578 research outputs found
Does biodiversity protect humans against infectious disease?
No full textControl of human infectious disease has been promoted as a valuable ecosystem service arising from the conservation of biodiversity. There are two commonly discussed mechanisms by which biodiversity loss could increase rates of infectious disease in a landscape. First, loss of competitors or predators could facilitate an increase in the abundance of competent reservoir hosts. Second, biodiversity loss could disproportionately affect non-competent, or less competent reservoir hosts, which would otherwise interfere with pathogen transmission to human populations by, for example, wasting the bites of infected vectors. A negative association between biodiversity and disease risk, sometimes called the "dilution effect hypothesis," has been supported for a few disease agents, suggests an exciting win-win outcome for the environment and society, and has become a pervasive topic in the disease ecology literature. Case studies have been assembled to argue that the dilution effect is general across disease agents. Less touted are examples in which elevated biodiversity does not affect or increases infectious disease risk for pathogens of public health concern. In order to assess the likely generality of the dilution effect, we review the association between biodiversity and public health across a broad variety of human disease agents. Overall, we hypothesize that conditions for the dilution effect are unlikely to be met for most important diseases of humans. Biodiversity probably has little net effect on most human infectious diseases but, when it does have an effect, observation and basic logic suggest that biodiversity will be more likely to increase than to decrease infectious disease risk
Roles and mechanisms of parasitism in aquatic microbial communities
No full textNext Generation Sequencing technologies are increasingly revealing that microbial taxa likely to be parasites or symbionts are probably much more prevalent and diverse than previously thought. Every well studied free-living species has parasites; parasites themselves can be parasitized. As a rule of thumb, there is an estimated 4 parasitic species for any given host, and the better a host is studied the more parasites are known to infect it. Therefore, parasites and other symbionts should represent a very large number of species and may far outnumber those with 'free-living' lifestyles. Paradoxically, free-living hosts, which form the bulk of our knowledge of biology, may be a minority! Microbial parasites typically are characterized by their small size, short generation time, and high rates of reproduction, with simple life cycle occurring generally within a single host. They are diverse and ubiquitous in the environment, comprising viruses, prokaryotes and eukaryotes. This Frontiers Research Topic sought to provide a broad overview but concise, comprehensive, well referenced and up-to-date state of the art for everyone involved with microbial parasites in aquatic microbial ecology
globalbioticinteractions/hechinger2011: prepare for publication to zenodo
No full textDiscover data in Ryan F. Hechinger, Kevin D. Lafferty, John P. McLaughlin, Brian L. Fredensborg, Todd C. Huspeni, Julio Lorda, Parwant K. Sandhu, Jenny C. Shaw, Mark E. Torchin, Kathleen L. Whitney, and Armand M. Kuris 2011. Food webs including parasites, biomass, body sizes, and life stages for three California/Baja California estuaries. Ecology 92:791–791. http://dx.doi.org/10.1890/10-1383.1
Pollution can drive marine diseases
No full textHumans pollute the marine environment biologically, chemically, and physically, which can potentially drive or facilitate the emergence, proliferation, or impact of disease. This chapter synthesizes what is known about the effects of biological (e.g., wastewater), chemical (e.g., pharmaceuticals), and physical (e.g., sound/light) pollution on marine disease dynamics. The presence of these pollutants has been found to alter disease prevalence, increase host susceptibility to infection, and alter the spread and host range of different diseases. Despite the importance of the marine environment as a primary food source for humans, many complexities linking disease ecology and pollution are yet to be explored. Future investigation of these connections would benefit from an integrated approach using experimental, environmental, molecular, and pathological methods
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The parasite ecology of the San Miguel Island Fox, Urocyon littoralis littoralis
No full textThe Channel Islands foxes are a popular conservation success story after managers, scientists, and zookeepers worked together to remove non-native predators, restore native habitat, and facilitate on-island captive breeding programs. However, although other island fox populations have recovered well, this success story may have been told too soon for the San Miguel Island (SMI) fox. This population experienced a decline of more than 70% between 2015 and 2018 and has been slow to recover since. This decline is attributed, in large part, to parasitism. Notably, a recently identified acanthocephalan parasite, Pachysentis canicola, has drawn considerable attention from Channel Islands National Park (CINP) managers. This parasite has not been detected on other California Channel Islands (CCI) or in mainland California canids, and little is known about the ecology of other helminth species that infect the SMI fox. Here, we sought to 1) describe the helminth assemblage of SMI foxes and the biogeographical patterns of parasitism across the CCI; 2) compare traditional methods of detecting infected foxes with new molecular DNA metabarcoding techniques; and 3) determine the spatial and temporal distribution of fox parasites. In addition to recording seven species of fox parasites, we successfully detected parasite DNA as well as DNA from prey items that may facilitate transmission using scat metabarcoding. Further, we established a baseline for the effects of temperature, rainfall, and habitat type on the prevalence and densities of parasite eggs across the island. The CINP needs a conservation plan to prevent parasite-induced extinction of the San Miguel Island fox, a vulnerable and charismatic species that exists nowhere else in the world. My dissertation provides a foundation for combining traditional and novel tools for managing wildlife threatened by emerging infectious diseases
A strong colonizer rules the trematode guild in an intertidal snail host
No full textWe examined the extent to which supply-side, niche, and competition theories and concepts help explain a trematode community in which one species comprises 87% of the trematode individuals, and the remaining 15 species each have <3%. We collected and dissected the common and wide-ranging snail host Heleobia australis over four seasons from three distinct habitats from the intertidal area of the Bahía Blanca estuary, Argentina. Inside a snail, trematodes interact with each other with outcomes that depend on facilitation, competition, and preemption, suggesting that dominant species should be common. The abundant trematode species, Microphallus simillimus, is a weak competitor, but has life-history traits and strategies associated with higher colonization ability that could increase its probability of invading the host first, allowing it to preempt the rare species. Rather than segregate by habitat, trematode species aggregated in pans during the summer where dominant trematode species often excluded subordinate ones. Despite losses to competition, and a lack of niche partitioning, M. simillimus ruled this species-rich trematode guild through strong recruitment and (potentially) preemption. Therefore, extremely skewed species abundance distributions, like this one, can derive from extremely skewed colonization abilities.Fil: Alda, Maria del Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados I; ArgentinaFil: Bonel, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados I; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Cazzaniga, Néstor Jorge. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Zoología de Invertebrados I; ArgentinaFil: Martorelli, Sergio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Lafferty, Kevin D.. University of California; Estados Unidos. United States Geological Survey; Estados Unido
Sea otter health: Challenging a pet hypothesis
No full textAbstractA recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission
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The Ecology and Transmission of the Raccoon Roundworm, Baylisascaris procyonis.
No full textEmerging infections in both humans and wildlife can often be traced back to human mediated changes in host densities, host communities, and the environment. In Chapter 1, I reviewed how humans affect wildlife nematodes. Nematode responses to human actions vary, thus knowing host and parasite natural history, and the mechanisms underlying disease dynamics are critical for predicting parasite responses and managing disease.Among wildlife nematodes, raccoon roundworm (Baylisascaris procyonis) is infamous for its ability to cause fatal disease in both humans and wildlife. This parasite infects millions of raccoons in North America. Although adult worms cause little pathology in raccoons, larval worms undergo extensive tissue migrations in other hosts, often causing neurological damage. Disease risk is driven by environmental egg contamination, which increases with raccoon density, worm intensity, and worm prevalence. In Chapter 2, I examined 189 raccoons from southern California to investigate how host age and season affect parasite abundance, demography, and fecundity. Roundworm infected 90% of Santa Barbara County raccoons, juveniles hosted more worms than adults, and more heavily infected raccoons released more eggs.In Chapter 3, I investigated whether animals can avoid raccoon roundworm contaminated sites, and if such avoidance balances disease costs and foraging preferences. Using wildlife cameras, I monitored animal behavior at raccoon latrines — sites that concentrate both seeds and pathogenic parasite eggs, and found that latrine contact rates reflected background activity, diet preferences and disease risk. Disease-tolerant raccoons and rats displayed significant site attraction, while susceptible birds and small mammals avoided these high-risk sites.The introduced black rat, Rattus rattus, occurs throughout the native range of the raccoon roundworm, Baylisascaris procyonis, and frequently forages in latrines. In Chapter 4, I examined the role of these rats and other California rodents in B. procyonis transmission. I surveyed wild rodents for B. procyonis and found that B. procyonis infected R. rattus at intensities more than 100 times greater than loads in co-occurring native Reithrodotomys megalotis and Peromyscus maniculatus. I also conducted scavenger trials using motion activated cameras and found that rodent carcasses were scavenged by opossums, skunks and raccoons, suggesting that these infected rodents, particularly R. rattus, contribute to B. procyonis transmission in this coastal California ecosystem.Raccoon roundworm infects both rodents and raccoons in southern California, but we know little about infection risk for other species. In Chapter 5, I used information on animal time allocation and behavior to build a model for predicting community-wide exposure risk for raccoon roundworm. This model suggests that larval worms are likely widespread in the animal community and provides a novel non-invasive method for identifying “at-risk” species.Raccoon roundworm infection can cause devastating pathology in humans, but there is growing evidence that subclinical cases also occur. As there is limited information on the frequency of these subclinical human infections, in Chapter 6 I surveyed 150 adults from California for B. procyonis antibodies. Eleven participants were seropositive suggesting that subclinical infection does occur and that previously undetectable infections warrant further study
First observation of Bs0 → D*s2+Xμ-ν decays
No full textUsing data collected with the LHCb detector in proton–proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays B0s→D+sXμ−ν and B0s→D0K+Xμ−ν are detected. Two structures are observed in the D0K+ mass spectrum at masses consistent with the known Ds1(2536)+ and D∗s22573)+ mesons. The measured branching fractions relative to the total B0s semileptonic rate are B(B0s→D∗+s2Xμ−ν)/B(B0s→Xμ−ν) = (3.3±1.0±0.4)%, and B(B0s→D+s1Xμ−ν)/B(B0s→Xμ−ν) = (5.4±1.2±0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D∗+s2 state in B0s decays; we also measure its mass and width
DIODE LASER STUDY OF THE FUNDAMENTAL OF
No full text W. J. Lafferty, A. G. Maki, and E. K. Plyler, J. Chem. Phys. 40, 224 (1964). A. W. Mantz, P. Connes, G. Guelachvili, and C. Amiot, J. Mol. Spectrosc. 54, 43 (1975).""Author Institution: Scientific Research Staff Ford Motor Company; Department of Physics, The University of MichiganWe have used current-tunable, thin-film PbTe diode lasers to obtain Doppler-limited resolution of the band of in the region 1565-1600 . Roughly 60\% of the interval was covered using different modes of 2 lasers, each mode giving a tuning range of 1-3 cm, Calibration was obtained with HO and NH, while the frequency scale was given by the fringes of a 4-cm Ge etalon, recorded simultaneously using a double beam technique. Near 1600 cm a set of strong regularly spaced lines stands out, which is the R branch of the ground state transition. This band as wel as the ``hot” bands due to the bending vibration indicate a linear structure for the molecule. Preliminary values in cm for the ground state are 1587.392, B^{\prime\prime} - 0.07557, and B - B. This B^{\prime\prime} value differs from that reported by Lafferty et al., but agrees with that by Mantz et al. The next 2 strongest series were interpretable as a band with = 1580.910, B = 0.07606, B - 0.07646, B - B = 4,178 X 10, B - B = 5.259 10. These B values agree with Assignment 2 by Lafferty et al. The assignment of the ground state transition and the shift of the “hot” bands toward lower frequency were substantiated by temperature-difference FTS spectra
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