Six costs of immunity to gastrointestinal nematode infections

The strength of the immune response and the outcome of the interaction of a host with a parasite are influenced by genetic and phenotypic characteristics of both parties, and by environmental variables. Allocation of host resources to immune defence reduces resources available for other life-history traits. This review identifies six potential costs to the host from immune activation. The costs are likely to be broadly applicable to other immune responses in vertebrate species. Five phenotypic costs arise from: (i) increased metabolic activity; (ii) reduced nutrient availability due to anorexia; (iii) altered priorities for nutrient utilization; (iv) change in size and turnover of pools of immune cells and proteins; and (v) immunopathology from inappropriate or excessive immune activation. Subsumed by these costs is the cost of altered efficiency of nutrient use. A sixth cost is the genetic cost which arises from a change in the capacity of offspring to express production and life-history traits following selection for parasite resistance. The sensitivity of immune responses to the phenotypic status of the host, and the role the immune system shares with the neuroendocrine system in controlling use of resources underpin the importance of immunocompetence to the life-history of the host.     

Conservation triage or injurious neglect in endangered species recovery

Listing endangered and threatened species under the US Endangered Species Act is presumed to offer a defense against extinction and a solution to achieve recovery of imperiled populations, but only if effective conservation action ensues after listing occurs. The amount of government funding available for species protection and recovery is one of the best predictors of successful recovery; however, government spending is both insufficient and highly disproportionate among groups of species, and there is significant discrepancy between proposed and actualized budgets across species. In light of an increasing list of imperiled species requiring evaluation and protection, an explicit approach to allocating recovery funds is urgently needed. Here I provide a formal decision-theoretic approach focusing on return on investment as an objective and a transparent mechanism to achieve the desired recovery goals. I found that less than 25% of the $1.21 billion/year needed for implementing recovery plans for 1,125 species is actually allocated to recovery. Spending in excess of the recommended recovery budget does not necessarily translate into better conservation outcomes. Rather, elimination of only the budget surplus for “costly yet futile” recovery plans can provide sufficient funding to erase funding deficits for more than 180 species. Triage by budget compression provides better funding for a larger sample of species, and a larger sample of adequately funded recovery plans should produce better outcomes even if by chance. Sharpening our focus on deliberate decision making offers the potential to achieve desired outcomes in avoiding extinction for Endangered Species Act-listed species.The magnitude of issues influencing global biodiversity dwarfs the resources available to mitigate impacts and sustain biodiversity. Thus, we are faced with making hard choices and striving for efficient conservation resource allocation. The US Endangered Species Act (ESA), now 40 years old, mandates protection of endangered species through identifying at-risk species and then implementing conservation strategies that ameliorate threatening activities and stabilize or increase abundances. The agencies responsible for implementing the ESA, the US Fish and Wildlife Service (FWS) and National Marine Fisheries Service, have been successful in preventing extinction, but recovering species to the point where they can be delisted has proven more difficult. At present, responsible agencies lack resources to implement all recovery plans and are faced with making difficult decisions about which species and which actions are of highest priority.Each year, agencies face the challenge of deciding whether and how to invest in the recovery of ∼1,500 listed species. Among species found in the United States, ∼50% of ESA-listed species continue to decline or remain at high risk for extinction, and the FWS is mandated to evaluate ∼800 more candidate species by 2018. This capacity challenge is acutely problematic, given the potential impacts of human activity on the wildlife and plants that the ESA’s protections are intended to benefit.In light of the growing list of imperiled species requiring evaluation and protection, an explicit decision framework to facilitate the setting of recovery priorities and allocation of recovery funds is urgently needed. Listing endangered and threatened species under the ESA is presumed to offer a defense against extinction and a solution to achieve the recovery of imperiled populations (1), but only if effective conservation action ensues after listing occurs.The amount of government funding available for species protection and recovery is one of the best predictors of successful recovery (2–7); however, government spending is both insufficient and highly disproportionate among groups of species (8). Most species recovery plans include cost estimates—a proposed budget for meeting recovery goals. Previous work has demonstrated a significant discrepancy between proposed and actualized budgets across species (9). Furthermore, the literature on formal decision theory and endangered species conservation suggests that the most efficient allocation of resources to conserve species is not always intuitive; for example, the level of investment should not necessarily reflect the level of threat, and is dependent on whether the time frame is short term or long term (9, 10).Resource managers are increasingly relying on formal decision theory and return on investment (ROI) approaches as a societally relevant scale to facilitate management of natural resources. ROI analysis has been applied to a number of conservation contexts, including resource allocation spatial prioritization and weighing of alternative conservation actions. Approaches based on ROI and grounded in decision theory offer promise in identifying cost-effective investments and efficiency in achieving conservation goals. In this paper, I consider recovery expenditures using a formal decision-theoretic approach that considers ROI to quantitatively examine the relationship between level of investment and level of threat (11). This approach includes the following elements: (i) identify a well-defined and measurable objective; (ii) evaluate conservation opportunities; (iii) include estimates of benefits; (iv) incorporate estimates of costs; and (v) allocate portfolio. This simple application demonstrates the potential relevance of ROI to achieving recovery objectives for a fixed conservation budget.     

Illustrative case using the RISK21 roadmap and matrix: prioritization for evaluation of chemicals found in drinking water

The HESI-led RISK21 effort has developed a framework supporting the use of twenty-first century technology in obtaining and using information for chemical risk assessment. This framework represents a problem formulation-based, exposure-driven, tiered data acquisition approach that leads to an informed decision on human health safety to be made when sufficient evidence is available. It provides a transparent and consistent approach to evaluate information in order to maximize the ability of assessments to inform decisions and to optimize the use of resources. To demonstrate the application of the framework’s roadmap and matrix, this case study evaluates a large number of chemicals that could be present in drinking water. The focus is to prioritize which of these should be considered for human health risk as individual contaminants. The example evaluates 20 potential drinking water contaminants, using the tiered RISK21 approach in combination with graphical representation of information at each step, using the RISK21 matrix. Utilizing the framework, 11 of the 20 chemicals were assigned low priority based on available exposure data alone, which demonstrated that exposure was extremely low. The remaining nine chemicals were further evaluated, using refined estimates of toxicity based on readily available data, with three deemed high priority for further evaluation. In the present case study, it was determined that the greatest value of additional information would be from improved exposure models and not from additional hazard characterization.     

Do we always prioritize balance when walking? Towards an integrated model of task prioritization

Previous studies suggest that strategies such as “posture first” are implicitly employed to regulate safety when healthy adults walk while simultaneously performing another task, whereas “posture second” may be inappropriately applied in the presence of neurological disease. However, recent understandings raise questions about the traditional resource allocation concept during walking while dual tasking. We propose a task prioritization model of walking while dual tasking that integrates motor and cognitive capabilities, focusing on postural reserve, hazard estimation, and other individual intrinsic factors. The proposed prioritization model provides a theoretical foundation for future studies and a framework for the development of interventions designed to reduce the profound negative impacts of dual tasking on gait and fall risk in patients with neurological diseases. © 2012 Movement Disorder Society     

The influence of the stigma of obesity on H1N1 influenza vaccine sequencing in Canada in 2009

In 2009, the Public Health Agency of Canada (PHAC) provided guidelines about which groups should be given first access to the H1N1 influenza vaccine. These guidelines recommended that people under 65 with chronic health conditions should be among the first groups to receive the H1N1 influenza vaccine. Severe obesity was among the relevant chronic health conditions identified by PHAC. Since health care is under the jurisdiction of the ten Canadian provinces, the provinces were not required to follow these recommendations in their respective mass vaccination campaigns. Only one province (Manitoba) followed the PHAC recommendations with respect to severe obesity. Four provinces did not offer early vaccination to this group. Other provinces listed severe obesity as a sequencing category late in the vaccination campaign or placed narrow age restrictions on those who were given early access. This commentary argues that the Canadian provinces demonstrated an ambiguous commitment to the early vaccination of people who were severely obese, and that there is evidence that the stigma of obesity influenced H1N1 influenza vaccine sequencing decisions in many Canadian provinces.     

Comparison of 3 systems for assigning priority to patients on waiting lists for cataract extraction

Objective: As the demand for cataract surgery grows, patients in some health care systems are assigned to a waiting list. Several explicit priority tools have been developed. We compared 3 of these: the IRYSS-Cataract Priority Score (ICPS), Catalan Agency for Health Technology Assessment and Research cataract priority system (CCPS), and Western Canada Waiting List project for cataract surgery (WCWL).Design: Prospective cohort study.Participants: A total of 1723 consecutive patients awaiting cataract surgery at 5 hospitals.Methods: The ICPS, CCPS, and WCWL were applied to these patients after the collection of data. The 3 prioritization systems were compared using correlation methods, 95% limits of agreement, and the kappa coefficient.Results: Means and standard deviations for the different prioritization systems were 60.9 (22.2) for the ICPS, 35.7 (20.4) forthe CCPS, and 25.7 (21.5) forthe WCWL. Pearson's correlation coefficients were 0.56 between the ICPS and the CCPS, 0.62 between the WCWL and CCPS, and 0.71 between the ICPS and WCWL. The kappa value among them ranged from 0.13 to 0.40, and the intraclass correlation coefficients ranged from 0.31 to 0.55.Conclusions: These 3 prioritization tools showed acceptable correlations but assigned significantly different point scores to similar scenarios. This may have consequences when using these tools for managing a waiting list for cataract extraction.     

Validation of priority criteria for cataract extraction

Rationale, aims and objectives  Given the increasing prevalence of cataract and demand for cataract extraction surgery, patients must often wait to undergo this procedure. We validated a previously developed priority scoring system in terms of clinical variables, pre-intervention health status, appropriateness of surgery and gain in visual acuity (VA) and health-related quality of life (HRQoL).
Methods  Explicit prioritization criteria for cataract extraction created by a variation of the Research and Development (RAND) and University of California Los Angeles appropriateness methodology were retrospectively applied to a prospective cohort of 5257 patients on waiting lists to undergo cataract by phacoemulsification at 17 hospitals in Spain. Demographic data, clinical data and data related to surgical technique were collected by trained ophthalmologists. Patients were evaluated by their ophthalmologist before the intervention and 6 weeks afterward. They also completed, by mail, the Visual Function Index (VF-14) before the intervention and 3 months afterward.
Results  High-priority patients experienced greater improvement in VA and HRQoL than those classified as intermediate or low-priority ( P  < 0.0001), even after adjusting by VA and the VF-14 score at baseline. The time to intervention was the same for high-priority patients as it was for intermediate and low-priority patients.
Conclusions  The priority score we developed identified patients most likely to experience the greatest improvements from cataract extraction. Use of this tool could provide a fairer and more rational way to prioritize patients for cataract extraction.