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1.
Proc Biol Sci ; 286(1909): 20191334, 2019 08 28.
Article in English | MEDLINE | ID: mdl-31431162

ABSTRACT

Why some Toxoplasma gondii-infected southern sea otters (Enhydra lutris nereis) develop fatal toxoplasmosis while others have incidental or mild chronic infections has long puzzled the scientific community. We assessed robust datasets on T. gondii molecular characterization in relation to detailed necropsy and histopathology results to evaluate whether parasite genotype influences pathological outcomes in sea otters that stranded along the central California coast. Genotypes isolated from sea otters were also compared with T. gondii strains circulating in felids from nearby coastal regions to assess land-to-sea parasite transmission. The predominant T. gondii genotypes isolated from 135 necropsied sea otters were atypical Type X and Type X variants (79%), with the remainder (21%) belonging to Type II or Type II/X recombinants. All sea otters that died due to T. gondii as a primary cause of death were infected with Type X or X-variant T. gondii strains. The same atypical T. gondii strains were detected in sea otters with fatal toxoplasmosis and terrestrial felids from watersheds bordering the sea otter range. Our results confirm a land-sea connection for virulent T. gondii genotypes and highlight how faecal contamination can deliver lethal pathogens to coastal waters, leading to detrimental impacts on marine wildlife.


Subject(s)
Otters/parasitology , Toxoplasma/genetics , Toxoplasmosis, Animal/parasitology , Virulence Factors/genetics , Animals , California , DNA, Protozoan , Genotype
2.
Parasitology ; 143(3): 276-88, 2016 Mar.
Article in English | MEDLINE | ID: mdl-26494610

ABSTRACT

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 disseminated toxoplasmosis. Toxoplasma gondii and S. neurona DNA was amplified from placental tissue culture, as well as from fetal lung tissue. Molecular characterization of T. gondii revealed a Type X genotype in isolates derived from placenta and fetal brain, as well as in all tested fetal organs (brain, lung, spleen, liver and thymus). This report provides the first evidence for transplacental transmission of T. gondii in a chronically infected wild sea otter, and the first molecular and immunohistochemical confirmation of concurrent transplacental transmission of T. gondii and S. neurona in any species. Repeated fetal and/or neonatal losses in the sea otter dam also suggested that T. gondii has the potential to reduce fecundity in chronically infected marine mammals through parasite recrudescence and repeated fetal infection.


Subject(s)
Abortion, Veterinary/etiology , Otters/parasitology , Sarcocystosis/veterinary , Toxoplasmosis, Animal/congenital , Toxoplasmosis, Animal/complications , Animals , Antibodies, Protozoan/blood , California , Cells, Cultured , Chronic Disease , DNA, Protozoan/analysis , Female , Genotype , Pregnancy , Sarcocystis/genetics , Sarcocystis/physiology , Sarcocystosis/complications , Sarcocystosis/congenital , Sarcocystosis/transmission , Toxoplasma/genetics , Toxoplasma/physiology , Toxoplasmosis, Animal/pathology , Toxoplasmosis, Animal/transmission
3.
Environ Microbiol ; 17(11): 4177-88, 2015 Nov.
Article in English | MEDLINE | ID: mdl-25367256

ABSTRACT

Coastal habitat contamination with Toxoplasma gondii is a health risk to humans and marine wildlife, with infections documented in both nearshore and pelagic marine mammals. Due to lack of sensitive methods for detection of T. gondii in water, this study utilized an alternative surveillance approach for evaluating marine habitat contamination using wild mussels. The objectives of this study were to (i) validate sensitive molecular tools for T. gondii detection in mussels and (ii) apply optimized methods in a surveillance study to determine the prevalence and genotype(s) of T. gondii in mussels. Simplex polymerase chain reaction screening and multiplex genotyping assays were validated and then applied on 959 wild-caught mussels collected from central California. Thirteen mussels (1.4%) had detectable T. gondii DNA and the presence of T. gondii in mussels was significantly associated with proximity to freshwater run-off and collection during the wet season. Molecular characterization revealed alleles from T. gondii types I, II/III, X at the B1 locus, and a novel atypical B1 allele that was recently documented in T. gondii-infected carnivores from California. Findings demonstrate higher than previously reported T. gondii contamination of California coastlines, and describe novel strains of the parasite that further link terrestrial sources with marine contamination.


Subject(s)
Environmental Monitoring/methods , Mytilus/parasitology , Seawater/parasitology , Toxoplasma/isolation & purification , Toxoplasmosis, Animal/prevention & control , Alleles , Animals , California/epidemiology , Carnivora/parasitology , DNA, Protozoan/genetics , Ecosystem , Genotype , Humans , Polymerase Chain Reaction/methods , Polymorphism, Restriction Fragment Length , Sequence Analysis, DNA , Toxoplasma/genetics , Toxoplasmosis, Animal/epidemiology
4.
Ecohealth ; 2024 Jun 08.
Article in English | MEDLINE | ID: mdl-38850367

ABSTRACT

Toxoplasmosis is a disease of primary concern for Hawaiian monk seals (Neomonachus schauinslandi), due to its apparently acute lethality and especially heavy impacts on breeding female seals. The disease-causing parasite, Toxoplasma gondii, depends on cats to complete its life cycle; thus, in order to understand how this pathogen infects marine mammals, it is essential to understand aspects of the terrestrial ecosystem and land-to-sea transport. In this study, we constructed a three-tiered model to assess risk of Hawaiian monk seal exposure to T. gondii oocysts: (1) oocyst contamination as a function of cat population characteristics; (2) land-to-sea transport of oocysts as a function of island hydrology, and (3) seal exposure as a function of habitat and space use. We were able to generate risk maps highlighting watersheds contributing the most to oocyst contamination of Hawaiian monk seal habitat. Further, the model showed that free-roaming cats most associated with humans (pets or strays often supplementally fed by people) were able to achieve high densities leading to high levels of oocyst contamination and elevated risk of T. gondii exposure.

5.
PLoS One ; 18(6): e0286808, 2023.
Article in English | MEDLINE | ID: mdl-37343040

ABSTRACT

Toxoplasma gondii is a ubiquitous zoonotic parasite that can infect warm-blooded vertebrates, including humans. Felids, the definitive hosts, drive T. gondii infections by shedding the environmentally resistant stage of the parasite (oocysts) in their feces. Few studies characterize the role of climate and anthropogenic factors in oocyst shedding among free-ranging felids, which are responsible for the majority of environmental contamination. We determined how climate and anthropogenic factors influence oocyst shedding in free-ranging domestic cats and wild felids using generalized linear mixed models. T. gondii oocyst shedding data from 47 studies were systematically reviewed and compiled for domestic cats and six wild felid species, encompassing 256 positives out of 9,635 total fecal samples. Shedding prevalence in domestic cats and wild felids was positively associated with human population density at the sampling location. Larger mean diurnal temperature range was associated with more shedding among domestic cats and warmer temperature in the driest quarter was associated with lower oocyst shedding in wild felids. Increasing human population density and temperature fluctuation can exacerbate environmental contamination with the protozoan parasite T. gondii. Management of free-ranging domestic cats could lower the burden of environmental oocysts due to their large population sizes and affinity with human settlements.


Subject(s)
Cat Diseases , Felidae , Parasites , Toxoplasma , Toxoplasmosis, Animal , Cats , Animals , Humans , Population Density , Temperature , Prevalence , Oocysts , Toxoplasmosis, Animal/epidemiology , Toxoplasmosis, Animal/parasitology , Felidae/parasitology , Feces/parasitology
6.
PLoS Negl Trop Dis ; 17(12): e0011829, 2023 Dec.
Article in English | MEDLINE | ID: mdl-38100522

ABSTRACT

Toxoplasma gondii is a zoonotic parasite that can cause severe morbidity and mortality in warm-blooded animals, including marine mammals such as sea otters. Free-ranging cats can shed environmentally resistant T. gondii oocysts in their feces, which are transported through rain-driven runoff from land to sea. Despite their large population sizes and ability to contribute to environmental oocyst contamination, there are limited studies on T. gondii oocyst shedding by free-ranging cats. We aimed to determine the frequency and genotypes of T. gondii oocysts shed by free-ranging domestic cats in central coastal California and evaluate whether genotypes present in feces are similar to those identified in sea otters that died from fatal toxoplasmosis. We utilized a longitudinal field study of four free-ranging cat colonies to assess oocyst shedding prevalence using microscopy and molecular testing with polymerase chain reaction (PCR). T. gondii DNA was confirmed with primers targeting the ITS1 locus and positive samples were genotyped at the B1 locus. While oocysts were not visualized using microscopy (0/404), we detected T. gondii DNA in 25.9% (94/362) of fecal samples. We genotyped 27 samples at the B1 locus and characterized 13 of these samples at one to three additional loci using multi locus sequence typing (MLST). Parasite DNA detection was significantly higher during the wet season (16.3%, 59/362) compared to the dry season (9.7%; 35/362), suggesting seasonal variation in T. gondii DNA presence in feces. High diversity of T. gondii strains was characterized at the B1 locus, including non-archetypal strains previously associated with sea otter mortalities. Free-ranging cats may thus play an important role in the transmission of virulent T. gondii genotypes that cause morbidity and mortality in marine wildlife. Management of free-ranging cat colonies could reduce environmental contamination with oocysts and subsequent T. gondii infection in endangered marine mammals and people.


Subject(s)
Cat Diseases , Otters , Toxoplasma , Toxoplasmosis, Animal , Humans , Cats , Animals , Animals, Wild , Toxoplasma/genetics , Multilocus Sequence Typing , Prevalence , Otters/genetics , Otters/parasitology , Toxoplasmosis, Animal/epidemiology , Toxoplasmosis, Animal/parasitology , DNA, Protozoan/genetics , DNA, Protozoan/analysis , California/epidemiology , Feces/parasitology , Oocysts , Cat Diseases/epidemiology
7.
Sustain Sci ; : 1-16, 2023 Mar 14.
Article in English | MEDLINE | ID: mdl-37363302

ABSTRACT

Coping with surprise and uncertainty resulting from the emergence of undesired and unexpected novelty or the sudden reorganization of systems at multiple spatiotemporal scales requires both a scientific process that can incorporate diverse expertise and viewpoints, and a scientific framework that can account for the structure and dynamics of interacting social-ecological systems (SES) and the inherent uncertainty of what might emerge in the future. We argue that combining a convergence scientific process with a panarchy framework provides a pathway for improving our understanding of, and response to, emergence. Emergent phenomena are often unexpected (e.g., pandemics, regime shifts) and can be highly disruptive, so can pose a significant challenge to the development of sustainable and resilient SES. Convergence science is a new approach promoted by the U.S. National Science Foundation for tackling complex problems confronting humanity through the integration of multiple perspectives, expertise, methods, tools, and analytical approaches. Panarchy theory is a framework useful for studying emergence, because it characterizes complex systems of people and nature as dynamically organized and structured within and across scales of space and time. It accounts for the fundamental tenets of complex systems and explicitly grapples with emergence, including the emergence of novelty, and the emergent property of social-ecological resilience. We provide an overview of panarchy, convergence science, and emergence. We discuss the significant data and methodological challenges of using panarchy in a convergence approach to address emergent phenomena, as well as state-of-the-art methods for overcoming them. We present two examples that would benefit from such an approach: climate change and its impacts on social-ecological systems, and the relationships between infectious disease and social-ecological systems.

8.
Pathogens ; 12(7)2023 Jun 25.
Article in English | MEDLINE | ID: mdl-37513717

ABSTRACT

Toxoplasma gondii is a globally distributed zoonotic protozoan parasite. Infection with T. gondii can cause congenital toxoplasmosis in developing fetuses and acute outbreaks in the general population, and the disease burden is especially high in South America. Prior studies found that the environmental stage of T. gondii, oocysts, is an important source of infection in Brazil; however, no studies have quantified this risk relative to other parasite stages. We developed a Bayesian quantitative risk assessment (QRA) to estimate the relative attribution of the two primary parasite stages (bradyzoite and oocyst) that can be transmitted in foods to people in Brazil. Oocyst contamination in fruits and greens contributed significantly more to overall estimated T. gondii infections than bradyzoite-contaminated foods (beef, pork, poultry). In sensitivity analysis, treatment, i.e., cooking temperature for meat and washing efficiency for produce, most strongly affected the estimated toxoplasmosis incidence rate. Due to the lack of regional food contamination prevalence data and the high level of uncertainty in many model parameters, this analysis provides an initial estimate of the relative importance of food products. Important knowledge gaps for oocyst-borne infections were identified and can drive future studies to improve risk assessments and effective policy actions to reduce human toxoplasmosis in Brazil.

9.
Transbound Emerg Dis ; 69(5): 2412-2423, 2022 Sep.
Article in English | MEDLINE | ID: mdl-34153160

ABSTRACT

Oocyst shedding in domestic and wild felids is a critical yet understudied topic in Toxoplasma gondii ecology and epidemiology that shapes human and animal disease burden. We synthesized published literature dating from the discovery of felids as the definitive hosts of T. gondii in the 1960s through March 2021 to examine shedding prevalence, oocyst genotypes, and risk factors for shedding. Oocyst shedding prevalence in many geographic regions exceeded the commonly accepted 1% reported for domestic cats; crude prevalence from cross-sectional field studies of domestic cat shedding ranged from 0% in Australia to 18.8% in Africa, with greater variation in reports of oocyst shedding in free-ranging, wild felids. Shedding in wild felid species has primarily been described in captive animals, with attempted detection of oocyst shedding reported in at least 31 species. Differences in lifestyle and diet play an important role in explaining shedding variation between free-ranging unowned domestic cats, owned domestic cats and wild felids. Additional risk factors for shedding include the route of infection, diet, age and immune status of the host. It is widely reported that cats only shed oocysts after initial infection with T. gondii, but experimental studies have shown that repeat oocyst shedding can occur. Factors associated with repeat shedding are common amongst free-ranging felids (domestic and wild), which are more likely to eat infected prey, be exposed to diverse T. gondii genotypes, and have coinfections with other parasites. Repeat shedding events could play a significant yet currently ignored role in shaping environmental oocyst loading with implications for human and animal exposure. Oocyst presence in the environment is closely linked to climate variables such as temperature and precipitation, so in quantifying risk of exposure, it is important to consider the burden of T. gondii oocysts that can accumulate over time in diverse environmental matrices and sites, as well as the spatial heterogeneity of free-ranging cat populations. Key directions for future research include investigating oocyst shedding in under-sampled regions, genotyping of oocysts detected in faeces and longitudinal studies of oocyst shedding in free-ranging felids.


Subject(s)
Cat Diseases , Felidae , Toxoplasma , Toxoplasmosis, Animal , Animals , Cats , Cross-Sectional Studies , Feces/parasitology , Humans , Oocysts , Toxoplasma/genetics , Toxoplasmosis, Animal/epidemiology , Toxoplasmosis, Animal/parasitology
10.
PLoS One ; 17(12): e0267871, 2022.
Article in English | MEDLINE | ID: mdl-36574374

ABSTRACT

Can comics effectively convey scientific knowledge about COVID-19 to youth? What types and how many sources of information did youth have about COVID-19 during the pandemic? How are sources of information associated with accurate COVID-19 knowledge? To answer these questions, we surveyed youth in grades 5-9 in a Midwestern United States school district in the winter of 2020-2021. The online survey used measures of COVID-19 knowledge and sources, with an embedded experiment on COVID-19 relevant comics. Guided by an integrated science capital and just-in-time health and science information acquisition model, we also measured level of science capital, science identity, and utility of science for health and society. The school district protocol required parental consent for participation; 264 of ~15,000 youth participated. Youth were randomly assigned one of four comic conditions before receiving an online survey. Results indicate that, similar to knowledge gains in comic studies on other science topics, reading the comics was associated with 7 to 29% higher accuracy about COVID-19. We found that youth reported getting information about COVID-19 from between 0-6 sources including media, family, friends, school, and experts. The bivariate positive association of news versus other sources with accuracy of knowledge did not persist in the full model, yet the positive association of a higher number of sources and accuracy did persist in the multivariate models. The degree of valuing the utility of science for their health moderated the number of sources to accuracy association. Those with less value on science for health had a stronger positive association of number of sources and accuracy in COVID-19 knowledge. We conclude that during a pandemic, even with health and science information ubiquitous in the news media, increasing youth access to a variety of accurate sources of information about science and health can increase youth knowledge.


Subject(s)
COVID-19 , Humans , Adolescent , COVID-19/epidemiology , Information Sources , Mass Media , Schools , Friends
11.
Sci Rep ; 12(1): 6532, 2022 04 26.
Article in English | MEDLINE | ID: mdl-35474071

ABSTRACT

Plastics are widely recognized as a pervasive marine pollutant. Microplastics have been garnering increasing attention due to reports documenting their ingestion by animals, including those intended for human consumption. Their accumulation in the marine food chain may also pose a threat to wildlife that consume species that can accumulate microplastic particles. Microplastic contamination in marine ecosystems has thus raised concerns for both human and wildlife health. Our study addresses an unexplored area of research targeting the interaction between plastic and pathogen pollution of coastal waters. We investigated the association of the zoonotic protozoan parasites Toxoplasma gondii, Cryptosporidium parvum, and Giardia enterica with polyethylene microbeads and polyester microfibers. These pathogens were chosen because they have been recognized by the World Health Organization as underestimated causes of illness from shellfish consumption, and due to their persistence in the marine environment. We show that pathogens are capable of associating with microplastics in contaminated seawater, with more parasites adhering to microfiber surfaces as compared with microbeads. Given the global presence of microplastics in fish and shellfish, this study demonstrates a novel pathway by which anthropogenic pollutants may be mediating pathogen transmission in the marine environment, with important ramifications for wildlife and human health.


Subject(s)
Cryptosporidiosis , Cryptosporidium , Parasites , Water Pollutants, Chemical , Animals , Animals, Wild , Ecosystem , Humans , Microplastics , Plastics , Seawater , Water Pollutants, Chemical/analysis
12.
J STEM Outreach ; 4(2)2021 Jul.
Article in English | MEDLINE | ID: mdl-34532652

ABSTRACT

In spring 2020 our team received funding from the Rapid Response Research program of the National Science Foundation to develop comics that would help youth understand the COVID-19 pandemic. Our project built on a decade of expertise creating comics about the biology of viruses. In collaboration with virologists and artists, we developed three comic stories about COVID-19 during the pandemic and posted them on-line during the last half of 2020. The fictional narratives address fundamental issues in biology, virology, and network science, in order to help readers understand the complexities of living through a viral pandemic. The stories focus on three themes: the biology and social context of the COVID-19 virus; the relationship of wild animals, particularly bats, to the pandemic; and the impact of the pandemic on Tribal communities. We describe the challenges of comic development during the pandemic and the feedback from youth on whether the comics were appealing, interesting, and understandable. The stories were posted on worldofviruses.unl.edu and are published by the University of Nebraska Press as the book, C'RONA Pandemic Comics, with essays for youth about the virus and the pandemic.

13.
Ecohealth ; 18(1): 84-94, 2021 03.
Article in English | MEDLINE | ID: mdl-34213686

ABSTRACT

Increasing reports of marine mammal deaths have been attributed to the parasite Sarcocystis neurona. Infected opossums, the only known definitive hosts, shed S. neurona sporocysts in their feces. Sporocysts can contaminate the marine environment via overland runoff, and subsequent ingestion by marine mammals can lead to fatal encephalitis. Our aim was to determine the prevalence of S. neurona in opossums from coastal areas of Washington State (USA) and to compare genetic markers between S. neurona in opossums and marine mammals. Thirty-two road-kill opossums and tissue samples from 30 stranded marine mammals meeting inclusion criteria were included in analyses. Three opossums (9.4%) and twelve marine mammals (40%) were confirmed positive for S. neurona via DNA amplification at the ITS1 locus. Genetic identity at microsatellites (sn3, sn7, sn9) and the snSAG3 gene of S. neurona was demonstrated among one harbor porpoise and two opossums. Watershed mapping further demonstrated plausible sporocyst transport pathways from one of these opossums to the location where an infected harbor porpoise carcass was recovered. Our results provide the first reported link between S. neurona genotypes on land and sea in the Pacific Northwest, and further demonstrate how terrestrial pathogen pollution can impact the health of marine wildlife.


Subject(s)
Caniformia , Didelphis , Sarcocystis , Sarcocystosis , Animals , Northwestern United States , Sarcocystis/genetics , Sarcocystosis/epidemiology , Sarcocystosis/parasitology , Sarcocystosis/veterinary
14.
Zoonoses Public Health ; 67(1): 70-78, 2020 02.
Article in English | MEDLINE | ID: mdl-31677251

ABSTRACT

BACKGROUND: Toxoplasma gondii is a zoonotic parasite that can have severe implications for human health. Acutely infected cats shed environmentally resistant T. gondii oocysts in their faeces that contaminate soil, and soil can serve as a reservoir of infection for humans. Free-roaming domestic cats are thought to play an important role in environmental contamination with T. gondii, but few studies have directly measured the direct contribution of free-roaming cats to T. gondii in soil. METHODS: Our goals were to determine whether T. gondii soil contamination occurs in public areas with free-roaming cat colonies in central California and examine spatial and temporal variation in soil contamination. We initially performed spiking experiments to compare the limit of T. gondii detection in soil using three conventional nested PCR assays and one real-time quantitative PCR. The nested PCR targeting the internal transcribed spacer (ITS-1) of the small subunit ribosomal RNA was the most sensitive assay, with a limit of detection between 20 and 200 oocysts per gram of soil. We applied the ITS1 PCR assay on soil from sites in city and state parks, public playgrounds and community gardens in central California, USA. Samples were collected during spring, summer and fall and in sites located along the coast and inland. RESULTS: We detected and sequence-confirmed T. gondii in 5.6% of all of our soil sub-samples, but with large seasonal and spatial variation in soil contamination: we only detected T. gondii during fall and only in coastal sites (44.3% soil prevalence), despite similar sampling intensity across space and time. CONCLUSIONS: Our results suggest that free-roaming cat colonies are an important source of T. gondii in spaces where people recreate and grow food and that soil contamination is highly seasonal and spatially variable. Management of free-roaming cats could prevent T. gondii infections by reducing environmental contamination with this zoonotic pathogen.


Subject(s)
Cat Diseases/parasitology , Seasons , Soil/parasitology , Toxoplasma/isolation & purification , Toxoplasmosis, Animal/parasitology , Animals , California , Cat Diseases/epidemiology , Cats , Feces/parasitology , Humans , Oocysts , Parks, Recreational , Real-Time Polymerase Chain Reaction/veterinary , Sports and Recreational Facilities , Toxoplasmosis, Animal/epidemiology , Zoonoses/epidemiology
15.
J Trop Med ; 2020: 6586182, 2020.
Article in English | MEDLINE | ID: mdl-33014074

ABSTRACT

In endemic African areas, such as Tanzania, Brucella spp. cause human febrile illnesses, which often go unrecognized and misdiagnosed, resulting in delayed diagnosis, underdiagnosis, and underreporting. Although rapid and affordable point-of-care tests, such as the Rose Bengal test (RBT), are available, acceptance and adoption of these tests at the national level are hindered by a lack of local diagnostic performance data. To address this need, evidence on the diagnostic performance of RBT as a human brucellosis point-of-care test was reviewed. The review was initially focused on studies conducted in Tanzania but was later extended to worldwide because few relevant studies from Tanzania were identified. Databases including Web of Science, Embase, MEDLINE, and World Health Organization Global Index Medicus were searched for studies assessing the diagnostic performance of RBT (sensitivity and specificity) for detection of human brucellosis, in comparison to the reference standard culture. Sixteen eligible studies were identified and reviewed following screening. The diagnostic sensitivity (DSe) and specificity (DSp) of RBT compared to culture as the gold standard were 87.5% and 100%, respectively, in studies that used suitable "true positive" and "true negative" patient comparison groups and were considered to be of high scientific quality. Diagnostic DSe and DSp of RBT compared to culture in studies that also used suitable "true positive" and "true negative" patient comparison groups but were considered to be of moderate scientific quality varied from 92.5% to 100% and 94.3 to 99.9%, respectively. The good diagnostic performance of RBT combined with its simplicity, quickness, and affordability makes RBT an ideal (or close to) stand-alone point-of-care test for early clinical diagnosis and management of human brucellosis and nonmalarial fevers in small and understaffed health facilities and laboratories in endemic areas in Africa and elsewhere.

16.
One Health Outlook ; 2(1): 16, 2020.
Article in English | MEDLINE | ID: mdl-32835170

ABSTRACT

BACKGROUND: Many ecologically important plants are pollinated or have their seeds dispersed by fruit bats, including the widely distributed African straw-colored fruit bats (Eidolon helvum). Their ability to fly long distances makes them essential for connecting plant populations across fragmented landscapes. While bats have been implicated as a reservoir of infectious diseases, their role in disease transmission to humans is not well understood. In this pilot study, we tracked E. helvum to shed light on their movement patterns in Tanzania and possible contact with other species. METHODS: Tracking devices were deployed on 25 bats captured in the Morogoro Municipal and Kilombero District area near the Udzungwa Mountains of Tanzania. Nightly flight patterns, areas corresponding to foraging bouts and feeding roosts, and new day roosts were determined from bat movement data and characterized according to their proximity to urban built-up and protected areas. Sites for additional environmental surveillance using camera traps were identified via tracking data to determine species coming in contact with fruits discarded by bats. RESULTS: Tracking data revealed variability between individual bat movements and a fidelity to foraging areas. Bats were tracked from one to six nights, with a mean cumulative nightly flight distance of 26.14 km (min: 0.33, max: 97.57) based on data from high-resolution GPS tags. While the majority of their foraging locations were in or near urban areas, bats also foraged in protected areas, of which the Udzungwa Mountains National Park was the most frequented. Camera traps in fruit orchards frequented by tracked bats showed the presence of multiple species of wildlife, with vervet monkeys (Chlorocebus pygerythrus) observed as directly handling and eating fruit discarded by bats. CONCLUSIONS: Because we observed multiple interactions of animals with fruits discarded by bats, specifically with vervet monkeys, the possibility of disease spillover risk exists via this indirect pathway. With flight distances of up to 97 km, however, the role of E. helvum in the seed dispersal of plants across both protected and urban built-up areas in Tanzania may be even more important, especially by helping connect increasingly fragmented landscapes during this Anthropocene epoch.

17.
Article in English | MEDLINE | ID: mdl-31795202

ABSTRACT

BACKGROUND: Agriculture contributes a third of Rwanda's GDP and is the main source of income for rural households, with 80% of the total population involved in crop and/or livestock production. The Government of Rwanda established the Muvumba rice project in 2011 amidst a policy shift towards rice as a national staple crop. However, the indiscriminate use of pesticides by local, low-income rice growers has raised concerns about potential human, animal and ecosystem health impacts as pesticide distribution and application are not strictly regulated. Although pesticide use can directly influence farmer health and ecosystems, little is known about small-scale farmers' pesticide application practices and knowledge. We aimed to assess local application practices and understanding of pesticides to identify gaps in farmers' knowledge on safe pesticide use and deviations from established standards and recommended practices. METHODS: We conducted a cross-sectional study consisting of observations of pesticide practices and interviews with 206 small-scale rice growers in Nyagatare District, Rwanda, in March 2017. Descriptive statistical analyses (sample means, standard deviation and range) were performed, and we evaluated the association between farmers' personal protective equipment (PPE) use and their education level and literacy status. RESULTS: Over 95% of observed farmers did not comply with minimum standards for safe pesticide use, and 80% of respondents reported that they stored pesticides in their homes without personal protection measures. Education and literacy level were not significantly associated with PPE use. Additionally, 90% of respondents had experienced adverse health effects after using pesticides including intense headache, dizziness, stomach cramps, skin pain and itching, and respiratory distress. All respondents also reported animals in and around the rice scheme (cattle, birds, and fish) behaving abnormally or with signs consistent with pesticide exposure in the six months preceding the study, which may be linked to pesticide-contaminated water. CONCLUSIONS: Our study demonstrates potential for high exposure to pesticides for farmers, their families, and animals sharing rice-growing or downstream environments and points to the need for training on safe and effective pesticide use.


Subject(s)
Farmers , Occupational Exposure/adverse effects , Oryza/chemistry , Pesticides/adverse effects , Agriculture , Animals , Cattle , Cross-Sectional Studies , Health Knowledge, Attitudes, Practice , Humans , Occupational Exposure/statistics & numerical data , Personal Protective Equipment , Rwanda
18.
Food Waterborne Parasitol ; 15: e00049, 2019 Jun.
Article in English | MEDLINE | ID: mdl-32095620

ABSTRACT

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.

19.
Ecohealth ; 16(2): 378-390, 2019 06.
Article in English | MEDLINE | ID: mdl-30945159

ABSTRACT

One Health is a collaborative, interdisciplinary effort that seeks optimal health for people, animals, plants, and the environment. Toxoplasmosis, caused by Toxoplasma gondii, is an intracellular protozoan infection distributed worldwide, with a heteroxenous life cycle that practically affects all homeotherms and in which felines act as definitive reservoirs. Herein, we review the natural history of T. gondii, its transmission and impacts in humans, domestic animals, wildlife both terrestrial and aquatic, and ecosystems. The epidemiology, prevention, and control strategies are reviewed, with the objective of facilitating awareness of this disease and promoting transdisciplinary collaborations, integrative research, and capacity building among universities, government agencies, NGOs, policy makers, practicing physicians, veterinarians, and the general public.


Subject(s)
One Health , Toxoplasmosis, Animal/epidemiology , Toxoplasmosis/epidemiology , Animals , Animals, Wild/parasitology , Ecosystem , Humans , Toxoplasma , Toxoplasmosis/prevention & control , Toxoplasmosis, Animal/prevention & control
20.
Ecohealth ; 16(2): 391, 2019 Jun.
Article in English | MEDLINE | ID: mdl-31168721

ABSTRACT

This article was originally published electronically on the publisher's internet portal (currently SpringerLink) on April 3, 2019 without open access.

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