PLOS Neglected Tropical Diseases

Introduction Schistosomiasis is one of the most pervasive neglected tropical diseases in sub-Saharan Africa as an acute and chronic disease. It presents significant public health challenges in both Madagascar and Burkina Faso. Though schistosomiasis is a high prevalence disease, the understanding of its economic burden is limited. Methods A case control study was designed to compare the out-of-pocket costs and productivity loss associated with infection. A patient-specific survey questionnaire for Cost of Illness and Health-Related Quality of Life was developed and applied in Madagascar and Burkina Faso. Multiple interviews were conducted to capture the costs incurred during the entire period of illness. Results A total of 371 participants were enrolled in this study: 224 in Madagascar and 147 in Burkina Faso. The average economic burden for individuals confirmed to be negative for schistosomiasis was US$ 6.4 in Madagascar and US$ 29.8 in Burkina Faso. For mild cases, average costs were US$ 8.4 and US$ 13.5, respectively. Severe cases with complications due to schistosomiasis incurred substantially higher costs, averaging US$ 60.0 in Madagascar and US$ 1,272 in Burkina Faso. Median Health-Related Quality of Life was significantly lower among severe cases compared with controls and mild cases. Conclusions The cost of illness for schistosomiasis is significant in both countries. This study indicates the potential economic burden of disease in Madagascar and Burkina Faso, where the existing evidence on schistosomiasis is limited. Our study can help decision makers set health policy priorities.

Background: Cutaneous leishmaniasis (CL) remains a major neglected tropical disease in Afghanistan; however, recent nationwide evidence on its geographical and temporal distribution is limited. This study assessed the reported burden, spatial distribution and seasonal variation of cutaneous leishmaniasis across Afghanistan during 2024. Methods: A nationwide retrospective ecological study was conducted using aggregated routine surveillance data obtained from the National Malaria and Other Vector-Borne Diseases Program. All cases reported from government health facilities across Afghanistans 34 provinces between 1 January and 31 December 2024 were included. Reported incidence rates were calculated per 10,000 population using national and subnational population estimates. Cases were analyzed by surveillance classification, province, city, rural district, month, and season. Results: A total of 87,245 cases were reported during 2024, corresponding to an overall incidence of 25.1/10,000 population. Anthroponotic and zoonotic CL accounted for 80,202 (91.9%) and 7,043 (8.1%) cases, respectively. Jowzjan recorded the highest provincial incidence (105.0/10,000), while Kabul and Herat contributed the largest absolute numbers of cases. Shiberghan had the highest urban incidence, whereas Panjwai, Ghoryan and Hazrat-e-Sultan recorded exceptionally high rural rates. May had the highest monthly burden, while August had the lowest. Autumn accounted for the largest seasonal proportion (27.92%), whereas summer had the lowest burden (16.98%). Considerable incompleteness in district-level reporting was observed. Conclusion: CL constituted a substantial but highly concentrated public health burden in Afghanistan during 2024. Strengthened surveillance, improved diagnostic confirmation and geographically targeted case-management and vector-control interventions are particularly needed in identified high-burden provinces, cities and rural districts.

Background Tsetse are vectors of trypanosomes responsible for African animal trypanosomosis (AAT) and human African trypanosomiasis (HAT). While Cote dIvoire has successfully eliminated HAT as a public health problem and approaches elimination of transmission, AAT remains a major obstacle to agriculture and livestock production. Understanding the spatial distribution of tsetse is essential for prioritizing and sustaining disease control and elimination efforts. Methodology/Principal Findings Using 1,702 occurrence records from the national tsetse atlas we modeled the habitat suitability of the nine tsetse species present in Cote dIvoire. We identified suitable habitats in unsampled areas and quantified environmental constraints on tsetse distribution. Resampling the data to a 1km x 1km grid produced spatially explicit outputs at a resolution more relevant for operational planning. An ensemble modeling approach was employed integrating four algorithms--Random Forest, XGBoost, Maximum Entropy (MaxEnt), and Generalized Additive Models (GAM)-- with satellite-derived environmental and anthropogenic predictors--which achieved high predictive accuracy, area under the curve and True Skill Statistics 0.80 and 0.83, respectively. Distance to waterbodies, soil moisture, distance to protected areas, maximum land surface temperature, and sheep density were key drivers of habitat suitability. Importantly, the models identified suitable habitats in 11 administrative regions not covered by the atlas, providing an improved national tsetse risk profile. Conclusions/Significance These results provide a detailed assessment of the ecological suitability of tsetse across Cote dIvoire and their persistence in agroecological mosaics with high human and livestock densities. We offer a high-resolution blueprint for vector and disease control, particularly in areas where field data are currently lacking. We provide a robust framework for evidence-based decision-making within the Progressive Control Pathway (PCP) for AAT by enabling the identification of priority areas and resource allocation optimization to improve livestock productivity through more effective AAT control and reduce the risk of resurgence of HAT.

Background Scrub typhus, an acute bacterial infection caused by Orientia tsutsugamushi, is an important, under-recognized etiology of febrile illness in South Asia. Accurate surveillance for scrub typhus in Nepal is challenging due to non-specific symptoms and limited diagnostic tools. Methods We conducted a representative school-based cross-sectional serosurvey in Kavrepalanchok and Dolakha, Nepal between November 2021 and April 2022 using two-stage sampling, we randomly selected 13 public schools and then up to 100 children aged 4-18 years per school. We collected capillary blood samples and tested for IgG responses to Orientia tsutsugamushi-derived recombinant 56-kDa antigen using commercially available ELISA kits. We estimated seroincidence rates using previously-published models of antibody decay dynamics from confirmed scrub typhus cases. We compared seroincidence to seroprevalence estimates using cutoffs derived from Gaussian finite mixture models applied to the study population. Results We enrolled a total of 827 children (participation rate: 94.8%). The median age was 10 years (IQR: 8-13), and 53.08% of the participants were female. The overall seroincidence rate was 6.3 new infections per 1000 person-years (95% CI: 4.7- 8.4), and the rate was slightly higher in peri-urban Kavrepalanchok (7.3; 95% CI: 4.9 - 10.3) compared with rural Dolakha (5.3; 95% CI: 3.3 - 8.5). Seroincidence increased with age, from 3.6 new infections per 1000 person-years (95% CI: 1.4- 9.7) among children aged 4- 7 years to 9.4 (95% CI: 6.2-14.3) among children aged 14-18 years. Seroincidence was higher in females (8.3; 95% CI: 5.9 -11.8) than in males (4.1; 95% CI: 2.4 - 6.9) (p=0.02). The overall seroprevalence was 6.5% (95% CI: 4.9-8.4) and followed a similar age and geographic trend to the seroincidence rate. Discussion Our findings reveal a substantial burden of pediatric scrub typhus in the Kavrepalanchok and Dolakha districts of Nepal. Seroincidence increased with age and was higher among females. School-based serosurveys offer an efficient sampling frame to rapidly assess population-level scrub typhus transmission intensity among children and adolescents, though may not represent out-of-school populations.

Background: Case fatality reflects the quality and timeliness of clinical care for leptospirosis, yet no study has examined it at a national level in the Dominican Republic (DR), where leptospirosis is endemic. We describe the case fatality rate (CFR) of leptospirosis in the DR between 2012 and 2026 and identify associations with mortality. Methods: We conducted an analytical cross-sectional study, using national surveillance records merged with a discharge-condition extract via a composite key. We calculated CFR with Wilson 95% confidence intervals among 5,412 valid cases (suspected, probable, or confirmed) reported from January 2012 through June 2026. We compared proportions with Pearson's chi-square test, assessed annual trend with ordinary least squares linear regression, and fitted multivariable logistic regression models to account for confounding. Results: Overall CFR was 8.5% (460/5,412), with no significant annual trend (p=0.372). CFR was higher in men than women (p < 0.001) and increased significantly with age (p < 0.001). Male gender (OR: 1.79; 95%CI: 1.18-2.73) and pre-existing comorbidity (OR: 1.76; 95% CI: 1.21- 2.57) were independent predictors of death. Clinical complications were the strongest predictor in the adjusted model (OR: 3.16; 95%CI: 2.17-4.61), attenuating the gender effect. CFR varied widely by province (2.43-22.22%) and correlated negatively with incidence at the province level (p = 0.066). Conclusions: Leptospirosis case fatality is concentrated among men, people with comorbidity, and those who develop clinical complications. These national, long-term findings can help prioritize clinical and surveillance resources as extreme weather events are expected to intensify across the Caribbean.

IntroductionDengue, one of the most important arboviral infections worldwide, is transmitted primarily by the mosquito Aedes aegypti, a vector closely associated with human habitations. Because vector control is the primary prevention strategy for this disease novel tools are urgently needed. We evaluated an Attractive Lethal OviTrap (ALOT) that targets epidemiologically relevant gravid female mosquitoes for public health impact against dengue disease. MethodsWe conducted a proof-of-concept field efficacy trial in the Amazonian city of Iquitos, Peru, to quantify the reduction of vector density, parity, and sex ratio and symptomatic human dengue infection over a 3.5 year follow-up period. After three baseline entomological surveys in core (753 houses), and buffer (1,549 houses) areas where traps were placed in and around homes, and a control (1,233 houses) area without traps, entomological surveys were carried out every 2 months, and household residents were monitored for dengue disease 3 times a week. Trap maintenance was conducted at 2-3 week intervals by study staff during the first 2.5 years and by residents in the final year. ResultsTotal and female Ae. aegypti abundance demonstrated a strong initial effect with 52% and 47% fewer mosquitoes after trap placement, respectively (Total: RR = 0.48, 95% CI: 0.40 - 0.58, p < 0.001; Females: RR = 0.53, 95% CI: 0.43 - 0.66, p < 0.001). The effect diminished significantly, however, over the study period (interaction coefficient = 0.035 per month, p < 0.001; interaction coefficient = 0.030 per month, p < 0.001). Female-to-male ratio decreased after trap deployment and impact on non-Aedes abundance was like that of Aedes. Cumulative symptomatic dengue incidence was 1.40% (95% CI: 1.00%-1.70%) in the ALOT area versus 3.20% (95% CI: 2.60%-3.80%) in the control area, a 56% relative reduction (log-rank {chi}{superscript 2}=30.0, p<0.001). Restricted mean survival time analysis showed participants in the intervention area on average remained dengue-free for 15.5 additional days (95% CI: 11.1-20.0, p<0.001). ConclusionsThe ALOT strategy functioned as predicted, decreasing but not eliminating female vector densities, with a clear public health impact, lowering dengue disease in areas where traps were deployed. Our study also illustrates the challenges associated with conducting large-scale vector control trials and the need to consider programmatic implementation early in the process of bringing a new product to market. Author SummaryDengue is one of the most important mosquito transmitted infections worldwide. Aedes aegypti, the most important species involved, has a unique biology living in containers associated with households. New methods to control this mosquito are needed and we present our evaluation of a novel trap called the Attractive Lethal OviTrap (ALOT) that targets older female mosquitoes that are the most important for dengue disease transmission. We conducted a trial in the Amazonian city of Iquitos, Peru, to measure reductions in mosquito numbers, age, and sex ratio and symptomatic human dengue infections over a 3.5 years. After baseline entomological surveys prior to placing ALOT traps in homes in a treatment area, which included a central core area with 753 houses and a protective buffer area with 1,549 houses areas. We also had a control area without any traps in 1,233 houses. Mosquito surveys were carried out every 2 months, and household residents were monitored for dengue disease 3 times per week. Trap maintenance was conducted at 2 - 3 week intervals by study staff during the first 2.5 years and by residents in the final year. The number of all Ae. aegypti were initially reduced by 52% after trap placement whereas females were reduced by 47%. The effect diminished significantly, however, over the study period. Female-to-male ratio decreased after trap deployment and impact on other mosquito species was like that of Aedes. Dengue incidence was 56% less in the area with traps compared to the control area, estimating that participants in the intervention area on average remained dengue-free for 15.5 additional days. The ALOT strategy functioned as predicted, decreasing but not eliminating female mosquitos and had a clear public health impact, lowering dengue disease in areas where traps were deployed. Our study also illustrates the challenges associated with conducting large-scale vector control trials and the need to consider programmatic implementation early in the process of bringing a new product to market.

Abstract Background: Urogenital schistosomiasis remains a major neglected tropical disease in rural communities, particularly in reservoir-adjacent settings where sustained human-water contact facilitates persistent transmission. Despite ongoing control efforts, communities located around reservoirs may experience persistent transmission partly due to socioeconomic water exposure and presence of infected intermediate host snails in aquatic habitats. This study assessed the prevalence, intensity, and epidemiological correlates of Schistosoma haematobium infection in reservoir-adjacent communities in Kano State, Nigeria to better understand local transmission. Methods: A community-based cross-sectional study was conducted among 447 consenting participants from six communities located around three water reservoirs in Kano State. Sociodemographic characteristics, water-contact behaviour, sanitation practices, treatment-seeking behaviour, and knowledge related to urogenital schistosomiasis were obtained using interviewer-administered questionnaires. Urine samples collected between 10:00 and 14:00 were examined using microscopy following centrifugation/sedimentation. Schistosoma haematobium isolates were characterised by molecular methods, using PCR and Sanger dideoxy sequencing. Bulinus snails were collected from the reservoirs by handpicking and scooping methods. Nucleotide sequences were analysed using NCBI BLAST to confirm species identity. Epidemiological data on Schistosoma haematobium infection were analysed using chi-square tests and univariate and multivariate logistic regression analyses to assess associations with explanatory variables. Results: The overall prevalence of S. haematobium infection was 34.23% (153/447), indicating moderate endemicity. Molecular study confirmed the occurrence of pure S. haematobium. Community-specific prevalence ranged from 32.35% to 37.84%. Heavy-intensity infection (>50 eggs/10 mL urine) occurred in 17.65% of infected participants. Infection was most common among children and adolescents and was higher in males than females, although the sex difference was not statistically significant. Water-contact behaviour was the strongest correlate of infection: participants reporting water contact had a markedly higher prevalence than those without such exposure (39.12% vs 3.28%; OR = 18.96, 95% CI: 4.56-78.73). Fetching water (aOR = 2.57; 95% CI = 1.53 -4.34; p < 0.001) and Swimming (aOR = 2.37; 95% CI = 1.42 -3.94; p = 0.001) were the specific activities most strongly associated with higher odds of S. haematobium infection. Age (aOR = 0.91; 95% CI = 0.87 - 0.95; p < 0.001) significantly reduced the odds of infection. In terms of gender, female participants had significantly lower odds of infection compared with males (aOR = 0.52; 0.29 0.92; p = 0.03). Knowledge of transmission was poor, with only a small proportion of participants correctly identifying contact with contaminated water as the cause of infection. A rare ectopic detection of S. mansoni eggs in urine was also observed. Presence of S. haematobium-infected Bulinus intermediate hosts in the water reservoirs was reported. Conclusions: Urogenital schistosomiasis remains actively transmitted in reservoir-adjacent communities in Kano State, with infection strongly associated with frequent human-water contact and poor disease knowledge. These findings support the need for integrated control strategies combining praziquantel-based preventive chemotherapy, targeted health education, improved water and sanitation, and behaviour-focused interventions to reduce reinfection and interrupt transmission. Keywords: Urogenital schistosomiasis, Schistosoma haematobium, water reservoirs, prevalence, risk factors

BackgroundMalaria caused by Plasmodium knowlesi and lymphatic filariasis caused by Brugia malayi are mosquito-borne infections with non-human primates as reservoirs. P. knowlesi has emerged as a significant cause of human malaria in Southeast Asia over the past two decades. Belitung district, Indonesia, was until recently assumed to have eliminated B. malayi until infections were detected in humans and long-tailed macaques. To investigate whether the local reservoir of B. malayi is also a reservoir for malaria we screened macaques from 4 areas in Belitung for malaria parasites. Methods and findingsBlood samples from 163 long-tailed macaques (Macaca fascicularis) that had been tested for B. malayi were examined by quantitative PCR assays specific for Plasmodium spp., P. knowlesi, P. inui, P. coatneyi and P. cynomolgi. A total of 130 macaques (79.8%) tested positive in the pan-Plasmodium qPCR assay. Plasmodium inui was most prevalent (41.7%), followed by P. knowlesi (38.7%), P. coatneyi (24.5%) and P. cynomolgi (13.5%). Multiple species infections, with 2-3 Plasmodium species were detected in 37% of macaques. Notably, 20 (91%) of 22 B. malayi-positive macaques were co-infected with at least one Plasmodium species. We sequenced the complete mitochondrion from 9 samples diagnosed by qPCR as mono-infections. Phylogenetic analysis confirmed 7 as P. knowlesi, and the other two as P. inui and P. coatneyi. Phylogenetic and pairwise analysis revealed that P. knowlesi isolates from Belitung were closely related to each other and to P. knowlesi from humans and monkeys from Thailand, Malaysia and Indonesia. ConclusionsMolecular evidence shows high prevalence of zoonotic malaria parasites in macaques from Belitung, emphasizing the risk of human transmission. Increased surveillance, improved diagnostics, and targeted interventions are needed to prevent zoonotic spillover of P. knowlesi as it has been observed for B. malayi in Belitung. Author summaryWe examined macaques for Plasmodium parasites in Belitung Island, Indonesia, a region classified as free of locally transmitted human malaria. Plasmodium knowlesi is a monkey parasite that commonly infects humans and has emerged as a concern in Southwest Asia over the last 20 years. In Belitung, macaques are infected with Brugia malayi, a filarial nematode, that causes lymphatic filariasis in humans. Blood samples from 163 macaques were screened for Plasmodium DNA and 80% carried malaria parasites. Plasmodium inui was most common, followed by P. knowlesi, P. coatneyi, and P. cynomolgi. Many macaques were infected with multiple parasites simultaneously, but no host was infected with all four Plasmodium species. Ninety one percent of B. malayi-positive macaques were co-infected with malaria parasites, including P. knowlesi, indicating multi-parasite infections that could potentially spread to humans. Analysis of the mitochondrial genome of 7 P. knowlesi isolates from Belitung showed that they were most similar to each other and both human and monkey samples from Malaysia, Thailand and Indonesia. The study highlights the need for enhanced malaria monitoring and prevention, given the complex epidemiology of co-infecting parasites and risk to humans and animals.

Identifying reliable indicators of dengue vector habitat is critical for proactive surveillance and spatially targeted vector control. Bird communities are sensitive to habitat quality and landscape condition, and their functional diversity may track ecological conditions that support Aedes mosquito populations. We tested whether bird functional diversity predicts dengue vector presence across two working landscapes in Costa Rica, comparing bird-based predictors against landscape composition, vegetation structure, and plant diversity. Bird functional dispersion (FDis), the spread of species in multidimensional trait space, was the top-ranked predictor for Ae. aegypti and Ae. albopictus larval presence and for adult Ae. aegypti, outperforming all other predictor classes. Probability of presence declined with increasing FDis, where functionally homogeneous bird communities, characteristic of disturbed landscapes, co-occur with higher vector presence, consistent with shared habitat filtering. Functional diversity estimations may offer a practical signal for identifying habitats at elevated dengue vector risk.

Traditional surveillance underestimates Lyme disease (LD) incidence in the United States (US). We aimed to estimate national LD incidence using validated algorithms to identify LD cases in administrative claims data. We identified potential LD cases in commercial and Medicare claims, classified cases by disease stage, adjusted case counts using algorithm-specific positive predictive values, and standardized the adjusted counts to the US population. The study population included >66 million individuals per year. After adjustment and standardization, we estimated 191.7, 26.8, and 16.6 new cases per 100,000 population in high-incidence, neighboring, and low-incidence states, respectively, with 24% of cases diagnosed with disseminated disease. The relative burden of disseminated LD was highest in low-incidence states (28.6%) and increased with age. This study corroborates published estimates of national LD incidence and elucidates patterns of disease stage at diagnosis. The substantial burden of disseminated LD underscores the need for earlier detection and treatment of LD.

While a causal link between urogenital schistosomiasis (Schistosoma haematobium) and anaemia is well established, quantitative associations between infection intensity and haemoglobin levels across endemic communities, at fine spatial scales, remain insufficiently characterized. As part of the broader Hybridisation in Urogenital Schistosomiasis (HUGS) investigation, we studied the micro-epidemiology of anaemia within two study communities in southern Malawi where S. haematobium remains endemic. Urine samples were examined by microscopy to quantify S. haematobium infection intensity, categorised as low (0-9 eggs/10 mL), moderate (10-49 eggs/10 mL), and heavy ([&ge;]50 eggs/10 mL). Individual haemoglobin concentrations were measured using a HemoCue photometer in 1,149 participants from Samama village (Mangochi District) and 977 participants from Mthawira village (Nsanje District). Linear geostatistical models incorporating individual-level characteristics and spatial covariates were used to estimate anaemia prevalence at fine geographical scales. Moderate anaemia (Hb 80-109 g/L) was most prevalent among children aged 6-12 years (45.30% in Samama and 39.54% in Mthawira), while severe anaemia was more frequent among adults aged [&ge;]19 years in both villages. Increasing S. haematobium infection intensity was associated with lower haemoglobin levels, with individuals harbouring heavy infections being at greater risk of moderate-to-severe anaemia. Spatial modelling revealed longer-range spatial correlation in Nsanje ({phi} = 66.7 km) than in Mangochi ({phi} = 25.5 km), indicating more spatially persistent risk in Nsanje and more localised heterogeneity in Mangochi. Predicted anaemia prevalence among female children aged 6-12 years with moderate infection intensity ranged from 25-65% in Mangochi and 64-76% in Nsanje. At the micro-epidemiological level, S. haematobium infection intensity was associated with the severity of anaemia, with substantial spatial heterogeneity within and between villages. Identification of high-risk clusters supports targeted interventions, including stepped-up preventive chemotherapy, improved water and sanitation, and iron supplementation.

Background Madagascar has one of the highest burdens of schistosomiasis globally, yet epidemiological evidence from the South-east of the country remains limited. Existing surveillance estimates suggest relatively low prevalence in this region. This contrasts with the region's environmental suitability for transmission and its population's high occupational risk through rice farming. Methods A cross-sectional exploratory study was conducted across 13 villages around the Manombo Special Reserve, Farafangana District, between May and July 2025. Participants were surveyed for geographic, environmental and behavioural risk factors for schistosomiasis infection. Infection was diagnosed by Kato-Katz stool microscopy. Multivariable mixed-effects logistic and linear regression, with village as a random intercept, estimated associations with infection and intensity respectively, adjusting for the water catchment area of household water sources, sex, age group, recent praziquantel treatment and village-level open defecation rate. Results 227 participants were included. Overall S. mansoni prevalence was 53.3% (95% CI 46.8-59.8%); median infection intensity was 96 (IQR 48-288) eggs per gram of stool among those infected. Surface water contact was near-universal (97.3%). Prevalence varied markedly between neighbouring villages. No demographic, behavioural, or WASH variable was independently associated with infection. The water catchment area of household water sources was the primary predictor of infection. Conclusions Prevalence substantially exceeded current surveillance estimates, suggesting this population is underserved by existing control programmes. Water catchment area was the dominant determinant of transmission heterogeneity, possibly consistent with Biomphalaria habitat suitability. Water catchment area may represent a valuable and underutilised unit for targeting schistosomiasis surveillance and control in Madagascar.

Background: Snakebite envenoming remains a major but neglected public health problem in sub-Saharan Africa, where access to antivenom is often limited and unevenly distributed. In Zambia, evidence on facility-level determinants of antivenom use is scarce. This study examined factors associated with antivenom administration among snakebite patients in selected health facilities. Methods: A retrospective cross-sectional study was conducted among 128 snakebite patients presenting to five health facilities in Zambia. Associations between antivenom administration and health facility, admission year, age group, and gender were assessed using Fisher's exact test, with statistical significance set at p < 0.05. Results: Overall, 16/128 patients (12.5%) received antivenom. Antivenom administration varied significantly by health facility (p < 0.0001). All patients at Kabwe General Hospital received antivenom (9/9, 100%), compared to 50% (2/4) at Commando Urban Health Centre and 22.7% (5/22) at Chipata Central Hospital. No patients received antivenom at Mpongwe Mission Hospital (0/70) or St. Dominic's Mission Hospital (0/23), where antivenom was not available. Admission year (2023 vs 2024; p = 0.78), age group (p = 0.53), and gender (p = 0.80) were not significantly associated with antivenom use. Conclusion: Antivenom administration in this setting is determined primarily by health facility-level availability rather than patient demographic or temporal factors. The very low overall treatment rate highlights critical inequities in access to life-saving therapy. Strengthening antivenom procurement, equitable distribution, and referral systems is urgently needed to reduce preventable morbidity and mortality from snakebite envenoming.

Background On the Zanzibar islands, Tanzania, mass drug administration (MDA) with praziquantel against Schistosoma haematobium infections has been implemented regularly since the early 2000s. Elimination of schistosomiasis as a public health problem has been achieved in most areas, with the goal of interruption of transmission. The RESIST project investigates the extent to which MDA-driven selection for praziquantel resistance is occurring and contributing to persistent transmission hotspots. Methodology As part of RESIST, the efficacy of praziquantel treatment was assessed in two schools on Pemba between October 2024 and March 2025. Longitudinal parasitological surveys were conducted before and two weeks after school-based MDA with praziquantel (40 mg/kg). Up to six urine samples per study participant were collected on different days pre- and post-MDA and examined for S. haematobium eggs by urine filtration microscopy. In a per-protocol analysis, drug efficacy was categorised as adequate, inconclusive, or reduced, based on hypothesis testing. A generalized linear mixed model was used to assess the association between pre-MDA infection intensity and drug efficacy at the individual level. Principal findings Pre-MDA, S. haematobium prevalence was 14.3% (62/434) in School 1 and 37.8% (233/617) in School 2. Post-MDA prevalence was 0.5% (2/434) and 9.6% (59/617), respectively. Egg reduction rates were 99.8% (90% confidence interval (CI): 99.2-100%) in School 1 and 94.8% (90% CI: 88.6-98.6%) in School 2, which were classified as adequate and inconclusive, respectively. In School 2, drug efficacy at the individual level was negatively associated with pre-MDA infection intensity. Conclusion/significance The efficacy of praziquantel on Pemba remains higher than the 90% threshold for optimal drug efficacy set by the World Health Organization. While the inconclusive efficacy results for School 2 can at least partially be explained by the variation in the participants pre-MDA infection intensities, further investigations are warranted to account for the disparity in praziquantel efficacy on Pemba. Trial registration: ISRCTN, ISRCTN59331501. Registered 24 October 2024, https://www.isrctn.com/ISRCTN59331501.

Rabies remains a major zoonotic public health threat, associated with approximately 59,000 annual deaths globally, with Africa bearing 36% of this burden. In Uganda, an estimated 36 human deaths and 1.8 million dog bite exposures occur annually, yet national dog vaccination coverage remains critically low at approximately 10%. This study investigated factors associated with rabies vaccination uptake among dog owners in Butaleja Town Council, Eastern Uganda, a high-risk setting. A cross-sectional survey was conducted among 173 dog owners between May 18 and June 28, 2024, using semi-structured questionnaires. The primary outcome was vaccination uptake ([&ge;]1 dose in the past year). Modified Poisson regression with robust variance estimated adjusted prevalence ratios for all socio-demographic, veterinary system, health system, dog-related, and knowledge factors. Among 173 dog owners, 57.2% vaccinated at least one dog, corresponding to 54.6% (166/304) of all dogs vaccinated. Factors associated with vaccination uptake included older age (21-40 years: aPR 1.43, 95% CI: 1.15-1.71; 41-60 years: aPR 1.53, 95% CI: 1.22-1.82; [&ge;]61 years: aPR 1.56, 95% CI: 1.33-2.23), higher education (primary: aPR 1.20, 95% CI: 1.00-1.45; secondary: aPR 1.55, 95% CI: 1.20-2.00), higher income, access to veterinary clinics (aPR 2.50, 95% CI: 1.52-3.75), and participation in community education sessions (aPR 1.71, 95% CI: 1.34-2.15). While household-level uptake showed moderate engagement, the resulting dog population vaccination coverage of 48.4% remained substantially below the 70% World Health Organization threshold required for herd immunity. Achieving the "Zero by 30" elimination dog-bite mediated Rabies target in this setting requires targeted interventions addressing the identified associated factors including; enhanced community education, improved veterinary service accessibility, reminder systems, and strategies to convert partial household vaccination into complete coverage particularly among younger, less educated, and lower-income dog owners.

Ivermectin is an important broad-spectrum anthelmintic used to treat nematode parasites including gastro-intestinal infections of humans and animals. The mode of action for Ivermectin is understood to involve activation of inhibitory glutamate-gated chloride channels (GluCls). Ivermectin has also been reported to inhibit the release of extracellular vesicles (EVs). We found that EVs are released from the whole intestine of the gastro-intestinal parasite, Ascaris suum. Proteomic analysis identified 1,574 proteins within these intestinal EVs, including 96 nematode proteins with putative immune-associated functions based on homology to proteins involved in host immune processes and 130 proteins with predicted digestive functions. Comparative analysis following ivermectin exposure revealed 38 differentially abundant proteins that included the putative immune-related proteins: transthyretin-like proteins, a small heat-shock antigen, a phospholipase A2, and the NF-{kappa}B subunit p105. Thus, ivermectin modulated the potential immune-related cargo of intestinal EVs. The ivermectin inhibition of intestinal EV release was concentration-dependent with an IC50 of 64 nM. We also identified the expression of GluCl subunit receptor genes in the Ascaris intestine. The potent inhibitory effect of ivermectin on the release of these EVs from the nematode intestine and the expression of GluCl channel subunits sheds further light on the site and mechanisms of action of this important anthelmintic.

Hemochromatosis and hemosiderosis are iron overload disorders that cause immune dysfunction and increase susceptibility to bacterial infections. There have been numerous case studies reporting septic-like outcomes for hemochromatosis patients infected with enteric Yersiniae; however, research regarding hemosiderosis and Yersinia infection is limited. Here, we have established a mouse model of hemosiderosis by feeding C57BL/6 mice a high-iron diet. These mice exhibit several indicators of iron overload that are seen clinically, including elevated serum iron levels and iron deposition in various tissues. Characterization of the iron overload mouse model shows that a high-iron diet induces local inflammation in the small intestine and systemic inflammation in a time-dependent manner. Oral infection with Yersinia enterocolitica causes complete mortality in the iron-overloaded mice, while wild-type mice all survive and effectively clear the infection. Lastly, we have observed that iron chelation therapies such as Deferoxamine and Deferisarox are detrimental to iron-overloaded mice during Yersinia infection. This work provides a model to further study iron overload disorders and Yersinia infection.

The Culex pipiens complex comprises globally distributed mosquito species that serve as vectors for various arboviruses and filariasis. Female mosquitoes within the Cx. pipiens complex are morphologically very similar, making species identification based on morphologically characteristics challenging. To date, Cx. pallens and Cx. pipiens f. molestus have been reported to inhabit the Republic of Korea (ROK). Conversely, Cx. quinquefasciatus, predominantly distributed in tropical regions, has not been documented in the country since a single record in the 1950s. Recently, however, Cx. quinquefasciatus was reported from the Jeju region of the ROK based on molecular identification. This study aimed to re-evaluate the occurrence of Cx. quinquefasciatus in the ROK by conducting molecular identification using the ace-2 and CQ11 markers on Cx. pipiens complex specimens collected nationwide, including from Jeju, where Cx. quinquefasciatus had previously been reported. Our analysis identified only Cx. quinquefasciatus-Cx. pallens hybrid individuals among the Cx. pipiens complex specimens from the Jeju region, highlighting the need to re-evaluate the analytical methods used in previous studies that reported the presence of pure Cx. quinquefasciatus. These findings provide essential evidence for future surveillance of the distribution, introduction, and establishment of Cx. quinquefasciatus and underscore the need for continuous monitoring.

Background Visceral leishmaniasis (VL), caused by Leishmania donovani (LD), is increasingly associated with the insect-restricted trypanosomatid Leptomonas seymouri (LS), which harbours the RNA virus Leptomonas seymouri narna-like virus 1 (Lepsey NLV1). Our recent study demonstrated that LS co-infection with LD enhances survival of murine (RAW 264.7) and mammalian (THP-1) macrophages and augments LD and LS persistence compared to LD or LS mono-infection in vitro. However, the in vivo fate of LS and its viral endosymbiont during chronic VL remains poorly understood. This study investigated the long-term dynamics of parasite persistence, tissue dissemination and viral maintenance during experimental mono- and co-infection. Methods and Findings BALB/c mice were infected with LD, Lepsey NLV1-positive LS, virus-positive AG83 isolate, or LD: LS co-infections (2:1, 5:1 and 10:1) and monitored for up to seven months. Parasite burden, species composition and viral load were quantified using ITS1 qPCR, densitometry, nested RT-PCR and qRT-PCR, supported by microscopy and immunofluorescence assay. LS established productive visceral infection independently, with parasite burdens exceeding the infecting inoculum, indicating active in vivo replication. Co-infection, particularly at a 10:1 LD: LS ratio, promoted the greatest long-term parasite persistence in visceral organs. Temporal analysis revealed early predominance of LS followed by progressive recovery of LD during chronic infection. Lepsey NLV1 was detected in visceral organs and blood for at least up to five months. Morphological analyses demonstrated intracellular LS amastigote-like forms in murine macrophages and transformation of splenic parasites into promastigotes, confirming parasite viability within mammalian tissues. Conclusions These findings demonstrate sustained visceral persistence of Lepsey NLV1-positive LS in mice and identify dynamic host-parasite-virus interactions that reshape infection during chronic co-infection. This work challenges the conventional view of VL as a strictly mono-parasitic disease and highlights a previously underappreciated tripartite interaction with potential implications of LS and its virus endosymbiont for VL pathogenesis.

Parasitic infections pose multifaceted threats to farmed fish, extending beyond direct pathogenicity to facilitate infections of bacteria, viruses, and microparasites. This synergistic interaction often leads to co-infections that significantly exacerbate disease outbreaks and mortality, presenting a severe challenge to aquaculture sustainability. Recently, a novel trypanosomiasis caused by the Trypanosoma carassii spectrum has emerged in cage-cultured Larimichthys crocea along the southeast coast of China, resulting in widespread prevalence and high mortality rates. Although this pathogen is hypothesized to originate from freshwater fish, its transmission route in marine environments has remained elusive. In this study, we investigated potential vectors and intermediate hosts of T. carassii spectrum, including leeches and monogenean in natural marine settings, and simulated transmission pathways using an established laboratory model involving T. carassii spectrum, Micropterus salmoides and the leech Poecilobdella manillensis. First, our field surveys in the coast of Ningde, Fujian Province, revealed a nearly 100% co-infection rate of T. carassii spectrum and the monogenean Neobenedenia girellae in diseased juvenile L. crocea. PCR analysis detected T. carassii spectrum traces in some N. girellae specimens, and subsequent experiments confirmed that N. girellae ingests the trypanosome while feeding on host blood. Furthermore, bacterial co-pathogens, such as Vibrio harveyi, were also detected within N. girellae. We also document two fatal leech infestations: Zeylanicobdella arugamensis in hybrid groupers (Epinephelus moara [female] X Epinephelus lanceolatus [male]) in Zhangpu, and Limnotrachelobdella okae in E. lanceolatus and E. fuscoguttatus in Raoping. These leeches tested negative for trypanosomes but carried pathogenic bacteria that co-infected the host fish; nonetheless, they are established vectors for trypanosome transmission. In a laboratory cohabitation model simulating T. carassii spectrum transmission, infected M. salmoides were housed with healthy conspecifics under three conditions: Group A (with the leech P. manillensis), Group B (no leeches), and Group C (no leeches, with physical separation between infected and healthy fish). After 14 days, blood smear microscopy and PCR analysis revealed infection rates in healthy fish of 58.33% in Group A, 40.00% in Group B, and 0% in Group C. Conclusively, T. carassii spectrum can be transmitted via leeches (with higher efficiency) and may also spread through direct contact under high-density aquaculture conditions, whereas N. girellae may act as an incidental vector, further research is warranted to clarify transmission dynamics in natural marine ecosystems. Additionally, our findings highlight the role of ectoparasites, including N. girellae and leeches, as potential reservoirs and vectors for bacterial pathogens of fish. In high-density intensive aquaculture, this vectorial capacity transforms parasites from primary pathogens into key drivers of polymicrobial disease outbreaks.