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Early detection of invaders requires finding small numbers of individuals across large landscapes. It has been argued that the only feasible way to achieve the sampling effort needed for early detection of an invader is to involve volunteer groups (citizen scientists, passive surveyors, etc.). A key concern is that volunteers may have a considerable false-positive and false-negative rate. The question then becomes whether verification of a report from a volunteer is worth the effort. This question is the topic of this paper.We show that the maximum plausible incidence when the expert samples on its own, , and the maximum plausible incidence when the expert only verifies cases reported by the volunteer surveyor to be infected, , are related as Where θfp and θfn are the false positive and false negative rate of the volunteer surveyor, respectively. We also show that the optimal monitoring programme consists of verifying only the cases reported by the volunteer surveyor if Where TN is the cost of a sample taken by the expert and TX is the cost of an expert verifying a case reported by a volunteer surveyor.

Emerging pests and pathogens of plants are a major threat to natural and managed ecosystems worldwide. Whilst it is well accepted that surveillance activities are key to both the early detection of new incursions and the ability to identify pest-free areas, the performance of these activities must be evaluated to ensure they are fit for purpose. This requires consideration of the number of potential hosts inspected or tested as well as the epidemiology of the pathogen and the detection method used. In the case of plant pathogens, one particular concern is whether the visual inspection of plant hosts for signs of disease is able to detect the presence of these pathogens at low prevalences, given that it takes time for these symptoms to develop. One such pathogen is the ST53 strain of the vector-borne bacterial pathogen Xylella fastidiosa in olive hosts, which was first identified in southern Italy in 2013. Additionally, X. fastidiosa ST53 in olive has a rapid rate of spread, which could also have important implications for surveillance. In the current study, we evaluate how well visual surveillance would be expected to perform for this pathogen and investigate whether molecular testing of either tree hosts or insect vectors offer feasible alternatives. Our results identify the main constraints to each of these strategies and can be used to inform and improve both current and future surveillance activities.

ObjectivesTo investigate whether MTX should be combined with an additional DMARD and bridging glucocorticoids as initial treatment for patients with early RA to induce an effective long-term response.MethodsThe Care in early RA study is a two-year investigator-initiated pragmatic multicentre randomized trial. Early RA patients, naïve to DMARDs and glucocorticoids, were stratified based on prognostic factors. High-risk patients were randomized to COBRA-Classic (n = 98): MTX, sulfasalazine, prednisone step-down from 60 mg; COBRA-Slim (n = 98): MTX, prednisone step-down from 30 mg; or COBRA-Avant-Garde (n = 93): MTX, leflunomide, prednisone step-down from 30 mg. Low-risk patients were randomized to COBRA-Slim (n = 43); or Tight Step Up (TSU) (n = 47): MTX without prednisone. Clinical/radiological outcomes at year 2, sustainability of response, safety and treatment adaptations were assessed.ResultsIn the high-risk group 71/98 (72%) patients achieved a DAS28-CRP < 2.6 with COBRA-Slim compared with 64/98 (65%) with COBRA-Classic and 69/93 (74%) with COBRA-Avant-Garde (P = 1.00). Other clinical/radiological outcomes and sustainability of response were similar. COBRA-Slim treatment resulted in less therapy-related adverse events compared with COBRA-Classic (P = 0.02) or COBRA-Avant-Garde (P = 0.005). In the low-risk group, 29/43 (67%) patients on COBRA-Slim and 34/47 (72%) on TSU achieved a DAS28-CRP < 2.6 (P = 1.00). On COBRA-Slim, low-risk patients had lower longitudinal DAS28-CRP scores over 2 years, a lower need for glucocorticoid injections and a comparable safety profile compared with TSU.ConclusionAll regimens combining DMARDs with glucocorticoids were effective for patients with early RA up to 2 years. The COBRA-Slim regimen, MTX monotherapy with glucocorticoid bridging, provided the best balance between efficacy and safety, irrespective of patients’ prognosis.Trial registrationClinicalTrials.gov, http://www.clinicaltrials.gov, NCT01172639.

The emergence of Xylella fastidiosa in Europe has highlighted the importance of surveillance for protection of host plants against exotic pathogens. However, surveillance for such pathogens is resource intensive and must therefore be efficient and sustainable. Using the example of the Apulian outbreak, we consider here how best to conduct surveillance in pest-free areas which are at a high risk of infection due to spread from adjacent outbreaks. To do this, we consider where inspection and survey sites should be, which diagnostic test to use during surveillance, and whether to sample hosts or insect vectors. We identify the optimal locations of surveillance sites by linking together an epidemiological model of pathogen spread and a statistically-informed sampling model with a computational optimisation routine. This approach allows us to demonstrate the considerable differences in survey deployment in order to maximise the number of infected hosts detected compared with maximising the overall probability of detection. We go on to consider the impact of the ""detection lag"" before infected hosts become detectable on both the detection probability and the expected prevalence of infection at the time of first detection. Finally, we consider whether sampling of hosts or sampling of vectors would be expected to facilitate earlier detection, and discuss some of the challenges associated with these strategies. As well as providing specific recommendations for improving surveillance activities for X. fastidiosa in Apulia, our methods are generic and can be applied in other areas and for a range of pests and pathogens.

Cassava is an important food crop for most small-holder growers across sub-Saharan Africa, where production is largely limited by the presence of two viral diseases: cassava mosaic disease (CMD) and cassava brown streak disease (CBSD), both propagated by a vector whitefly and via human-mediated movement of infected cassava stems. Despite its importance, there is limited knowledge of growers’ behaviour related to planting material movement, as well as growers’ perception and knowledge of cassava diseases, which have major implications for disease spread and control. This study was conducted to address this knowledge gap by surveying small-holder growers in Zambia. A total of 96 subsistence cassava growers across five provinces were surveyed between 2015 and 2017. Most growers interviewed used planting materials from their own fields (94%) or those of nearby (