequencies of 90 and 66%, respectively. In 32 attempts to isolate Toxoplasma gondii from wild mammals with positive (> or = 1:4) titers, only six (19%) were successful: a gray squirrel (Sciurus carolinensis), a beaver (Castor canadensis), an opossum (Didelphis marsupialis), a red fox and two mink. These findings are consistent with the hypothesis that the probability of infection with Toxoplasma gondii, and therefore prevalence of antibodies in wildlife, is greatest in carnivores.
In 1983-1990, 256 muskrats (Ondatra zibethicus) were examined at four sites near Brno (South Moravia, Czech Republic) for the presence of the protozoan parasite Toxoplasma gondii. T. gondii infection was demonstrated in 47% of muskrats from one site with water heavily polluted with municipal wastes and 9% in muskrats from 3 sites with water slightly polluted with wastes, the difference being significant (chi 2 test, P < 0.001).
Outbreaks of toxoplasmosis are recognised infrequently. In March, 1995, a sudden increase of serologically diagnosed cases of acute toxoplasmosis was noted in the Greater Victoria area of British Columbia, Canada. Concurrently, but independently, seven cases of acute toxoplasma retinitis were diagnosed against a background of no cases in the previous 5 years.
Cases were defined by serological testing, clinical presentation, and residence in Greater Victoria. A screening programme for women who were or had been pregnant was started. Geographical mapping of cases, and case-control studies of symptomatic cases and of women enrolled in the screening programme were done.
100 individuals aged 6 to 83 years met the definition for an acute, outbreak-related case. 94 resided in Greater Victoria and six had visited it; 19 had retinitis, 51 had lymphadenopathy, four others had symptoms consistent with toxoplasmosis, seven had other symptoms, 18 were symptom-free, and one would not provide information. 36 (0.9%) of 3812 screened pregnant and postnatal women were cases. Excess cases were not detected outside Greater Victoria and no conventional source of toxoplasmosis was implicated. Mapping studies of cases and of the screened women, and both case-control studies showed significant associations between acute infection and residence in the distribution system of one reservoir supplying water to Greater Victoria (ORs or RRs: 3.53, 3.05, 8.27, and 5.42, respectively). The epidemic curve appeared bimodal, with peaks in December, 1994, and March, 1995, that were preceded by increased rainfall and turbidity in the implicated reservoir.
A municipal water system that uses unfiltered, chloraminated surface water was the likely source of this large community-wide outbreak of toxoplasmosis.
The prevalence of Toxoplasma gondii was determined in wild mammals in the Czech Republic from 1981 to 1990. The biological prevalence of T. gondii was < 1% in insectivores (n = 578), 12% in carnivores (n = 112), 1% in rodents except muskrats (Ondatra zibethicus) (n = 5,163), 24% in muskrats (n = 437), 5% in lagomorphs (n = 293), 0% in ruminants (n = 456), and 2% in wild boars (Sus scrofa) (n = 136). The seroprevalence (Sabin-Feldman dye test, titre > or = 1:4) of T. gondii was 15% in ruminants (n = 421), and 15% in wild boars (n = 124). Antibodies to T. gondii also were found in four of 10 carnivores. Toxoplasmosis is a common infection in wild mammals from the Czech Republic, but its prevalence varies considerable according to taxonomic groups and different localities where wild mammals live.
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 and factors contributing to the apparent emergence of T. gondii in southern sea otters, we compiled environmental, demographic and serological data from 223 live and dead sea otters examined between 1997 and 2001. The T. gondii seroprevalence was 42% (49/116) for live otters, and 62% (66/107) for dead otters. Demographic and environmental data were examined for associations with T. gondii seropositivity, with the ultimate goal of identifying spatial clusters and demographic and environmental risk factors for T. gondii infection. Spatial analysis revealed clusters of T. gondii-seropositive sea otters at two locations along the coast, and one site with lower than expected T. gondii seroprevalence. Risk factors that were positively associated with T. gondii seropositivity in logistic regression analysis included male gender, older age and otters sampled from the Morro Bay region of California. Most importantly, otters sampled near areas of maximal freshwater runoff were approximately three times more likely to be seropositive to T. gondii than otters sampled in areas of low flow. No association was found between seropositivity to T. gondii and human population density or exposure to sewage. This study provides evidence implicating land-based surface runoff as a source of T. gondii infection for marine mammals, specifically sea otters, and provides a convincing illustration of pathogen pollution in the marine ecosystem.
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 California coast from 1998 to 2004 were infected with T. gondii. Areas with high T. gondii exposure were predominantly sandy bays near urban centres with freshwater runoff. Genotypic characterisation of 15 new T. gondii isolates obtained from otters in 2004 identified only X alleles at B1 and SAG1. A total of 38/50 or 72% of all otter isolates so far examined have been infected with a Type X strain. Type X isolates were also obtained from a Pacific harbor seal (Phoca vitulina) and California sea lion (Zalophus californianus). Molecular analysis using the C8 RAPD marker showed that the X isolates were more genetically heterogeneous than archetypal Type I, II and III genotypes of T. gondii. The origin and transmission of the Type X T. gondii genotype are not yet clear. Sea otters do not prey on known intermediate hosts for T. gondii and vertical transmission appears to play a minor role in maintaining infection in the populations. Therefore, the most likely source of infection is by infectious, environmentally resistant oocysts that are shed in the feces of felids and transported via freshwater runoff into the marine ecosystem. As nearshore predators, otters serve as sentinels of protozoal pathogen flow into the marine environment since they share the same environment and consume some of the same foods as humans. Investigation into the processes promoting T. gondii infections in sea otters will provide a better understanding of terrestrial parasite flow and the emergence of disease at the interface between wildlife, domestic animals and humans.
Toxoplasma gondii is a protozoan parasite that infects up to a third of the world's population. Infection is mainly acquired by ingestion of food that is contaminated with oocysts. We report an outbreak of ocular toxoplasmosis, which is an acute acquired type rather than reactivation of congenital toxoplasmosis. Our preliminary investigation points to municipal water contamination. This outbreak only proves the need of an effective public health system and health education in curtailing any outbreak.
Aquatic synthesis for Voyageurs National Park: U.S. Geological Survey, Information and
- L W Kallemeyn
- K Holmberg
- J A Perry
KALLEMEYN, L. W., K. L HOLMBERG, J. A. PERRY, AND B. Y.
ODDE. 2003. Aquatic synthesis for Voyageurs National Park:
U.S. Geological Survey, Information and Technology Report
2003-0001, 95 p.
Patterns of mortality in southern seas otters
- C Kreuder
- M A Miller
- D A Jessup
- L J Lowenstine
- M D Harris
- J A Ames
- T E Carpenter
- P A Conrad
- J A K Mazet
KREUDER, C., M. A. MILLER, D. A. JESSUP, L. J. LOWENSTINE, M.
D. HARRIS, J. A. AMES, T. E. CARPENTER, P. A. CONRAD, AND
J. A. K. MAZET. 2003. Patterns of mortality in southern seas
otters (Enhydra lutris nereis) from 1998-2001. Journal of
Wildlife Diseases 39: 495-509.