There is a high prevalence of smoking among people who experience severe mental ill health (SMI).... more There is a high prevalence of smoking among people who experience severe mental ill health (SMI). Helping people with disorders such as bipolar illness and schizophrenia to quit smoking would help improve their health, increase longevity and also reduce health inequalities. Around half of people with SMI who smoke express an interest in cutting down or quitting smoking. There is limited evidence that smoking cessation can be achieved for people with SMI. Those with SMI rarely access routine NHS smoking cessation services. This suggests the need to develop and evaluate a behavioural support and medication package tailored to the needs of people with SMI. The objective in this project was to conduct a pilot trial to establish acceptability of the intervention and to ensure the feasibility of recruitment, randomisation and follow-up. We also sought preliminary estimates of effect size in order to design a fully powered trial of clinical effectiveness and cost-effectiveness. The pilot should inform a fully powered trial to compare the clinical effectiveness and cost-effectiveness of a bespoke smoking cessation (BSC) intervention with usual general practitioner (GP) care for people with SMI. A pilot pragmatic two-arm individually randomised controlled trial (RCT). Simple randomisation was used following a computer-generated random number sequence. Participants and practitioners were not blinded to allocation. Primary care and secondary care mental health services in England. Smokers aged > 18 years with a severe mental illness who would like to cut down or quit smoking. A BSC intervention delivered by mental health specialists trained to deliver evidence-supported smoking cessation interventions compared with usual GP care. The primary outcome was carbon monoxide-verified smoking cessation at 12 months. Smoking-related secondary outcomes were reduction of number of cigarettes smoked, Fagerstrom test of nicotine dependence and motivation to quit (MTQ). Other secondary outcomes were Patient Health Questionnaire-9 items and Short Form Questionnaire-12 items to assess whether there were improvements or deterioration in mental health and quality of life. We also measured body mass index to assess whether or not smoking cessation was associated with weight gain. These were measured at 1, 6 and 12 months post randomisation. The trial recruited 97 people aged 19-73 years who smoked between 5 and 60 cigarettes per day (mean 25 cigarettes). Participants were recruited from four mental health trusts and 45 GP surgeries. Forty-six people were randomised to the BSC intervention and 51 people were randomised to usual GP care. The odds of quitting at 12 months was higher in the BSC intervention (36% vs. 23%) but did not reach statistical significance (odds ratio 2.9; 95% confidence interval 0.8% to 10.5%). At 3 and 6 months there was no evidence of difference in self-reported smoking cessation. There was a non-significant reduction in the number of cigarettes smoked and nicotine dependence. MTQ and number of quit attempts all increased in the BSC group compared with usual care. There was no difference in terms of quality of life at any time point, but there was evidence of an increase in depression scores at 12 months for the BSC group. There were no serious adverse events thought likely to be related to the trial interventions. The pilot economic analysis demonstrated that it was feasible to carry out a full economic analysis. It was possible to recruit people with SMI from primary and secondary care to a trial of a smoking cessation intervention based around behavioural support and medication. The overall direction of effect was a positive trend in relation to biochemically verified smoking cessation and it was feasible to obtain follow-up in a substantial proportion of participants. A definitive trial of a bespoke cessation intervention has been prioritised by the National Institute for Health Research (NIHR) and the SCIMITAR pilot trial forms a template for a fully powered RCT to examine clinical effectiveness and cost-effectiveness. Current Controlled Trials ISRCTN79497236. This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment, Vol. 19, No. 25. See the NIHR Journals Library website for further project information.
To assess how initial severity of depression affects the benefit derived from low intensity inter... more To assess how initial severity of depression affects the benefit derived from low intensity interventions for depression. Meta-analysis of individual patient data from 16 datasets comparing low intensity interventions with usual care. Primary care and community settings. 2470 patients with depression. Low intensity interventions for depression (such as guided self help by means of written materials and limited professional support, and internet delivered interventions). Depression outcomes (measured with the Beck Depression Inventory or Center for Epidemiologic Studies Depression Scale), and the effect of initial depression severity on the effects of low intensity interventions. Although patients were referred for low intensity interventions, many had moderate to severe depression at baseline. We found a significant interaction between baseline severity and treatment effect (coefficient -0.1 (95% CI -0.19 to -0.002)), suggesting that patients who are more severely depressed at basel...
Background: The COINCIDE trial aims to evaluate the effectiveness and cost-effectiveness of a col... more Background: The COINCIDE trial aims to evaluate the effectiveness and cost-effectiveness of a collaborative care intervention for depression in people with diabetes and/or coronary heart disease attending English general practices. Design: This update details changes to the cluster and patient recruitment strategy for the COINCIDE study. The original protocol was published in Trials (http://www.trialsjournal.com/content/pdf/1745-6215-13-139.pdf). Modifications were made to the recruitment targets in response to lower-than-expected patient recruitment at the first ten general practices recruited into the study. In order to boost patient numbers and retain statistical power, the number of general practices recruited was increased from 30 to 36. Follow-up period was shortened from 6 months to 4 months to ensure that patients recruited to the trial could be followed up by the end of the study. Results: Patient recruitment began on the 01/05/2012 and is planned to be completed by the 30/04/2013. Recruitment for general practices was completed on 31/10/2012, by which time the target of 36 practices had been recruited. The main trial results will be published in a peer-reviewed journal.
Proceedings of the Royal Society B: Biological Sciences, 2013
Simultaneous infection by multiple parasite species is ubiquitous in nature. Interactions among c... more Simultaneous infection by multiple parasite species is ubiquitous in nature. Interactions among co-infecting parasites may have important consequences for disease severity, transmission and community-level responses to perturbations. However, our current view of parasite interactions in nature comes primarily from observational studies, which may be unreliable at detecting interactions. We performed a perturbation experiment in wild mice, by using an anthelminthic to suppress nematodes, and monitored the consequences for other parasite species. Overall, these parasite communities were remarkably stable to perturbation. Only one non-target parasite species responded to deworming, and this response was temporary: we found strong, but short-lived, increases in the abundance of Eimeria protozoa, which share an infection site with the dominant nematode species, suggesting local, dynamic competition. These results, providing a rare and clear experimental demonstration of interactions between helminths and co-infecting parasites in wild vertebrates, constitute an important step towards understanding the wider consequences of similar drug treatments in humans and animals.
Computerised therapies play an integral role in efforts to improve access to psychological treatm... more Computerised therapies play an integral role in efforts to improve access to psychological treatment for patients with depression and anxiety. However, despite recognised problems with uptake, there has been a lack of investigation into the barriers and facilitators of engagement. We aimed to systematically review and synthesise findings from qualitative studies of computerised therapies, in order to identify factors impacting on engagement. Systematic review and meta-synthesis of qualitative studies of user experiences of computer delivered therapy for depression and/or anxiety. 8 studies were included in the review. All except one were of desktop based cognitive behavioural treatments. Black and minority ethnic and older participants were underrepresented, and only one study addressed users with a co-morbid physical health problem. Through synthesis, we identified two key overarching concepts, regarding the need for treatments to be sensitive to the individual, and the dialectal nature of user experience, with different degrees of support and anonymity experienced as both positive and negative. We propose that these factors can be conceptually understood as the 'non-specific' or 'common' factors of computerised therapy, analogous to but distinct from the common factors of traditional face-to-face therapies. Experience of computerised therapy could be improved through personalisation and sensitisation of content to individual users, recognising the need for users to experience a sense of 'self' in the treatment which is currently absent. Exploiting the common factors of computerised therapy, through enhancing perceived connection and collaboration, could offer a way of reconciling tensions due to the dialectal nature of user experience. Future research should explore whether the findings are generalisable to other patient groups, to other delivery formats (such as mobile technology) and other treatment modalities beyond cognitive behaviour therapy. The proposed model could aid the development of enhancements to current packages to improve uptake and support engagement.
Although trade-offs between reproductive effort and other fitness components are frequently docum... more Although trade-offs between reproductive effort and other fitness components are frequently documented in wild populations, the underlying physiological mechanisms remain poorly understood. Parasitism has been suggested to mediate reproductive trade-offs, yet only a limited number of parasite taxa have been studied, and reproductive effort-induced changes in parasitism are rarely linked to trade-offs observed in the same population. We conducted a brood size manipulation experiment in blue tits (Cyanistes caeruleus) infected with malaria (Plasmodium) parasites, and used quantitative PCR to measure changes in parasitaemia. In one of two years investigated, parasitaemia increased as a result of brood enlargement, and was also positively associated with two other indicators of reproductive effort: clutch size and single parenthood. These associations between both experimental and naturally varying reproductive effort and parasitaemia suggest that immune control of chronic malaria infections can be compromised when parents are working hard. Brood size manipulation significantly affected the number of independent offspring produced, which was maximised when brood size was unchanged. Moreover, when parents were infected with one of two common Plasmodium species, the shape of this trade-off curve was more pronounced, suggesting that parasitic infection may exacerbate the trade-off between quantity and quality of offspring. Although the involvement of parasites in survival costs of reproduction has received much attention, these results suggest their role in other commonly documented reproductive trade-offs, such as that between number and quality of offspring, warrants further study.
The development of molecular genetic screening techniques for avian blood parasites has revealed ... more The development of molecular genetic screening techniques for avian blood parasites has revealed many novel aspects of their ecology, including greatly elevated diversity and complex host-parasite relationships. Many previous studies of malaria in birds have treated single study populations as spatially homogeneous with respect to the likelihood of transmission of malaria to hosts, and we have very little idea whether any spatial heterogeneity influences different malaria lineages similarly. Here, we report an analysis of variation in the prevalence and cytochrome b lineage distribution of avian malaria infection with respect to environmental and host factors, and their interactions, in a single blue tit ( Cyanistes caeruleus ) population. Of 11 Plasmodium and Haemoproteus cytochrome b lineages found in 997 breeding individuals, the three most numerous (pSGS1, pTURDUS1 and pBT7) were considered separately, in addition to analyses of all avian malaria lineages pooled. Our analyses revealed marked spatial differences in the prevalence and distribution of these lineages, with local prevalence of malaria within the population ranging from over 60% to less than 10%. In addition, we found several more complex patterns of prevalence with respect to local landscape features, host state, parasite genotype, and their interactions. We discuss the implications of such heterogeneity in parasite infection at a local scale for the study of the ecology and evolution of infectious diseases in natural populations. The increased resolution afforded by the combination of molecular genetic and geographical information systems (GIS) tools has the potential to provide many insights into the epidemiology, evolution and ecology of these parasites in the future.
Avian malaria (Plasmodium spp.) and other blood parasitic infections of birds constitute increasi... more Avian malaria (Plasmodium spp.) and other blood parasitic infections of birds constitute increasingly popular model systems in ecological and evolutionary host-parasite studies. Field studies of these parasites commonly use two traits in hypothesis testing: infection status (or prevalence at the population level) and parasitaemia, yet the causes of variation in these traits remain poorly understood. Here, we use quantitative PCR to investigate fine-scale environmental and host predictors of malaria infection status and parasitaemia in a large 4-year data set from a well-characterized population of blue tits (Cyanistes caeruleus). We also examine the temporal dynamics of both traits within individuals. Both infection status and parasitaemia showed marked temporal and spatial variation within this population. However, spatiotemporal patterns of prevalence and parasitaemia were non-parallel, suggesting that different biological processes underpin variation in these two traits at this scale. Infection probability and parasitaemia both increased with host age, and parasitaemia was higher in individuals investing more in reproduction (those with larger clutch sizes). Several local environmental characteristics predicted parasitaemia, including food availability, altitude, and distance from the woodland edge. Although infection status and parasitaemia were somewhat repeatable within individuals, infections were clearly dynamic: patent infections frequently disappeared from the bloodstream, with up to 26% being lost between years, and parasitaemia also fluctuated within individuals across years in a pattern that mirrored annual population-level changes. Overall, these findings highlight the ecological complexity of avian malaria infections in natural populations, while providing valuable insight into the fundamental biology of this system that will increase its utility as a model host-parasite system.
1. Reliable assessments of infection status and population prevalence are critical for epidemiolo... more 1. Reliable assessments of infection status and population prevalence are critical for epidemiological modelling and disease management, but can be greatly biased when disease state is determined from imperfect diagnostic tests. Available statistical methods to adjust test-based prevalence estimates by correcting for test accuracy demand that many stringent requirements and assumptions be met (knowledge about underlying population prevalence or multiple diagnostic methods), limiting their utility for wildlife disease surveys. 2. In this paper, we present site-occupancy modelling as a flexible approach to derive estimates of population prevalence and test sensitivity under imperfect pathogen detection without a need for restrictive requirements or assumptions. We extend the utility of the standard site-occupancy framework for pathogen detection data by novel application of abundance-induced heterogeneity (AIH) models ) that allow test sensitivity to vary with host pathogen load or infection intensity. 3. We demonstrate the utility of this approach for wildlife disease studies by applying site-occupancy models to a data set consisting of replicate quantitative (q)PCR diagnoses of malaria parasites (Plasmodium spp.) in blood samples from wild blue tits (Cyanistes caeruleus). 4. Model selection revealed that Plasmodium detection rates by qPCR were strongly dependent on host parasite load. Estimates of parasite detection rates revealed the qPCR assay to be highly sensitive, with accordingly, a very low probability of false negative diagnosis for the majority of infected hosts in our population and little bias in naive estimates of population prevalence, although this will be a system-specific result. 5. Our results demonstrate the utility of a site-occupancy approach for deriving estimates of population prevalence under imperfect pathogen detection and reveal that accounting for host variation in pathogen load allows a more accurate assessment of diagnostic test sensitivity. 6. By identifying factors that influence pathogen detection rates, and revealing optimal protocols for obtaining unbiased prevalence estimates, while minimising the probability of false negative diagnoses, we also show that this approach can enhance both diagnostic accuracy and cost-efficiency in wildlife disease surveys.
An infant of 30 weeks gestation developed necrotizing enterocolitis (NEC) 8 days after birth and ... more An infant of 30 weeks gestation developed necrotizing enterocolitis (NEC) 8 days after birth and died 2 days later after a fulminating course. During her illness she received two blood transfusions, both of which produced sub-optimal rises in her haemoglobin and were associated with evidence of haemolysis. Retrospective analysis demonstrated T antigen (Tk) polyagglutination of the infant's red blood cells and donor plasma. Although bacterial cultures were negative throughout the course of the illness in this case, T antigen exposure is associated with certain anaerobic infections and with severity of NEC. Infants with NEC should be regularly screened for T antigen exposure and if this test is positive, plasma (immunoglobulin) containing infusions should be avoided.
1. Parasites can have important effects on host populations influencing either fecundity or morta... more 1. Parasites can have important effects on host populations influencing either fecundity or mortality, but understanding the magnitude of these effects in endemic host-parasite systems is challenging and requires an understanding of ecological processes affecting both host and parasite. 2. Avian blood parasites (Haemoproteus and Plasmodium) have been much studied, but the effects of these parasites on hosts in areas where they are endemic remains poorly known. 3. We used a multistate modelling framework to explore the effects of chronic infection with Plasmodium on survival and recapture probability in a large data set of breeding blue tits, involving 3424 individuals and 3118 infection diagnoses over nine years. 4. We reveal strong associations between chronic malaria infection and both recapture and survival, effects that are dependent on the clade of parasite, on host traits and on the local risk of infection. 5. Infection with Plasmodium relictum was associated with reduced recapture probability and increased survival, compared to P. circumflexum, suggesting that these parasites have differing virulence and cause different types of selection on this host. 6. Our results suggest a large potential survival cost of acute infections revealed by modelling host survival as a function of the local risk of infection. 7. Our analyses suggest not only that endemic avian malaria may have multiple fitness effects on their hosts and that these effects are species dependent, but also that adding ecological structure (in this case parasite species and spatial variation in disease occurrence) to analyses of host-parasite interactions is an important step in understanding the ecology and evolution of these systems.
1. Investigating the ecological context in which host-parasite interactions occur and the roles o... more 1. Investigating the ecological context in which host-parasite interactions occur and the roles of biotic and abiotic factors in forcing infection dynamics is essential to understanding disease transmission, spread and maintenance. 2. Despite their prominence as model host-pathogen systems, the relative influence of environmental heterogeneity and host characteristics in influencing the infection dynamics of avian blood parasites has rarely been assessed in the wild, particularly at a within-population scale. 3. We used a novel multievent modelling framework (an extension of multistate mark-recapture modelling) that allows for uncertainty in disease state, to estimate transmission parameters and assess variation in the infection dynamics of avian malaria in a large, longitudinally sampled data set of breeding blue tits infected with two divergent species of Plasmodium parasites. 4. We found striking temporal and spatial heterogeneity in the disease incidence rate and the likelihood of recovery within this single population and demonstrate marked differences in the relative influence of environmental and host factors in forcing the infection dynamics of the two Plasmodium species. 5. Proximity to a permanent water source greatly influenced the transmission rates of P. circumflexum, but not of P. relictum, suggesting that these parasites are transmitted by different vectors. 6. Host characteristics (age/sex) were found to influence infection rates but not recovery rates, and their influence on infection rates was also dependent on parasite species: P. relictum infection rates varied with host age, whilst P. circumflexum infection rates varied with host sex. 7. Our analyses reveal that transmission of endemic avian malaria is a result of complex interactions between biotic and abiotic components that can operate on small spatial scales and demonstrate that knowledge of the drivers of spatial and temporal heterogeneity in disease transmission will be crucial for developing accurate epidemiological models and a thorough understanding of the evolutionary implications of pathogens.
Understanding exactly when, where and how hosts become infected with parasites is critical to und... more Understanding exactly when, where and how hosts become infected with parasites is critical to understanding host-parasite co-evolution in natural populations. However, for host-parasite systems in which hosts or parasites are mobile, for example in vector-borne diseases, the spatial location of infection and the relative importance of parasite exposure at successive host life-history stages are often uncertain. Here, using a 6-year longitudinal data set from a spatially referenced population of blue tits, we test the extent to which infection by avian malaria parasites is determined by conditions experienced at natal or breeding sites, as well as by postnatal dispersal between the two. We show that the location and timing of infection differs markedly between two sympatric malaria parasite species. For one species (Plasmodium circumflexum), our analyses indicate that infection occurs after birds have settled on breeding territories, and because the distribution of this parasite is temporally stable across years, hosts born in malarious areas could in principle alter their exposure and potentially avoid infection through postnatal dispersal. Conversely, the spatial distribution of another parasite species (Plasmodium relictum) is unpredictable and infection probability is positively associated with postnatal dispersal distance, potentially indicating that infection occurs during this major dispersal event. These findings suggest that hosts in this population may be subject to divergent selection pressures from these two parasites, potentially acting at different life-history stages. Because this implies parasite species-specific predictions for many coevolutionary processes, they also illustrate the complexity of predicting such processes in multi-parasite systems.
Interactions among coinfecting parasites have the potential to alter host susceptibility to infec... more Interactions among coinfecting parasites have the potential to alter host susceptibility to infection, the progression of disease and the efficacy of disease control measures. It is therefore essential to be able to accurately infer the occurrence and direction of such interactions from parasitological data. Due to logistical constraints, perturbation experiments are rarely undertaken to directly detect interactions, therefore a variety of approaches are commonly used to infer them from patterns of parasite association in observational data. However, the reliability of these various approaches is not known. We assess the ability of a range of standard analytical approaches to detect known interactions between infections of nematodes and intestinal coccidia (Eimeria) in natural small-mammal populations, as revealed by experimental perturbations. We show that correlation-based approaches are highly unreliable, often predicting strong and highly significant associations between nematodes and Eimeria in the opposite direction to the underlying interaction. The most reliable methods involved longitudinal analyses, in which the nematode infection status of individuals at one month is related to the infection status by Eimeria the next month. Even then, however, we suggest these approaches are only viable for certain types of infections and datasets. Overall we suggest that, in the absence of experimental approaches, careful consideration be given to the choice of statistical approach when attempting to infer interspecific interactions from observational data.
We report a second-generation gene annotation of human chromosome 22. Using expressed sequence da... more We report a second-generation gene annotation of human chromosome 22. Using expressed sequence databases, comparative sequence analysis, and experimental verification, we have extended genes, fused previously fragmented structures, and identified new genes. The total length in exons of annotation was increased by 74% over our previously published annotation and includes 546 protein-coding genes and 234 pseudogenes. Thirty-two potential protein-coding annotations are partial copies of other genes, and may represent duplications on an evolutionary path to change or loss of function. We also identified 31 non-protein-coding transcripts, including 16 possible antisense RNAs. By extrapolation, we estimate the human genome contains 29,000-36,000 protein-coding genes, 21,300 pseudogenes, and 1500 antisense RNAs. We suggest that our revised annotation criteria provide a paradigm for future annotation of the human genome.
In recent years there has been much interest in physiological trade-offs involving host immune fu... more In recent years there has been much interest in physiological trade-offs involving host immune function and parasite defence, with the suggestion that they could play a pivotal role in mediating well-documented life-history trade-offs, such as the cost of reproduction. 2. Among studies of birds, the hypothesized link between reproductive effort and parasite defence has received particular attention, yet support for a trade-off between these two traits remains equivocal. 3. We used meta-regression analysis and an information-theoretic approach to investigate, among avian studies, how strong the effect of experimentally altered reproductive effort is on (i) infection with blood parasites from four common genera ( Haemoproteus , Leucocytozoon , Trypanosoma and Plasmodium ) and (ii) the ability of hosts to mount an immune response to novel antigenic challenge. 4. Across studies, there was a relatively weak but well-supported positive effect of reproductive effort on blood parasite infection levels. Importantly, this effect was significantly influenced by the parasitological measure employed; where parasitaemia (proportion of parasitized cells within infected hosts) was used as the response variable, effect size was almost three times as large as where infection prevalence (presence vs. absence of infection among hosts) was measured.
Sex biases in adult aggression have been well studied and commonly arise when resources which aff... more Sex biases in adult aggression have been well studied and commonly arise when resources which affect survival or lifetime reproductive success are less abundant or more valuable for individuals of one sex. Despite the prevalence of sex biases in adult aggression, evidence for sex biases in juvenile aggression is scant. Here, we present evidence for female-biased juvenile aggression in cooperatively breeding pied babblers (Turdoides bicolor). Unlike most cases of non-lethal sibling aggression, juvenile aggression in pied babblers does not seem to be determined by food availability. Instead, we found that juvenile aggression was related to adult dispersal patterns. This study shows that females that were more aggressive as juveniles attempted dispersal earlier than less aggressive females. Potential explanations for the association between juvenile aggression and adult dispersal patterns are discussed.
There is a high prevalence of smoking among people who experience severe mental ill health (SMI).... more There is a high prevalence of smoking among people who experience severe mental ill health (SMI). Helping people with disorders such as bipolar illness and schizophrenia to quit smoking would help improve their health, increase longevity and also reduce health inequalities. Around half of people with SMI who smoke express an interest in cutting down or quitting smoking. There is limited evidence that smoking cessation can be achieved for people with SMI. Those with SMI rarely access routine NHS smoking cessation services. This suggests the need to develop and evaluate a behavioural support and medication package tailored to the needs of people with SMI. The objective in this project was to conduct a pilot trial to establish acceptability of the intervention and to ensure the feasibility of recruitment, randomisation and follow-up. We also sought preliminary estimates of effect size in order to design a fully powered trial of clinical effectiveness and cost-effectiveness. The pilot should inform a fully powered trial to compare the clinical effectiveness and cost-effectiveness of a bespoke smoking cessation (BSC) intervention with usual general practitioner (GP) care for people with SMI. A pilot pragmatic two-arm individually randomised controlled trial (RCT). Simple randomisation was used following a computer-generated random number sequence. Participants and practitioners were not blinded to allocation. Primary care and secondary care mental health services in England. Smokers aged > 18 years with a severe mental illness who would like to cut down or quit smoking. A BSC intervention delivered by mental health specialists trained to deliver evidence-supported smoking cessation interventions compared with usual GP care. The primary outcome was carbon monoxide-verified smoking cessation at 12 months. Smoking-related secondary outcomes were reduction of number of cigarettes smoked, Fagerstrom test of nicotine dependence and motivation to quit (MTQ). Other secondary outcomes were Patient Health Questionnaire-9 items and Short Form Questionnaire-12 items to assess whether there were improvements or deterioration in mental health and quality of life. We also measured body mass index to assess whether or not smoking cessation was associated with weight gain. These were measured at 1, 6 and 12 months post randomisation. The trial recruited 97 people aged 19-73 years who smoked between 5 and 60 cigarettes per day (mean 25 cigarettes). Participants were recruited from four mental health trusts and 45 GP surgeries. Forty-six people were randomised to the BSC intervention and 51 people were randomised to usual GP care. The odds of quitting at 12 months was higher in the BSC intervention (36% vs. 23%) but did not reach statistical significance (odds ratio 2.9; 95% confidence interval 0.8% to 10.5%). At 3 and 6 months there was no evidence of difference in self-reported smoking cessation. There was a non-significant reduction in the number of cigarettes smoked and nicotine dependence. MTQ and number of quit attempts all increased in the BSC group compared with usual care. There was no difference in terms of quality of life at any time point, but there was evidence of an increase in depression scores at 12 months for the BSC group. There were no serious adverse events thought likely to be related to the trial interventions. The pilot economic analysis demonstrated that it was feasible to carry out a full economic analysis. It was possible to recruit people with SMI from primary and secondary care to a trial of a smoking cessation intervention based around behavioural support and medication. The overall direction of effect was a positive trend in relation to biochemically verified smoking cessation and it was feasible to obtain follow-up in a substantial proportion of participants. A definitive trial of a bespoke cessation intervention has been prioritised by the National Institute for Health Research (NIHR) and the SCIMITAR pilot trial forms a template for a fully powered RCT to examine clinical effectiveness and cost-effectiveness. Current Controlled Trials ISRCTN79497236. This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment, Vol. 19, No. 25. See the NIHR Journals Library website for further project information.
To assess how initial severity of depression affects the benefit derived from low intensity inter... more To assess how initial severity of depression affects the benefit derived from low intensity interventions for depression. Meta-analysis of individual patient data from 16 datasets comparing low intensity interventions with usual care. Primary care and community settings. 2470 patients with depression. Low intensity interventions for depression (such as guided self help by means of written materials and limited professional support, and internet delivered interventions). Depression outcomes (measured with the Beck Depression Inventory or Center for Epidemiologic Studies Depression Scale), and the effect of initial depression severity on the effects of low intensity interventions. Although patients were referred for low intensity interventions, many had moderate to severe depression at baseline. We found a significant interaction between baseline severity and treatment effect (coefficient -0.1 (95% CI -0.19 to -0.002)), suggesting that patients who are more severely depressed at basel...
Background: The COINCIDE trial aims to evaluate the effectiveness and cost-effectiveness of a col... more Background: The COINCIDE trial aims to evaluate the effectiveness and cost-effectiveness of a collaborative care intervention for depression in people with diabetes and/or coronary heart disease attending English general practices. Design: This update details changes to the cluster and patient recruitment strategy for the COINCIDE study. The original protocol was published in Trials (http://www.trialsjournal.com/content/pdf/1745-6215-13-139.pdf). Modifications were made to the recruitment targets in response to lower-than-expected patient recruitment at the first ten general practices recruited into the study. In order to boost patient numbers and retain statistical power, the number of general practices recruited was increased from 30 to 36. Follow-up period was shortened from 6 months to 4 months to ensure that patients recruited to the trial could be followed up by the end of the study. Results: Patient recruitment began on the 01/05/2012 and is planned to be completed by the 30/04/2013. Recruitment for general practices was completed on 31/10/2012, by which time the target of 36 practices had been recruited. The main trial results will be published in a peer-reviewed journal.
Proceedings of the Royal Society B: Biological Sciences, 2013
Simultaneous infection by multiple parasite species is ubiquitous in nature. Interactions among c... more Simultaneous infection by multiple parasite species is ubiquitous in nature. Interactions among co-infecting parasites may have important consequences for disease severity, transmission and community-level responses to perturbations. However, our current view of parasite interactions in nature comes primarily from observational studies, which may be unreliable at detecting interactions. We performed a perturbation experiment in wild mice, by using an anthelminthic to suppress nematodes, and monitored the consequences for other parasite species. Overall, these parasite communities were remarkably stable to perturbation. Only one non-target parasite species responded to deworming, and this response was temporary: we found strong, but short-lived, increases in the abundance of Eimeria protozoa, which share an infection site with the dominant nematode species, suggesting local, dynamic competition. These results, providing a rare and clear experimental demonstration of interactions between helminths and co-infecting parasites in wild vertebrates, constitute an important step towards understanding the wider consequences of similar drug treatments in humans and animals.
Computerised therapies play an integral role in efforts to improve access to psychological treatm... more Computerised therapies play an integral role in efforts to improve access to psychological treatment for patients with depression and anxiety. However, despite recognised problems with uptake, there has been a lack of investigation into the barriers and facilitators of engagement. We aimed to systematically review and synthesise findings from qualitative studies of computerised therapies, in order to identify factors impacting on engagement. Systematic review and meta-synthesis of qualitative studies of user experiences of computer delivered therapy for depression and/or anxiety. 8 studies were included in the review. All except one were of desktop based cognitive behavioural treatments. Black and minority ethnic and older participants were underrepresented, and only one study addressed users with a co-morbid physical health problem. Through synthesis, we identified two key overarching concepts, regarding the need for treatments to be sensitive to the individual, and the dialectal nature of user experience, with different degrees of support and anonymity experienced as both positive and negative. We propose that these factors can be conceptually understood as the 'non-specific' or 'common' factors of computerised therapy, analogous to but distinct from the common factors of traditional face-to-face therapies. Experience of computerised therapy could be improved through personalisation and sensitisation of content to individual users, recognising the need for users to experience a sense of 'self' in the treatment which is currently absent. Exploiting the common factors of computerised therapy, through enhancing perceived connection and collaboration, could offer a way of reconciling tensions due to the dialectal nature of user experience. Future research should explore whether the findings are generalisable to other patient groups, to other delivery formats (such as mobile technology) and other treatment modalities beyond cognitive behaviour therapy. The proposed model could aid the development of enhancements to current packages to improve uptake and support engagement.
Although trade-offs between reproductive effort and other fitness components are frequently docum... more Although trade-offs between reproductive effort and other fitness components are frequently documented in wild populations, the underlying physiological mechanisms remain poorly understood. Parasitism has been suggested to mediate reproductive trade-offs, yet only a limited number of parasite taxa have been studied, and reproductive effort-induced changes in parasitism are rarely linked to trade-offs observed in the same population. We conducted a brood size manipulation experiment in blue tits (Cyanistes caeruleus) infected with malaria (Plasmodium) parasites, and used quantitative PCR to measure changes in parasitaemia. In one of two years investigated, parasitaemia increased as a result of brood enlargement, and was also positively associated with two other indicators of reproductive effort: clutch size and single parenthood. These associations between both experimental and naturally varying reproductive effort and parasitaemia suggest that immune control of chronic malaria infections can be compromised when parents are working hard. Brood size manipulation significantly affected the number of independent offspring produced, which was maximised when brood size was unchanged. Moreover, when parents were infected with one of two common Plasmodium species, the shape of this trade-off curve was more pronounced, suggesting that parasitic infection may exacerbate the trade-off between quantity and quality of offspring. Although the involvement of parasites in survival costs of reproduction has received much attention, these results suggest their role in other commonly documented reproductive trade-offs, such as that between number and quality of offspring, warrants further study.
The development of molecular genetic screening techniques for avian blood parasites has revealed ... more The development of molecular genetic screening techniques for avian blood parasites has revealed many novel aspects of their ecology, including greatly elevated diversity and complex host-parasite relationships. Many previous studies of malaria in birds have treated single study populations as spatially homogeneous with respect to the likelihood of transmission of malaria to hosts, and we have very little idea whether any spatial heterogeneity influences different malaria lineages similarly. Here, we report an analysis of variation in the prevalence and cytochrome b lineage distribution of avian malaria infection with respect to environmental and host factors, and their interactions, in a single blue tit ( Cyanistes caeruleus ) population. Of 11 Plasmodium and Haemoproteus cytochrome b lineages found in 997 breeding individuals, the three most numerous (pSGS1, pTURDUS1 and pBT7) were considered separately, in addition to analyses of all avian malaria lineages pooled. Our analyses revealed marked spatial differences in the prevalence and distribution of these lineages, with local prevalence of malaria within the population ranging from over 60% to less than 10%. In addition, we found several more complex patterns of prevalence with respect to local landscape features, host state, parasite genotype, and their interactions. We discuss the implications of such heterogeneity in parasite infection at a local scale for the study of the ecology and evolution of infectious diseases in natural populations. The increased resolution afforded by the combination of molecular genetic and geographical information systems (GIS) tools has the potential to provide many insights into the epidemiology, evolution and ecology of these parasites in the future.
Avian malaria (Plasmodium spp.) and other blood parasitic infections of birds constitute increasi... more Avian malaria (Plasmodium spp.) and other blood parasitic infections of birds constitute increasingly popular model systems in ecological and evolutionary host-parasite studies. Field studies of these parasites commonly use two traits in hypothesis testing: infection status (or prevalence at the population level) and parasitaemia, yet the causes of variation in these traits remain poorly understood. Here, we use quantitative PCR to investigate fine-scale environmental and host predictors of malaria infection status and parasitaemia in a large 4-year data set from a well-characterized population of blue tits (Cyanistes caeruleus). We also examine the temporal dynamics of both traits within individuals. Both infection status and parasitaemia showed marked temporal and spatial variation within this population. However, spatiotemporal patterns of prevalence and parasitaemia were non-parallel, suggesting that different biological processes underpin variation in these two traits at this scale. Infection probability and parasitaemia both increased with host age, and parasitaemia was higher in individuals investing more in reproduction (those with larger clutch sizes). Several local environmental characteristics predicted parasitaemia, including food availability, altitude, and distance from the woodland edge. Although infection status and parasitaemia were somewhat repeatable within individuals, infections were clearly dynamic: patent infections frequently disappeared from the bloodstream, with up to 26% being lost between years, and parasitaemia also fluctuated within individuals across years in a pattern that mirrored annual population-level changes. Overall, these findings highlight the ecological complexity of avian malaria infections in natural populations, while providing valuable insight into the fundamental biology of this system that will increase its utility as a model host-parasite system.
1. Reliable assessments of infection status and population prevalence are critical for epidemiolo... more 1. Reliable assessments of infection status and population prevalence are critical for epidemiological modelling and disease management, but can be greatly biased when disease state is determined from imperfect diagnostic tests. Available statistical methods to adjust test-based prevalence estimates by correcting for test accuracy demand that many stringent requirements and assumptions be met (knowledge about underlying population prevalence or multiple diagnostic methods), limiting their utility for wildlife disease surveys. 2. In this paper, we present site-occupancy modelling as a flexible approach to derive estimates of population prevalence and test sensitivity under imperfect pathogen detection without a need for restrictive requirements or assumptions. We extend the utility of the standard site-occupancy framework for pathogen detection data by novel application of abundance-induced heterogeneity (AIH) models ) that allow test sensitivity to vary with host pathogen load or infection intensity. 3. We demonstrate the utility of this approach for wildlife disease studies by applying site-occupancy models to a data set consisting of replicate quantitative (q)PCR diagnoses of malaria parasites (Plasmodium spp.) in blood samples from wild blue tits (Cyanistes caeruleus). 4. Model selection revealed that Plasmodium detection rates by qPCR were strongly dependent on host parasite load. Estimates of parasite detection rates revealed the qPCR assay to be highly sensitive, with accordingly, a very low probability of false negative diagnosis for the majority of infected hosts in our population and little bias in naive estimates of population prevalence, although this will be a system-specific result. 5. Our results demonstrate the utility of a site-occupancy approach for deriving estimates of population prevalence under imperfect pathogen detection and reveal that accounting for host variation in pathogen load allows a more accurate assessment of diagnostic test sensitivity. 6. By identifying factors that influence pathogen detection rates, and revealing optimal protocols for obtaining unbiased prevalence estimates, while minimising the probability of false negative diagnoses, we also show that this approach can enhance both diagnostic accuracy and cost-efficiency in wildlife disease surveys.
An infant of 30 weeks gestation developed necrotizing enterocolitis (NEC) 8 days after birth and ... more An infant of 30 weeks gestation developed necrotizing enterocolitis (NEC) 8 days after birth and died 2 days later after a fulminating course. During her illness she received two blood transfusions, both of which produced sub-optimal rises in her haemoglobin and were associated with evidence of haemolysis. Retrospective analysis demonstrated T antigen (Tk) polyagglutination of the infant's red blood cells and donor plasma. Although bacterial cultures were negative throughout the course of the illness in this case, T antigen exposure is associated with certain anaerobic infections and with severity of NEC. Infants with NEC should be regularly screened for T antigen exposure and if this test is positive, plasma (immunoglobulin) containing infusions should be avoided.
1. Parasites can have important effects on host populations influencing either fecundity or morta... more 1. Parasites can have important effects on host populations influencing either fecundity or mortality, but understanding the magnitude of these effects in endemic host-parasite systems is challenging and requires an understanding of ecological processes affecting both host and parasite. 2. Avian blood parasites (Haemoproteus and Plasmodium) have been much studied, but the effects of these parasites on hosts in areas where they are endemic remains poorly known. 3. We used a multistate modelling framework to explore the effects of chronic infection with Plasmodium on survival and recapture probability in a large data set of breeding blue tits, involving 3424 individuals and 3118 infection diagnoses over nine years. 4. We reveal strong associations between chronic malaria infection and both recapture and survival, effects that are dependent on the clade of parasite, on host traits and on the local risk of infection. 5. Infection with Plasmodium relictum was associated with reduced recapture probability and increased survival, compared to P. circumflexum, suggesting that these parasites have differing virulence and cause different types of selection on this host. 6. Our results suggest a large potential survival cost of acute infections revealed by modelling host survival as a function of the local risk of infection. 7. Our analyses suggest not only that endemic avian malaria may have multiple fitness effects on their hosts and that these effects are species dependent, but also that adding ecological structure (in this case parasite species and spatial variation in disease occurrence) to analyses of host-parasite interactions is an important step in understanding the ecology and evolution of these systems.
1. Investigating the ecological context in which host-parasite interactions occur and the roles o... more 1. Investigating the ecological context in which host-parasite interactions occur and the roles of biotic and abiotic factors in forcing infection dynamics is essential to understanding disease transmission, spread and maintenance. 2. Despite their prominence as model host-pathogen systems, the relative influence of environmental heterogeneity and host characteristics in influencing the infection dynamics of avian blood parasites has rarely been assessed in the wild, particularly at a within-population scale. 3. We used a novel multievent modelling framework (an extension of multistate mark-recapture modelling) that allows for uncertainty in disease state, to estimate transmission parameters and assess variation in the infection dynamics of avian malaria in a large, longitudinally sampled data set of breeding blue tits infected with two divergent species of Plasmodium parasites. 4. We found striking temporal and spatial heterogeneity in the disease incidence rate and the likelihood of recovery within this single population and demonstrate marked differences in the relative influence of environmental and host factors in forcing the infection dynamics of the two Plasmodium species. 5. Proximity to a permanent water source greatly influenced the transmission rates of P. circumflexum, but not of P. relictum, suggesting that these parasites are transmitted by different vectors. 6. Host characteristics (age/sex) were found to influence infection rates but not recovery rates, and their influence on infection rates was also dependent on parasite species: P. relictum infection rates varied with host age, whilst P. circumflexum infection rates varied with host sex. 7. Our analyses reveal that transmission of endemic avian malaria is a result of complex interactions between biotic and abiotic components that can operate on small spatial scales and demonstrate that knowledge of the drivers of spatial and temporal heterogeneity in disease transmission will be crucial for developing accurate epidemiological models and a thorough understanding of the evolutionary implications of pathogens.
Understanding exactly when, where and how hosts become infected with parasites is critical to und... more Understanding exactly when, where and how hosts become infected with parasites is critical to understanding host-parasite co-evolution in natural populations. However, for host-parasite systems in which hosts or parasites are mobile, for example in vector-borne diseases, the spatial location of infection and the relative importance of parasite exposure at successive host life-history stages are often uncertain. Here, using a 6-year longitudinal data set from a spatially referenced population of blue tits, we test the extent to which infection by avian malaria parasites is determined by conditions experienced at natal or breeding sites, as well as by postnatal dispersal between the two. We show that the location and timing of infection differs markedly between two sympatric malaria parasite species. For one species (Plasmodium circumflexum), our analyses indicate that infection occurs after birds have settled on breeding territories, and because the distribution of this parasite is temporally stable across years, hosts born in malarious areas could in principle alter their exposure and potentially avoid infection through postnatal dispersal. Conversely, the spatial distribution of another parasite species (Plasmodium relictum) is unpredictable and infection probability is positively associated with postnatal dispersal distance, potentially indicating that infection occurs during this major dispersal event. These findings suggest that hosts in this population may be subject to divergent selection pressures from these two parasites, potentially acting at different life-history stages. Because this implies parasite species-specific predictions for many coevolutionary processes, they also illustrate the complexity of predicting such processes in multi-parasite systems.
Interactions among coinfecting parasites have the potential to alter host susceptibility to infec... more Interactions among coinfecting parasites have the potential to alter host susceptibility to infection, the progression of disease and the efficacy of disease control measures. It is therefore essential to be able to accurately infer the occurrence and direction of such interactions from parasitological data. Due to logistical constraints, perturbation experiments are rarely undertaken to directly detect interactions, therefore a variety of approaches are commonly used to infer them from patterns of parasite association in observational data. However, the reliability of these various approaches is not known. We assess the ability of a range of standard analytical approaches to detect known interactions between infections of nematodes and intestinal coccidia (Eimeria) in natural small-mammal populations, as revealed by experimental perturbations. We show that correlation-based approaches are highly unreliable, often predicting strong and highly significant associations between nematodes and Eimeria in the opposite direction to the underlying interaction. The most reliable methods involved longitudinal analyses, in which the nematode infection status of individuals at one month is related to the infection status by Eimeria the next month. Even then, however, we suggest these approaches are only viable for certain types of infections and datasets. Overall we suggest that, in the absence of experimental approaches, careful consideration be given to the choice of statistical approach when attempting to infer interspecific interactions from observational data.
We report a second-generation gene annotation of human chromosome 22. Using expressed sequence da... more We report a second-generation gene annotation of human chromosome 22. Using expressed sequence databases, comparative sequence analysis, and experimental verification, we have extended genes, fused previously fragmented structures, and identified new genes. The total length in exons of annotation was increased by 74% over our previously published annotation and includes 546 protein-coding genes and 234 pseudogenes. Thirty-two potential protein-coding annotations are partial copies of other genes, and may represent duplications on an evolutionary path to change or loss of function. We also identified 31 non-protein-coding transcripts, including 16 possible antisense RNAs. By extrapolation, we estimate the human genome contains 29,000-36,000 protein-coding genes, 21,300 pseudogenes, and 1500 antisense RNAs. We suggest that our revised annotation criteria provide a paradigm for future annotation of the human genome.
In recent years there has been much interest in physiological trade-offs involving host immune fu... more In recent years there has been much interest in physiological trade-offs involving host immune function and parasite defence, with the suggestion that they could play a pivotal role in mediating well-documented life-history trade-offs, such as the cost of reproduction. 2. Among studies of birds, the hypothesized link between reproductive effort and parasite defence has received particular attention, yet support for a trade-off between these two traits remains equivocal. 3. We used meta-regression analysis and an information-theoretic approach to investigate, among avian studies, how strong the effect of experimentally altered reproductive effort is on (i) infection with blood parasites from four common genera ( Haemoproteus , Leucocytozoon , Trypanosoma and Plasmodium ) and (ii) the ability of hosts to mount an immune response to novel antigenic challenge. 4. Across studies, there was a relatively weak but well-supported positive effect of reproductive effort on blood parasite infection levels. Importantly, this effect was significantly influenced by the parasitological measure employed; where parasitaemia (proportion of parasitized cells within infected hosts) was used as the response variable, effect size was almost three times as large as where infection prevalence (presence vs. absence of infection among hosts) was measured.
Sex biases in adult aggression have been well studied and commonly arise when resources which aff... more Sex biases in adult aggression have been well studied and commonly arise when resources which affect survival or lifetime reproductive success are less abundant or more valuable for individuals of one sex. Despite the prevalence of sex biases in adult aggression, evidence for sex biases in juvenile aggression is scant. Here, we present evidence for female-biased juvenile aggression in cooperatively breeding pied babblers (Turdoides bicolor). Unlike most cases of non-lethal sibling aggression, juvenile aggression in pied babblers does not seem to be determined by food availability. Instead, we found that juvenile aggression was related to adult dispersal patterns. This study shows that females that were more aggressive as juveniles attempted dispersal earlier than less aggressive females. Potential explanations for the association between juvenile aggression and adult dispersal patterns are discussed.
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Papers by Sarah Knowles