Acta Tropica
○ Elsevier BV
Preprints posted in the last 30 days, ranked by how well they match Acta Tropica's content profile, based on 13 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.
Williams, P. D. E.; Borts, D. J.; Liu, D.; Byerley-Duke, J.; VanVeller, B.; Martin, R. J.
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Anthelmintic drugs are used to control soil-transmitted helminths that infect a third of the worlds human population. There is increasing concern about the development of resistance to anthelmintic drugs because of the limited number of compounds available and there is an unmet need for new resistance-busting drugs. Here we describe the presence of a previously unrecognized endogenous acetylcholine analogue, {beta}-alanine betaine, which may serve as an endogenous ligand for an alternate subfamily of nicotinic receptors (DEG-3/DES-2) that could be developed as novel drug targets because their analogues are not present in their human or animal hosts. We collected peri-enteric fluid from female Ascaris suum (a model for the human parasite, Ascaris lumbricoides) and subjected it to chromatography and MS/MS to reveal signals consistent with acetylcholine, choline, and {beta}-alanine betaine but we did not recover betaine. We injected betaine into female Ascaris suum which produced no effect. However, injection of {beta}-alanine betaine, produced characteristic pretzel coiling and injection of levamisole produced a rod-like spastic paralysis. The differences between {beta}-alanine betaine and levamisole suggested that they activate different nAChRs subfamilies. PCR showed that messages of the DEG-3 subfamily of nAChR channels, which are betaine targets and were present in the intestine and body wall of A. suum. Calcium signaling experiments showed that {beta}-alanine betaine increased intracellular calcium of the intestine enterocytes and electrophysiology of the body muscle cells demonstrated that {beta}-alanine betaine produced membrane potential depolarization. In N2 elegans, application of {beta}-alanine betaine produced gradual inhibition of motility, which was reduced in acr-20, acr-23, des-2, deg-3 and lgc-41 null-mutants. These observations suggest that, in addition to acetylcholine, {beta}-alanine betaine - an anaerobic analog of betaine - may function as an endogenous ligand in anaerobic nematodes such as A. suum. An expanded repertoire of nicotinic acetylcholine receptor subfamilies in nematodes relative to mammals may reflect a corresponding need for diversification of cholinergic endogenous ligands in these organisms. This repertoire could allow their simpler neuronal system to perform more complex controls and be exploited for development of different and novel subfamily selective cholinergic anthelmintics.
Bamgboye, E.; Adeleke, M. A.; Surakat, O.; Mhlanga, L.; Fasasi, K.; Rufai, A. M.; Popoola, K. O.; Aminu, U. M.; Ogbulafor, N.; Ozodiegwu, I. D.
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Larval source management (LSM) is a complementary malaria control intervention, yet evidence to guide context-specific implementation remains limited. Nigeria's recent national commitment to LSM scale-up makes the need for operational evidence particularly urgent. Informal settlements embedded within wards of differing dominant settlement archetypes may present distinct Anopheles larval habitat profiles with implications for how LSM strategies should be tailored. We evaluated Anopheles larval habitats within informal settlement areas across wards with contrasting settlement archetypes in Ibadan metropolis, Nigeria, to inform targeted larval source management. Potential breeding habitats were surveyed in dry and wet seasons within informal settlement areas across three wards -- Olopomewa, Challenge, and Agugu -- representing formal, informal, and slum settlement-dominant archetypes respectively. Habitats were characterized and assessed for Anopheles larval presence. Pareto analysis identified habitats accounting for 80% of larval abundance. Breeding habitat density per km{superscript 2} was estimated using a simulated pathway technique. Associations between mosquito dispersal scale and household malaria infections identified through Rapid Diagnostic Testing were evaluated using kernel-based distance-decay weighting. Environmental drivers of habitat suitability were modeled in MaxEnt. Of 420 potential breeding habitats identified, 31 (7.4%) contained Anopheles larvae, predominantly during the wet season (26, 83.9%). Puddles, dug wells, drainages/gutters/ditches and canals accounted for 80% of site-level larval abundance when standardized by sampling effort. Larval and breeding habitat density were highest in Agugu, the slum-dominant ward, across both seasons. Modeled mosquito dispersal scale showed best fit at 30-32m in Challenge (OR 1.41, 95% CI: 1.05-1.89) during the wet season and 16-18m in Agugu (OR 1.29, 95% CI: 1.04-1.60) during the dry season. Habitat suitability in Agugu was higher farther from large water bodies and in areas with higher population density and positive Normalized Difference Water Index values. In Challenge, suitability was higher in areas with lower nighttime light levels, positive Normalized Difference Water Index values, and negative Normalized Difference Moisture Index values. Further studies incorporating multiple wards across diverse urban settings are needed to determine whether differences in larval ecology between settlement archetypes provide a reliable basis for planning larval source management.
Kurucz, K.; Zeghbib, S.; Abraham, A.; Tauber, Z.; Banyai, K.; Eritja, R.; Kemenesi, G.
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BackgroundThe invasive mosquito Aedes koreicus has established populations in several European countries during the past decade, raising increasing public health concerns due to its potential role as a vector of pathogens. While species identification is primarily based on morphological characters, Ae. koreicus exhibits distinct morphological variants originating from mainland Korea and Jeju Island, which complicates surveillance and may lead to misidentification, particularly in regions where closely related species co-occur. To date, the genetic basis and population-level relevance of these morphological forms in Europe remain poorly understood. MethodsWe investigated the co-occurrence of two morphological forms of Ae. koreicus in Hungary, representing the first confirmed European location where both forms were detected sympatrically and even within the same breeding sites. Adult mosquitoes were morphologically characterised using diagnostic traits, and individuals representing both morphotypes were subjected to comprehensive genetic analyses. We sequenced multiple mitochondrial markers (COX1, COX2, COX3, ATP6, ND1, ND3) and the nuclear ITS2 region using Oxford Nanopore long-read sequencing. Phylogenetic reconstructions and haplotype network analyses were applied to assess genetic differentiation between morphotypes and to compare them with Aedes japonicus as a closely related reference species. ResultsAcross all analysed mitochondrial and nuclear markers, no genetic differentiation was detected between specimens identified as the "mainland" or "Jeju-do" morphological forms of Ae. koreicus. Phylogenetic and haplotype network analyses consistently grouped individuals independently of their morphotype, indicating a shared genetic background at the population level. In contrast, Ae. japonicus formed a clearly distinct genetic lineage, confirming the robustness of the applied markers for interspecific discrimination. ConclusionsOur results demonstrate that the observed morphological variability in Ae. koreicus populations are not underpinned by detectable genetic differentiation using commonly applied mitochondrial and genomic markers. These findings highlight the limitations of using morphology alone to infer population origin or structure and emphasise the need for heightened awareness of intraspecific variability in routine surveillance. Accurate morphological identification remains critical, particularly in citizen science-based monitoring programmes and AI-based automatization platforms, such as Mosquito Alert, to avoid confusion with morphologically similar invasive species. Further studies integrating genomic and ecological approaches are required to elucidate the mechanisms underlying morphological variability in this emerging vector species.
Partsch, V.; Crudo, F.; Schröeder, C.; Del Favero, G.; Marko, D.
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Alternaria fungi produce various structurally diverse mycotoxins, several of which exhibit immunomodulatory properties. Among these, alternariol monomethyl ether (AME), alternariol (AOH), alterperylenol (ALTP), altertoxin I (ATX-I), and altersetin (AST) have been reported to suppress lipopolysaccharide (LPS)-induced inflammatory responses. However, the precise molecular mechanisms underlying these effects remain unclear. The present study aimed to elucidate how these selected Alternaria mycotoxins (0.1-50 M) target the NF-{kappa}B signaling pathway in THP-1 monocytes. Key components of the NF-{kappa}B cascade were analyzed by immunofluorescence microscopy, Western blotting and qRT-PCR. Nuclear translocation of NF-{kappa}B p65 and its phosphorylated form (p- NF-{kappa}B p65) was assessed by Western blot, while cytokine responses were determined at transcript (qRT-PCR) and protein (ELISA) levels. Moreover, in silico docking analyses were performed to investigate potential interactions of the toxins with IKK{beta}, and receptor-mediated crosstalk was studied using the glucocorticoid receptor (GR) antagonist RU486. Co-treatment with RU486 attenuated the immunosuppressive effects of 1 and 5 M AOH, indicating partial involvement of GR-dependent mechanisms. AME, AOH, ALTP, ATX-I, and AST increased total I{kappa}B levels while reducing its phosphorylated form. Additionally, AST and ALTP decreased the protein levels of Toll-like receptor 4 (TLR4), the I{kappa}B kinase (IKK) complex, NF-{kappa}B p65, and p- NF-{kappa}B p65. While AOH (5 M) and AST (25 M) reduced nuclear translocation of p65 and p-p65, ALTP (2 M) enhanced nuclear localization despite decreasing cytokine expression. Together, these findings suggest toxin-specific interference at multiple regulatory levels of NF-{kappa}B signaling and provide novel mechanistic insight into the immunomodulatory effects of Alternaria mycotoxins.
Csivincsik, A.; Nagy, E.; Zam, I.; Tari, T.; Kucsera, I.; Nagy, G.; Sreter, T.
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Background: Dirofilaria repens is a zoonotic parasite expanding unnoticed across Europe due to climate change. We hypothesised that in this process, the Carpathian Basin has a facilitating effect. Methods: Using 426 georeferenced European cases, the probability of infection occurrence was determined in relation to climatic factors, surface water availability, regional social deprivation, and stray dog population density. To analyse the potential impacts of ecological and social factors (deprivation and stray dog population density), the MaxEnt algorithm, and spatial Empirical Bayes smoothing and Bivariate Local Indicators of Spatial Association (BiLISA) index calculation were employed, respectively. Results: MaxEnt analysis revealed that the mean warmest month temperature (22.8 - 25.1 oC), winter mean minimum temperature (> -2.1 oC), and summer precipitation (28.6 - 231 mm) have the strongest impact on the probability of the parasite's occurrence in Europe. Social factors have significance in the eastern Balkans and the Carpathian Basin, but not in Western Europe. The Carpathian Basin appears to be a hotspot, similar to Mediterranean coastal areas. Furthermore, the Danube Valley acts as an ecological corridor for subtropical vector-borne parasites. Conclusions: Our findings confirm that summer warmth is the primary ecological driver of the parasite's range expansion, which is facilitated by the Carpathian Basin due to climatic and socioeconomic conditions.
Soumaoro, L.; Coulibaly, M. E.; Diallo, A. A.; Sangare, M.; Diabate, A. F.; Coulibaly, S. Y.; Doumbia, S. S.; Koureichi, M. M.; Kone, A. K.; Dembele, K.; Dolo, H.; Yaro, A. S.; Coulibaly, Y. I.
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Entomological surveillance is essential for the control of lymphatic filariasis (LF). This xenomonitoring study, conducted in 2022-2023, evaluated the effectiveness of three mosquito trapping methods to identify the most suitable tool for surveillance following the discontinuation of mass drug administration. The surveys took place in two Malian villages: Konfra (seasonal watercourse) and Siradjouba (permanent watercourse). Three techniques were compared: Pyrethrum spray catch (PSC) conducted at the end of each visit inside 30 randomly selected houses, and different collection points were chosen based on the characteristics of the study area to place the Ifakara Type C tent (Ifakara) and the gravid trap (GT). Collections were conducted simultaneously at both sites. All Anopheles gambiae and Culex spp. collected in 2022-2023 were morphologically identified and then analyzed in the laboratory for their infectious status. Data was processed using SPSS v25; Fishers exact test was used to compare proportions, with a significance threshold of p < 0.05. A total of 4,732 mosquitoes were captured (95.05% in 2022). In 2022, the Anopheles were predominant in Konfra (91.38%), while Culex predominated in Siradjouba (63.41%). In 2023, Anopheles was found only in Konfra (3 specimens), while Culex was predominant in Siradjouba (64.07%). In 2022, PSC collected 90.57% of Anopheles, Ifakara 9.43%, and GT 0%. For Culex, GT collected 53.67%, PSC 36.62%, and Ifakara 9.71%. In 2023, the few Anopheles (3) came from PSC; Culex were mainly collected by the Ifakara tent (43.29%). For FL xenomonitoring, the combination of PSC and the GT appear to be effective collection methods.
Wang, S.; Carruth, S. G.; Vasquez, C.; Townsend, J.; Raman, V.; Mutebi, J.-P.; Ajelli, M.; Wilke, A. B. B.
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Locally acquired arboviral infections are an increasing public health concern in the United States. Aedes aegypti and Culex quinquefasciatus, vectors of dengue virus and West Nile virus, respectively, are established in regions where local transmission has been reported. Seasonal variation in mosquito abundance affects vector density, human-vector contact, and arbovirus transmission risk. The aim of this study is to investigate seasonal variations in Ae. aegypti and Cx. quinquefasciatus population dynamics in Miami-Dade County, Florida; Maricopa County, Arizona; and Clark County, Nevada. Monthly relative abundance, average mosquitoes collected per trap-night, normalized abundance ratios, and seasonal-trend decomposition were used to evaluate species- and location-specific seasonal patterns. Mosquito population dynamics differed by species and location. In Miami-Dade County, the two species showed seasonal turnover, with Cx. quinquefasciatus peaking during winter and spring and Ae. aegypti peaking during summer. In Maricopa and Clark counties, both species peaked primarily between August and September. Species dominance also differed by site, with Ae. aegypti more abundant than Cx. quinquefasciatus in Maricopa County and Cx. quinquefasciatus more abundant than Ae. aegypti in Clark and Miami-Dade counties. Seasonal decomposition showed that Ae. aegypti peaked earlier in Miami-Dade County than in Maricopa and Clark counties, whereas Cx. quinquefasciatus showed a spring peak in Miami-Dade County and bimodal seasonal patterns in Maricopa and Clark counties. These results suggest that mosquito population dynamics are species- and location-specific and support the use of local surveillance data to guide the timing of mosquito control and arbovirus preparedness.
Catrupay-Valdebenito, C.; Burgos, C. F.; Salgado-Martinez, B.; Vejar, C.; Fuentes, N. A.; Yevenes, G. E.; Moraga-Cid, G.; Castro, P. A.
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BackgroundNeurulation is a fundamental process in the formation of the central nervous system (CNS). The process begins with the folding and fusion of the neural plate to form the neural tube which subsequently gives rise to the development of the brain and spinal cord. Environmental and genetic factors that disrupt neurulation can induce neural tube defects (NTDs) and consequently cause additional developmental complications, including motor impairments. Purinergic signaling is a conserved form of extracellular communication (i.e. paracrine, synaptic signaling) that plays a role in early development. This signaling is mediated by purine nucleotides and nucleosides, which activate metabotropic P2Y and ionotropic P2X purinoceptors, respectively. Distinct patterns of intracellular calcium dynamics are observed throughout vertebrate development, from fertilization through organogenesis, including neurulation. Among P2X receptors, P2X4 is an ATP-modulated, Ca2+-permeable, ligand-gated ion channel characterized by having the highest Ca2+ permeability and is known to be modulated by ivermectin (IVM). ObjectiveOur investigation focuses on assessing the effects of IVM treatment during neurulation and evaluating the impact of this drug on phenotype, motor behavior and neuromuscular junction (NMJ) structure at tadpole stage. These results were compared with those obtained following separate treatments with compounds that specifically block glycine, GABA(A) and nACh receptors, all which have been described as IVM targets. ResultsIn this study we demonstrate the transcriptional expression for both P2X and P2Y purinergic receptors during neurulation, as well as the expression of P2X4. Following IVM neurula-treatments, we observed neural tube defects (NTDs), pigmentation changes, motor paralysis and alterations in neuromuscular junction (NMJ) structure, particularly affecting axonal branching. In contrast, treatment with the blockers strychnine, bicuculline and -bungarotoxin, used to assess the involvement of GlyR, GABA(A)R and 7nAChR, respectively, failed to show similar outcomes. ConclusionsIn summary, our results highlight the critical role of purinergic signaling during early development, particularly P2X4 receptor mediated signaling during neurulation which may account for the pharmacological effects induced by the positive allosteric modulator ivermectin.
Geng, L.; Ross, P. S.; Cai, Y.; Huang, T.; Chow, J.; Wang, Z.; Choo, E. L. W.; Chang, C.-C.; Couper, L.; Gu, X.; Hoffmann, A.; Lim, J. T.
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Wolbachia-mediated incompatible-insect technique (IIT) via wAlbB, wMel or wPip/wAlbA/wAlbB strains are promising approaches for suppressing wildtype Aedes mosquitoes and therefore Aedes-borne diseases. Yet, the effectiveness of this technique under climate change remains uncertain. Here, we evaluate the long-term robustness of male Wolbachia-infected mosquito releases to suppress wildtype Aedes aegypti and Ae. albopictus populations across future climate scenarios across diverse geographical regions. We compiled large publicly available datasets on Aedes abundance across Singapore, China, the European Union and the United States, historical and projected climatic conditions in these regions and conducted experiments to test the thermal stability of cytoplasmic incompatibility in Wolbachia-infected male Aedes aegypti and albopictus. A climatically-driven entomological model was developed and calibrated using a Bayesian approach to model observed Aedes population dynamics and infer area-specific climate-driven variation in mosquito life-history traits. We back-inferred historical mosquito abundance and projected mosquito abundance in future climate change scenarios incorporating experimental and locally inferred entomological parameters and then simulated the counterfactual implementation of IIT in these regions. We find that Aedes populations are projected to increase in most regions across all climate change scenarios from 2050-2100 even under high heat conditions in the absence of interventions. While we found that IIT can suppress wild-type populations effectively across all future scenarios and in high heat conditions, effectiveness was found to depend heavily on mosquito emigration rates, overflooding ratios, release intervals and release strategies Extensive robustness checks confirmed that the model reproduced historical temporal trends, captured the influence of individual parameters on outcome and was sensitive to changes in values of inferred parameters and implement policy. These findings demonstrate that IIT may be a robust vector control tool under future climate conditions.
Li, X.
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Thymosin {beta}4 (T{beta}4) is a conserved acidic polypeptide with 43-amino acids participating in multiple pathophysiological processes. In this study in vivo effects of T{beta}4 on liver regeneration are investigated in carbon-tetrachloride (CCL4) induced rodent animal liver jury models. Results illustrate that exogenous T{beta}4 treatment significantly reduced CCL4-rendered liver necrosis around central vein. At 48 hours after CCL4 insults hepatocytes proliferation occur mainly around the periportal area, while hepatocytes proliferation around the necrosis area is prominently increased by exogenous T{beta}4 treatment. The holistic proliferation level of liver tissues are also enhanced by exogenous T{beta}4. Hepatocyte proliferation activities negatively correlate with the necrosis extent of the liver tissue. These results suggested firstly exogenous T{beta}4 treatment could enhance liver regeneration and exhibit prosperous potential for application in clinical conditions such as liver transplantation.
Nimalrathna, S. U.; Harischandra, H.; Kimber, M.; Chandrasena, N.; De Silva, N.; Mallawarachchi, H.; De Silva, B. G. D. N. K.
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The World Health Organization (WHO) validated Sri Lanka had eliminated lymphatic filariasis as a public health problem in 2016, the second country in Southeast Asia to attain this status. However, post-validation surveillance has identified sporadic cases of brugian filariasis. The reemergence of Brugia malayi infections in Sri Lanka warrants urgent investigations. Recent studies have shown that the parasite responsible for the reemergence is a novel zoonotic Brugia sp. maintained among dogs that is closely related but distinct to the human-infecting B. malayi species. The current study employed morphological and morphometric assessments, revealing that this novel zoonotic Brugia sp. is within the B. malayi morphological range. Molecular characterization of three genomic regions, the nuclear genomic region SLXI, the non-coding region HhaI, and the mitochondrial genomic region COXI confirmed it as a genetic variant more closely related to B. malayi than to B. pahangi. Phylogenetic analysis further indicated it as a distinct genomic variant, closely related to a B. malayi-like parasite reported from India. Notably, that same parasite was identified in infected humans, animals, and potential vector mosquitoes. This, together with the detection of both human and animal blood within the same brugian infective mosquitoes, and delineating the canine origin of the parasites in human infections, provides compelling evidence supporting zoonotic transmission of this parasite. To our knowledge, this is the first report demonstrating the presence of the same brugian parasite in humans, domestic animals, and potentially infective mosquitoes in Sri Lanka, supported by multi-genomic evidence. The recent identification of multiple potential mosquito vector species suggests that this parasite may have undergone adaptive changes, facilitating its ability to overcome the species barrier. These findings substantiate the long-held hypothesis of zoonotic transmission of the reemerged brugian parasite, highlighting significant implications for ongoing surveillance and control strategies.
Shrestha, A.; Thapa, M.; Shrestha, S.; Tamrakar, S.; Ranjitkar, U.; Katuwal, N.; Shahi, S. B.; Naga, S. R.; Andrews, J. R.; Shrestha, R.; Aiemjoy, K.; Tamrakar, D.
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Background Dengue is intensifying globally due to climate change, urbanization, and land use changes. In Nepal, dengue has expanded from lowland regions to higher altitudes, with record outbreaks in 2022 and 2023. However, reliance on passive surveillance and hospital-based studies may underestimate community level infection burden. Methods We conducted a population-based serologic cohort study in Kathmandu and Kavrepalanchok districts, Nepal, enrolling a geographically representative, age stratified random sample of residents aged 0 to 25 years from pre-defined hospital catchment areas. Enrollment occurred in two phases: Phase I (February 2019 to April 2021) with follow-up visits at approximately 3, 6, and 12 months, and Phase II (February to June 2023) revisiting the original cohort. At each household visit, we collected capillary blood samples by finger-prick onto filter paper and tested the samples for IgG responses against dengue-derived recombinant antigen using InBios DENV DetectTM ELISA. Serostatus was classified using the manufacturer's recommended immune status ratio (ISR) cutoffs. We calculated seroprevalence at each time point and estimated seroincidence rates by identifying seroconversion events per 1,000 person-years. We assessed risk factors using multivariable regression models. Results Between 2019 and 2023, we enrolled 840 participants and collected 2,082 blood samples. The overall seroincidence rate was 33.8 per 1,000 person-years (95% CI [24.9 to 45.0]), with the highest rates in urban Kathmandu ([105.7], 95% CI [75.1 to 144.4]). Seroincidence increased with age and over time from 46.1 in 2019 to 51.0 in 2023. Participants living with a dengue-positive individual in the same household (adjusted RR [4.65], 95% CI [2.72 to 8.0]) and households with water-filled flower basins (adjusted RR [2.53], 95% CI [1.28 to 5.74]) had significantly higher risk of seroconversion. Conclusions This study reveals a significant and increasing burden of dengue infection in the Kathmandu Valley between 2019 and 2023. highlighting an urgent need for immediate public health interventions to mitigate dengue's rise in Nepal's higher-altitude regions.
Inziku, D. C.; Mukoda, G.; Ahumuza, A.; Patrick, A.; Kitimbo, M. B.; Kalyetsi, R.; Kalembe, S.
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Background: Human Tungiasis is a neglected tropical skin disease caused by the sand flea Tunga penetrans, associated with pain, inflammation, secondary bacterial infections, and significant morbidity. Despite its health impact on school children, it remained understudied in Kamushoko Parish, Bubaare Sub-County, Mbarara District, Uganda. Objectives: To determine the prevalence and identify associated factors of human Tungiasis among primary school children in Kamushoko Parish, Bubaare Sub-County, Mbarara District. Methods: A school-based cross-sectional descriptive study was conducted among 415 primary school children (P1-P7) at Katooma II and Komuyaga Primary Schools in March 2026. A census sampling approach enrolled all eligible pupils. Data were collected through structured face-to-face questionnaires and clinical examination of exposed areas. Tungiasis diagnosis was based on clinical identification of characteristic lesions with microscopic confirmation of extracted specimens. Bivariate and multivariate logistic regression analyses identified independently associated factors. Results: Of 415 children examined, 22 had active Tungiasis lesions, yielding an overall prevalence of 5.3% (95% CI: 3.53%-7.90%). Katooma II Primary School recorded a slightly higher prevalence (6.29%) than Komuyaga Primary School (4.78%), though the difference was not statistically significant (p = 0.499). Male children had higher odds of infection than females (7.1% vs. 3.7%). Children aged 9-10 years had the highest prevalence (7.7%). In the multivariate logistic regression, walking barefoot at school was the only independently significant predictor of infection (aOR = 0.18 for home vs. school; 95% CI: 0.04-0.78, p = 0.022). Conclusion: The prevalence of Tungiasis among primary school children in Kamushoko Parish was 5.3%, confirming ongoing transmission in the community. Walking barefoot at school was the only independent predictor of infection, highlighting the school environment as a critical intervention site. School-based strategies including grounds improvement, routine classroom cleaning, enforcing no-barefoot policies, and health education are recommended.
Shahheidari, R.; Moemenbellah-Fard, M. D.; Osanloo, M.; Paksa, A.; Roozitalab, A. H.; Fakhraei, M.; Zarenezhad, E.
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Background: The development of safe and effective plant-based repellents is crucial to control malaria transmission, particularly given the spread of insecticide resistance in major vectors like Anopheles stephensi. Essential oils (EOs) are promising candidates, yet their high volatility and hydrophobicity limit their efficacy. This study aimed to design and evaluate nanoliposomal gels containing Syzygium aromaticum (clove) or Melaleuca alternifolia (tea tree) EOs to enhance their repellent durability against An. stephensi. Methods: The chemical profiles of the EOs were determined via Gas Chromatography-Mass Spectrometry (GC-MS). Nanoliposomes bearing 3% of each EO were made ready with the ethanol injection method, and incorporated into a carboxymethyl cellulose (CMC) gel. Formulations were characterized for particle size, zeta potential, viscosity, and chemical interactions (FTIR). Repellent efficacy was evaluated using the arm-in-cage method, recording the complete protection time (CPT) for nanoliposomal gels (LipoGel 3%), in comparison with nonformulated EOs and the gold-standard repellent, DEET (40%). Results: GC-MS analysis identified eugenol (79.51%) and terpinen-4-ol (73.53%) as the major constituents of clove and tea tree EOs, respectively. Nanoliposomes exhibited sizes of 82.3 nm (clove) and 102 nm (tea tree), with narrow size distributions. The clove LipoGel demonstrated a significantly enhanced CPT (341 min), which was statistically comparable to 40% DEET (351 min, P>0.05). In contrast, the nonformulated EOs resulted in only 45 min of protection, highlighting the critical role of the nanocarrier system. Conclusion: The nanoliposomal gel formulation, particularly containing clove EO, represents a potent and safe botanical alternative to conventional synthetic repellents. This approach offers a promising strategy for integrated vector management, warranting further field-based investigations.
QIN, Y.; Gao, Q.; Liu, H.; Fan, H.; Wang, Q.; Zhang, W.; Li, C.; Chen, Q.; Cui, Z.
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Background Brucellosis is a severe zoonotic disease with pronounced seasonality and regional heterogeneity in high-incidence areas of China. Reliable forecasting tools are needed to inform prevention strategies, but the optimal modeling approach across different regions remains unclear. Principal Findings We collected monthly brucellosis incidence and 17 environmental variables from 2014 to 2024 across five high-incidence provinces: Inner Mongolia, Xinjiang, Shanxi, Heilongjiang, and Hebei. A three-step procedure--cross-correlation analysis, multicollinearity diagnostics, and stepwise regression--was used to select exogenous predictors. We then compared four time-series models: seasonal autoregressive integrated moving average (SARIMA), SARIMA with exogenous variables (SARIMAX), long short-term memory (LSTM), and LSTM with exogenous variables (LSTMX). All five provinces showed a unimodal seasonal pattern with peaks between April and July, though environmental drivers and optimal lag periods varied substantially by region, ranging from 1 to 6 months. In forecasting performance, LSTM achieved the highest accuracy in Shanxi (R2=0.925), Hebei (R2=0.876), and Xinjiang (R2=0.829), outperforming SARIMA and SARIMAX. LSTMX performed best in Inner Mongolia (R2=0.759) and Heilongjiang (R2=0.772) but showed weaker performance than LSTM in Shanxi and Hebei. Overall, adding exogenous variables did not consistently improve predictions across provinces. Conclusions Our findings demonstrate that LSTM-based models offer clear advantages for brucellosis forecasting in most high-incidence provinces, but the value of incorporating environmental predictors is region-dependent. These results support the development of tailored early warning systems and precision prevention strategies for brucellosis in high-risk areas of China.
Ndenga, B. A.; Agola, G. A.; Owuor, K. O.; Mbakaya, J. O.; Ronga, C. O.; Chepkorir, E.; Kibe, L. W.; Akala, H. M.
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Introduction Malaria is a global public health problem especially in sub Saharan Africa. In Kenya, it varies across ecological zones with limited evidence comparing vector ecology, climate, topography and risk of infection in western lowlands and central highlands. Objective To compare levels of malaria infection, vector densities, rainfall, temperature, relative humidity and topography in lowland Busia and highland Meru counties. Methods A cross sectional survey was conducted using larval dipping for aquatic habitats, pyrethrum spray catches for indoor resting mosquitoes, and malaria diagnosis using rapid diagnostic tests and microscopy. Rainfall, temperature, and relative humidity were recorded using automated data loggers. Topography was noted by ground truthing. Data were analysed using chi square tests, analysis of variance, and logistic regression. Results Early instar Anopheles larvae were significantly less likely to be detected in the highland site than in the lowland site (unadjusted Odds Ratio = 0.33; 95% CI: 0.11 - 0.97). Malaria prevalence by rapid diagnostic tests was 0% in the highland site and significantly higher in lowland sites (p < 0.001), with microscopy confirming the absence of infections in the highland area. Highland sites experienced significantly cooler temperatures, including more hours below 16 degrees Celsius (p = 0.006), whereas lowland sites recorded significantly higher minimum, mean, and maximum temperatures (p < 0.001). Rainfall did not differ significantly between the two ecological zones (p = 0.090), average minimum RH in the highland was significantly higher than in the lowland site (p < 0.001). Valleys in Baragu are mainly V-shaped while Maduwa and Budalangi are generally flat areas in the lower courses of rivers prone to flooding. Conclusion Cooler highland climates and topographic features likely limit vector presence, abundance, development and malaria transmission, while warmer lowland environments sustain residual transmission.
Marcolin, L.; Bella, A.; Del Manso, M.; Dorigatti, I.; Pezzotti, P.; Poletti, P.; Riccardo, F.; Di Marco, M.
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Abstract BACKGROUND West Nile virus (WNV) is a growing health burden in Italy. Anticipating human infection risk is hampered by the pathogen's complex ecology, highlighting the need for comprehensive early-warning tools. AIM We aimed to model municipal-level WNV risk in Italy and characterize its decadal expansion in Italy, providing a comprehensive ecological understanding of viral emergence. METHODS We applied a machine learning framework to annual human WNV case data from 2014 to 2024. The model integrated a suite of environmental, socio-economic, and macroecological predictors to generate risk projections. We evaluated the model's performance through multiple validation settings. We also performed an anticipation test for the 2025 epidemic season, using 2024 environmental data to assess the model's predictive accuracy against observed 2025 human cases. RESULTS Our model achieved robust performance (True Skill Statistic > 0.4) and captured WNV progressive expansion from 184 predicted positive municipalities in 2014 to 2,012 in 2024 (an 11-fold increase in 11 years). Seasonal minimum temperature was the primary risk driver, followed by monitoring year and population density, indicating active spatial spread. Environmental suitability consistently preceded clinical detection. Municipalities with cases in 2023-2024 exhibited significantly higher predicted suitability during 2018-2022 than those without cases (average risk 0.58 vs 0.20). Our model successfully identified emerging risk hotspots along the Adriatic coast and southern Italy before the official human spillover of 2025. CONCLUSION Embedding macroecological drivers into WNV risk modelling provides an improved understanding of drivers of rapid WNV expansion. Our model enables proactive risk mapping, surveillance efforts, and targeted public health measures.
Asa-Atiemo, C. K. M.; Agbo, D.; Acquah, F. K.; Obboh, E. K.; Poinsignon, A.; Tahar, R.; Amoah, L. E.
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Asymptomatic Plasmodium falciparum carriers are cryptic reservoirs that sustain malaria transmission, undermining control efforts. However, its temporal dynamics and drivers remain underexplored. A total of 845 asymptomatic individuals in Simiw were screened for P. falciparum carriage in May, August, and October 2021, as well as February 2022, representing the pre-peak, peak and post peak malaria transmission seasons that fall in either the wet or dry seasons. Meteorological data from March 2021 to March 2022 was obtained. Descriptive and inferential statistical analyses, such as Poisson Generalised Linear and Distributed Lag Nonlinear Models, were conducted in R to investigate the influence of seasonality and meteorological factors on PET-PCR-detected asymptomatic Plasmodium falciparum infections. In Simiw, the prevalence of asymptomatic P. falciparum infections ranged from 6.2% to 14.0% by RDT and 13.4% to 32.0% by PET-PCR during the study period. Asymptomatic malaria cases were highest in February 2022, during the dry season. Younger participants (median age: 14 years) had more infections than adults. Seasonal trend showed the strongest nonlinear relationship (exp({beta}) = 190.38, p = 0.01). Features of the dry season predicted asymptomatic malaria cases, as average maximum temperature (exp({beta}) = 1.30, p < 0.001) was a positive nonlinear predictor, whereas average humidity (exp({beta}) = 0.73, p = 0.02) and precipitation (exp({beta}) = 0.99, p < 0.001) were negative nonlinear predictors. According to regression models, the highest counts of asymptomatic malaria cases occur at a monthly maximum temperature of 32oC, monthly average relative humidity of 91% and monthly precipitation of 20 mm, similar to records in February 2022 in the dry season. Additionally, a precipitation of 150 mm forecasted the highest number of cases two months later (exp({beta}) = 3.20, p < 0.001). In this study, the seasonal trend had a much stronger effect on asymptomatic malaria than meteorological factors, such as rainfall.
Eya'ane Meva, F.; Gouli Lougui, L. P.; Nguemfo, E. L.; Fannang, S. v.; Ntoumba, A. A.; Bamal, H.-D.; Beglau, T. H. Y.; Tako Djimefo, A. K.; Mintang Fongang, U. A.; Sone Enone, B.; Tchangou Njiemou, A. F.; Evouna, D. I. M.; Yinyang, J.; Chimi Tchatchouang, G.; Fonye Nyuyfoni, G.; Janiak, C.
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Introduction: Thromboinflammation, which represents the pathological interplay between inflammation and thrombosis, is a leading cause of global mortality. Current therapies are frequently associated with an increased risk of bleeding and do not adequately address the inflammatory component of the disease. The African tree Guibourtia tessmannii represents a promising source of natural anti-inflammatory compounds. This study aimed to synthesize and characterize silver nanoparticles using an aqueous bark extract of G. tessmannii (GT-AgNPs) and to evaluate their anti-inflammatory and anticoagulant properties. Methods: GT-AgNPs were synthesized by reducing silver nitrate with an aqueous extract of G. tessmannii bark. The nanoparticles were comprehensively characterized using UV-Vis spectroscopy, FTIR spectroscopy, powder X-ray diffraction, and scanning electron microscopy. In vitro anti-inflammatory activity was evaluated through inhibition of bovine serum albumin denaturation, whereas in vivo anti-inflammatory activity was assessed using the carrageenan-induced rat paw edema model. Anticoagulant activity was investigated by measuring activated partial thromboplastin time (aPTT) and prothrombin time (PT), corresponding to the intrinsic and extrinsic coagulation pathways, respectively. Results: The synthesis successfully produced GT-AgNPs with an average particle size of approximately 20 nm. Both the aqueous extract and GT-AgNPs exhibited marked anti-inflammatory activity. The nanoparticles achieved 95% inhibition of protein denaturation in vitro and 95% inhibition of carrageenan-induced paw edema in vivo at a dose of 0.4 mg/kg body weight after 5 h. Furthermore, both the extract and GT-AgNPs demonstrated dose-dependent anticoagulant activity. Conclusion: The study demonstrated that GT-AgNPs, synthesized from the bark of G. tessmannii, possess significant anti-inflammatory and anticoagulant properties. These findings highlight the potential of GT-AgNPs as nanotherapeutic candidates for the management of thrombo-inflammatory disorders.
Oladimeji, D. M.; Mustapha, A. K.; Ekop, E. E.
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Abstract Background: Despite considerable reductions in under-five mortality during the Millennium Development Goal era, progress towards Sustainable Development Goal (SDG) 3.2 remains uneven across Africa. Identifying countries at greatest risk of missing the target is essential for prioritizing interventions and resource allocation. Methods: A Bayesian spatial forecasting ecological study was conducted using 2024 country-level data from 49 African countries obtained from UNICEF. Spatial dependence was assessed using Global Moran's I and Local Indicators of Spatial Association. Bayesian structured additive regression models with Gaussian, Gamma, and Exponential likelihoods were fitted using Integrated Nested Laplace Approximation (INLA) and compared using the Deviance Information Criterion (DIC), Watanabe-Akaike Information Criterion (WAIC), and conditional predictive ordinates. Posterior exceedance probabilities were estimated, an SDG Failure Index (SFI) and a Priority Intervention Index (PII) were developed, and Bayesian posterior predictive simulations were performed to estimate country-specific probabilities of attaining SDG 3.2 by 2030. Results: Significant spatial clustering of under-five mortality was observed with (Moran's I = 0.355, p < 0.001), and hotspots in Benin, Cameroon, and Nigeria. The Gamma model provided the best fit (DIC = 114.92; WAIC = 111.71). Diarrhoea was the only significant predictor (posterior mean=0.030; 95% credible interval: 0.004-0.056). Twenty-three countries (46.9%) were classified as high risk, whereas only five (10.2%) had achieved SDG 3.2. West Africa recorded the highest mean mortality (7.05%) and North Africa the lowest (1.64%). Bayesian projections indicated that only five countries were likely to achieve SDG 3.2 by 2030, while 41 (83.7%) were unlikely to do so. Conclusion: Considerable geographical inequalities in under-five mortality persist across Africa, and most countries remain off-track for achieving SDG 3.2 by 2030. The integration of exceedance probability mapping, the SDG Failure Index, the Priority Intervention Index, and Bayesian probability forecasting provides a practical framework for monitoring progress and prioritizing countries requiring accelerated action towards achieving SDG 3.2.