Epidemiology and Infection

Seroprevalence surveys reveal the extent of humoral immunity against pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and under some circumstances represent cumulative incidence of prior infection. However, antibody waning - or seroreversion - biases these estimates by reducing assay sensitivity in a time-varying manner. Because assay sensitivity decays over time, naively using serosurveys can substantially bias estimates of SARS-CoV-2 cumulative incidence and fatality rates. The Bayesian assay-specific, time-varying sensitivity adjustment developed in this paper can reliably correct for this bias and account for the delay between infection and serosurvey. In seroprevalence studies conducted in the United States in 2020, adjusting for time-varying sensitivity increased cumulative incidence by up to 1.4-fold, with an adjustment of 1.08 for a national study. Our estimates contrast with a previously published 2-fold adjustment that did not account for assay design. This suggests that previous analyses overestimated cumulative incidence by applying seroreversion corrections that did not account for assay-specific effects, or underestimated cumulative incidence by not applying seroreversion corrections. These biases imply fatality rate underestimation and overestimation, respectively. Our model provides a framework for design-specific time-varying sensitivity corrections in seroprevalence surveys for other pathogens.

Background. The 2026 Bundibugyo virus disease (BVD) epidemic in the Democratic Republic of the Congo (DRC) was declared on 15 May 2026 and determined a public health emergency of international concern on 17 May 2026. Public surveillance reporting consists of cumulative counts by report date; no line list with symptom-onset dates is available. Widely circulated characterisations - that this is the fastest-growing Ebola outbreak on record, that reported cases are doubling every 22 days, and that the case fatality ratio (CFR) is 37.5% - rest on these aggregates. We examined what the published data actually support. Methods. We assembled twelve published anchor points from 15 May to 13 July 2026 from WHO, WHO AFRO, NICD and the DRC National Institute of Public Health; one was recovered by back-calculation and checked against the directly reported subsequent total. We computed mean daily incidence between anchors and the within-interval death-to-case ratio. We reconstructed symptom-onset dates by Richardson-Lucy deconvolution with right-truncation correction under assumed onset-to-report delays with means of 5, 7 and 9 days, estimated the instantaneous reproduction number using the Cori method, and computed three CFR estimators: crude, resolved-case and outcome-delay-adjusted. Provincial CFRs used exact binomial intervals. Results. Confirmed cases plateaued at 40-52 per day for eighteen days, from 25 June to 13 July. Over the same period, the within-interval death-to-case ratio rose from 0.28 to 0.58. Reconstructed Rt was 1.28, with a 95% credible interval of 1.15-1.41, on 7 July, having fallen from approximately 2.9 in mid-May. Growth on the reconstructed onset curve corresponded to a doubling time of approximately 90 days, compared with 22 days computed from cumulative counts. CFR estimates were 37.5% for the crude estimator, 50.2% for the outcome-delay-adjusted estimator and 67.3% for the resolved-case estimator. Crude provincial CFR was 34.9% with a 95% confidence interval of 32.7-37.1 in Ituri, 58.2% with a 95% confidence interval of 50.7-65.5 in North Kivu, and 81.0% with a 95% confidence interval of 58.1-94.6 in newly affected provinces. Conclusions. A flat case count accompanied by a rising death-to-case ratio is difficult to reconcile with a transmission plateau and is consistent with saturated case detection. Reported case counts appear to have substantially decoupled from transmission and cannot presently distinguish control from detection failure. Doubling times computed from cumulative totals are artefacts. Test volume and positivity by health zone are the critical missing denominators.

Background: High national vaccination coverage may conceal age-specific and spatially concentrated measles susceptibility. Objective: To assess whether published age-specific seropositivity results can be converted into a time-updated susceptibility profile that corresponds with subsequent measles incidence, while distinguishing susceptibility from infectious introductions and transmission conditions. Methods: For Israel, published 2015 age-specific seropositivity estimates were mapped to monthly birth cohorts and projected to 1 March 2018, accounting for births, aging, maternal antibody, routine vaccination, vaccine effectiveness, and uncertainty in assay interpretation. The primary outcome was reported age-specific incidence during the 2018-2019 outbreak; national and Jerusalem District case burdens were secondary outcomes. Published evidence from the Netherlands, Czechia, and Australia was compared using a common framework covering age distribution, assay classification, vaccination, importation, spatial concentration, and transmission context. Results: The estimated number susceptible in Israel on 1 March 2018 ranged from approximately 0.55 million (6.3% of the modelled population) to 1.92 million (22.4%), with a central estimate of 1.22 million (14.2%). Children aged <1 year had the highest central susceptible proportion (75.7%) and the highest later incidence (196.0 per 100,000). Jerusalem District accounted for 2,202 of 4,311 reported national cases, consistent with susceptibility concentrated in communities with lower first-dose coverage. The external comparisons showed that clustering amplified Dutch outbreak risk, survey design affected Czech estimates, and importation dominated Australian activity. Conclusions: Published seropositivity can identify immunity gaps, but useful outbreak-risk assessment must also represent susceptible density and distribution, introduction pressure, and local transmission conditions. Although the model was not designed to compare alternative vaccination schedules directly, its identification of substantial susceptibility during early childhood provides epidemiological support for Israel's recent decision to advance the second routine MMRV dose from 6 years to 18 months of age, thereby shortening the period during which young children remain dependent on single-dose protection.

Communities exposed to flooding can experience markedly different mental health outcomes, yet conventional resilience indicators capture only part of the social and contextual conditions that may explain this variation. This study develops a multilevel and predictive framework for examining community resilience and depressive symptoms following flood exposure in Indonesia. Data were drawn from 20,303 respondents aged 15 years and older nested within 312 communities in the Indonesia Family Life Survey (IFLS-5). Depressive symptoms were assessed using the 10-item Centre for Epidemiologic Studies Depression Scale (CES-D-10), with Rasch Partial Credit Model calibration used to examine measurement properties. Bayesian multilevel models quantified between-community heterogeneity and assessed how far observable structural resources accounted for this variation. Community resilience was represented through two complementary constructs: structural resilience, based on observable socioeconomic and social-capital resources, and Latent Community Protective Capacity (LCPC), a model-derived proxy for residual contextual variation in depressive-symptom risk. Approximately 6 percent of variation was attributable to between-community differences, while observable structural resources explained only part of this heterogeneity. Structural resilience and LCPC were weakly correlated (r = 0.155). Moderation analyses provided no clear evidence that structural resilience altered the flood-depression association, while LCPC showed a directionally consistent but uncertain buffering pattern. Predictive models incorporating community-level information improved discrimination, with the best-performing model reaching an ROC-AUC of approximately 0.71. The findings suggest that observable resource-based indices provide an incomplete account of community-level mental health vulnerability and that residual contextual measures may provide complementary information, while requiring cautious interpretation and independent validation.

Background. In 2026, the Democratic Republic of the Congo (DRC) experienced the largest recorded outbreak of Ebola disease caused by Bundibugyo virus, with epidemiologically linked importations and secondary transmission in Uganda. This study analysed the publicly reported trajectory and assessed the risk of introduction and onward transmission in North Africa and Europe. Methods. Public surveillance reports from the World Health Organization (WHO), European Centre for Disease Prevention and Control (ECDC), Africa CDC, national ministries of health, and peer-reviewed sources were synthesised through 15-17 July 2026. Headline counts and crude case-fatality ratios were restricted to laboratory-confirmed cases. Average notification rates were calculated from cumulative DRC counts. Exact Poisson intervals used the Garwood method, and the June-July rate ratio was estimated on the log scale. Risk was assessed across introduction likelihood, conditional onward-transmission likelihood, impact, and confidence. Results. By 15 July, the DRC had reported 2,124 confirmed cases and 828 deaths (crude confirmed-case fatality ratio, 39.0%) across 46 health zones in five provinces. Uganda had reported 20 confirmed cases and two confirmed deaths: 15 imported infections and five secondary cases, with no documented community transmission. DRC notifications averaged 47.4 per day during 1-15 July versus 35.9 per day during 2-29 June (rate ratio 1.32; counting-model 95% interval 1.20-1.46). WHO reported that more than 80% of new cases were detected outside known contact lists, while 119 confirmed healthcare-worker infections and 36 deaths had occurred. Introduction likelihood was assessed as very low to low for North Africa and very low for the general European population; delayed recognition in routine healthcare was the principal scenario for limited secondary transmission. Interpretation. Available indicators were inconsistent with effective control in eastern DRC at the data cut-off. Public reporting-date series cannot separate transmission from changing ascertainment, but they showed no sustained decline. Preparedness in North Africa and Europe should prioritise complete exposure histories, rapid isolation, validated diagnostics, protected clinical care, and contact management rather than reliance on border screening. Keywords: Bundibugyo virus; Ebola disease; outbreak surveillance; rapid risk assessment; importation; North Africa; Europe; Algeria; International Health Regulations.

Abstract Background. During an active outbreak, deaths divided by confirmed cases can be mistaken for biological severity or quality of care even though outcomes remain unresolved and reporting and ascertainment differ across places. We examined what health-zone case-fatality ratios measured during the 2026 Bundibugyo virus disease epidemic in the Democratic Republic of the Congo. Methods and principal findings. We analysed national and health-zone cumulative confirmed cases and deaths through 20 July 2026. We calculated reported crude case-fatality ratios, examined case-death reporting synchronisation, and fitted beta-binomial partial-pooling models with four-chain Markov chain Monte Carlo. Exploratory models added mapped clinical-facility availability or distance to the nearest mapped hospital. Reporting-date delay, under-ascertainment, and mortality forecasting were evaluated as diagnostics, scenarios, or developmental analyses rather than patient-level fatality estimation. The national ratio reached 40.4% (999/2,473). Among 14 zones with at least 20 cases, crude ratios ranged from 28.3% to 68.5%. In the primary model, North Kivu had higher posterior odds than Ituri, but with substantial uncertainty (OR 1.80, 95% credible interval 0.92-3.37); epidemic maturity was positively associated (1.49, 1.04-2.19). In exploratory models, greater mapped clinical-facility availability was associated with lower reported fatality (0.67, 0.48-0.96), while greater distance to a mapped hospital was associated with higher reported fatality (1.46, 1.06-2.00). Same-day case-death co-reporting was common, and materially different reporting-delay assumptions fitted similarly. Interpretation. Health-zone ratios revealed meaningful surveillance heterogeneity but did not identify biological fatality risk or causal effects of facilities, access, care, or conflict. Epidemic maturity, selective ascertainment, referral, and administrative reporting plausibly shaped the numerator and denominator. These ratios should guide investigation rather than rank health-zone performance; linked patient records are required for clinical fatality and competing-risks analyses.

Background Scrub typhus is a major cause of febrile illness in Southeast Asia, with particularly high burdens reported in northern Thailand. Environmental exposures and use of preventive measures remain incompletely understood. Methods We conducted a population-based cross-sectional serosurvey in Chiang Rai province, Thailand in 2022-2023. Adults aged [&ge;]15 years from 74 villages were selected by two-stage random sampling and interviewed regarding demographic characteristics, agricultural and domestic exposures, and preventive behaviours. IgG antibodies against Orientia tsutsugamushi were measured using a Luminex xMAP Intelliflex(R) platform. Mixed-effects logistic regression models stratified by ethnicity (highland people vs Thai) were used to identify factors associated with seropositivity, with village as a random intercept. Results Among 1,194 participants with valid serology, seroprevalence was higher among highland people than Thai ones (60% vs 13%, p<0.001). Seropositivity increased with age in both groups (p<0.001, and p=0.006), more markedly among highland people. Exposure to forest/high hill (adjusted odds ratio [aOR] 2.87, 95%CI 1.07-7.70) and agroforestry plantations (aOR 1.74, 95%CI 1.04-2.99) were associated with seropositivity among Thai participants, but not among highland people. High-risk occupations were associated with increased odds of seropositivity across both groups, p=0.006 and p=0.043. No clear associations were observed between seropositivity and duration of exposure, domestic/peridomestic risk factors, individual preventive practices, or overall prevention quality. Significant village-level heterogeneity persisted after adjustment, particularly among highland people. Conclusions Scrub typhus exposure is common in rural Chiang Rai and disproportionately affects highland people; whose risk was poorly explained by classical environmental risk factors, suggesting distinct and incompletely understood exposure pathways. Current prevention strategies based on conventional risk messaging may therefore have limited effectiveness in these high-risk communities.

This study investigates excess mortality in Germany in the years from 2020 to 2023 and its temporal alignment with reported COVID-19 deaths. The analysis uses annual and weekly all-cause mortality data and linear baseline trends derived from pre-pandemic years. Possible effects of demographic and population changes on baseline trends were also examined. Excess mortality was analysed over time and across age groups. Excess mortality was observed in all investigated years, rising from 2020 to its highest value in 2022. In absolute terms, the age group [&ge;]80 years accounted for the largest proportion of excess deaths throughout the study period. After 2021, elevated mortality relative to baseline was also observed in younger age groups down to 15 years of age, although absolute numbers remained substantially lower than in older groups. No evidence of excess mortality was observed for individuals younger than 15 years. Periods of excess mortality were temporally aligned with waves of reported COVID-19 deaths. In 2020, cumulative excess mortality after calendar week 11 closely matched reported COVID-19 deaths (43 876 vs. 41 835 deaths). Weekly excess mortality, reported COVID-19 deaths and wastewater viral load, when available showed strong temporal synchrony, although excess mortality increasingly exceeded reported COVID-19 deaths during later pandemic waves. Temporal patterns differed from the typical seasonal mortality peaks commonly associated with influenza epidemics during the early months of the year. In 2023, excess mortality declined substantially, possibly indicating a return to mortality levels before the emergence of SARS-CoV-2.

Objectives: To characterise the national epidemiology of tick-induced mammalian meat allergy (MMA) in Australia, including temporal trends in Gal specific IgE testing and case detection, geographic distribution, demographic risk factors, and longitudinal antibody dynamics. Design: Retrospective analysis of Gal sIgE ImmunoCAP test results from 1 January 2014 to 31 December 2024. Setting, Participants: Deidentified laboratory records from 14,075 individuals tested across Australia, with residential postcodes mapped to Statistical Areas Level 3 (SA3). A subset of 1,515 individuals with repeat testing contributed to longitudinal analyses. Main outcome measures: Test volumes, suspected MMA case counts, positivity rates, spatial clustering metrics, demographic risk ratios, and longitudinal Gal sIgE trajectories. Results: Overall, 35.7% (5,025) of individuals tested positive. Testing volume increased 331% over the study period, with case detection accelerating sharply from 2020. Decomposition analysis attributed 59-81% of case growth to expanded testing, with the remainder unexplained by surveillance expansion alone. Cases were concentrated along the eastern seaboard within the range of Ixodes holocyclus, with extreme spatial clustering: three SA3 regions accounted for over one-quarter of national cases. Females comprised the majority of positive cases, and MMA risk increased with age, peaking at 45-74 years. Among 1,515 individuals with serial testing, Gal sIgE levels antibodies declined predictably in 93% of people. Conclusions: This first national assessment of MMA in Australia reveals a substantial, geographically concentrated, and growing burden. The extreme spatial concentration of cases suggests that targeted public health interventions could efficiently address a large proportion of national disease burden. While testing expansion is the dominant driver of rising case numbers, it does not fully account for observed trends, and prospective studies are needed to disentangle surveillance effects from genuine disease emergence. Declining antibody levels support the utility of serial testing for clinical monitoring, though persistent sensitisation underscores the need for sustained risk mitigation and continued surveillance.

In a population model for an infectious disease, we consider the early stochastic dynamics of an emergent 'mutant' strain, appearing and spreading during an epidemic of another 'wildtype' strain. The mutant may not reach establishment in the host population. The time at which the mutant first appears determines its probability of establishment. We calculate this establishment probability with two methods. The first method assumes a classical branching process, with a constant transmission rate. The second method reflects the changing size of the pool of susceptible hosts, due to the dynamics of the wildtype. We find that susceptible depletion can substantially impact the establishment probability. We explore the consequences of this stochastic establishment on the "escape pressure" acting on a pathogen to produce immune escape variants. We find that the overall escape pressure rate depends strongly on the appearance time of the mutant, especially if the establishment probability is itself shaped by the continued spread of the wildtype. In most scenarios, the escape pressure rate (and thus, the risk of new escape variants) peaks slightly earlier than the prevalence of the wildtype strain. Integrating the escape pressure over time, we obtain the cumulative escape pressure generated by the wildtype epidemic. The relationship between the escape pressure and the vaccination coverage depends on the cross-immunity, due to susceptible depletion. For example, with intermediate cross-immunity, the risk of immune escape may be lowest at intermediate vaccination coverages. Thus, these results raise important considerations for vaccination strategies in response to novel outbreaks.

Introduction Measles remains a major public health threat worldwide. Following a resurgence of cases, Ho Chi Minh City (HCMC) experienced a severe outbreak in 2024-2025 that differed from the 2018-2020 epidemic. We compared the epidemiology and transmission dynamics of these two outbreaks to inform future surveillance and vaccination strategies. Methods Line-list data for measles cases reported in HCMC between 2018 and 2025 were extracted from the infectious disease surveillance system. Demographic changes were assessed using cross-sectional age distributions and longitudinal birth-cohort analyses. Transmission dynamics were characterized by estimating the effective reproduction number (Rt) using the Cori and Wallinga-Teunis methods. Age-stratified Who-Infected-Whom transmission matrices were constructed to quantify within- and between-age-group transmission before and after interventions. Results The 2018-2020 outbreak primarily affected children under five years of age (median age 3.75 years, IQR 0.9-9.1), whereas the 2024-2025 outbreak shifted toward older age groups (median age 8.4 years, IQR 1-14). Birth-cohort analyses identified two major immunity gaps: children born during the COVID-19 immunization disruption (2019-2023) and adolescents and young adults born before 2014 who were not eligible for the 2018 outbreak response immunization campaign. The 2024-2025 outbreak also showed broader spatial spread and a reversed geographic trajectory compared with the earlier epidemic. Transmission patterns changed substantially, with the 2018-2020 outbreak sustained mainly by transmission among young children, whereas the 2024-2025 outbreak was driven by older age groups, with individuals >15 years acting as an important source of infection for infants. Conclusion The epidemiology of measles in HCMC has shifted from predominantly pediatric transmission to increasing involvement of adolescents and adults, reflecting accumulated immunity gaps across multiple birth cohorts. These findings suggest that age-restricted outbreak response immunization may leave residual susceptible populations that contribute to future outbreaks. Achieving sustainable measles elimination will require vaccination strategies that address historical immunity gaps across all vulnerable age groups, in addition to maintaining high routine childhood vaccination coverage.

Background: Q fever, caused by Coxiella burnetii, is a zoonosis with significant public health implications. Spain has the highest number of cases in the European Union/European Economic Area, but the clinical and hospitalization burdens remain poorly characterized. This study described the epidemiology, demographic and clinical characteristics, and geographical distribution of hospitalized Q fever patients in Spain from 2016 to 2023. Methods: We conducted a nationwide, retrospective study using the Spanish Minimum Basic Data Set for Hospitalization (MBDS-H). All hospital admissions with an ICD-10-CM code for Q fever (A78) between 2016 and 2023 were included. We analyzed demographic data, comorbidities, complications, length of stay, intensive care unit (ICU) admission, and mortality. We calculated hospitalization rates per 100,000 population. Temporal trends were assessed using Poisson regression. Results: We identified 3,358 hospitalizations for Q fever, representing an overall hospitalization rate of 0.89 per 100,000 population. The median patient age was 56 years (interquartile range [IQR] 42-70), and the cohort was predominantly male (72%). The median hospital length of stay was 9 days (IQR 6-15), and 8.3% required ICU admission. The overall mortality rate was 2.4%. The most common complication was pneumonia (32%). Significant upward trends were observed over the study period for patient age, hypertension, and acute heart failure (p<0.05). Geographical analysis revealed the highest hospitalization rates in the Canary Islands (2.33), La Rioja (2.16), and the Balearic Islands (1.93). Conclusion: This study highlights the hospitalization burden due to Q fever in Spain. The risk of hospitalization increases with age and the presence of predisposing conditions. The marked regional heterogeneity and high frequency of complications such as pneumonia underscore the need for enhanced surveillance and a strengthened One Health approach to control this zoonosis.

Violent conflicts increasingly involve multiple armed actors competing for influence over shared civilian populations, creating complex dynamics that challenge conventional security analysis and policy design. We present a framework that adapts epidemiological methods informed by the conflict landscape in Nigeria to model multi-actor violent conflict as an epidemic process. We derive a basic insecurity reproduction number ($R_0$), identify violence-free and persistent-violence equilibria, and introduce a novel Civilian Harm Index (CHI) to quantify humanitarian impact. Sensitivity analyses identify recruitment, ideological support from civilian populations, and abduction as the key drivers of conflict persistence and civilian harm. The framework reveals several counterintuitive findings. Interventions that most effectively suppress violence transmission are not necessarily those that minimise civilian harm, demonstrating that epidemic control and humanitarian protection may require distinct optimisation criteria. Likewise, interventions effective against one armed actor may be ineffective, or even counterproductive, when applied uniformly across groups. In addition, prisoner exchange and ransom payments increase violence persistence and civilian harm. Although developed as an illustrative rather than predictive framework, our results show that epidemiological methods provide quantitative metrics for evaluating intervention priorities and trade-offs in complex multi-actor conflicts.

Snakebite envenoming is a major neglected tropical disease disproportionately affecting rural populations in sub-Saharan Africa. In Ghana, evidence on the spatial and temporal distribution of risk remains limited, constraining targeted prevention and resource allocation. This study quantified district-level snakebite risk across Ghana, identified persistent hotspots and environmental drivers, and evaluated the relationship between snakebite burden and geographic access to treatment. Monthly district-level snakebite cases from Ghana's District Health Information Management System (2020 to 2025) were analyzed across all 261 districts using a Bayesian spatio-temporal model incorporating spatial effects, a temporal random effect, and a space-time interaction, fitted via Integrated Nested Laplace Approximation. Environmental covariates including rainfall, temperature, humidity, and NDVI quantified associations with risk. Relative risks, exceedance probabilities, Local Indicators of Spatial Association, and geographic accessibility identified priority districts. Snakebite risk showed strong spatial clustering and temporal variation. Persistent high risk districts were concentrated in Upper West (Daffiama Bussie Issa, Wa East, Wa West, Sissala East), Savannah (Bole, Gonja), North East (Mamprugu Moagduri), Western North (Bia East), Bono (Banda), Oti (Krachi Nchumuru), Western (Wassa East), and Eastern Region (Nsawam Adoagyiri, Fanteakwa North), though patterns evolved. Fanteakwa North emerged as the highest risk district nationally in 2025. Humidity and temperature were associated with increased risk, while rainfall and NDVI showed no significant effect. High risk districts often had poor treatment access, revealing inequities. This first nationwide Bayesian spatio temporal assessment provides an evidence base for surveillance, antivenom distribution, and interventions supporting WHO's 2030 snakebite reduction goals.

Bangladesh reported a nationwide measles outbreak in April 2026 involving over 19,000 suspected cases, despite high reported first-dose vaccine coverage ([&ge;]95%). We assessed whether publicly available molecular data could support epidemiologic interpretation of this resurgence and evaluated broader sequence sharing practices across South Asia. We analyzed public outbreak reports, WHO/UNICEF Estimates of National Immunization Coverage (WUENIC), PubMed indexed literature, and NCBI GenBank records from nine regional countries. Public sequence visibility across the region was highly uneven. While India and Pakistan associated records dominated the public dataset, only 32 Bangladesh origin records were retrieved, and notably, none were collected after 2019. The sole 2026 Bangladesh linked molecular record was a travel associated genotype B3 genome isolated in Australia (PZ189094.1). Its closest public N450 relative was a contemporaneous Pakistan sequence (2-nucleotide difference). The historical Bangladesh sequences were more distant, precluding robust phylogenetic inference regarding local viral persistence, cross-border importation, or transmission direction. Immunization data revealed a high regional baseline but highlighted subnational vulnerability and a significant pandemic era coverage collapse in neighboring Myanmar. The absence of timely, publicly available genomic data during the critical early months of the outbreak highlights a severe genomic surveillance gap. Public molecular records were historically sparse and insufficient to reconstruct outbreak transmission dynamics. To support elimination goals, establishing targeted sequencing pipelines, enforcing minimum metadata standards, and ensuring rapid public data deposition are urgently needed. Keywords: measles; Bangladesh; South Asia; genomic surveillance; molecular epidemiology; immunization coverage

Background Cholera remains a recurrent public health emergency in Zamfara State, northwestern Nigeria, where communities depend predominantly on untreated and poorly protected water sources. Environmental water bodies serve as reservoirs for Vibrio cholerae, sustaining transmission cycles between outbreaks. Despite the severity of recurrent outbreaks in the region, data on the molecular characteristics and serogroup distribution of V. cholerae across different drinking water source types in Zamfara State remain critically limited. Methodology/Principal Findings A cross-sectional environmental surveillance study was conducted between 13 October and 26 November 2025 across five cholera-affected Local Government Areas (LGAs) of Zamfara State: Gusau, Bungudu, Talata Mafara, Zurmi, and Shinkafi. A total of 142 water samples were collected from five source types -- rivers, boreholes, wells, tap water, and sachet water. Presumptive isolation was performed on Thiosulfate-Citrate-Bile Salts-Sucrose (TCBS) agar following alkaline peptone water enrichment. Fifty-five presumptive isolates underwent PCR-based molecular confirmation and serotyping using three gene targets: ompW (species confirmation, 588 bp), ctxA (O1 toxigenicity marker, 302 bp), and tcpA (O139 colonisation factor, 120 bp). Presumptive V. cholerae was recovered from 55 of 142 samples (38.7%; 95% CI: 30.5-47.3%), with well water recording the highest positivity rate (69.7%; 95% CI: 51.3-83.7%). A statistically significant association was observed between water source type and presumptive V. cholerae occurrence ({chi}2 = 23.11, df = 4, p < 0.001). Molecular analysis confirmed 29 isolates (52.7%; 95% CI: 39.2-66.0%) as V. cholerae, comprising 22 O1 serotypes (75.9%), one O139 serotype (3.4%), and six non-O1/non-O139 serotypes (20.7%). Toxigenic O1 strains were detected across all five LGAs and in all five water source types, including commercially packaged sachet water. The O139 serotype was identified in a single well-water isolate from Zurmi LGA, representing the first environmental detection of this serotype in Zamfara State. Conclusions/Significance The co-circulation of toxigenic O1, O139, and non-toxigenic non-O1/non-O139 V. cholerae serogroups across five distinct drinking water source types confirms that community water environments serve as genetically diverse reservoirs sustaining cholera transmission in Zamfara State. These findings underscore the urgent need for integrated water quality surveillance, sanitation infrastructure investment, and sustained molecular monitoring of environmental V. cholerae populations.

In September 2023, the first infections with a novel lineage of mpox were detected in South Kivu. Since then, the virus has spread regionally, nationally and internationally. As part of continued efforts to understand the mpox ecology and epidemiology, the South Kivu district of public health and partners have set up systematic case finding and follow-up, including strain characterisation through PCR and sequencing. Samples were collected from 595 hospitalized patients with a confirmed mpox virus infection. A clade differentiating RT-PCR showed that 545 (92%) of samples were positive for clade Ib but also remarkably that Clade Ia infections were diagnosed for the first time in South Kivu. First detected in cases in week 7 in Kamituga, 50 cases were identified over the whole study period (8,40% of all cases). Phylogenetic analysis of initial cases revealed introductions of clade Ia into the South Kivu province alongside the continuation of the clade Ib mpox virus outbreak. These findings underscore the increasing complexity of clade I mpox virus outbreaks in the DRC.

Background Decision-making in emergency services involving the allocation of scarce resources is a key challenge for large, complex organisations required to prioritise demand against multiple, often competing criteria. Emergency Medical Dispatch is a case in point, where Enhanced and Critical Care Teams (ECCTs) represent a scarce and lifesaving clinical resource. Despite its operational and system-level significance, the allocation of ECCTs remains under-researched. Methods We conducted a methodological development study using the P.A.T.H.S. framework (Participants, Artefacts, Transition Stages, Historicity, Setting). We designed and piloted this in our previous work under the 999 R.E.S.P.O.N.D. project, which examined the decision-making process for ECCT dispatch. We applied P.A.T.H.S. to 17 dispatch cases (comprising 100 decision-making episodes). We analysed five data sources: recordings of emergency calls and internal dispatch-related interactions, sequence-of-events records, policy documents, and ethnographic observations. A four-phase analysis--indexing & data mapping, transcription & coding, charting, and synthesising & outputs--was undertaken taking Interactional Sociolinguistics as the theoretical approach and methodology. Results P.A.T.H.S. enables the mapping of non-linear, multifactorial textual trajectories across human and non-human actors. The case example presented herein illustrates how information on key risk indicators (e.g. mechanism of injury) were often delayed, fragmented, or lost between the caller, call-handler, and written records. P.A.T.H.S. provides a framework and analytical tool capturing the textual trajectory of information flow, and trace how dispatch decision making unfolds. We subsequently developed a template and codebook for other researchers to further study complex decision making in multi-actoral systems using a textual trajectory approach. Conclusion This methodological development work demonstrates the potential of P.A.T.H.S. to capture and clarify complex decision-making processes. P.A.T.H.S. offers a practical and theoretically grounded framework for future research, training, and policy that addresses risk points in communication between oral and written forms among teams of actors, to support optimal deployment of scarce resources.

This brief work discusses potential superspreading events that may occur during the World Cup in Mexico. The study is particularly focused on the city of Guadalajara due to a large recent outbreak in January and February and insufficient vaccine coverage prior to 2026. Keywords: Superspreading; measles outbreak; branching process; individual reproduction number; World Cup

Background: Urogenital schistosomiasis caused by Schistosoma haematobium remains a major public health concern in the Lake Chad region. This study aimed to estimate the cumulative prevalence of S. haematobium infection and to identify factors associated with test positivity within an intervention zone of the Ngouri health district, Lac Province, Chad. Methods: A cross-sectional analytical study was conducted using routinely collected data from the Dawa Mobile Health system between February 2024 and April 2025. A total of 4,504 individuals were included after data cleaning and biological consistency correction (22 haematuria cases recoded as positive). Bivariate analysis (Chi-square test) and multivariable logistic regression were performed. Results: The overall prevalence was 19.5% (95% CI: 18.4% - 20.7%). No statistically significant association was found for age (p=0.163), sex (p=0.939), marital status (p=0.858), occupation (p=0.704), or urine appearance in the binary model (p=0.116). Education level approached significance (p=0.078), with the highest prevalence observed at the primary level (23.0%). In multivariable analysis, only primary education was independently associated with positivity (adjusted OR=1.29, 95% CI: 1.06 - 1.57; p=0.011). Conclusion: Nearly one in five participants tested positive, confirming the high endemicity of the Ngouri district. The homogeneous distribution across demographic subgroups suggests widespread community exposure, supporting mass drug administration beyond school-aged children, strengthened WASH interventions, and consolidation of mobile health surveillance. Keywords: Schistosoma haematobium; urogenital schistosomiasis; prevalence; Lake Chad; Chad; mobile health; logistic regression.