MEMO: Monitoring of exotic mosquitoes in Belgium

'MEMO

Monitoring of Exotic MOsquitoes in Belgium' is a sampling event dataset published by the Institute of Tropical Medicine (ITM) in Antwerp, Belgium. It forms part of the early detection of exotic mosquito species (EMS) along high-risk introduction routes in Belgium, where data are collected at defined points of entry (PoEs) using a standardised protocol. The MEMO dataset contains mosquito sampling counts performed between 2017 and 2020. MEMO+2020, an extension of the MEMO dataset, contains only Aedes albopictus mosquito trap counts performed in 2020. Here, we present these data published as a standardised Darwin Core archive, which includes, for each sampling event, an eventID, date, location and sampling protocol (in the event core); and an occurrenceID for each occurrence (tube), the number of collected individuals per tube, species status (present/absent), information on the identification and scientific name (in the occurrence extension).

Two fatal autochthonous cases of airport malaria, Belgium, 2020

We report an outbreak investigation of two fatal cases of autochthonous Plasmodium falciparum malaria that occurred in Belgium in September 2020. Various hypotheses of the potential source of infection were investigated. The most likely route of transmission was through an infectious exotic Anopheles mosquito that was imported via the international airport of Brussels or the military airport Melsbroek and infected the cases who lived at 5 km from the airports. Based on genomic analysis of the parasites collected from the two cases, the most likely origin of the Plasmodium was Gabon or Cameroon. Further, the parasites collected from the two Belgian patients were identical by descent, which supports the assumption that the two infections originated from the bite of the same mosquito, during interrupted feeding. Although airport malaria remains a rare event, it has significant implications, particularly for the patient, as delayed or missed diagnosis of the cause of illness often results in complications and mortality. Therefore, to prevent such severe or fatal outcomes, we suggest a number of public health actions including increased awareness among health practitioners, especially those working in the vicinity of airports, and increased surveillance of exotic mosquito species at airports.

First Detections of Culiseta longiareolata (Diptera: Culicidae) in Belgium and the Netherlands

Culiseta (Allotheobaldia) longiareolata (Macquart) (Diptera: Culicidae) is an ornithophilic mosquito species that occurs in the southern Palaearctic Region from the Azores to Central Asia, the Ethiopian Region, India, and Pakistan. Although it has a widespread distribution range, the species was only recently reported in Western and Central Europe. Between 2017 and 2020, larvae, pupae, and adults of Cs. longiareolata (n = 161) were found at 13 distinct locations in Belgium (n = 4) and The Netherlands (n = 9). Collected mosquitoes were morphologically identified and the identification was then validated by COI DNA barcoding. These are the first records of the species in the above-mentioned countries. The present results suggest that Cs. longiareolata could be increasing its distribution range in temperate regions, indicating a warming climate. As the species might be a potential vector of bird pathogens (e.g., West Nile virus), its spread in Western Europe is noteworthy.

Population genetic structure of the Asian bush mosquito, Aedes japonicus (Diptera, Culicidae), in Belgium suggests multiple introductions

BACKGROUND

Aedes japonicus japonicus has expanded beyond its native range and has established in multiple European countries, including Belgium. In addition to the population located at Natoye, Belgium, locally established since 2002, specimens were recently collected along the Belgian border. The first objective of this study was therefore to investigate the origin of these new introductions, which were assumed to be related to the expansion of the nearby population in western Germany. Also, an intensive elimination campaign was undertaken at Natoye between 2012 and 2015, after which the species was declared to be eradicated. This species was re-detected in 2017, and thus the second objective was to investigate if these specimens resulted from a new introduction event and/or from a few undetected specimens that escaped the elimination campaign.

METHODS

Population genetic variation at nad4 and seven microsatellite loci was surveyed in 224 and 68 specimens collected in Belgium and Germany, respectively. German samples were included as reference to investigate putative introduction source(s). At Natoye, 52 and 135 specimens were collected before and after the elimination campaign, respectively, to investigate temporal changes in the genetic composition and diversity.

RESULTS

At Natoye, the genotypic microsatellite make-up showed a clear difference before and after the elimination campaign. Also, the population after 2017 displayed an increased allelic richness and number of private alleles, indicative of new introduction(s). However, the Natoye population present before the elimination programme is believed to have survived at low density. At the Belgian border, clustering results suggest a relation with the western German population. Whether the introduction(s) occur via passive human-mediated ground transport or, alternatively, by natural spread cannot be determined yet from the dataset.

CONCLUSION

Further introductions within Belgium are expected to occur in the near future, especially along the eastern Belgian border, which is at the front of the invasion of Ae. japonicus towards the west. Our results also point to the complexity of controlling invasive species, since 4 years of intense control measures were found to be not completely successful at eliminating this exotic at Natoye.

Detection of Exotic Mosquito Species (Diptera: Culicidae) at International Airports in Europe

In Europe, the air-borne accidental introduction of exotic mosquito species (EMS) has been demonstrated using mosquito surveillance schemes at Schiphol International Airport (Amsterdam, The Netherlands). Based upon these findings and given the increasing volume of air transport movements per year, the establishment of EMS after introduction via aircraft is being considered a potential risk. Here we present the airport surveillance results performed by the Centre for Monitoring of Vectors of the Netherlands, by the Monitoring of Exotic Mosquitoes (MEMO) project in Belgium, and by the Public Health England project on invasive mosquito surveillance. The findings of our study demonstrate the aircraft mediated transport of EMS into Europe from a wide range of possible areas in the world. Results show accidental introductions of Aedes aegypti and Ae. albopictus, as well as exotic Anopheles and Mansonia specimens. The findings of Ae. albopictus at Schiphol airport are the first evidence of accidental introduction of the species using this pathway in Europe. Furthermore, our results stress the importance of the use of molecular tools to validate the morphology-based species identifications. We recommend monitoring of EMS at airports with special attention to locations with a high movement of cargo and passengers.

Urbanization drives cross-taxon declines in abundance and diversity at multiple spatial scales

The increasing urbanization process is hypothesized to drastically alter (semi-)natural environments with a concomitant major decline in species abundance and diversity. Yet, studies on this effect of urbanization, and the spatial scale at which it acts, are at present inconclusive due to the large heterogeneity in taxonomic groups and spatial scales at which this relationship has been investigated among studies. Comprehensive studies analysing this relationship across multiple animal groups and at multiple spatial scales are rare, hampering the assessment of how biodiversity generally responds to urbanization. We studied aquatic (cladocerans), limno-terrestrial (bdelloid rotifers) and terrestrial (butterflies, ground beetles, ground- and web spiders, macro-moths, orthopterans and snails) invertebrate groups using a hierarchical spatial design, wherein three local-scale (200 m × 200 m) urbanization levels were repeatedly sampled across three landscape-scale (3 km × 3 km) urbanization levels. We tested for local and landscape urbanization effects on abundance and species richness of each group, whereby total richness was partitioned into the average richness of local communities and the richness due to variation among local communities. Abundances of the terrestrial active dispersers declined in response to local urbanization, with reductions up to 85% for butterflies, while passive dispersers did not show any clear trend. Species richness also declined with increasing levels of urbanization, but responses were highly heterogeneous among the different groups with respect to the richness component and the spatial scale at which urbanization impacts richness. Depending on the group, species richness declined due to biotic homogenization and/or local species loss. This resulted in an overall decrease in total richness across groups in urban areas. These results provide strong support to the general negative impact of urbanization on abundance and species richness within habitat patches and highlight the importance of considering multiple spatial scales and taxa to assess the impacts of urbanization on biodiversity.

Evolution at two time frames: Polymorphisms from an ancient singular divergence event fuel contemporary parallel evolution

When environments change, populations may adapt surprisingly fast, repeatedly and even at microgeographic scales. There is increasing evidence that such cases of rapid parallel evolution are fueled by standing genetic variation, but the source of this genetic variation remains poorly understood. In the saltmarsh beetle Pogonus chalceus, short-winged 'tidal' and long-winged 'seasonal' ecotypes have diverged in response to contrasting hydrological regimes and can be repeatedly found along the Atlantic European coast. By analyzing genomic variation across the beetles' distribution, we reveal that alleles selected in the tidal ecotype are spread across the genome and evolved during a singular and, likely, geographically isolated divergence event, within the last 190 Kya. Due to subsequent admixture, the ancient and differentially selected alleles are currently polymorphic in most populations across its range, which could potentially allow for the fast evolution of one ecotype from a small number of random individuals, as low as 5 to 15, from a population of the other ecotype. Our results suggest that cases of fast parallel ecological divergence can be the result of evolution at two different time frames: divergence in the past, followed by repeated selection on the same divergently evolved alleles after admixture. These findings highlight the importance of an ancient and, likely, allopatric divergence event for driving the rate and direction of contemporary fast evolution under gene flow. This mechanism is potentially driven by periods of geographic isolation imposed by large-scale environmental changes such as glacial cycles.

Body-size shifts in aquatic and terrestrial urban communities

Body size is intrinsically linked to metabolic rate and life-history traits, and is a crucial determinant of food webs and community dynamics^1,2. The increased temperatures associated with the urban-heat-island effect result in increased metabolic costs and are expected to drive shifts to smaller body sizes ³ . Urban environments are, however, also characterized by substantial habitat fragmentation ⁴ , which favours mobile species. Here, using a replicated, spatially nested sampling design across ten animal taxonomic groups, we show that urban communities generally consist of smaller species. In addition, although we show urban warming for three habitat types and associated reduced community-weighted mean body sizes for four taxa, three taxa display a shift to larger species along the urbanization gradients. Our results show that the general trend towards smaller-sized species is overruled by filtering for larger species when there is positive covariation between size and dispersal, a process that can mitigate the low connectivity of ecological resources in urban settings ⁵ . We thus demonstrate that the urban-heat-island effect and urban habitat fragmentation are associated with contrasting community-level shifts in body size that critically depend on the association between body size and dispersal. Because body size determines the structure and dynamics of ecological networks ¹ , such shifts may affect urban ecosystem function.

Combined high dose radiation and pazopanib in metastatic renal cell carcinoma: a phase I dose escalation trial

Background

The primary objective was to determine maximum tolerated radiation dose in patients with metastatic renal cell carcinoma on pazopanib treatment.

Methods

Treatment-naïve patients received pazopanib according to standard of care. Stereotactic body radiotherapy (SBRT) was delivered concurrently to the largest metastatic lesion at day 8, 10 and 12. SBRT doses were escalated in 3 dose levels (24 Gy/3, 30 Gy/3 and 36 Gy/3). Dose level was assigned using Time-to-Event Continual Reassessment Method with the target dose-limiting toxicity rate set to 0.25.

Results

Thirteen patients were included. One patient experienced dose limiting toxicity (DLT) at dose level 3 (grade 4 hypoglycemia). Maximum tolerated dose was not reached with a recommended dose of 36 Gy/3 having a probability of DLT of 11%. One-year local control was 83% (95% confidence interval 61–100) and 1-year progression-free survival was 28% (95% confidence interval 1–55).

Conclusions

SBRT in combination with pazopanib is well tolerated with good local control and response rates outside the radiation field.

Trial registration

This trial was retrospectively registered on clinicaltrials.gov(NCT02334709) on January 6th, 2015.

Electronic supplementary material

The online version of this article (10.1186/s13014-017-0893-x) contains supplementary material, which is available to authorized users.

Urbanization drives community shifts towards thermophilic and dispersive species at local and landscape scales

The increasing conversion of agricultural and natural areas to human-dominated urban landscapes is predicted to lead to a major decline in biodiversity worldwide. Two conditions that typically differ between urban environments and the surrounding landscape are increased temperature, and high patch isolation and habitat turnover rates. However, the extent and spatial scale at which these altered conditions shape biotic communities through selection and/or filtering on species traits are currently poorly understood. We sampled carabid beetles at 81 sites in Belgium using a hierarchically nested sampling design wherein three local-scale (200 × 200 m) urbanization levels were repeatedly sampled across three landscape-scale (3 × 3 km) urbanization levels. First, we showed that communities sampled in the most urbanized locations and landscapes displayed a distinct species composition at both local and landscape scale. Second, we related community means of species-specific thermal preferences and dispersal capacity (based on European distribution and wing morphology, respectively) to the urbanization gradients. We showed that urban communities consisted on average of species with a preference for higher temperatures and with better dispersal capacities compared to rural communities. These shifts were caused by an increased number of species tolerating higher temperatures, a decreased richness of species with low thermal preference, and an almost complete depletion of species with very low-dispersal capacity in the most urbanized localities. Effects of urbanization were most clearly detected at the local scale, although more subtle effects could also be found at the scale of entire landscapes. Our results demonstrate that urbanization may fundamentally and consistently alter species composition by exerting a strong filtering effect on species dispersal characteristics and favouring replacement by warm-dwelling species.

A phase I/II trial of fixed-dose stereotactic body radiotherapy with sequential or concurrent pembrolizumab in metastatic urothelial carcinoma: evaluation of safety and clinical and immunologic response

Background

Current first-line standard of therapy for metastatic urothelial carcinoma is platinum-based combination chemotherapy. Pembrolizumab in phase III has demonstrated a promising overall response rate of 21.1% in patients with progression or recurrence after platinum-based chemotherapy. Preclinical and clinical evidence suggests that radiotherapy has a systemic anti-cancer immune effect and can increase the level of PD-L1 and tumor infiltrating lymphocytes in the tumor microenvironment. These findings gave rise to the hypothesis that the combination of radiotherapy with anti-PD1 treatment could lead to a synergistic effect, hereby enhancing response rates.

Methods

The phase I part will assess the dose limiting toxicity of the combination treatment of stereotactic body radiotherapy (SBRT) with four cycles of pembrolizumab (200 mg intravenously, every 3 weeks) in patients with metastatic urothelial carcinoma. The dose of both pembrolizumab and SBRT will be fixed, yet the patients will be randomized to receive SBRT either before the first cycle of pembrolizumab or before the third cycle of pembrolizumab. SBRT will be delivered (24 Gy in 3 fractions every other day) to the largest metastatic lesion. Secondary objectives include response rate according to RECIST v1.1 and immune related response criteria, progression-free survival and overall survival. The systemic immune effect triggered by the combination therapy will be monitored on various time points during the trial. The PD-L1/TIL status of the tumors will be analyzed via immunohistochemistry and response rates in the subgroups will be analyzed separately. A Simon’s two-stage optimum design is used to select the treatment arm associated with the best response rate and with acceptable toxicity to proceed to the phase II trial. In this phase, 13 additional patients will be accrued to receive study treatment.

Discussion

The progress made in the field of immunotherapy has lead to promising breakthroughs in various solid malignancies. Unfortunately, the majority of patients do not respond. The current trial will shed light on the toxicity and potential anti-tumor activity of the combination of radiotherapy with anti-PD1 treatment and may identify potential new markers for response and resistance to therapy. Trial registration this trial is registered on clinicaltrials.gov (NCT02826564).

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1251-3) contains supplementary material, which is available to authorized users.

A phase II trial of stereotactic body radiotherapy with concurrent anti-PD1 treatment in metastatic melanoma: evaluation of clinical and immunologic response

Background

Antibodies blocking programmed cell death 1 (PD-1) have encouraging responses in patients with metastatic melanoma. Response to anti-PD-1 treatment requires pre-existing CD8+ T cells that are negatively regulated by PD-1-mediated adaptive immune resistance. Unfortunately, less than half of melanoma tumours have these characteristics. Combining anti-PD-1 treatment with other immunomodulating treatments to activate CD8+ T cells is therefore of vital importance to increase response rates and long-term survival benefit in melanoma patients. Both preclinical and retrospective clinical data support the hypothesis that radiotherapy increases the response rates to anti-PD-1 treatment by stimulating the accumulation and activation of CD8+ T cells in the tumour microenvironment. Combining radiotherapy with a PD-1 blocking antibody might therefore increase response rates and even induce long-term survival. The current phase II study will be testing these hypotheses and aims to improve local and distant tumour responses by exploiting the pro-immunogenic effects of radiotherapy in addition to anti-PD-1 treatment.

Methods

The trial will be conducted in patients with metastatic melanoma. Nivolumab or pembrolizumab, both antibodies that target PD-1, will be administrated according to the recommended dosing schedule. Prior to the 2nd cycle, radiotherapy will be delivered in three fractions of 8 Gy to the largest FDG-avid metastatic lesion. The primary endpoint is the proportion of patients with a partial or complete response in non-irradiated metastases according to RECIST v1.1. Secondary endpoints include response rate according to immune related response criteria, metabolic response, local control and survival. To identify peripheral blood biomarkers, peripheral blood mononuclear cells and serum samples will be collected prospectively before, during and after treatment and subjected to flow cytometry and cytokine measurement.

Discussion

The current phase II trial aims at exploring the suggested benefits of combining anti-PD-1 treatment and radiotherapy. The translational focus on immunologic markers might be suitable for predicting efficacy and monitoring the effect so to improve patient selection for future clinical applications.

ClinicalTrials.gov Identifier NCT02821182

Variations in target volume definition and dose to normal tissue using anatomic versus biological imaging (18 F-FDG-PET) in the treatment of bone metastases: results from a 3-arm randomized phase II trial

INTRODUCTION

To report the impact on target volume delineation and dose to normal tissue using anatomic versus biological imaging (¹⁸ F-FDG-PET) for bone metastases.

METHODS

Patients with uncomplicated painful bone metastases were randomized (1:1:1) and blinded to receive either 8 Gy in a single fraction with conventionally planned radiotherapy (ConvRT-8 Gy) or 8 Gy in a single fraction with dose-painting-by-numbers (DPBN) dose range between 6 and 10 Gy) (DPBN-8 Gy) or 16 Gy in a single fraction with DPBN (dose range between 14 and 18 Gy) (DPBN-16 Gy). The primary endpoint was overall pain response at 1 month. Volumes of the gross tumour volume (GTV) - both biological (GTV_PET ) and anatomical (GTV_CT ) -, planning target volume (PTV), dose to the normal tissue and maximum standardized-uptake values (SUV_MAX ) were analysed (secondary endpoint).

RESULTS

Sixty-three percent of the GTV_CT volume did not show ¹⁸ F-FDG-uptake. On average, 20% of the GTV_PET volume was outside GTV_CT . The volume of normal tissue receiving 4 Gy, 6 Gy and 8 Gy was at least 3×, 6× and 13× smaller in DPBN-8 Gy compared to ConvRT-8 Gy and DPBN-16 Gy (P < 0.05).

CONCLUSION

Positron emitting tomography-information potentially changes the target volume for bone metastases. DPBN between 6 and 10 Gy significantly decreases dose to the normal tissue compared to conventional radiotherapy.

Behavioral adaptations imply a direct link between ecological specialization and reproductive isolation in a sympatrically diverging ground beetle

Adaptation to a previously unoccupied niche within a single population is one of the most contentious topics in evolutionary biology as it assumes the simultaneous evolution of ecologically selected and preference traits. Here, we demonstrate behavioral adaptation to contrasting hydrological regimes in a sympatric mosaic of Pogonus chalceus beetle populations, and argue that this adaptation may result in nonrandom gene flow. When exposed to experimental inundations, individuals from tidal marshes, which are naturally subjected to frequent but short floods, showed a higher propensity to remain submerged compared to individuals from seasonal marshes that are inundated for several months. This adaptive behavior is expected to decrease the probability that individuals will settle in the alternative habitat, resulting in spatial sorting and reproductive isolation of both ecotypes. Additionally, we show that this difference in behavior is induced by the environmental conditions experienced by the beetles during their nondispersive larval stages. Hence, accidental or forced ovipositioning in the alternative habitat may induce both an increased performance and preference to the natal habitat type. Such plastic traits could play an important role in the most incipient stages of divergence with gene flow.

The potential of radiotherapy to enhance the efficacy of renal cell carcinoma therapy

Renal cell carcinoma (RCC) is an immunogenic tumor, but uses several immune-suppressive mechanisms to shift the balance from tumor immune response toward tumor growth. Although RCC has traditionally been considered to be radiation resistant, recent evidence suggests that hypofractionated radiotherapy contributes to systemic antitumor immunity. Because the efficacy of antitumor immune responses depends on the complex balance between diverse immune cells and progressing tumor cells, radiotherapy alone is unlikely to induce persistent antitumor immunity. Therefore, the combination of radiotherapy with drugs having synergistic immunomodulatory properties holds great promise with the optimal timing and sequence of modalities depending on the agent used. We highlight the immunomodulatory properties of targeted therapies, such as tyrosine kinase inhibitors, mammalian target of rapamycin (mTOR) inhibitors and vascular endothelial growth factor (VEGF) neutralizing antibodies, and will suggest a combination schedule with radiotherapy based on the available literature. We also address the combination of radiotherapy with innovative treatments in the field of immunotherapy.