Search

Background: Invasive mosquito species (IMS) and their associated mosquito-borne diseases are emerging in Europe. In Belgium, the first detection of Aedes albopictus occurred in 2000 and of Aedes japonicus in 2002. Early detection and control of these IMS at points of entry (PoE’s) are of paramount importance to slow down any possible establishment. This paper gives an account of the IMS surveillance in Belgium between 2007 and 2020 and reviews the introductions and establishments recorded in that period.Methods: In total 52 PoE’s were monitored at least once for the presence of IMS between 2007 and 2020. These included used tyre and lucky bamboo import companies, airports, ports, parking lots along highways, shelters for imported cutting plants, wholesale markets, industrial areas, recycling areas, and cemeteries and an allotment garden at the country border with colonised areas. In general, monitoring was performed between April and November. Mosquitoes were captured with adult and oviposition traps, as well as by larval sampling. A logistic regression was performed to investigate the percentage of positive PoE’s for Ae. albopictus over the years. Results: Aedes albopictus has been detected at ten PoE’s, Ae. japonicus at three PoE’s and Aedes koreicus at two PoE’s. The latter two species have established overwintering populations. The percentage of PoE’s positive for Ae. albopictus increased significantly over time. Aedes albopictus is currently entering Belgium through lucky bamboo trade, used tyre trade and passive ground transport, while Ae. japonicus only through the latter two pathways. In Belgium, the import through passive ground transport was first recorded in 2018 and its importance seems to grow.Conclusion: Belgium is currently at the invasion front of Ae. albopictus and Ae. japonicus. The surveillance and control management actions at well-known PoE‘s associated to long-distance introductions are more straightforward than at less-defined PoE’s associated with short-distance introductions from colonised areas. These latter PoE’s represent a new challenge for IMS management in Belgium in the coming years and stresses the urgence of implementing a sustainable, structured and long-term IMS management programme, integrating active and passive surveillance and control.

Invasive mosquito species (IMS) and their associated mosquito-borne diseases are emerging in Europe. In Belgium, the first detection of Aedes albopictus (Skuse 1894) occurred in 2000 and of Aedes japonicus japonicus (Theobald 1901) in 2002. Early detection and control of these IMS at points of entry (PoEs) are of paramount importance to slow down any possible establishment. This article reviews the introductions and establishments recorded of three IMS in Belgium based on published (2007–2014) and unpublished (2015–2020) data collected during several surveillance projects. In total, 52 PoEs were monitored at least once for the presence of IMS between 2007 and 2020. These included used tyre and lucky bamboo import companies, airports, ports, parking lots along highways, shelters for imported cutting plants, wholesale markets, industrial areas, recycling areas, cemeteries and an allotment garden at the country border with colonised areas. In general, monitoring was performed between April and November. Mosquitoes were captured with adult and oviposition traps as well as by larval sampling. Aedes albopictus was detected at ten PoEs, Ae. japonicus at three PoEs and Aedes koreicus (Edwards 1917) at two PoEs. The latter two species have established overwintering populations. The percentage of PoEs positive for Ae. albopictus increased significantly over years. Aedes albopictus is currently entering Belgium through lucky bamboo and used tyre trade and passive ground transport, while Ae. japonicus through used tyre trade and probably passive ground transport. In Belgium, the import through passive ground transport was first recorded in 2018 and its importance seems to be growing. Belgium is currently at the invasion front of Ae. albopictus and Ae. japonicus. The surveillance and control management actions at well-known PoEs associated to long-distance introductions are more straightforward than at less-defined PoEs associated with short-distance introductions from colonised areas. These latter PoEs represent a new challenge for IMS management in Belgium in the coming years. Aedes albopictus is expected to become established in Belgium in the coming years, hence increasing the likelihood of local arbovirus transmission. The implementation of a sustainable, structured and long-term IMS management programme, integrating active and passive entomological surveillance, vector control and Public Health surveillance is therefore pivotal. Graphical Abstract

Background The onchocerciasis focus surrounding the lower Mbam and Sanaga rivers, where Onchocerca volvulus is transmitted by Simulium damnosum s.l. (Diptera: Simuliidae), was historically the largest in the southern regions of Cameroon. Annual community-directed treatment with ivermectin (CDTI) has been taking place since 2000, but recent studies have shown that new infections are occurring in children. We aimed to investigate blackfly biting and O. volvulus transmission rates along the lower Mbam river 16 years after the formal onset of annual CDTI. Methods Black flies were collected for three consecutive days each month between July 2016 and June 2017 at two riverside villages and two inland sites situated 4.9 km and 7.9 km from the riverside. Specimens collected at each site were dissected on one of the three collection days each month to estimate parity rates and O. volvulus infection rates, while the remaining samples were preserved for pool screening. Results In total, 93,573 S. damnosum s.l. black flies were recorded biting humans and 9281 were dissected. Annual biting rates of up to 606,370 were estimated at the riverside, decreasing to 20,540 at 7.9 km, while, based on dissections, annual transmission potentials of up to 4488 were estimated at the riverside, decreasing to 102 and 0 at 4.9 km and 7.9 km, respectively. However, pool screening showed evidence of infection in black flies at the furthest distance from the river. Results of both methods demonstrated the percentage of infective flies to be relatively low (0.10–0.36%), but above the WHO threshold for interruption of transmission. In addition, a small number of larvae collected during the dry season revealed the presence of Simulium squamosum E. This is the first time S. squamosum E has been found east of Lake Volta in Ghana, but our material was chromosomally distinctive, and we call it S. squamosum E2. Conclusions Relatively low O. volvulus infection rates appear to be offset by extremely high densities of biting black flies which are sustaining transmission along the banks of the lower Mbam river. Graphical Abstract

The overall aim of this scientific report is the assessment of the probability of entry of Rift Valley fever virus (RVFV) into the European Union (EU) through active or passive movement of vectors. Two different import pathways were considered in this report, i.e. import through flights and import via cargo on ships. The import through road transport, eggs or immature stages, and wind was not considered in this report as thought to be zero or negligible. In total 39 potential RVFV vectors were identified based on our review. Of the 39 identified potential vectors of RVFV, the five highest ranked based on their distribution in the African at‐risk countries, their potential role as vector, and their behavioural and ecological traits influencing the risk of transportation were: Anopheles pharoensis, Aedes aegypti, Mansonia uniformis, Aedes mcintoshi, and Culex quinquefasciatus. Four of these species were also detected in airports or airplanes in the EU. The estimated probability of entry of RVFV infected mosquito vectors into the EU through the passive movement of mosquito vectors by flights is medium for the Netherlands, France, Germany and Italy. These countries are heavily connected through direct flights from the 14 at‐risk countries in Africa. A low risk of RVFV import was estimated for Spain, Poland, Belgium and Austria and for 16 countries the risk was zero. Overall the risk of RVFV import through ship‐cargo was zero for most of the EU Member States and low for the Netherlands, Spain, Germany and Belgium.

Background Genetic polymorphisms in the human immune system modulate susceptibility to malaria. However, there is a paucity of data on the contribution of immunogenetic variants to malaria susceptibility in infants, who present differential biological features related to the immaturity of their adaptive immune system, the protective effect of maternal antibodies and fetal haemoglobin. This study investigated the association between genetic variation in innate immune response genes and malaria susceptibility during the first year of life in 656 infants from a birth cohort survey performed in Nanoro, Burkina Faso. Methods Seventeen single nucleotide polymorphisms (SNPs) in 11 genes of the immune system previously associated with different malaria phenotypes were genotyped using TaqMan allelic hybridization assays in a Fluidigm platform. Plasmodium falciparum infection and clinical disease were documented by active and passive case detection. Case–control association analyses for both alleles and genotypes were carried out using univariate and multivariate logistic regression. For cytokines showing significant SNP associations in multivariate analyses, cord blood supernatant concentrations were measured by quantitative suspension array technology (Luminex). Results Genetic variants in IL-1β (rs1143634) and FcγRIIA/CD32 (rs1801274)—both in allelic, dominant and co-dominant models—were significantly associated with protection from both P. falciparum infection and clinical malaria. Furthermore, heterozygote individuals with rs1801274 SNP in FcγRIIA/CD32 showed higher IL-1RA levels compared to wild-type homozygotes (P = 0.024), a cytokine whose production is promoted by the binding of IgG immune complexes to Fcγ receptors on effector immune cells. Conclusions These findings indicate that genetic polymorphisms in genes driving innate immune responses are associated to malaria susceptibility during the first year of life, possibly by modulating production of inflammatory mediators.

International audience; This paper presents an up-to-date review of Goodness-of-Fit (GoF) tests for the two-parameter Weibull and Extreme Value distributions. This review includes classical tests and more recent ones. An extensive comparison study is presented, which allows to identify the most powerful tests. The comparison is made using the EWGoF R package. Some guidance is given on the selection of the most appropriate tests based on the features of the studied data. Finally, an application to industrial data is presented.

Background Intestinal schistosomiasis is still a public health problem in Burundi. Since 2008, annual mass drug administration with praziquantel has been rolled out in 11 endemic districts. The national programme relies on school-based surveys with kato-katz to monitor the impact of mass drug administration. We explored whether routine data on intestinal schistosomiasis as determined by direct fecal smears at health centre level could be used. Methods From the Burundian National Health Information System, we collected routine incidence data on intestinal schistosomiasis as determined by direct smear examination in all 45 sanitary districts during 2011–2015. A temporal trends analysis was performed using a mixed negative binomial regression. Sanitary districts with mass drug administration campaigns with praziquantel (n = 11) were compared with those without (n = 34). In addition, prevalence data on intestinal schistosomiasis based on kato-katz results from a school-based national mapping in 2014 were compared with the incidence data in health centres based on direct smear results, in the same 45 sanitary districts. Results In the 11 sanitary districts applying mass drug administration with praziquantel, the incidence rate decreased significantly for the years 2014 (β2014 = − 0.826, P = 0.010) and 2015 (β2015 = − 1.294, P < 0.001) and for the five-year period (β = − 0.286, P < 0.001), whereas in the 34 districts where mass drug administration was not delivered, there was no significant decrease over time (β = − 0.087, P = 0.219). In most of the 45 sanitary districts, the low prevalence based on kato-katz in school children was confirmed by low incidence rates based on direct smears in the health centres. Conclusions National Health Information System surveillance data, based on routinely collected direct smear results at health centre level, may be able to monitor the impact of mass drug administration with praziquantel on intestinal schistosomiasis in Burundi. Control and elimination of intestinal schistosomiasis call for integration of adequate diagnosis and treatment into routine activities of primary health care facilities, as recommended by the World Health Organization since more than 20 years. When moving towards elimination, more sensitive tests, such as the point-of-care circulating cathodic antigen assay are desirable.

Rift Valley fever (RVF) is one of the major viral zoonoses in Africa, affecting humans and several domestic animal species. The epidemics in eastern Africa occur in a 5-15 year cycle coinciding with abnormally high rainfall generally associated to the warm phase of the El Nino event. However, recently, evidence has been gathered of inter-epidemic transmission. An open-source, easily applicable, accessible and modifiable model was built to simulate the transmission dynamics of RVF. The model was calibrated using data collected in the Kilombero Valley in Tanzania with people and cattle as host species and AEdes mcintoshi, AE. aegypti and two Culex species as vectors. Simulations were run over a period of 27 years using standard parameter values derived from two previous studies in this region. Our model predicts low-level transmission of RVF, which is in line with epidemiological studies in this area. Emphasis in our simulation was put on both the dynamics and composition of vector populations in three ecological zones, in order to elucidate the respective roles played by different vector species: the model output did indicate the necessity of Culex involvement and also indicated that vertical transmission in AEdes mcintoshi may be underestimated. This model, being built with open-source software and with an easy-to-use interface, can be adapted by researchers and control program managers to their specific needs by plugging in new parameters relevant to their situation and locality.

Additional file 1: Table S1. Genotypic-based association analysis for malaria infection using co-dominant models.

Additional file 2: Table S2. Genotypic-based association analysis for clinical malaria using co-dominant models.

Additional file 2: Table S2. Genotypic-based association analysis for clinical malaria using co-dominant models.

Background Malaria “hotspots” have been proposed as potential intervention units for targeted malaria elimination. Little is known about hotspot formation and stability in settings outside sub-Saharan Africa. Methods Clustering of Plasmodium infections at the household and hotspot level was assessed over 2 years in 3 villages in eastern Cambodia. Social and spatial autocorrelation statistics were calculated to assess clustering of malaria risk, and logistic regression was used to assess the effect of living in a malaria hotspot compared to living in a malaria-positive household in the first year of the study on risk of malaria infection in the second year. Results The crude prevalence of Plasmodium infection was 8.4% in 2016 and 3.6% in 2017. Living in a hotspot in 2016 did not predict Plasmodium risk at the individual or household level in 2017 overall, but living in a Plasmodium-positive household in 2016 strongly predicted living in a Plasmodium-positive household in 2017 (Risk Ratio, 5.00 [95% confidence interval, 2.09–11.96], P < .0001). There was no consistent evidence that malaria risk clustered in groups of socially connected individuals from different households. Conclusions Malaria risk clustered more clearly in households than in hotspots over 2 years. Household-based strategies should be prioritized in malaria elimination programs in this region., In a low-transmission setting in eastern Cambodia, malaria risk clustered more clearly in households than in hotspots over 2 years. Household-based strategies should be prioritized in malaria elimination programs in this region.