Parasites & Vectors
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Preprints posted in the last 30 days, ranked by how well they match Parasites & Vectors's content profile, based on 60 papers previously published here. The average preprint has a 0.07% match score for this journal, so anything above that is already an above-average fit.
Coleman, G. A.; Hamik, J.; Smith, H.; Mucha, T.; Rault, L. C.; Anderson, T. D.
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Aedes albopictus (Skuse), the Asian tiger mosquito, is a highly competent arboviral vector whose range has expanded substantially across the United States over the past four decades. Despite predictive models placing Nebraska within the species' climatically suitable range, its establishment status in the state has remained poorly characterized. Here, we report results from a nine-year mosquito surveillance program (2017-2025) conducted across 44 Nebraska counties in collaboration with the Nebraska Department of Health and Human Services. Ae. albopictus was detected in five counties, with sustained, annually increasing populations documented in Richardson, Douglas, and Lancaster counties. Richardson County recorded continuous detections during 2017-2025, with proportional representation rising to 60.50% of collected mosquitoes by 2025. In Douglas and Lancaster counties, temporal advancement of first seasonal detection in 2024 and 2025 provide evidence consistent with successful overwintering rather than annual reintroduction. A cumulative degree-day model predicted adult emergence in mid-May across all county-year combinations, consistently preceding trap deployment by two to seven weeks and revealing a systematic early-season surveillance gap. Generalized linear mixed-effects models indicated that trap-level detection persistence, rather than urban location, was the primary predictor of yearly Ae. albopictus positivity, suggesting that current invasion dynamics are driven by focal source populations. These findings provide strong evidence for the establishment of Ae. albopictus in eastern Nebraska and highlight the need for earlier seasonal surveillance and standardized criteria to define establishment in northward-expanding vector populations.
Hussain, A.; Bhowmick, S.; Mateus-Pinilla, N.; Smith, R. L.
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Tick-borne disease risk reflects the combined influence of vector abundance, pathogen prevalence, human exposure, and seasonal activity, yet these components are rarely integrated at the county level. We developed species-specific ecological risk scores for three medically important tick species (Acari: Ixodidae): Amblyomma americanum (L.), Dermacentor variabilis (Say), and Ixodes scapularis Say, across all 102 Illinois counties using data from 2019 to 2022. County-level predicted tick abundance and pathogen prevalence were scaled and combined using equal weights to generate primary vector-level risk scores. Robustness to the equal-weight assumption was evaluated by systematically varying the relative weights assigned to abundance and pathogen prevalence, while a separate sensitivity analysis incorporated reported tick-bite incidence where available. Associations with human disease were evaluated using negative binomial regression of tick-borne disease case counts on the corresponding risk scores, with county population included as an offset. Monthly phenology indicators were constructed by integrating human disease cases, reported tick bites, and sampled tick abundance and were evaluated in relation to temperature and precipitation. Seasonal risk was estimated by combining county-level vector risk with species-specific monthly phenology, generating monthly risk surfaces that were deployed through an interactive R Shiny application. Higher risk scores were significantly associated with greater disease case rates for each tick species. County rankings were highly stable under moderate changes in abundance and prevalence weighting. Seasonal activity differed among species, with A. americanum and D. variabilis showing concentrated warm-season risk and I. scapularis exhibiting a broader seasonal profile. These county-level seasonal risk maps identify where and when relative tick-borne disease risk is elevated in Illinois, supporting targeted prevention, surveillance, and clinical awareness.
Vandenberghe, E.; Vereecken, S.; Reuss, F.; Brusius, I.; Janssens, C.; Magdeburg, A.; Groneberg, D. A.; Muller, R.; Kramer, I. M.
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In Germany, insecticide use is recommended during mosquito-borne disease outbreaks, yet nationwide data on insecticide resistance in key vector species are scarce. This is particularly relevant for Culex pipiens s.l., a vector of West Nile virus. Here, we provide the first broad-scale assessment of molecular insecticide resistance (kdr and ace-1 mutations) in Cx. pipiens f. pipiens across Germany. We associated insecticide resistances with environmental conditions, potential links with mitochondrial variation of the cytochrome c oxidase I (COI) gene as well as phenotypic resistance (CDC bottle assay with permethrin) of the Frankfurt population with elevated kdr frequencies. Kdr resistance alleles were detected in German Cx. pipiens f. pipiens reaching frequencies of up to 50% in the metropolitan areas of Berlin and Frankfurt am Main. Annual precipitation was negatively associated with kdr allele frequency. Interestingly, ace-1 resistance mutations were only present in the metropolitan area of Frankfurt am Main and in Muggensturm (Rhine valley, southwestern Germany). COI haplotype analyses revealed low genetic variability within German Cx. pipiens f. pipiens populations with no association to the insecticide resistance genotype. Phenotypic assays of the Frankfurt population showed early signs of permethrin resistance, but unmatched genotypic and phenotypic resistance state. This study provides the first broad-scale assessment of molecular insecticide resistance in Cx. pipiens f. pipiens across Germany, establishing a baseline for resistance surveillance and vector control. Further research is needed to identify factors shaping phenotypic resistance, as molecular markers alone may not reliably predict resistance. Since sampling was restricted to urban green spaces, broader sampling across environmental gradients is needed to identify additional environmental effectors.
DE MEEUS, T.; Ravel, S.; Kagbadouno, M.; BERTE, D.; SEGARD, A.; LEPAIS, O.
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Tsetse flies are strictly found is sub-Saharan Africa where they are responsible for the transmission and maintenance of African trypanosomiases in humans (HAT) and animals (AAT). Vector control has been recognized as an essential tool to fight against these diseases. Nevertheless, it requires the best possible knowledge of the biology of the targeted population. Population genetics tools can prove very useful to obtain such information but require the use of polymorphic and reliable genetic markers. In this paper we present the development of microsatellite markers using a new high-throughput sequencing based technology (SSRseq). We applied it on two species of tsetse flies from three HAT foci and obtained more accurate results as compared to microsatellite loci developed with classic methods. We could indeed use 9 to 14 SSRseq loci without the several problems generally met with classic microsatellites, as all were located in autosomes, without short allele dominance or stuttering and very few null alleles. SSRseq loci appeared much more polymorphic in tsetse flies as compared to other species (fungi, trees, bees, or fishes), which suggested much higher effective population sizes, much higher mutation rates of the genome or both, suggesting high capacities for evolutionary adaptation. With the 9-14 loci kept, we confirmed the propensity of these flies to move almost freely in the whole zones investigated, and also highlighted the possible evolutionary response of one of the unkept loci regarding vector control devices used in these HAT foci, which will require further studies. We suggest for further population structure studies to use only loci with less than 1% missing data, which proved being a good and fast selection strategy to get the most reliable results.
Bakhoum, M. T.; Fall, A. G.; Segard, A.; Seck, M. T.; Thiall, A. S.; Gimonneau, G.; Ravel, S.; DE MEEUS, T.
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In sub-Saharan Africa, human and animal health is threatened by African trypanosomoses. These diseases are caused by trypanosomes that are transmitted primarily by tsetse flies. Vector control remains one of the most effective strategies for reducing disease transmission, but requires a minimum level of knowledge of the population biology, ecology and dispersal patterns of the targeted vectors. In this respect, population genetic approaches using appropriate polymorphic genetic markers can provide valuable tools to inform and optimize control strategies. Senegal is currently engaged in a national tsetse control programme and has been identified as a study country within a European Union-funded research initiative, COMBAT (controlling and progressively minimizing the burden of animal trypanosomosis). Baseline entomological studies are currently underway in the Sine Saloum (Southern Senegal). This preliminary study aimed to characterize the population genetic structure and connectivity of tsetse fly species present in Southern Senegal, Glossina palpalis gambiensis and G. morsitans submorsitans, in order to assess their population sizes (geographically and demographically), population densities and dispersal capacities. The two species exhibited markedly contrasting population structures. The first, G. p. gambiensis, displayed an isolation by distance with rather dense subpopulations exchanging immigrants at short distances (1.6 km/generation) and continuously from Sine-Saloum to Casamance, in line with the apparent continuity of the mangrove network found along this coast. In contrast, G. m. submorsitans presented a relatively dense population over a 75 km wide area, fragmented into sparsely distributed, very dense and interconnected pockets. These findings indicate that G. p. gambiensis likely constitutes a large metapopulation comprising 3266 effective individuals on average (and up to 7765), whereas G. m. submorsitans appeared as a single and large population, scattered in small pockets that could be readily replenished by immigrants from distant areas in case of control. These results suggest that elimination is not a realistic option for any of these two populations. Alternatively, localized integrated pest management is likely to be the most effective approach for controlling the negative effects of these biting flies on domestic animals, by reducing trypanosome transmission. However, further entomological investigations and the use of more informative genetic markers are needed to obtain a more precise understanding of the epidemiological processes involved.
Tsalah, J. M.; Bobskill, V.; Ravenhurst, J.; Ross, K.; Gardner, A.; Landesman, W.; Lover, A. A.
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Vegetation plays a critical role in shaping fine-scale tick density by structuring local microclimates, habitat resources, and host interactions that largely determine tick survival and activity, with implications for tick-borne disease transmission. Tick burden in the United States continues to increase, with annual reported tick-borne disease cases more than doubling from 2004 through 2019. These trends call for a broader scope of tick-mitigation strategies that go beyond traditional prevention measures that focus on personal protection; and there is an opportunity to inform habitat-level interventions. Here, we quantify fine-scale vegetation structure across 48 subplots at tick surveillance sites in Western Massachusetts to assess local habitat features associated with Ixodes scapularis density and potential for human-tick contact risk. In assessing understory and overstory vegetation attributes, this study identified life stage-specific differences in predicted tick density, with higher adult densities in areas with deeper leaf litter and presence of invasive plant species and nymphs associated with high presence of ferns. Both adult and nymphal Ix. scapularis were predicted at higher densities in relatively low basal area forests (18.9 to 26.9 m2/hectare). This study design provides a simple, low-cost framework for organizations looking to incorporate tick-informed forest measurement ecology into their public health tick surveillance protocols with minimal training.
Carmichael, R. M.; Kirby, G.; Sloan, L.; Desjardins, A.; Parvy, J.-P.; Baldini, F.; Pondeville, E.; Dick, J. T. A.; Ferguson, H. M.; Cuthbert, R. N.
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While mosquito invasions and associated pathogens are increasingly prominent in Europe, evidence gaps remain for many northerly regions where proactive management interventions may be most effective. At the regional periphery of Europe, there remains a significant knowledge gap concerning mosquito vector distributions in Northern Ireland. This study aimed to address this major gap by systematically surveying larval and adult mosquito populations in key habitats (ponds, reedbeds, saltmarsh, wet grasslands, wet woodlands, and urban gardens). We further identified environmental drivers of important vector species abundance and screened collected specimens with molecular techniques to identify presence of cryptic human-biting vector species. In Northern Ireland, mosquitoes (including potential bridge vectors of West Nile and Usutu viruses) were found to be widely distributed. Between May and August 2025, a total of 2430 mosquitoes (951 adults and 1479 larvae) were collected over 196 trap nights and 76 larval collections. Collections encompassed 17 species, with Culex pipiens/torrentium being the most widely distributed and abundant taxon recorded. Mosquito abundances were greatest in reedbed habitats, related negatively with rainfall and peaked in June and July. A subset of Culex pipiens/torrentium mosquitoes were identified to species/biotype level using PCR, with the majority (89.3%) identified as Culex pipiens pipiens and 9.3% as Culex torrentium. Importantly, the first detections of Culex pipiens/molestus hybrids (1.8%) on the island of Ireland were found. This work underscores the wide, yet previously undocumented abundance and distribution of potential zoonotic vectors in Northern Ireland and provides an important baseline for management planning and future research, while contributing to broader understandings of environmental population drivers and distributions.
Bout, A.; Warot, S.; Cesari, L.; Hamidi, R.; Caravel, C.; Talamas, E.; Tortorici, F.; Ris, N.
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Stink bugs (Hemiptera Pentatomidae) are major agricultural pests worldwide, including both native and invasive species. In France, for instance, Halyomorpha halys has rapidly expanded its range, affecting key crops such as hazelnuts, apples, and vegetables. Meanwhile, several native, polyphagous species - Nezara viridula, Palomena prasina and, to a lesser extent, Graphosoma italicum - are re-emerging and impacting diverse crops because of changes in agricultural practices and climatic conditions. Egg parasitoids represent promising biological control agents for these pests, be it through conservation, augmentation or introduction biological control. However, their actual potential is not precisely documented due to a lack of ambitious surveys and possible taxonomic issues. This study aims to address this gap by compiling results obtained from various of egg parasitism surveys of Pentatomidae in France and implementing a large-scale DNA Barcoding approach (2000 individuals) for the emerged parasitoids. Our results indicate a high diversity of egg parasitoids, and detected some taxonomic issues and molecular inconsistencies that warrant further study. Among the three families of egg parasitoids recovered (Encyrtidae, Eupelmide, and Scelionidae), Scelionidae was the most abundant and diverse with nine species of Trissolcus (including the two adventive species, Tr. japonicus and Tr. mitsukurii) and four Telenomus species (including two unidentified to species). Scelionidae dominated the parasitoid assemblages associated with most of the Pentatomidae host species, except for H. halys for which the eupelmid Anastatus bifasciatus was the most common species.
Karume, K. L.; Noyes, H.; Nyangiri, O.; Mulindwa, J.; Fataki, O. L.; Kiabanzawoko, O. N.; Kyong-Shin, R. F.; Nassuuna, J.; Elliott, A.; Masacuberta-Partal, M.; Lyaki, J.; Mukendi, J. P. K.; Mbemba, T. F.; Ngoyi, D. M.
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Background Schistosomiasis is a parasitic disease caused by flatworms known as schistosomes. The infection cycle starts when people shed eggs through the stool or the urine. Larva infects freshwater snails to later infect humans through the skin during water based activities. Schistosomiasis is commonly associated with rural areas. In this study, we wanted to see if the schistosomiasis distribution is different in rural and urban areas, along with potential risk factors associated with schistosomiasis distribution. Methodology Fresh urine samples were collected from 1,699 school-aged children (5 - 15 years old) in urban and rural sites in the Kimpese health district. Prevalence of haematobium and mansoni schistosomiasis was determined using, respectively, the urine sedimentation and the Point-of-Care Circulating Cathodic Antigen test with a quantitative estimate of infection intensity obtained with an RDT-Reader. Collected risk factors were tested for association with schistosomiasis infection and its intensity. Results The overall prevalence of schistosomiasis found in urban and rural areas was 75% and 82% respectively, with higher prevalence of S. mansoni in rural schools, and higher S. haematobium prevalence in urban schools. The difference in total prevalence between schools in urban and rural areas was significant, X2 (1, N = 1699) = 13.03, p = .0003. S. mansoni intensity of infection was also higher in rural children (mean = 162 mV) compared to those in urban areas (mean = 76 mV) (p < 2e-16). Male gender, washing dishes in the river, and swimming were associated with schistosomiasis in urban areas. Age, Springs, and rivers were significant factors in rural sites. Age, river, and washing dishes in the river were factors associated with the intensity of infection. Conclusion Our results showed very high prevalence in both rural and urban areas, which implies that control programs should consider them with the same interest and also revise control strategies.
Govindarajan, R.; Gowri Sankar, S.; Rahi, M.; Philip Samuel, P.; Alwin Prem Anand, A.
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Orientia tsutsugamushi is the causative agent of scrub typhus infection in humans. This pathogen is transmitted into mammalian hosts including humans through Leptotrombidium mites. Till date, detection of O. tsutsugamushi in human was performed using PCR assay with 56kDa type specific antigen (TSA56), 47kDa outer membrane protein (47kDa-OMP) and groEL chaperonin gene. To understand the efficiency of different genes for the detection of O. tsutsugamushi in Leptotrombidium mites, we performed a comparative PCR assay with various universal primers targeting different genes including TSA56, 47kDa-OMP and groEL gene. We have collected 500 Leptotrombidium mites from Vellore, Tamil Nadu and, the mites were segregated into 50 pools with 10 mites in each pool were used for DNA extraction. The molecular detection of O. tsutsugamushi was performed using PCR assays (including conventional, nested and duplex PCR). The comparative PCR analysis showed nested PCR of groEL gene has high efficiency in detecting the presence of O. tsutsugamushi in chigger samples compared to other genes. Interestingly, groEL target demonstrated high efficiency for detection of O. tsutsugamushi in chigger samples and, when used with nested primers, can facilitate differentiation of O. tsutsugamushi from other rickettsial pathogens. Thus, we conclude groEL gene nested PCR assay can be used routinely to detect O. tsutsugamushi in trombiculid mites.
Lindell, H. M. K.; Jenkins, A.; Evens, K. C.; Dinnetz, P.; Lehtilä, K.
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Neoehrlichia mikurensis is widely detected in tick populations across Europe, yet its host range beyond small rodents remains poorly understood. Large wild mammals are frequently exposed to tick vectors, but their role in the transmission cycle of this bacterium is unclear. Wild boars (Sus scrofa) are among the most abundant large mammals in southern Sweden and commonly inhabit tick-infested environments, making them a potentially relevant host species. In this study, spleen samples from 87 wild boars collected between 2023 and 2025 across southern and central Sweden were analysed for the presence of N. mikurensis DNA using quantitative polymerase chain reaction. N. mikurensis DNA was not detected in any of the analysed samples, despite sampling in regions where the bacterium is known to be prevalent in ticks. These results indicate that wild boars may have a limited role in the maintenance of N. mikurensis in Sweden, although the possibility of rare or transient infection cannot be excluded. Despite being based on negative findings, this study contributes to a more comprehensive understanding of the host range of N. mikurensis and highlights the importance of continued evaluation of wildlife species in the transmission dynamics of tick-borne pathogens.
Yokoi, K.; Kainoh, Y.; Kanda, M.; Kuwasaki, S.; Kimura, K.; Bono, H.
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Parasitoid wasps develop in or on other arthropods and have evolved a wide range of strategies for exploiting their hosts. Ascogaster reticulata is a solitary egg to larval endoparasitoid wasp belonging to the subfamily Cheloninae of Braconidae. We constructed a genome assembly using long-read sequence data. The assembled genome was 280.5 Mbp, consisting of 209 contigs. The N50 value and GC content ratio were 13.9 Mbp and 30.43%, respectively. The percentage of transposable elements and repetitive regions was 52.43%. The predicted number of genes is 27,261. Merqury revealed that the QV value and completeness of the genome were 61.79 and 99.3917%, respectively. BUSCO analysis detected approximately 99% of the core genes. These results suggest that the genome data were of sufficient quality for use as a reference genome. Therefore, these data can be utilized as a genomic resource for comparative studies within Braconidae and for future investigations into the biology and evolution of Cheloninae parasitoid wasps.
Oyibo, W.; Blair, A. M.; Oladipo, O.; Ogbulafor, N.; Urude, R. O.; Onwuachusi, G.; Anabike, C.; Ntadom, G.; Okoronkwo, C.; Uhomoibhi, P.; Eze, N.; Oresanya, O.; Mahmoud, A.; Okoro, O.; Aduagba, B.; Ijezie, S.; Okoh, F.; Kawu, I.; Ozor, L.; Maikore, I.; Maxwell, K.; Ezeiru, S.; Nwokolo, E.; Amajoh, C.; Audu, M.; Mokuolu, O.; Biyama, Z.; Adeyoju, T.; Obike, N.; Ilelaboye, J.; Lawson, A.; Conway, D. J.
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Introduction: The continuing high and inequitable global malaria burden requires improved methods to understand trends and target control. Current methods often involve infection prevalence surveys, but additional parasitological measures could increase precision in estimating infection burdens of communities. Methods: Focusing on the country with most malaria globally, examinations of slides from 10,651 children under five sampled in the 2021 national Malaria Indicator Survey in Nigeria were performed to measure asexual parasite densities in infected children and discriminate sexual stages and species. Variation in these indices among the six different geopolitical zones and 37 individual states including the Federal Capital Territory were compared with the variation indicated by infection prevalence alone. Results: Among the six major geopolitical zones, only one had significantly higher asexual parasite prevalence than others, but parasite densities within infected children revealed more significant variation among the different zones. Comparing results for 2021 with previous data from 2018, one zone showed lower asexual parasite prevalence and two had lower sexual parasite prevalence, but three had higher asexual parasite densities in infected children. Variation in parasite densities among individual states also highlighted significant geographical and temporal differences, extending the detection of heterogeneity within each geopolitical zone. Overall trends were driven by the predominant parasite species Plasmodium falciparum as prevalence and density of the other species were much lower. Conclusions: Findings indicate that understanding complex patterns of geographical and temporal variation is enhanced by including asexual parasite density measurement, providing opportunities for more precise targeting of malaria control within high burden countries.
Ozkirim, A.; Uzunov, A.; Costa, C.; Kandemir, I.
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The honey bee ectoparasitic mite Tropilaelaps mercedesae is an emerging threat to Western beekeeping, as it is expanding its range from native Asia. In this study, the first record of the presence of Tropilaelaps mercedesae in Turkiye, in the Artvin province, in the north-east of the country is documented. Following reports of weakening colonies, eight apiaries were inspected using the rapid brood decapping method. All apiaries were found positive, and infestation was detected in 22 of 24 examined colonies. Mite samples were analysed with morphometry and barcoding and were confirmed as T. mercedesae. In the paper, we discuss the impact of imports and migration practices on the mites occurrence in Turkiye. In addition, we forecast the potential corridors and means of further invasion and address the implications for European and global apiculture.
Singh, S.; Raikar, M.; Dongardive, S.; Ramdasi, A.; Kumar, S.; Dhaigude, S.; Kadam, P.; Viswanathan, R.; Yadav, A.; Karmodiya, K.; Lole, K. S.; Banerjee, K.; PR, S.; De, T. D.
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Aedes aegypti, an important vector of several arboviral diseases, is highly adapted to human-associated environments and commonly exploits anthropogenic water-holding containers for breeding. Understanding the ecological factors governing oviposition-site selection is essential for developing sustainable vector control strategies. Previous studies have established that microbial communities in breeding waters influence mosquito oviposition-site selection through the production of volatile organic compounds. Importantly, rapid urbanization in India has increased the availability of artificial breeding habitats for Ae. aegypti, potentially facilitating the transmission and persistence of arboviral diseases. However, the composition of bacterial communities in these larval habitats and their potential role in shaping the oviposition behavior of Ae. aegypti remain poorly characterized in the Indian context. Here, we investigated the bacterial diversity and community composition of Aedes larval habitats during the 2024 Zika and chikungunya outbreaks in Pune, India. Water samples, collected from artificial urban containers and natural freshwater habitats, were subjected to 16S rRNA amplicon sequencing. Artificial breeding habitats exhibited significantly higher bacterial diversity and were enriched with Enterobacter spp. compared with natural habitats. Oviposition bioassays further demonstrated a strong preference of gravid Ae. aegypti females for Enterobacter-conditioned water. GCMS analysis of bacterial suspension identified indole as a prominent volatile metabolite associated with Enterobacter, suggesting its possible role in mediating oviposition site selection. Together, these findings provide insights into the microbial and chemical ecology of Ae. aegypti breeding habitats and establish a basis for investigating microbial volatile cues as potential targets for vector surveillance and environmentally sustainable attract-and-kill strategies.
Ngmembong, C. N.; Captain-Esoah, M.; Lareef, S.; Angyiereyiri, E. D.; Donkor, M. N.; Dassah, S. D.; Azameti, M. K.; Motey, G. A.; Adetunde, L. A.; Abalori, T. A.; Frempong, K. K.; Kubio, C.; Asoala, V.; Boakye, D. A.; Dadzie, S. K.; Antwi, F. O.; Adjei, M. R.; Grobusch, M. P.; Bakajika, D.; Lule, F. J.; Juma, E.; Braka, F.; Achu, D.
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Objectives To assess microfilaraemia, chronic lymphatic filariasis (LF)-related morbidity, and community knowledge and self-reported preventive behaviours in a rural community in northern Ghana following prolonged mass drug administration (MDA). Design Community-based cross-sectional study. Setting Birifor community, Lawra Municipality, Upper West Region, northern Ghana, from October 2024 to January 2025. Participants A total of 261 community members aged 10 years and above were selected using random sampling and participated in the study. Outcome measures Outcome measures included microfilaraemia detected by night blood microscopy, chronic LF-related morbidity identified through clinical examination, and community knowledge and self-reported preventive behaviours assessed using a structured questionnaire. Results No microfilariae were detected (0/261; 0%). Chronic lymphoedema was identified in five individuals (1.9%), all aged over 40 years. Awareness of LF was high (95.8%), yet only 39.5% of participants demonstrated good community knowledge and self-reported preventive behaviours. Misconceptions regarding transmission, particularly beliefs that LF is hereditary or caused by spiritual factors, were common. MDA participation was high (93.1%). All five individuals with chronic lymphoedema reported loss of income, and three (60%) reported additional household income loss due to caregiving responsibilities. Conclusions No microfilaraemia was detected, suggesting very low transmission in the study area, although residual infection cannot be excluded. Chronic LF-related morbidity and gaps in community knowledge persist despite high MDA participation. Sustained surveillance using more sensitive diagnostic approaches, together with morbidity management and disability prevention, community education and support for affected households, will be important to sustain LF elimination efforts.
Holmes, A. L.; de Glanville, W. A.; Katiti, W. A.; Mendes, A. J. F.; Bodenham, R. F.; Lukambagire, A.; Mmbaga, B. T.; Rubach, M. P.; Crump, J. A.; Cleaveland, S.; Viana, M.; Halliday, J. E. B.
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Brucellosis is a globally distributed and widely under-appreciated zoonotic bacterial disease that causes infertility and abortion in livestock and febrile illness in humans, sometimes with debilitating sequelae. Brucellosis incidence estimates typically focus on acute presentations and range from 50 to 100 per 100,000 people per year for endemic settings, showing marked variation within and between countries. Estimating brucellosis incidence in low-resource settings is complicated by lack of access to and utilisation of health care and high-quality diagnostic testing for many people in rural communities. To estimate brucellosis incidence in a pastoralist population in northern Tanzania, we developed a Bayesian model that integrates multiple data sources including diagnostic test results from a hospital-based prevalence study performed in 2016-2017, test sensitivity and specificity, and data from a community-based healthcare utilisation survey in 2019-2020. We show that this population experienced a high incidence of brucellosis with wide uncertainty, with estimates of 387.6 (95% HPDI: 103.3 - 903.5) illnesses per 100,000 people per year for the total population, 199.7 (95% HPDI: 16.2 - 584.6) for individuals aged >15 years, and 632.4 (95% HPDI: 180.1 - 1379.4) for children aged [≤]15 years. These incidence estimates were among the highest in the world to date. The wide density intervals for these incidence estimates reflect uncertainty in the underlying parameter values used. Sensitivity analyses show that healthcare utilisation influenced incidence estimates the most. This result indicates that accounting for low levels of healthcare utilisation is essential to avoid under-estimating disease incidence. Our findings illustrate that brucellosis is a frequent cause of illness in this population. Increased access to treatment, prevention, and accurate diagnostic testing would greatly improve understanding of brucellosis epidemiology and the health of many people living in similar at-risk communities.
Peralta, C.; Torres-Sanz, N.; Palma, L.
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A native entomopathogenic nematode isolate, Heterorhabditis indica Che4.1, was recovered from soils in Valencia (Spain), and its symbiotic bacterium, Photorhabdus akhurstii Che4.1, was isolated and characterized. Nematode identification was confirmed by ITS and 28S rDNA sequencing, while genome-based analyses supported the taxonomic assignment of the bacterial symbiont. The nematode-bacterium complex exhibited insecticidal activity against Spodoptera exigua and Spodoptera littoralis. H. indica Che4.1 showed an LC of 53.7 infective juveniles (IJs)/mL against S. exigua, comparable to that of the commercial reference Larvanem (54.3 IJs/mL). Against S. littoralis, Che4.1 exhibited an approximately twofold lower LC than Larvanem (77.3 versus 155.9 IJs/mL), with non-overlapping 95% confidence intervals. The complete genome of P. akhurstii Che4.1 consists of a single circular chromosome of 5.66 Mb encoding a diverse repertoire of putative virulence factors, including toxin complex (Tc) components, YenTc-like proteins, Mcf toxins, App-family proteins, Pra/Prb proteins, and chitinases, together with several predicted secondary metabolite biosynthetic gene clusters. LC-MS/MS analyses of bacterial culture supernatants and infected insect cadavers detected multiple predicted virulence-associated proteins, including Tc-related, YenTc-like, App-family, and Pra/Prb proteins. In addition, bacterial cell-free supernatants caused 68.8-81.3% mortality in S. exigua neonates under laboratory conditions. Together, these findings reveal a diverse repertoire of potential virulence determinants in P. akhurstii Che4.1 and demonstrate the insecticidal potential of its native nematodebacterium complex. The performance of H. indica Che4.1 relative to a commercial reference supports further evaluation of this isolate for biological control of Spodoptera spp., particularly under greenhouse and field conditions.
Kohli, M. K.; Tolman, E.; Thompson, V.
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Whole genome analysis of spittlebug populations, an Aphrophora species (Hemiptera: Aphrophoridae) known to spread Pierce's disease, from various vineyards in Napa and Sonoma Counties demonstrates that these insects are conspecific with Aphrophora permutata found in quasi-natural populations. The genomes analyzed fall in three autosomal clusters with two sympatric populations (based on admixture) that diverged around 40,000-90,000 years before present according to demographic models. We also recover three related but distinct mitochondrial clusters. There is no genetic differentiation between Napa and Sonoma County vineyard populations and very modest differentiation among vineyards and quasi-natural Berkeley/Oakland Hills population. These vineyard and quasi-natural populations have distinct life histories, including divergent oviposition hosts (understory herbs versus pines) and different patterns of adult seasonal migration (out-migration and return versus simple movement from the understory to the pine canopy). Analysis of the mitochondrial gene COI indicates that A. permutata, Aphrophora fulva and Aphrophora maculosa are intermingled in the same mitochondrial clade, along with the more distantly related species Aphrophora gelida. Further, all three autosomal genetic clusters show evidence of selection for insecticide resistance. We also find that endosymbionts Wolbachia and Rickettsia were both present in a substantial fraction of specimens analyzed, but neither appears to influence population structure. Overall, our findings elucidate an intriguing degree of life history divergence between geographically proximate, conspecific populations linked by gene flow and may have implications for the continued management of vineyard populations.
Chen, C.; Alassal, A.; Reinke, A. W.
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Microsporidia are a group of parasites that exhibit vast morphological, ecological, and genetic diversity. To catalog this diversity, we previously generated a database of attributes for microsporidia species. Here we expand this database to include species described since 2021, previously missed descriptions, and provisional species defined by clustering GenBank 18S rRNA sequences, resulting in 1,795 species. Using these data, we describe when and where microsporidia have been reported, their hosts and host habitats, the tissues they infect, and their spore morphology. A phylogeny of 18S sequence clusters shows that closely related microsporidia tend to infect closely related hosts, such that sequence identity is predictive of host taxonomy. Clustering also reveals previously unappreciated genetic diversity within some named species, in particular the human pathogen Vittaforma corneae, suggesting that these may comprise multiple species. We have also generated a web portal through which new species information can be submitted, which will facilitate regular updates. This database provides a resource for systematic analysis of microsporidia properties and a reference for taxonomic descriptions.