Possible expansion of Ixodes ricinus in the United Kingdom identified through the Tick Surveillance Scheme between 2013 and 2020

The tick Ixodes ricinus (Ixodida: Ixodidae, Linnaeus) is the main vector of several pathogens including Borrelia burgdorferi s.l. (agent of Lyme borreliosis) and tick-borne encephalitis virus. Its distribution depends on many factors including suitable habitat, climate and presence of hosts. In this study, we present records of I. ricinus bites on humans, dogs (Canis lupus familiaris; Carnivora: Canidae, L.) and cats (Felis catus; Carnivora: Felidiae, L.) in the United Kingdom (UK) obtained through the Tick Surveillance Scheme between 2013 and 2020. We divided the UK into 20 km x 20 km grids and 9.2% (range 1.2%–30%) of grids had at least one record every year since 2013. Most regions reported a yearly increase in the percentage of grids reporting I. ricinus since 2013 and the highest changes occurred in the South and East England with 5%–6.7% of new grids reporting I. ricinus bites each year in areas that never reported ticks before. Spatiotemporal analyses suggested that, while all regions recorded I. ricinus in new areas every year, there was a yearly decline in the percentage of new areas covered, except for Scotland. We discuss potential drivers of tick expansion, including reforestation and increase in deer populations.     

Principal climatic and edaphic determinants of Culicoides biting midge abundance during the 2007–2008 bluetongue epidemic in the Netherlands,based on OVI light trap data

Palaearctic Culicoides midges (Diptera: Ceratopogonidae) represent a vital link in the northward advance of certain arboviral pathogens of livestock such as that caused by bluetongue virus. The effects of relevant ecological factors on weekly Culicoides vector abundances during the bluetongue virus serotype 8 epidemics in the Netherlands in 2007 and 2008 were quantified within a hurdle modelling framework. The relative role of meteorological parameters showed a broadly consistent association across species, with larger catches linked to temperature‐related variables and lower wind speed. Moreover, vector abundance was found to be influenced by edaphic factors, likely related to species‐specific breeding habitat preferences that differed markedly amongst some species. This is the first study on Culicoides vector species in the Netherlands identified during an entomological surveillance programme, in which an attempt is made to pinpoint the factors that influence midge abundance levels. In addition to providing key inputs into risk‐mitigating tools for midge‐borne pathogens and disease transmission models, the adoption of methods that explicitly address certain features of abundance datasets (frequent zero‐count observations and over‐dispersion) helped enhance the robustness of the ecological analysis.     

Locating eutrophication effects across British vegetation between 1990 and 1998

Large‐scale ecological surveillance data were analysed to determine the locations of apparent eutrophication effects across common British vegetation types between 1990 and 1998. Plant species composition was recorded from a total of 9514 fixed plots located in a stratified, random sample of 501 1 km squares across Britain. Changes in plant species composition along a gradient of substrate fertility were inferred from statistical tests of change in mean Ellenberg fertility value calculated for each fixed plot. Plots were grouped by eight vegetation types, five landscape features (hedges, road verges, watercourse banks, small biotopes, larger units in fields and unenclosed land) and six environmental zones. Tests of change in mean Ellenberg value were carried out on all combinations of these strata. Decision tree modelling was used to identify groups of test outcomes sharing the same direction of change and where each group was defined by a minimum number of strata. Post hoc power analysis was used to select statistically non‐significant test outcomes that could be used to infer stability in the sampled sub‐population. Out of a total of 142 tests of change in fertility value, 67% were increases, 8% were reductions and 25% indicated stability. The best overall predictor of increases in fertility value, and therefore of shifts in favour of plants suited to higher substrate fertility, was vegetation type. Irrespective of landscape feature and environmental zone, increased means were associated with infertile grasslands, moorland, upland woodlands and heath/bog. Already highly fertile grasslands and woodland assemblages in lowland Britain remained largely stable. The small number of decreasing test outcomes were associated with arable land in Scotland, Wales and western England. These patterns of change are hypothesized to reflect pervasive land‐use drivers combined with the inherent responsiveness of the vegetation.     

A hierarchical model for analyzing multisite individual-level disease surveillance data from multiple systems

Passive surveillance systems are widely used to monitor diseases occurrence over wide spatial areas due to their cost-effectiveness and integration into broadly distributed healthcare systems. However, such systems are generally associated with imperfect ascertainment of disease cases and with heterogeneous capture probabilities arising from factors such as differential access to care. Augmenting passive surveillance systems with other surveillance efforts provides a way to estimate the true number of incident cases. We develop a hierarchical modeling framework for analyzing data from multiple surveillance systems that allows for individual-level covariate-dependent heterogeneous capture probabilities, and borrows information across surveillance sites to improve estimation of the true number of incident cases. Inference is carried out via a two-stage Bayesian procedure. Simulation studies illustrated superior performance of the proposed approach with respect to bias, root mean square error, and coverage compared to a model that does not borrow information across sites. We applied the proposed model to data from three surveillance systems reporting pulmonary tuberculosis (PTB) cases in a major center of ongoing transmission in China. The analysis yielded bias-corrected estimates of PTB cases from the passive system and led to the identification of risk factors associated with PTB rates, as well as factors influencing the operating characteristics of the implemented surveillance systems.     

An investigation on the Culicoides species composition at seven sites in southern Switzerland

In the past decade, there have been regular outbreaks of bluetongue (BT) in many parts of Europe. Owing to the presence of BT disease and its vectors in countries adjacent to Switzerland, an initial entomological survey was conducted in 2003, which established the presence of several midges of the genus Culicoides (Diptera: Ceratopogonidae). Subsequently, a sentinel herd monitoring system was established with the primary entomological aim being the determination and further study of Culicoides population compositions. Insects were collected in 2005 and 2006 at seven sentinel herd sites in the south of Switzerland (canton of Ticino) near the border of Italy, using Onderstepoort-type light traps. This region is botanically and zoologically similar to the Mediterranean and is one of the warmest and most humid areas of the country, hence it is considered a potential access path for BT disease into Switzerland. Collections were made at four cattle farms, two equestrian centres and one goat farm. Sites were sampled four times per month from June to October. Traps were operated from dusk until dawn and samples were collected monthly for analysis through microscopy as well as a Culicoides imicola -specific PCR. Results confirmed the absence of C. imicola (Kieffer) and demonstrated that the potential BT virus vectors are highly abundant, notably: Culicoides obsoletus (Meigen), Culicoides scoticus (Downes & Kettle) and Culicoides dewulfi (Goetghebuer) subgenus Avaritia and Culicoides pulicaris (Linnaeus) subgenus Culicoides . These findings expand the current knowledge of Culicoides population composition in the southern part of the Switzerland. Culicoides cataneii (Clastrier), Culicoides flavipulicaris (Dzhafarov), Culicoides indistinctus (Khalaf), Culicoides nubeculosus (Meigen) and species of the Grisescens complex were reported for the first time in Switzerland.     

Declining tree growth resilience mediates subsequent forest mortality in the US Mountain West

Climate change-triggered forest die-off is an increasing threat to global forests and carbon sequestration but remains extremely challenging to predict. Tree growth resilience metrics have been proposed as measurable proxies of tree susceptibility to mortality. However, it remains unclear whether tree growth resilience can improve predictions of stand-level mortality. Here, we use an extensive tree-ring dataset collected at ~3000 permanent forest inventory plots, spanning 13 dominant species across the US Mountain West, where forests have experienced strong drought and extensive die-off has been observed in the past two decades, to test the hypothesis that tree growth resilience to drought can explain and improve predictions of observed stand-level mortality. We found substantial increases in growth variability and temporal autocorrelation as well declining drought resistance and resilience for a number of species over the second half of the 20th century. Declining resilience and low tree growth were strongly associated with cross- and within-species patterns of mortality. Resilience metrics had similar explicative power compared to climate and stand structure, but the covariance structure among predictors implied that the effect of tree resilience on mortality could partially be explained by stand and climate variables. We conclude that tree growth resilience offers highly valuable insights on tree physiology by integrating the effect of stressors on forest mortality but may have only moderate potential to improve large-scale projections of forest die-off under climate change.     

Suspected quinine resistant P. falciparum severe malaria possibly acquired in Ivory Coast

An expatriate to Ivory Coast (supposedly allergic to artemether-lumefantrine) was diagnosed with severe malaria in Spain. Parasitemia increased from 2% up to 21% within 24?h under quinine (10?mg/kg) and clindamycin (450?mg/8?h) combination treatment. Molecular profiling of the patient revealed the presence of molecular markers of quinine and other antimalarials resistance. Additionally, multiple copies of pfpm2 gene were also noticed in the patient sample, despite the absence of piperaquine drug pressure in Ivory Coast. Parasitemia was cleared with artesunate (2.4?mg/kg) under a desensitization protocol. Nevertheless, detection of early treatment failure is needed mainly in cases of suspected antimalarial resistance.