Efficacy of Wolbachia-Infected Mosquito Deployments for the Control of Dengue.

BACKGROUND: Aedes aegypti mosquitoes infected with the wMel strain of Wolbachia pipientis are less susceptible than wild-type A. aegypti to dengue virus infection. METHODS: We conducted a cluster-randomized trial involving releases of wMel-infected A. aegypti mosquitoes for the control of dengue in Yogyakarta, Indonesia. We randomly assigned 12 geographic clusters to receive deployments of wMel-infected A. aegypti (intervention clusters) and 12 clusters to receive no deployments (control clusters). All clusters practiced local mosquito-control measures as usual. A test-negative design was used to assess the efficacy of the intervention. Patients with acute undifferentiated fever who presented to local primary care clinics and were 3 to 45 years of age were recruited. Laboratory testing was used to identify participants who had virologically confirmed dengue (VCD) and those who were test-negative controls. The primary end point was symptomatic VCD of any severity caused by any dengue virus serotype. RESULTS: After successful introgression of wMel into the intervention clusters, 8144 participants were enrolled; 3721 lived in intervention clusters, and 4423 lived in control clusters. In the intention-to-treat analysis, VCD occurred in 67 of 2905 participants (2.3%) in the intervention clusters and in 318 of 3401 (9.4%) in the control clusters (aggregate odds ratio for VCD, 0.23; 95% confidence interval [CI], 0.15 to 0.35; P = 0.004). The protective efficacy of the intervention was 77.1% (95% CI, 65.3 to 84.9) and was similar against the four dengue virus serotypes. The incidence of hospitalization for VCD was lower among participants who lived in intervention clusters (13 of 2905 participants [0.4%]) than among those who lived in control clusters (102 of 3401 [3.0%]) (protective efficacy, 86.2%; 95% CI, 66.2 to 94.3). CONCLUSIONS: Introgression of wMel into A. aegypti populations was effective in reducing the incidence of symptomatic dengue and resulted in fewer hospitalizations for dengue among the participants. (Funded by the Tahija Foundation and others; AWED ClinicalTrials.gov number, NCT03055585; Indonesia Registry number, INA-A7OB6TW.).

Association between increased signal intensity at the proximal patellar tendon and patellofemoral geometry in community-based asymptomatic middle-aged adults: a cross-sectional study.

BACKGROUND: Histological and epidemiological data suggest that increased signal intensity at the proximal patellar tendon on magnetic resonance imaging is a response to tendon loading. As patellofemoral geometry is a mediator of loading, we examined the association between patellofemoral geometry and the prevalence of increased signal intensity at the patellar tendon in community-based middle-aged adults. METHODS: Two hundred-one adults aged 25-60 years in a study of obesity and musculoskeletal health had the patellar tendon assessed from magnetic resonance imaging. Increased signal intensity at the proximal patellar tendon was defined as hyper-intense regions of characteristic pattern, size and distribution on both T1- and T2-weighted sequences. Indices of patellofemoral geometry, including Insall-Salvati ratio, patellofemoral congruence angle, sulcus angle, and lateral condyle-patella angle, were measured from magnetic resonance imaging using validated methods. Binary logistic regression was used to examine the association between patellofemoral geometrical indices and the prevalence of increased signal intensity at the patellar tendon. RESULTS: The prevalence of increased signal intensity at the patellar tendon was 37.3%. A greater Insall-Salvati ratio (odds ratio 0.80, 95% confidence interval 0.66-0.97 per 0.1 change in the ratio, p = 0.02), indicative of a higher-riding patella, and a larger patellofemoral congruence angle (odds ratio 0.91, 95% confidence interval 0.85-0.98 per 5 degree change in the angle, p = 0.01), indicating a more laterally placed patella, were associated with reduced odds of increased signal intensity at the patellar tendon. Sulcus angle and lateral condyle-patella angle were not significantly associated with the odds of increased signal intensity at the patellar tendon. CONCLUSIONS: In community-based asymptomatic middle-aged adults, increased signal intensity at the patellar tendon was common and associated with Insall-Salvati ratio and patellofemoral congruence angle, suggesting a biomechanical mechanism. Such work is likely to inform tissue engineering and cell regeneration approaches to improving outcomes in those with tendon pathology.

Survival analysis with time-dependent covariates subject to missing data or measurement error: Multiple Imputation for Joint Modeling (MIJM).

Modern epidemiological studies collect data on time-varying individual-specific characteristics, such as body mass index and blood pressure. Incorporation of such time-dependent covariates in time-to-event models is of great interest, but raises some challenges. Of specific concern are measurement error, and the non-synchronous updating of covariates across individuals, due for example to missing data. It is well known that in the presence of either of these issues the last observation carried forward (LOCF) approach traditionally used leads to bias. Joint models of longitudinal and time-to-event outcomes, developed recently, address these complexities by specifying a model for the joint distribution of all processes and are commonly fitted by maximum likelihood or Bayesian approaches. However, the adequate specification of the full joint distribution can be a challenging modeling task, especially with multiple longitudinal markers. In fact, most available software packages are unable to handle more than one marker and offer a restricted choice of survival models. We propose a two-stage approach, Multiple Imputation for Joint Modeling (MIJM), to incorporate multiple time-dependent continuous covariates in the semi-parametric Cox and additive hazard models. Assuming a primary focus on the time-to-event model, the MIJM approach handles the joint distribution of the markers using multiple imputation by chained equations, a computationally convenient procedure that is widely available in mainstream statistical software. We developed an R package "survtd" that allows MIJM and other approaches in this manuscript to be applied easily, with just one call to its main function. A simulation study showed that MIJM performs well across a wide range of scenarios in terms of bias and coverage probability, particularly compared with LOCF, simpler two-stage approaches, and a Bayesian joint model. The Framingham Heart Study is used to illustrate the approach.

Urine metabolites are associated with glomerular lesions in type 2 diabetes.

INTRODUCTION: Little is known about the association of urine metabolites with structural lesions in persons with diabetes. OBJECTIVES: We examined the relationship between 12 urine metabolites and kidney structure in American Indians with type 2 diabetes. METHODS: Data were from a 6-year clinical trial that assessed renoprotective efficacy of losartan, and included a kidney biopsy at the end of the treatment period. Metabolites were measured in urine samples collected within a median of 6.5 months before the research biopsy. Associations of the creatinine-adjusted urine metabolites with kidney structural variables were examined by Pearson's correlations and multivariable linear regression after adjustment for age, sex, diabetes duration, hemoglobin A1c, mean arterial pressure, glomerular filtration rate (iothalamate), and losartan treatment. RESULTS: Participants (n = 62, mean age 45 ± 10 years) had mean ± standard deviation glomerular filtration rate of 137 ± 50 ml/min and median (interquartile range) urine albumin:creatinine ratio of 34 (14-85) mg/g near the time of the biopsy. Urine aconitic and glycolic acids correlated positively with glomerular filtration surface density (partial r = 0.29, P = 0.030 and r = 0.50, P < 0.001) and total filtration surface per glomerulus (partial r = 0.32, P = 0.019 and r = 0.43, P = 0.001). 2-ethyl 3-OH propionate correlated positively with the percentage of fenestrated endothelium (partial r = 0.32, P = 0.019). Citric acid correlated negatively with mesangial fractional volume (partial r=-0.36, P = 0.007), and homovanillic acid correlated negatively with podocyte foot process width (partial r=-0.31, P = 0.022). CONCLUSIONS: Alterations of urine metabolites may associate with early glomerular lesions in diabetic kidney disease.

White blood cell fractions correlate with lesions of diabetic kidney disease and predict loss of kidney function in Type 2 diabetes.

Background: Inflammation linked to diabetic kidney disease (DKD) may affect white blood cell (WBC) counts and differentials. We examined the cross-sectional associations of total WBC count and WBC fractions with structural lesions of DKD in 108 Pima Indians with Type 2 diabetes who underwent research kidney biopsies. We also examined the longitudinal association of these WBC variables with renal function loss (RFL) in 941 Europeans with Type 2 diabetes from the SURDIAGENE study. Methods: Associations of WBC variables with morphometric parameters were assessed by linear regression. RFL was defined as≥40% loss of estimated glomerular filtration rate from baseline. Associations with RFL were evaluated by Cox regression. Hazard ratios (HRs) were reported per standard deviation increment of each WBC variable. Results: After multivariable adjustment, lymphocyte (r  = -0.20, P = 0.043) and eosinophil (r = 0.21, P = 0.032) fractions in the Pima Indians correlated with glomerular basement membrane width. Eosinophil fraction also correlated with glomerular filtration surface density (r  = -0.21, P = 0.031). Lymphocyte fraction (r = 0.25, P = 0.013), neutrophil fraction (r  = -0.23, P = 0.021) and the neutrophil:lymphocyte ratio (r  = -0.22, P = 0.024) correlated with percentage of normally fenestrated endothelial cells. During median follow-up of 4.5 years, 321 SURDIAGENE participants developed RFL. Lower lymphocyte fraction [HR = 0.67, 95% confidence interval (95% CI) 0.60-0.76] and higher neutrophil fraction (HR = 1.35, 95% CI 1.20-1.52), total WBC count (HR = 1.20, 95% CI 1.08-1.35) and neutrophil:lymphocyte ratio (HR = 1.44, 95% CI 1.28-1.62) each predicted RFL in this cohort. Conclusions: WBC fractions associate with morphometric lesions of DKD and predict RFL in individuals with Type 2 diabetes.

Changes in waist circumference independent of weight: Implications for population level monitoring of obesity.

Population monitoring of obesity is most commonly conducted using body mass index (BMI). We test the hypothesis that because of increases in waist circumference (WC) independent of increases in weight, BMI alone detects an increasingly smaller proportion of the population with obesity. METHODS: Australian adults with measured height, weight, and WC were selected from three nationally representative cross-sectional surveys (1989, 1999-2000, 2011-12; n=8313, 5903 & 3904). Participants were defined as having obesity using classifications for an obese BMI (≥30kg·m-2) and substantially-increased-risk WC (≥88cm [women], ≥102cm [men]). Age-standardised prevalence of obesity according to BMI and/or WC, and the proportion of these detected by BMI and by WC were compared across surveys. FINDINGS: Between 1989 and 2011-12, weight and WC increased by 5.4kg and 10.7cm (women), and by 7.0kg and 7.3cm (men). For women and men, 63% and 38% of increases in WC were independent of increases in weight. Over this period, the prevalence of obesity according to BMI and/or WC increased by 25.3 percentage-points for women (18.9% to 44.3%) and 21.1 percentage-points for men (17.1% to 38.2%). The proportion of these detected by BMI decreased for women by 20 percentage-points (77% to 57%) with no change for men. The proportion of these detected by WC increased for women and men by 10 percentage-points (87% to 97%) and 6 percentage-points (85% to 91%) respectively. CONCLUSION: BMI alone is detecting a decreasing proportion of those considered obese by BMI and/or WC. Renewed discussion regarding how we monitor obesity at the population level is required.

Effect of severe obesity in childhood and adolescence on risk of type 2 diabetes in youth and early adulthood in an American Indian population.

OBJECTIVES: The risk of early-onset type 2 diabetes associated with the severity of obesity in youth is not well understood. This study aims to determine metabolic alterations and type 2 diabetes risk among American Indian children who are obese or severely obese. METHODS: Incidence rates of diabetes before 20 years (youth-onset) and 45 years were computed in 2728 children who were from 5 to <10 years and 4317 adolescents who were from 10 to <18 years without diabetes examined between 1965 and 2007. Obesity was defined as age-sex-adjusted body mass index (BMI) ≥95th percentile, and its severity was quantified as the percentage of the 95th percentile (%BMIp95 ). RESULTS: In the younger cohort, 0.9% of those non-obese and 2.9% of those with 100% to <120%BMIp95 had impaired glucose tolerance (IGT) compared to 8.6% of those with ≥140%BMIp95 . In the older cohort, 2.9% of those non-obese and 9.8% of those with 100% to <120%BMIp95 had IGT compared to 13.3% of those with ≥160%BMIp95 . The incidence of youth-onset diabetes was 3.8 and 4.9/1000 person-years in the child and adolescent cohorts, respectively, and before the age of 45 was 12.3 and 16.8/1000 person-years, respectively. Incidence rates of youth-onset diabetes in those with the most severe obesity (≥140%BMIp95 ) were 2.3 to 5.1 times as high as in those with the least severe obesity (100 to <120%BMIp95 ), and for onset of diabetes before the age of 45 were 1.6 to 2.2 times as high. CONCLUSIONS: Severe obesity in an American Indian population is a major driver of type 2 diabetes developing in adolescents and young adults.

Association of Serum Amyloid A with Kidney Outcomes and All-Cause Mortality in American Indians with Type 2 Diabetes.

BACKGROUND: Serum amyloid A (SAA) induces inflammation and apoptosis in kidney cells and is found to be causing the pathologic changes that are associated with diabetic kidney disease (DKD). Higher serum SAA concentrations were previously associated with increased risk of end-stage renal disease (ESRD) and death in persons with type 2 diabetes and advanced DKD. We explored the prognostic value of SAA in American Indians with type 2 diabetes without DKD or with early DKD. METHODS: SAA concentration was measured in serum samples obtained at the start of follow-up. Multivariate proportional hazards models were employed to examine the magnitude of the risk of ESRD or death across tertiles of SAA concentration after adjustment for traditional risk factors. The C statistic was used to assess the additional predictive value of SAA relative to traditional risk factors. RESULTS: Of 256 participants (mean ± SD glomerular filtration rate [iothalamate] = 148 ± 45 mL/min, and median [interquartile range] urine albumin/creatinine = 39 [14-221] mg/g), 76 developed ESRD and 125 died during a median follow-up period of 15.2 and 15.7 years, respectively. After multivariable proportional hazards regression, participants in the 2 highest SAA tertiles together exhibited a 53% lower risk of ESRD (hazard ratio [HR] 0.47, 95% CI 0.29-0.78), and a 30% lower risk of death (HR 0.70, 95% CI 0.48-1.02), compared with participants in the lowest SAA tertile, although the lower risk of death was not statistically significant. Addition of SAA to the ESRD model increased the C statistic from 0.814 to 0.815 (p = 0.005). CONCLUSIONS: Higher circulating SAA concentration is associated with a reduced risk of ESRD in American Indians with type 2 diabetes.

Cystatin C estimated glomerular filtration rate and all-cause and cardiovascular disease mortality risk in the general population: AusDiab study.

AIMS: Uncertainties about the role of cystatin C-based estimated glomerular filtration rate (eGFR) in the prediction of cardiovascular disease (CVD) beyond traditional CVD risk factors remain. We assessed contributions of eGFR to CVD and mortality in the general population. METHODS: Using 14 year follow-up data on 9353 adults without a reported history of CVD from the Australian Diabetes, Obesity and Lifestyle study, we assessed the contributions of eGFR (assessed by cystatin C (eGFRcysC ) and serum creatinine (eGFRcr ) and albuminuria (uACR) to total and CVD mortality. RESULTS: After adjusting for age, sex, CVD risk factors and uACR, compared with an eGFRcysC >90 mL/min per 1.73 m2 , eGFRcysC <60 mL/min per 1.73 m2 was associated with 56% and 73% increases in the risks for all-cause and CVD mortality, respectively. The respective changes for the c-statistic when eGFRcysC was added to a risk prediction model were 0.003 (95% confidence interval: 0.001 to 0.005) and 0.002 (95% confidence interval: -0.001 to 0.006). The net proportion of non-events assigned a lower-risk category significantly improved with the addition of eGFR (non-event net reclassification index eGFRcr : 1.0% and eGFRcysC : 1.5%) for all-cause mortality, but for CVD mortality, improvements were only significant when eGFR was combined with uACR. The net proportion of events assigned a higher-risk category was not significantly improved. CONCLUSION: In our community-based cohort, reduced eGFRcysC was associated with all-cause and CVD mortality. The addition of chronic kidney disease measures to risk prediction models improved overall risk stratification among those at low risk as opposed to those at high baseline risk of mortality.

Adverse associations of car time with markers of cardio-metabolic risk.

OBJECTIVE: To examine associations of time spent sitting in cars with markers of cardio-metabolic risk in Australian adults. METHOD: Data were from 2800 participants (age range: 34-65) in the 2011-12 Australian Diabetes, Obesity and Lifestyle Study. Self-reported time spent in cars was categorized into four groups: ≤15min/day; >15 to ≤30min/day; >30 to ≤60min/day; and >60min/day. Markers of cardio-metabolic risk were body mass index (BMI), waist circumference, systolic and diastolic blood pressure, triglycerides, HDL (high-density lipoprotein)-cholesterol, fasting plasma glucose, 2-h plasma glucose, a clustered cardio-metabolic risk score, and having the metabolic syndrome or not. Multilevel linear and logistic regression analyses examined associations of car time with each cardio-metabolic risk outcome, adjusting for socio-demographic and behavioral variables and medication use for blood pressure and cholesterol/triglycerides. RESULTS: Compared to spending 15min/day or less in cars, spending more than 1h/day in cars was significantly associated with higher BMI, waist circumference, fasting plasma glucose, and clustered cardio-metabolic risk, after adjusting for socio-demographic attributes and potentially relevant behaviors including leisure-time physical activity and dietary intake. Gender interactions showed car time to be associated with higher BMI in men only. CONCLUSIONS: Prolonged time spent sitting in cars, in particular over 1h/day, was associated with higher total and central adiposity and a more-adverse cardio-metabolic risk profile. Further studies, ideally using objective measures of sitting time in cars and prospective designs, are needed to confirm the impact of car use on cardio-metabolic disease risk.

Weight change and change in tibial cartilage volume and symptoms in obese adults.

INTRODUCTION: There is a paucity of data examining the effects of weight change on knee joint structures and symptoms. This study examined the effect of weight change on change in knee cartilage volume and symptoms in an obese cohort. METHODS: 112 obese subjects (Body Mass Index ≥30 kg/m(2)) were recruited from various community sources to examine the effect of obesity on musculoskeletal health. Tibial cartilage volume, determined by MRI, and knee symptoms, determined by the Western Ontario and McMaster Osteoarthritis Index (WOMAC) were collected at baseline and an average of 2.3 years later. RESULTS: Percentage weight change was associated with change in medial tibial cartilage volume (ß -1.2 mm(3), 95% CI -2.3 to -0.1 mm(3), p=0.03) that was consistent throughout the spectrum of weight loss through to mild weight gain. Percentage weight change was not associated with change in the lateral tibial (p=0.93) or patella (p=0.32) cartilage volumes. Percentage weight change was associated with change in all WOMAC subscales (all p≤0.01): pain (ß -1.8 mm, 95% CI -3.2 to -0.4 mm), stiffness (ß -1.6 mm, 95% CI -2.5 to -0.7 mm) and function (ß -6.9 mm, 95% CI -11.6 to -2.1 mm). CONCLUSIONS: The linearity of effect implies that weight loss is associated with reduced medial cartilage volume loss and improved knee symptoms, while weight gain is associated with increased medial cartilage volume loss and worse knee symptoms. These results suggest that in obese people, small amounts of weight change may have the potential for a disease modifying effect on both knee joint structure and symptoms. While weight loss is an important primary management strategy in obese individuals, avoidance of further weight gain should also be a clinical goal.

Reanalysis of cluster randomised trial data to account for exposure misclassification using a per-protocol and complier-restricted approach.

The intention-to-treat (ITT) analysis of the Applying Wolbachia to Eliminate Dengue (AWED) trial estimated a protective efficacy of 77.1% for participants resident in areas randomised to receive releases of wMel-infected Aedes aegypti mosquitoes, an emerging dengue preventive intervention. The limiting assumptions of ITT analyses in cluster randomised trials and the mobility of mosquitoes and humans across cluster boundaries indicate the primary analysis is likely to underestimate the full public health benefit. Using spatiotemporally-resolved data on the distribution of Wolbachia mosquitoes and on the mobility of AWED participants (n = 6306), we perform complier-restricted and per-protocol re-examinations of the efficacy of the Wolbachia intervention. Increased intervention efficacy was estimated in all analyses by the refined exposure measures. The complier-restricted analysis returned an estimated efficacy of 80.7% (95% CI 65.9, 89.0) and the per-protocol analysis estimated 82.7% (71.7, 88.4) efficacy when comparing participants with an estimated wMel exposure of ≥ 80% compared to those with <20%. These reanalyses demonstrate how human and mosquito movement can lead to underestimation of intervention effects in trials of vector interventions and indicate that the protective efficacy of Wolbachia is even higher than reported in the primary trial results.

Successful introgression of wMel Wolbachia into Aedes aegypti populations in Fiji, Vanuatu and Kiribati.

Pacific Island countries have experienced periodic dengue, chikungunya and Zika outbreaks for decades. The prevention and control of these mosquito-borne diseases rely heavily on control of Aedes aegypti mosquitoes, which in most settings are the primary vector. Introgression of the intracellular bacterium Wolbachia pipientis (wMel strain) into Ae. aegypti populations reduces their vector competence and consequently lowers dengue incidence in the human population. Here we describe successful area-wide deployments of wMel-infected Ae. aegypti in Suva, Lautoka, Nadi (Fiji), Port Vila (Vanuatu) and South Tarawa (Kiribati). With community support, weekly releases of wMel-infected Ae. aegypti mosquitoes for between 2 to 5 months resulted in wMel introgression in nearly all locations. Long term monitoring confirmed a high, self-sustaining prevalence of wMel infecting mosquitoes in almost all deployment areas. Measurement of public health outcomes were disrupted by the Covid19 pandemic but are expected to emerge in the coming years.

Applying the standardized infection ratio for reporting surgical site infections in Australian healthcare facilities.

Objective: We explored the utility of the standardized infection ratio (SIR) for surgical site infection (SSI) reporting in an Australian jurisdiction. Design: Retrospective chart review. Setting: Statewide SSI surveillance data from 2013 to 2019. Patients: Individuals who had cardiac bypass surgery (CABG), colorectal surgery (COLO), cesarean section (CSEC), hip prosthesis (HPRO), or knee prosthesis (KPRO) procedures. Methods: The SIR was calculated by dividing the number of observed infections by the number of predicted infections as determined using the National Healthcare Safety Network procedure-specific risk models. In line with a minimum precision criterion, an SIR was not calculated if the number of predicted infections was <1. Results: A SIR >0 (≥1 observed SSI, predicted number of SSI ≥1, no missing covariates) could be calculated for a median of 89.3% of reporting quarters for CABG, 75.0% for COLO, 69.0% for CSEC, 0% for HPRO, and 7.1% for KPRO. In total, 80.6% of the reporting quarters, when the SIR was not calculated, were due to no observed infections or predicted infections <1, and 19.4% were due to missing covariates alone. Within hospitals, the median percentage of quarters during which zero infections were observed was 8.9% for CABG, 20.0% for COLO, 25.4% for CSEC, 67.3% for HPRO, and 71.4% for KPRO. Conclusions: Calculating an SIR for SSIs is challenging for hospitals in our regional network, primarily because of low event numbers and many facilities with predicted infections <1. Our SSI reporting will continue to use risk-indexed rates, in tandem with SIR values when predicted number of SSI ≥1.

Impact of randomised wmel Wolbachia deployments on notified dengue cases and insecticide fogging for dengue control in Yogyakarta City.

BACKGROUND: Releases of Wolbachia (wMel)-infected Aedes aegypti mosquitoes significantly reduced the incidence of virologically confirmed dengue in a previous cluster randomised trial in Yogyakarta City, Indonesia. Following the trial, wMel releases were extended to the untreated control areas, to achieve city-wide coverage of Wolbachia. OBJECTIVE: In this predefined analysis, we evaluated the impact of the wMel deployments in Yogyakarta on dengue hemorrhagic fever (DHF) case notifications and on the frequency of perifocal insecticide spraying by public health teams. METHODS: Monthly counts of DHF cases notified to the Yogyakarta District Health Office between January 2006 and May 2022 were modelled as a function of time-varying local wMel treatment status (fully- and partially-treated vs untreated, and by quintile of wMel prevalence). The frequency of insecticide fogging in wMel-treated and untreated areas was analysed using negative binomial regression. RESULTS: Notified DHF incidence was 83% lower in fully treated vs untreated periods (IRR 0.17 [95% CI 0.14, 0.20]), and 78% lower in areas with 80-100% wMel prevalence compared to areas with 0-20% wMel (IRR 0.23 [0.17, 0.30]). A similar intervention effect was observed at 60-80% wMel prevalence as at 80-100% prevalence (76% vs 78% efficacy, respectively). Pre-intervention, insecticide fogging occurred at similar frequencies in areas later randomised to wMel-treated and untreated arms of the trial. After wMel deployment, fogging occurred significantly less frequently in treated areas (IRR 0.17 [0.10, 0.30]). CONCLUSIONS: Deployments of wMel-infected Aedes aegypti mosquitoes resulted in an 83% reduction in the application of perifocal insecticide spraying, consistent with lower dengue case notifications in wMel-treated areas. These results show that the Wolbachia intervention effect demonstrated previously in a cluster randomised trial was also measurable from routine surveillance data.

Reduced dengue incidence following city-wide wMel Wolbachia mosquito releases throughout three Colombian cities: Interrupted time series analysis and a prospective case-control study.

BACKGROUND: The introduction of Wolbachia (wMel strain) into Aedes aegypti mosquitoes reduces their capacity to transmit dengue and other arboviruses. Randomised and non-randomised studies in multiple countries have shown significant reductions in dengue incidence following field releases of wMel-infected Ae. aegypti. We report the public health outcomes from phased, large-scale releases of wMel-Ae. aegypti mosquitoes throughout three contiguous cities in the Aburrá Valley, Colombia. METHODOLOGY/PRINCIPAL FINDINGS: Following pilot releases in 2015-2016, staged city-wide wMel-Ae. aegypti deployments were undertaken in the cities of Bello, Medellín and Itagüí (3.3 million people) between October 2016 and April 2022. The impact of the Wolbachia intervention on dengue incidence was evaluated in two parallel studies. A quasi-experimental study using interrupted time series analysis showed notified dengue case incidence was reduced by 95% in Bello and Medellín and 97% in Itagüí, following establishment of wMel at ≥60% prevalence, compared to the pre-intervention period and after adjusting for seasonal trends. A concurrent clinic-based case-control study with a test-negative design was unable to attain the target sample size of 63 enrolled virologically-confirmed dengue (VCD) cases between May 2019 and December 2021, consistent with low dengue incidence throughout the Aburrá Valley following wMel deployments. Nevertheless, VCD incidence was 45% lower (OR 0.55 [95% CI 0.25, 1.17]) and combined VCD/presumptive dengue incidence was 47% lower (OR 0.53 [95% CI 0.30, 0.93]) among participants resident in wMel-treated versus untreated neighbourhoods. CONCLUSIONS/SIGNIFICANCE: Stable introduction of wMel into local Ae. aegypti populations was associated with a significant and sustained reduction in dengue incidence across three Colombian cities. These results from the largest contiguous Wolbachia releases to-date demonstrate the real-world effectiveness of the method across large urban populations and, alongside previously published results, support the reproducibility of this effectiveness across different ecological settings. TRIAL REGISTRATION: NCT03631719.

Disruption of spatiotemporal clustering in dengue cases by wMel Wolbachia in Yogyakarta, Indonesia.

Dengue exhibits focal clustering in households and neighborhoods, driven by local mosquito population dynamics, human population immunity, and fine scale human and mosquito movement. We tested the hypothesis that spatiotemporal clustering of homotypic dengue cases is disrupted by introduction of the arbovirus-blocking bacterium Wolbachia (wMel-strain) into the Aedes aegypti mosquito population. We analysed 318 serotyped and geolocated dengue cases (and 5921 test-negative controls) from a randomized controlled trial in Yogyakarta, Indonesia of wMel deployments. We find evidence of spatial clustering up to 300 m among the 265 dengue cases (3083 controls) in the untreated trial arm. Participant pairs enrolled within 30 days and 50 m had a 4.7-fold increase (compared to 95% CI on permutation-based null distribution: 0.1, 1.2) in the odds of being homotypic (i.e. potentially transmission-related) as compared to pairs occurring at any distance. In contrast, we find no evidence of spatiotemporal clustering among the 53 dengue cases (2838 controls) resident in the wMel-treated arm. Introgression of wMel Wolbachia into Aedes aegypti mosquito populations interrupts focal dengue virus transmission leading to reduced case incidence; the true intervention effect may be greater than the 77% efficacy measured in the primary analysis of the Yogyakarta trial.

Aedes aegypti abundance and insecticide resistance profiles in the Applying Wolbachia to Eliminate Dengue trial.

The Applying Wolbachia to Eliminate Dengue (AWED) trial was a parallel cluster randomised trial that demonstrated Wolbachia (wMel) introgression into Ae. aegypti populations reduced dengue incidence. In this predefined substudy, we compared between treatment arms, the relative abundance of Ae. aegypti and Ae. albopictus before, during and after wMel-introgression. Between March 2015 and March 2020, 60,084 BG trap collections yielded 478,254 Ae. aegypti and 17,623 Ae. albopictus. Between treatment arms there was no measurable difference in Ae. aegypti relative abundance before or after wMel-deployments, with a count ratio of 0.96 (95% CI 0.76, 1.21) and 1.00 (95% CI 0.85, 1.17) respectively. More Ae. aegypti were caught per trap per week in the wMel-intervention arm compared to the control arm during wMel deployments (count ratio 1.23 (95% CI 1.03, 1.46)). Between treatment arms there was no measurable difference in the Ae. albopictus population size before, during or after wMel-deployment (overall count ratio 1.10 (95% CI 0.89, 1.35)). We also compared insecticide resistance phenotypes of Ae. aegypti in the first and second years after wMel-deployments. Ae. aegypti field populations from wMel-treated and untreated arms were similarly resistant to malathion (0.8%), permethrin (1.25%) and cyfluthrin (0.15%) in year 1 and year 2 of the trial. In summary, we found no between-arm differences in the relative abundance of Ae. aegypti or Ae. albopictus prior to or after wMel introgression, and no between-arm difference in Ae. aegypti insecticide resistance phenotypes. These data suggest neither Aedes abundance, nor insecticide resistance, confounded the epidemiological outcomes of the AWED trial.

Effectiveness of Wolbachia-infected mosquito deployments in reducing the incidence of dengue and other Aedes-borne diseases in Niterói, Brazil: A quasi-experimental study.

BACKGROUND: The introduction of the bacterium Wolbachia (wMel strain) into Aedes aegypti mosquitoes reduces their capacity to transmit dengue and other arboviruses. Evidence of a reduction in dengue case incidence following field releases of wMel-infected Ae. aegypti has been reported previously from a cluster randomised controlled trial in Indonesia, and quasi-experimental studies in Indonesia and northern Australia. METHODOLOGY/PRINCIPAL FINDINGS: Following pilot releases in 2015-2016 and a period of intensive community engagement, deployments of adult wMel-infected Ae. aegypti mosquitoes were conducted in Niterói, Brazil during 2017-2019. Deployments were phased across four release zones, with a total area of 83 km2 and a residential population of approximately 373,000. A quasi-experimental design was used to evaluate the effectiveness of wMel deployments in reducing dengue, chikungunya and Zika incidence. An untreated control zone was pre-defined, which was comparable to the intervention area in historical dengue trends. The wMel intervention effect was estimated by controlled interrupted time series analysis of monthly dengue, chikungunya and Zika case notifications to the public health surveillance system before, during and after releases, from release zones and the control zone. Three years after commencement of releases, wMel introgression into local Ae. aegypti populations was heterogeneous throughout Niterói, reaching a high prevalence (>80%) in the earliest release zone, and more moderate levels (prevalence 40-70%) elsewhere. Despite this spatial heterogeneity in entomological outcomes, the wMel intervention was associated with a 69% reduction in dengue incidence (95% confidence interval 54%, 79%), a 56% reduction in chikungunya incidence (95%CI 16%, 77%) and a 37% reduction in Zika incidence (95%CI 1%, 60%), in the aggregate release area compared with the pre-defined control area. This significant intervention effect on dengue was replicated across all four release zones, and in three of four zones for chikungunya, though not in individual release zones for Zika. CONCLUSIONS/SIGNIFICANCE: We demonstrate that wMel Wolbachia can be successfully introgressed into Ae. aegypti populations in a large and complex urban setting, and that a significant public health benefit from reduced incidence of Aedes-borne disease accrues even where the prevalence of wMel in local mosquito populations is moderate and spatially heterogeneous. These findings are consistent with the results of randomised and non-randomised field trials in Indonesia and northern Australia, and are supportive of the Wolbachia biocontrol method as a multivalent intervention against dengue, chikungunya and Zika.