Eco-epidemiological screening of multi-host wild rodent communities in the UK reveals pathogen strains of zoonotic interest

Wild rodent communities represent ideal systems to study pathogens and parasites shared among sympatric species. Such studies are useful in the investigation of eco-epidemiological dynamics, improving disease management strategies and reducing zoonotic risk. The aim of this study was to investigate pathogen and parasites shared among rodent species (multi-host community) in West Wales in an area where human/wildlife disease risk was not previously assessed. West Wales is predominantly rural, with human settlements located alongside to grazing areas and semi-natural landscapes, creating a critical human-livestock-wildlife interface. Ground-dwelling wild rodent communities in Wales were live-trapped and biological samples – faeces and ectoparasites – collected and screened for a suite of pathogens and parasites that differ in types of transmission and ecology. Faecal samples were examined to detect Herpesvirus, Escherichia coli, and Mycobacterium microti. Ticks and fleas were collected, identified to species based on morphology and genetic barcodes, and then screened for Anaplasma phagocytophilum, Babesia microti, Borrelia burgdorferi sensu lato, and Bartonella sp. All the pathogens and parasites screened pose a characteristic epidemiological challenge, such as variable level of generalism, unknown zoonotic potential, and lack of data. The results showed that the bank vole Myodes glareolus had the highest prevalence of all pathogens and parasites. Higher flea species diversity was detected than in previous studies, and at least two Bartonella species were found circulating, one of which has not previously been detected in the UK. These key findings offer new insights into the distribution of selected pathogen and parasites and subsequent zoonotic risk, and provide new baselines and perspectives for further eco-epidemiological research

Database of host-pathogen and related species interactions, and their global distribution

Interactions between species, particularly where one is likely to be a pathogen of the other, as well as the geographical distribution of species, have been systematically extracted from various web-based, free-access sources, and assembled with the accompanying evidence into a single database. The database attempts to answer questions such as what are all the pathogens of a host, and what are all the hosts of a pathogen, what are all the countries where a pathogen was found, and what are all the pathogens found in a country. Two datasets were extracted from the database, focussing on species interactions and species distribution, based on evidence published between 1950–2012. The quality of their evidence was checked and verified against well-known, alternative, datasets of pathogens infecting humans, domestic animals and wild mammals. The presented datasets provide a valuable resource for researchers of infectious diseases of humans and animals, including zoonoses

River Dolphins Can Act as Population Trend Indicators in Degraded Freshwater Systems

Conservation attention on charismatic large vertebrates such as dolphins is often supported by the suggestion that these species represent surrogates for wider biodiversity, or act as indicators of ecosystem health. However, their capacity to act as indicators of patterns or trends in regional biodiversity has rarely been tested. An extensive new dataset of >300 last-sighting records for the Yangtze River dolphin or baiji and two formerly economically important fishes, the Yangtze paddlefish and Reeves’ shad, all of which are probably now extinct in the Yangtze, was collected during an interview survey of fishing communities across the middle-lower Yangtze drainage. Untransformed last-sighting date frequency distributions for these species show similar decline curves over time, and the linear gradients of transformed last-sighting date series are not significantly different from each other, demonstrating that these species experienced correlated population declines in both timing and rate of decline. Whereas species may be expected to respond differently at the population level even in highly degraded ecosystems, highly vulnerable (e.g. migratory) species can therefore display very similar responses to extrinsic threats, even if they represent otherwise very different taxonomic, biological and ecological groupings. Monitoring the status of river dolphins or other megafauna therefore has the potential to provide wider information on the status of other threatened components of sympatric freshwater biotas, and so represents a potentially important monitoring tool for conservation management. We also show that interview surveys can provide robust quantitative data on relative population dynamics of different species

Economic impact of HIV and antiretroviral therapy on education supply in high prevalence regions.

BACKGROUND: We set out to estimate, for the three geographical regions with the highest HIV prevalence, (sub-Saharan Africa [SSA], the Caribbean and the Greater Mekong sub-region of East Asia), the human resource and economic impact of HIV on the supply of education from 2008 to 2015, the target date for the achievement of Education For All (EFA), contrasting the continuation of access to care, support and Antiretroviral therapy (ART) to the scenario of universal access. METHODOLOGY/PRINCIPAL FINDINGS: A costed mathematical model of the impact of HIV and ART on teacher recruitment, mortality and absenteeism (Ed-SIDA) was run using best available data for 58 countries, and results aggregated by region. It was estimated that (1) The impact of HIV on teacher supply is sufficient to derail efforts to achieve EFA in several countries and universal access can mitigate this. (2) In SSA, the 2008 costs to education of HIV were about half of those estimated in 2002. Providing universal access for teachers in SSA is cost-effective on education returns alone and provides a return of $3.99 on the dollar. (3) The impacts on education in the hyperendemic countries in Southern Africa will continue to increase to 2015 from its 2008 level, already the highest in the world. (4) If treatment roll-out is successful, numbers of HIV positive teachers are set to increase in all the regions studied. CONCLUSIONS/SIGNIFICANCE: The return on investing in care and support is also greater in those areas with highest impact. SSA requires increased investment in teacher support, testing and particularly ART if it is to achieve EFA. The situation for teachers in the Caribbean and East Asia is similar but on a smaller scale proportionate to the lower levels of infection and greater existing access to care and support

The population dynamics of plasmid-mediated antibiotic resistance in salmonella typhimurium in chickens

A model of growth and plasmid transfer between strains of Escherichia coli and Salmonella typhimurium was developed with reference to the literature. This was the organising principle for the collection of a complete set of in vitro life history parameters of one S. typhimurium and one E. coli strain. In the course of estimating these parameters two results of note were obtained. Fits of the Lotka-Volterra competition model were obtained for data on S. typhimuiurm growing in competition with E. coli. The first noteworthy discovery was the failure of this model to account for several characteristics of growth of these strains under competition. The growth rates of plasmid-bearing and plasmid-free strains were obtained. The second main result came from examination of the results of the growth rate data, which revealed that the cost to S. typhimuiurm 576 of bearing the resistance plasmid was low (4%). The model was also used to simulate the effect of antibiotic dose on the density of the donor, recipient and transconjugant populations over time. These simulations predicted that there would be a convex relationship between antibiotic dose and transconjugant density (i.e. that the density would first rise, then fall, with increasing dose). Following from this result, laboratory experiments and in vivo experiments in chickens were directed towards obtaining information on the relationship between these two variables. This convex relationship was not demonstrated within a single experiment, although some experimental environments produced an increase in transconjugant density with dose, and others, a decrease. Few transconjugants were formed in vivo. In order to investigate the low cost of resistance and low rate of in vivo transconjugant production, cost of resistance and plasmid transfer rate of this plasmid in several strain combinations of E. coli and S. typhimuiurm was evaluated.</p

Identification of individuals with gonorrhoea within sexual networks: a population-based study.

BACKGROUND: Molecular typing of Neisseria gonorrhoeae and contact tracing provide a combined approach for analysis of sexual networks in metropolitan areas, although there are some difficulties in application. Our aim was to examine the application of high-throughput molecular approaches that can identify individuals in linked sexual networks. METHODS: We characterised 2045 isolates of N gonorrhoeae from patients presenting at 13 major sexually transmitted infection clinics in London, UK, between June 1 and Nov 30, 2004. All isolates were assigned a sequence type (strain) on the basis of the sequences of internal fragments of two highly polymorphic loci, por and tbpB. These types were matched to demographic and behavioural data obtained at the clinic for each patient. We assessed the congruence in the demographic and behavioural characteristics of individuals infected with the same strain. FINDINGS: We identified 21 prevalent strains in this diverse gonococcal population, each infecting between 20 and 124 individuals. Seven of these strains were predominantly from men who have sex with men; the remaining 14 were predominantly from heterosexual people. No differences were recorded between the strains associated with men who have sex with men in the demographic or behavioural characteristics of infected individuals. By contrast, significant differences in age (p<0.0001), ethnicity (p=0.001), proportion of women (p=0.01), and HIV status (p=0.03) were noted between the 14 prevalent heterosexual-associated strains. Heterosexuals with strains not shared by others in the sample were significantly older (p=0.0005) and more likely to have had sex outside the UK (p<0.0001) than those sharing a strain with at least one other. INTERPRETATION: The discriminatory high throughput strain characterisation method applied here identified localised transmission networks and suggests little bridging between networks of men who have sex with men and heterosexual networks

Could brown bears (Ursus arctos) have survived in Ireland during the Last Glacial Maximum?

Brown bears are recorded from Ireland during both the Late Pleistocene and early–mid Holocene. Although most of the Irish landmass was covered by an ice sheet during the Last Glacial Maximum (LGM), Irish brown bears are known to have hybridized with polar bears during the Late Pleistocene, and it is suggested that the Irish brown bear population did not become extinct but instead persisted in situ through the LGM in a southwestern ice-free refugium. We use historical population modelling to demonstrate that brown bears are highly unlikely to have survived through the LGM in Ireland under any combination of life-history parameters shown by living bear populations, but instead would have rapidly become extinct following advance of the British–Irish ice sheet, and probably recolonized Ireland during the end-Pleistocene Woodgrange Interstadial from a closely related nearby source population. The time available for brown bear–polar bear hybridization was therefore restricted to narrow periods at the beginning or end of the LGM. Brown bears would have been extremely vulnerable to extinction in Quaternary habitat refugia and required areas substantially larger than southwestern Ireland to survive adverse glacial conditions

The population dynamics of plasmid-mediated antibiotic resistance in salmonella typhimurium in chickens

A model of growth and plasmid transfer between strains of Escherichia coli and Salmonella typhimurium was developed with reference to the literature. This was the organising principle for the collection of a complete set of in vitro life history parameters of one S. typhimurium and one E. coli strain. In the course of estimating these parameters two results of note were obtained. Fits of the Lotka-Volterra competition model were obtained for data on S. typhimuiurm growing in competition with E. coli. The first noteworthy discovery was the failure of this model to account for several characteristics of growth of these strains under competition. The growth rates of plasmid-bearing and plasmid-free strains were obtained. The second main result came from examination of the results of the growth rate data, which revealed that the cost to S. typhimuiurm 576 of bearing the resistance plasmid was low (4%). The model was also used to simulate the effect of antibiotic dose on the density of the donor, recipient and transconjugant populations over time. These simulations predicted that there would be a convex relationship between antibiotic dose and transconjugant density (i.e. that the density would first rise, then fall, with increasing dose). Following from this result, laboratory experiments and in vivo experiments in chickens were directed towards obtaining information on the relationship between these two variables. This convex relationship was not demonstrated within a single experiment, although some experimental environments produced an increase in transconjugant density with dose, and others, a decrease. Few transconjugants were formed in vivo. In order to investigate the low cost of resistance and low rate of in vivo transconjugant production, cost of resistance and plasmid transfer rate of this plasmid in several strain combinations of E. coli and S. typhimuiurm was evaluated.</p