In this article, we integrate the release of Wolbachia-carrying male mosquitoes with chemical insecticide spraying to formulate a coupled model that incorporates mosquito stage structure and malaria transmission dynamics. The model accounts for mating competition influenced by cytoplasmic incompatibility and employs a Holling-II type saturated release mechanism to dynamically match the release intensity of infected male mosquitoes with the density of wild mosquitoes. The study first verifies the positive invariance and boundedness of solutions of the model. It then derives the basic reproduction number, followed by the existence conditions and stability properties of equilibria. Subsequently, it reveals saddle-node bifurcation, forward bifurcation, backward bifurcation and their compound phenomena, thereby elucidating the abrupt dynamic changes near parameter thresholds of the system. Numerical simulations validate the theoretical results, quantify the regulatory effects of key parameters, and confirm that the combined strategy effectively suppresses mosquito population growth and interrupts malaria transmission through synergistic effects. The results illustrate that accurate tuning of critical parameters for the integrated control strategy and exploitation of synergism between Wolbachia and chemical insecticides can effectively modulate mosquito populations and block malaria transmission.

The Meriones unguiculatus plague focus in China constitutes a key zoonotic-disease hotspot where brucellosis and plague co-circulate, posing a syndemic public-health challenge. An integrated spatial risk assessment framework was constructed to systematically contrast the spatial patterns and drivers of the two pathogens and to pinpoint potential interfaces for integrated surveillance. During 2022-2025, 17,289 blood samples were collected from 13,703 individuals. The overall seroprevalence was 19.50% for brucellosis and 0.47% for plague. Spatial analysis revealed pronounced spatial clustering of brucellosis (global Moran's I = 0.295, P < 0.05), while plague seropositivity was sporadic or locally clustered; areas of dual high-risk for both diseases were specifically identified. By integrating serological results with multi-dimensional data, a spatially enhanced random forest model (MSE = 0.005, RMSE = 0.068; AUC = 0.878) was constructed for risk assessment. Significant predictors for brucellosis included male gender, livestock-related occupation, higher vegetation index (NDVI), elevated PM10 levels, sheep density, and proximity to dairy retail outlets. NDVI and livestock operation density emerged as key indicators for joint surveillance. These findings suggest that the interplay between agricultural intensification and climate variability appears to jointly facilitate transmission, underscoring the importance of adopting integrated surveillance strategies to control these zoonotic diseases.

Hemorrhagic fever with renal syndrome (HFRS), caused by Seoul orthohantavirus (SEOV) and Hantaan orthohantavirus (HTNV), remains a neglected rodent-borne zoonosis with persistent residual spillover risk in low-incidence regions of China. This study assessed human HFRS occurrence and small-mammal hantavirus surveillance signals in small-mammal hosts across Zhejiang Province, China, in 2025. Reported human cases were obtained from the National Notifiable Disease Surveillance System, and animal host surveillance was conducted at five designated monitoring sites. A total of 107 HFRS cases were reported, occurring year-round with peaks in June and December and showing spatial heterogeneity, presenting a predominance of males, adults aged ≥40 years, and farmers. Animal host surveillance captured 617 small mammals (566 rodents and 51 shrews) from 15,457 valid trap-nights, with Apodemus agrarius (30.31%) and Rattus norvegicus (29.98%) as the dominant species. Sixteen animals were positive for hantavirus RNA and/or antibody, including 12 for hantavirus RNA and 6 antibody-positive animals; two were positive for both markers. Positive animals were detected in multiple species, including Niviventer confucianus, R. norvegicus, Rattus losea, A. agrarius, Suncus murinus, and Rattus tanezumi. Human incidence, small-mammal density, host species composition, and hantavirus-positive rates were not fully concordant across surveillance sites. Our findings reveal sustained cryptic orthohantavirus circulation in low-endemic Zhejiang, highlighting that integrated human-reservoir One Health surveillance is indispensable for precise spillover risk prediction and targeted zoonotic disease intervention.

Influenza poses a significant threat to global public health and socioeconomic stability. To account for the heterogeneity in vaccination coverage and contact patterns across different age groups, we develop a multi-group influenza model that incorporates population dynamics, incomplete immunity, and preferential mixing within each age group. Theoretically, the basic reproduction number ℛ_0 is given by using the next-generation matrix approach, and through the persistence theory, the existence and globally asymptotic stability of both disease-free equilibrium and a unique endemic equilibrium is derived through the consistent persistence theory. Numerically, using the 2015-2016 influenza epidemic in Shenzhen as a case study, we estimate age-specific transmission rates, identifying preschool children as the most susceptible group, followed by school-aged students, the elderly, and adults. Sensitivity analysis reveals that preferential within-group contact raises ℛ_0 due to clustering effects. The average contact level exhibits a nonlinear relationship with ℛ_0 , which means there exists an optimal level that minimizes ℛ_0 , while both excessive and insufficient contacts facilitate transmission. Vaccination, meanwhile, effectively reduces incidence. For example, the free-vaccination policy in Shenzhen significantly suppresses influenza transmission and reduces incidence among the elderly by 25.34

ObjectiveMeteorological factors influence dengue transmission through nonlinear and lagged effects. This study assessed these associations in Hainan Province and developed an early risk prediction index.MethodsWeekly dengue case and meteorological data from Hainan Province (2018–2019 and 2023–2024) were analyzed using distributed lag non-linear models (DLNMs). An early risk prediction index(ERPI) was constructed from DLNM-derived cumulative meteorological risk signals and imported cases. Predictive performance was evaluated using leave-one-year-out cross-validation and assessed by the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).ResultsAmong 927 dengue cases reported during the four modelled years, 727 (78.43%) were locally acquired. Weekly mean daily maximum temperature (Tmax), precipitation (Pmean), wind speed (WSmean), and diurnal temperature range (DTRmean) showed nonlinear, lag-dependent associations with dengue risk, with distinct temporal patterns. Higher Tmax showed longer-lag effects, peaking at 33.73 °C at lag 8 weeks (RR = 2.45, 95% CI: 1.70–3.63). Its cumulative effect was strongest over lags 5–8 weeks, peaking at approximately 32 °C. Pmean showed a nonlinear association, peaking at 4 mm/day at a lag of 4 weeks (RR = 1.92, 95% CI: 1.59–2.31), with significant cumulative effect across both the 1–4- and 5–8-week windows. Low WSmean and moderate DTRmean showed their strongest cumulative associations over lags 1–4 weeks, peaking at 2.0 m/s and 6.1 °C, respectively. These harmful associations attenuated over lags 5–8 weeks, whereas higher WSmean and DTRmean were generally protective. The ERPI predicted local dengue occurrence within the subsequent 1–4-week windows, with AUCs of 0.762–0.843. Across these windows, sensitivities were 0.768–0.797, specificities were 0.644–0.708, PPVs were 0.468–0.624, and NPVs were 0.822–0.911.ConclusionIn Hainan, high temperature was primarily associated with medium-to-long-term dengue risk, whereas low-to-moderate diurnal temperature range increased short-term risk. Precipitation was associated with risk across both short and medium-to-long lags, while cumulative wind-speed associations were strongest over shorter lags and attenuated thereafter. The DLNM-based early risk prediction index may support meteorology-informed early warning and dengue control in tropical settings, although requiring external validation is needed before operational implementation.

BACKGROUND:COVID-19 non-pharmaceutical interventions disrupted respiratory syncytial virus (RSV) transmission globally. In Australia, RSV surged back after restrictions eased, whether this reflected immunity debt repayment or epidemic amplification is untested. METHODS:We conducted a national interrupted time-series analysis using Australian Institute of Health and Welfare hospitalisation data from financial years (FY) 2010/11-2023/24. The primary outcome was RSV-attributable fraction (RSV-AF) of bronchiolitis in infants and children 1-4 years. Pre-pandemic counterfactual trends were estimated by linear extrapolation of FY2010/11-2019/20 training data, this was appropriate given the stable, low-gradient pre-pandemic RSV-AF trends in both groups. For adults ≥ 65 years, a flat counterfactual (pre-pandemic mean) to bound estimates where a secular ascertainment rise made linear extrapolation inappropriate. Formal amplification test: one-sided Z-test of whether rebound exceeded suppression deficit. Influenza-attributable fraction used as a pathogen-specific comparator to isolate RSV from general respiratory rebound. Non-RSV bronchiolitis decomposed to rule out general post-pandemic denominator effects. RESULTS:In infants, pre-pandemic RSV-AF was 32.3% (SD 1.8%). In FY 2022/23, it reached 52.0% (z = 10.78; p < 0.001), 19.7 %age points above the pre-pandemic upper control limit. RSV bronchiolitis accounted for 95.1% of the total bronchiolitis increase; non-RSV bronchiolitis remained below counterfactual. In 1-4-year-olds, RSV-AF of bronchiolitis reached 49.1%, against a pre-pandemic mean of 23.2%. Formal testing found rebound significantly exceeded deficit in infants, 1-4-year-olds, and 5-19-year-olds (all p < 0.001). Adults 20-64 years showed significantly incomplete discharge (β=0.71, meaning the rebound recovered only 71% of the accumulated suppression deficit; p = 0.020). CONCLUSIONS:The RSV rebound in young children significantly exceeded the suppression deficit, consistent with epidemic amplification potentially reflecting accumulated primary-infection susceptibility in unvaccinated cohorts. After explanations (testing intensity, admission thresholds, demography, and coding changes) were accounted for. The FY2022/23 baseline provides the pre-vaccination reference for evaluating Australia's RSV immunisation program.

Seasonal influenza transmission is influenced by environmental and climatic factors, but the role of particulate matter (PM2.5) and its organic constituent remains unclear. This study uses Bayesian spatiotemporal models to explore the effects of PM2.5 and Organic Matters (OM) on influenza transmission and identify spatiotemporal heterogeneity across socio-economic statuses to enhance early warning systems (EWS) for seasonal influenza. Weekly influenza cases number from 2014 to 2018 were collected at the county level in Guangzhou, Beijing, and Wuhan. PM2.5 and OM data were sourced from Tracking Air Pollution, and socio-economic factors, including floating population, population density, and GDP per capita, were obtained from government records. A spatiotemporal model with spatial and temporal autoregression terms, implemented under the Bayesian inference framework, and generalized linear models (GLMs) were used to assess associations and compared with spatiotemporal models. PM2.5 was positively associated with increased influenza transmission in all cities under the Bayesian spatiotemporal models (Guangzhou: Relative Risk (RR) = 1.16, 95 % Credible interval (95 % CrI): 1.08-1.23; Beijing: RR = 1.37, 95 % CrI: 1.18-1.60; Wuhan: RR = 1.18, 95 % CrI: 1.10-1.26). OM showed significant associations in Guangzhou (RR = 1.16, 95 % CrI: 1.10-1.23) and Wuhan (RR = 1.15, 95 % CrI: 1.08-1.22). Spatiotemporal models had better performance than regression models and identified high-risk clusters of influenza in suburban areas. PM2.5 and OM significantly influence seasonal influenza transmission, even after adjusting for socio-economic factors. Bayesian spatiotemporal models outperformed GLMs in capturing environmental effects and identifying high-risk areas, supporting their use in EWS to enhance public health interventions.

ObjectiveAdolescent depression has emerged as a significant public health concern globally, including in China, and grasping a better understanding of adolescents’ views on depression could help design more adapted policies. This study aims to assess the prevalence of depressive symptoms among adolescents and examine their knowledge, attitudes, and practices (KAP) related to depression.MethodsA cross-sectional survey was conducted between September 23, 2024, and December 3, 2024, in primary and middle schools in Shuangliu District, Chengdu. Data were collected through self-administered questionnaires, which included demographic information, assessments of KAP regarding depression, and the Self-Rating Depression Scale (SDS). The possible attitude and practice scores ranged from 9 to 45, interpreted as negative (9-22), moderate (23-31), and positive (32-45).ResultsA total of 541 valid questionnaires were analyzed. Of the respondents, 308 (56.93%) were female, and 109 (20.15%) were from single-parent households. SDS scores indicated that 18 participants (3.33%) exhibited depressive symptoms. The mean knowledge, attitude, practice, and SDS scores were 9.07±5.08 (possible range: 0-18), 33.37±4.28 (possible range: 9-45), 35.77±6.84 (possible range: 9-45), and 37.35±9.07, respectively. Mediation analysis showed that knowledge directly affected attitude (β = 0.128, P=0.019), attitude directly affected practice (β = 0.250, P=0.011), while SDS directly affected both attitude (β = -0.366, P=0.007) and practice (β = -0.637, P=0.008). Meanwhile, SDS has an indirect negative effect on practice (β = -0.090, P=0.005), and knowledge has an indirect positive effect on practice (β = 0.032, P=0.012).ConclusionAdolescents in Chengdu had insufficient knowledge about depression while exhibiting positive attitudes and proactive practices, and most of them were without depressive symptoms. The study identified knowledge items that should be reinforced through educational interventions on adolescent depression. These findings emphasize the need for enhanced mental health education to improve adolescents’ understanding of depression, reinforce positive attitudes, and support proactive mental health practices.

This article modifies a mathematical dynamics model to analyze mosquito control strategies using the combined incompatible and sterile insect techniques. To regulate mosquito populations precisely, the model uses a Holling-II type proportional saturation release. The study first proves the existence of up to three equilibria and analyzes stability. It then investigates the potential saddle-node bifurcation that occurs under the threshold release rate, which is crucial for understanding mosquito population dynamics and developing an optimal control strategy. Numerical simulations confirm the accuracy of the model and show its dynamic behavior. The results suggest that by precisely controlling the release rate, mosquito population density can be effectively reduced, interrupting disease transmission chains.

Norovirus (NoV) represents a major cause of acute diarrhea among children under 5 years old in China, yet its overall disease burden is frequently underestimated in systematic reporting. This meta-analysis aimed to provide a comprehensive assessment of the burden of NoV-related diarrhea in Chinese children under 5 years of age based on published literature between 2020 and 2024. We conducted a systematic search across PubMed, Web of Science, CNKI, and WanFang Data, identifying 60 eligible studies. The quality of these studies was assessed using the STROBE checklist. Heterogeneity was evaluated through Cochran’s Q test and the I² statistic, while publication bias was examined using Egger’s test and funnel plots. Pooled positivity rates were analyzed employing a random-effects model. All analyses were done at 95

Background: Several studies have examined the effect of non-pharmaceutical interventions (NPIs) on COVID-19 and other infectious diseases in Australia and globally. However, to our knowledge none have sufficiently explored their impact on other infectious diseases with robust time series model. In this study, we aimed to use Bayesian Structural Time Series model (BSTS) to systematically assess the impact of NPIs on 64 National Notifiable Infectious Diseases (NNIDs) by conducting a comprehensive and comparative analysis across eight disease categories within each Australian state and territory, as well as nationally. Methods: Monthly data on 64 NNIDs from eight categories were obtained from the Australian National Notifiable Disease Surveillance System. The incidence rates for each infectious disease in 2020 were compared with the 2015-2019 average and then with the expected rates in 2020 using a BSTS model. The study investigated the causal effects of 2020 interventions and analysed the impact of government policy restrictions at the national level from January 2020 to December 2022. Results: During the COVID-19 pandemic interventions in Australia, there was a 38 % (95 % Credible Interval [CI] [9 %, 54 %]) overall relative reduction in incidence reported across all disease categories compared to the 2015-2019 average. Significant reductions were observed in bloodborne diseases: 20 % (95 % CI [10 %, 29 %]), respiratory diseases: 79 % (95 % CI [52 %, 91 %]), and zoonoses: 8 % (95 % CI [1 %, 17 %]). Conversely, vectorborne diseases increased by 9 % over the same period. Reductions and intervention effects varied by state and territory, with higher policy stringency linked to fewer cases for some diseases. Conclusions: COVID-19 NPIs also impacted the transmission of other infectious diseases, with varying effects across regions reflecting diverse outcomes in response strategies throughout Australia. The findings could inform public health strategies and provide scientific evidence to support the development of early warning systems for future disease outbreaks. (c) 2025 Published by Elsevier Ltd on behalf of King Saud Bin Abdulaziz University for Health Sciences. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Group A rotavirus (RVA) is a leading cause of childhood diarrhea globally. Despite its status as a reportable infectious diarrhea in China, comprehensive and specific national RVA surveillance data remain scarce. This study analyzed the National Science and Technology Major Project (NSTMP) database (2009–2020) to characterize RVA epidemiology in Chinese children under 5 presenting with diarrhea. RVA detection data from children under 5 with diarrhea were analyzed from the NSTMP database. Positivity rates and genotype spatiotemporal distribution were assessed using descriptive epidemiology. Temporal trends were evaluated with Joinpoint regression; significance of differences was assessed using chi-square tests. The overall positivity rate of RVA among children under 5 years old in China was 28.7

Introduction: Human brucellosis poses a serious public health concern in China, however, epidemiological evolution of disease in southern and northern China remains unclear. Methods: The number of cases, incidence rate, geographic and temporal distribution, and social factors were analyzed to illustrate the epidemiological change. Results: About 97.6% of cases consistently located in the northern area are attributed to the tens of thousands of livestock farming. This underscores the need to prioritize strengthening surveillance and control measures in the northern. By contrast, only 2.4% of cases were in the southern area. These data indicate that controlling brucellosis in the northern will help reduce the incidence in the southern. There was an apparent shift from historical multiple-species prevalence to the present dominance of a single species, Brucella melitensis. Mutton price and production were closely correlated with the number of cases, implying that B. melitensis strains were accompanied by these factors, co-driving the persistent epidemic of brucellosis and expanding from the northern toward the southern. Conclusions: The control and prevention of brucellosis in the northern have become extremely complex sociological issues. It is important to draw attention to the worsening epidemic situation and to mobilize the nation's full strength to curb this trend. numbers have shown continuous growth in recent years, driven by multiple socioeconomic factors, particularly the expansion of sheep and goat livestock industries and increased economic development (3). Understanding the epidemiological change between southern and northern areas is therefore crucial for developing targeted and effective control measures. This study aims to elucidate the epidemiological evolutionary characteristics of human brucellosis and examining the relationships among multiple contributing social factors. These insights will contribute to the development of tailored countermeasures to combat the spread of brucellosis.

This study delves into the dynamics of the Zika virus using a reaction–advection–diffusion model that incorporates the periodic release of Wolbachia-harboring male mosquitoes, vector-bias, and seasonal influences. We define the basic reproduction number R_0 . The threshold dynamics are analyzed to identify critical points that determine disease persistence or elimination. When R_0<1 , there exists a globally attractive disease-free T-periodic solution. If R_0>1 , then the disease persists uniformly across the population. Numerical simulations are employed to validate these theoretical insights and to demonstrate the effectiveness of the Wolbachia release strategy, vector-bias, and advection in controlling Zika transmission. These results indicate that the implementation of Wolbachia incompatible insect technique can effectively control the spread of Zika, failing to account for seasonality or vector-bias may lead to an underestimation of the risk of Zika spread, and increasing the advection rate can help reduce the risk of disease transmission.

Novel bat influenza viruses show different features in contrast to classical influenza A viruses (IAVs). The M2 of IAVs functions as an ion channel that plays an important role in virus entry, viral assembly, and release and also serves as the antiviral target. To date, whether bat influenza M2 functions as the ion channel like classical IAV M2 remains unknown. Here, we show that the bat influenza M2 amino acid at position 31 (N/S) is critical for sensitivity to antivirals targeting the ion channel such as amantadine and other tested antivirals and that the amino acids at position 37 (H/G) and 41 (W/A) are crucial for virus replication and survival. The results indicate that bat influenza M2 functions similarly to conventional IAVs despite the low identity between the two.

Porcine reproductive and respiratory syndrome virus (PRRSV) is responsible for one of the most prevalent and economically damaging diseases in the pig industry. Surveillance of its epidemic profile and genetic Characteristics is critical for developing effective control strategies. In this study, 213 clinical samples were collected from pigs displaying typical symptoms of porcine reproductive and respiratory syndrome from swine farms of varying sizes in 13 cities of Henan and Shanxi provinces, China, between 2023 and 2024. All samples were screened via RT-PCR, and the ORF5 and Nsp2 genes of the viruses found in positive samples were sequenced and analyzed. The results revealed a PRRSV positivity rate of 19.72% (42/213). Phylogenetic analysis based on ORF5 showed that all 35 sequenced strains belong to the genotype PRRSV-2, with 27 strains clustering within sublineage 1.8 (NADC30-like), five in sublineage 5.1 (VR2332-like), and the remaining strains distributed among sublineages 8.7 (HP-PRRSV-like), 1.5 (NADC34-like), and 3.5 (QYYZ-like), indicating the dominance of NADC30-like strains in Henan and Shanxi provinces. Additionally, Nsp2 gene analysis of 10 selected strains (sublineages 5.1 and 1.8) revealed a unique 131-amino-acid (aa) deletion in the hypervariable region. Notably, two novel discontinuous deletions were identified: a 7-aa deletion (PVSLGGD) at positions 216-222 and a 3-aa deletion (GVL) at positions 453-455. Additionally, strains HNLY-6, HNLY-11, and HNLY-14 exhibited evidence of possible recombination events between NADC30-like and VR2332-like strains. These findings provide critical insights into the epidemiology of PRRSV in Henan and Shanxi provinces from 2023 to 2024, supporting the development of targeted prevention and control strategies.

Rotavirus (RV) is a leading cause of severe diarrhea among children under five years of age in China. In this meta-analysis, we assessed the disease burden of RV-related diarrhea by analyzing 73 studies retrieved from the PubMed, Web of Science, China National Knowledge Infrastructure, and Wanfang databases (2013-2023). The incidence of RV-related diarrhea ranged from 0.637 /1000 to 31.46/1000 persons. The pooled RV positivity rate for the under-5 age group was 24.7% (95% confidence interval: 22.1-27.4), with higher positivity rates observed among inpatients compared to outpatients (24.1% vs. 22.2%). Notably, the RV positivity rate declined from 27.3 to 21.5% pre- and post- the RotaTeq® licensure and 28.8-22.5% following the COVID-19 pandemic. The G9P[8] genotype was predominant, accounting for 71.7% of the RV cases in the under-5 age group. Given the dynamic nature of the incidence rate of RV-related diarrhea and the prevalence of the G9P[8] genotype, it is imperative to enhance surveillance efforts targeting incidence of RV-related diarrhea and the circulating genotypes of rotavirus.

Malaria continues to pose a considerable threat to global health. This study investigates the use of releasing Wolbachia-infected male mosquitoes as a method to mitigate the spread of malaria. We have formulated a reaction-diffusion model with nonlocal delays that includes the Wolbachia release strategy. The basic reproduction number $ R_0 $ is defined within our model framework, serving as a critical threshold parameter that dictates the dynamic behavior of the model. A thorough dynamic analysis of the model reveals that when $ R_0 < 1 $, a globally attractive infection-free steady state is established. In contrast, if $ R_0 > 1 $, the disease persists uniformly. Numerical simulations are conducted to validate the theoretical results and to further illustrate the effectiveness of the Wolbachia release strategy on transmission and control of malaria. These simulations underscore the potential of using Wolbachia-infected male mosquitoes to significantly reduce spread of malaria.

Previous research has linked seasonal influenza transmission with particulate matters (PM2.5). However, the effect of PM2.5 on seasonal influenza transmission varied by region. This study aims explore how PM2.5 influenced seasonal influenza transmission in the elderly across 1330 counties in two Köppen Geiger climate zones in China, incorporating the socio-economic factors to enhance climate-driven early warning systems (EWS) for influenza. Data included weekly 2015-2019 influenza cases in those aged >65 from China's national influenza surveillance system for 1330 counties in two Köppen Geiger climate zones: Temperate, Hot Summer with Dry Winter (Cwa) and No Dry Season (Cfa). PM2.5 data from 2015 to 2019 were sourced from Copernicus Atmosphere Monitoring Services. Additional data on floating population, population density and Gross Domestic Product (GDP) per capita were collected from pertinent departments. A Bayesian spatial autoregressive model assessed the association of PM2.5 and influenza transmission after adjustment of socio-economic factors. Our research results showed PM2.5 (per 1 μg/m³ increase) was linked to increased influenza transmission in the Cwa zone during winter season (Relative Risk (RR) = 1.023, 95% Credible Interval (CI):1.008-1.040) but not in the Cfa winter (RR = 1.003, 95% CI: 0.992-1.015). Floating population significantly enhanced transmission in both zones (highest RR = 1.362, 95% CI:1.181-1.583), while GDP per capita growth was associated with reduced transmission risk (highest RR = 0.619, 95% CI: 0.445-0.861). The study identifies PM2.5 as a significant factor influencing influenza transmission in the elderly, with effects varying by climate zone, suggesting the need to incorporate PM2.5 and socio-economic factors into seasonal influenza EWS.