Vector control is usually designed as a top-down system with limited capacity to respond to the unique characteristics of each epidemiological setting, or to adjust to routine stressors that challenge ongoing programs, such as resource limitations and competing priorities. Here, we investigated barriers in Chagas disease vector surveillance and control systems in Arequipa, Peru. We conducted in-depth interviews and a focus group with key stakeholders (n = 32) at different levels of the health system and community. For interviews, we used process maps to illustrate the workflow for passive and active surveillance. Additionally, we held a focus group with vector control specialists to present the findings from the interviews and discuss the results. We identified barriers at each step of the process, including systemic, operational, financial, and policy limitations. For passive surveillance, community participation was limited by practical challenges in capturing the insect and uncertainty about the pathways to report it. Systemic barriers were related to the use of a data system that did not meet the needs for recording and managing data on vector control activities. At the policy level, the establishment of quotas on the number of houses staff are required to inspect ignores important determinants for infestation and lacks an appropriate sampling design. We discuss the impact of the reported barriers to effective conduction of surveillance and control activities and the initiatives and strategies that have been designed and assessed to bridge these gaps in order to collaboratively design a more resilient health system.

BACKGROUND:The city of El Pedregal grew out of a desert, following an agricultural irrigation project in southern Peru. OBJECTIVES:To describe infestation patterns by triatomines and bed bugs and their relationship to migration and urbanization. METHODS:We conducted door-to-door entomological surveys for triatomines and bed bugs. We assessed spatial clustering of infestations and compared the year of construction of infested to un-infested households. To gain a better understanding of the context surrounding triatomine infestations, we conducted in-depth interviews with residents to explore their migration histories, including previous experiences with infestation. FINDINGS:We inspected 5,164 households for Triatoma infestans (known locally as the Chirimacha); 21 (0.41%) were infested. These were extremely spatially clustered (Ripley's K p-value < 0.001 at various spatial scales). Infested houses were older than controls (Wilcoxon rank-sum: W = 33; p = 0.02). We conducted bed bug specific inspections in 34 households; 23 of these were infested. These were spatially dispersed across El Pedregal, and no difference was observed in construction age between bed bug infested houses and control houses (W = 6.5, p = 0.07). MAIN CONCLUSIONS:The establishment of agribusiness companies in a desert area demanded a permanent work force, leading to the emergence of a new city. Migrant farmers, seeking work opportunities or escaping from adverse climatic events, arrived with few resources, and constructed their houses with precarious materials. T. infestans, a Chagas disease vector, was introduced to the city and colonized houses, but its dispersal was constrained by presence of vacant houses. We discuss how changes in the socioeconomic and agricultural landscape can increase vulnerability to vector-borne illnesses.

Vector-borne diseases remain a significant public health threat in many regions of the world. Traditional vector surveillance and control methods have relied on active and passive surveillance programs, which are often costly and time-consuming. New internet-based vector surveillance systems have shown promise in removing some of the cost and labor burden from health authorities. We developed and evaluated the effectiveness of a new internet-based surveillance system, "AlertaChirimacha", for detecting Triatoma infestans (known locally by its Quechua name, Chirimacha), the Chagas disease vector, in the city of Arequipa, Peru. In the first 26 months post-implementation, AlertaChirimacha received 206 reports of residents suspecting or fearing triatomines in their homes or neighborhoods, of which we confirmed, through pictures or inspections, 11 (5.3%) to be Triatoma infestans. After microscopic examination, none of the specimens collected were infected with Trypanosoma cruzi. AlertaChirimacha received 57% more confirmed reports than the traditional surveillance system and detected 10% more infested houses than active and passive surveillance approaches combined. Through in-depth interviews we evaluate the reach, bilateral engagement, and response promptness and efficiency of AlertaChirimacha. Our study highlights the potential of internet-based vector surveillance systems, such as AlertaChirimacha, to improve vector surveillance and control efforts in resource-limited settings. This approach could decrease the cost and time horizon for the elimination of vector-mediated Chagas disease in the region.

The city of El Pedregal grew out of a desert, following an agricultural irrigation project in Southern Peru. We conducted door-to-door entomological surveys to document the emergence of triatomines and bed bugs into this new urban environment. We inspected 5,191 households for Triatoma infestans (known locally as the Chirimacha ); 21 (0.41%) were infested. These were extremely spatially clustered (Ripley’s K p-value <0.001 at various spatial scales). Using remote sensing we compared the year of construction of infested to un-infested households and found that infested houses were older than controls (Wilcoxon rank-sum: W=33; p=0.02). We confirmed infestations through a subsequent bed bug specific inspection in 34 households. These households were more spatially disperse across El Pedregal. To gain a better understanding of the context surrounding triatomine infestations, we conducted in-depth interviews with residents to explore their migration histories and previous experiences with Chirimachas . Main reasons for migration includes searching for work on land, opportunity to buying a house, and scape adverse climate effects. Permanent migration flow and poor housing conditions create suitable environment for emergence triatomine infestation. We discuss how changes in the landscape could potentially heighten vulnerability to vector-borne illnesses.Author summary Large-scale irrigation and changes in land-use have been linked with emergence of infectious disease worldwide. In El Pedregal, Southern Peru, the Majes-Siguas irrigation was designed to supply water to agribusiness companies installed in a desert area. This project has propelled a constant migration flow and the growth of this new city, promoting conditions to emergence of Triatoma infestans , an insect vector of Chagas disease, as well as bed bugs. Triatomine infestation presented a clustered pattern, its dispersion limited by unoccupied houses. Triatomine infested houses tend to be older than other houses. Bed bug infestations were more spread out, and not related to construction age. Householders’ stories of migration shed light on some of the socioeconomic determinants that promote conditions for infestation. Amongst these, living in poor housing conditions, and the constant migration flow; driven by seeking opportunities to work, to buy a house, or to escape from adverse climate effects in other farming regions. Environmental and socioeconomic impacts of large-scale development disproportionately affect vulnerable populations. Design of surveillance systems that account for these contexts is urgently needed to support early detection and control of emergence of vector-borne diseases.### Competing Interest StatementThe authors have declared no competing interest.### Funding StatementThis work was supported by the National Institute of Health [NIH-NIAID 1R01AI146129]### Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:The study was approved by the ethical review board of the Universidad Peruana Cayetano Heredia (protocol #103096), the University of Pennsylvania (protocol #833122), and the Tulane School of Public Health and Tropical Medicine (#2019-909).I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.YesAll data produced in the present study are available upon reasonable request to the authors

Background The rising incidence of visceral leishmaniasis due to Leishmania infantum requires novel methods to control transmission by the sand fly vector. Indoor residual spraying of insecticide (IRS) against these largely exophilic / exophagic vectors may not be the most effective method. A synthetic copy of the male sex-aggregation pheromone of the key vector species Lutzomyia longipalpis in the Americas, was co-located with residual pyrethroid insecticide, and tested for its effects on vector abundance, hence potential transmission, in a Brazilian community study. Methods Houses within eight defined semi-urban blocks in an endemic municipality in Brazil were randomised to synthetic pheromone + insecticide or to placebo treatments. A similar number of houses located >100m from each block were placebo treated and considered as “True Controls” (thus, analysed as three trial arms). Insecticide was sprayed on a 2.6m 2 surface area of the property boundary or outbuilding wall, co-located within one metre of 50mg synthetic pheromone in controlled-release dispensers. Vector numbers captured in nearby CDC light traps were recorded at monthly intervals over 3 months post intervention. Recruited sentinel houses under True Control and pheromone + insecticide treatments were similarly monitored at 7–9 day intervals. The intervention effects were estimated by mixed effects negative binomial models compared to the True Control group. Results Dose-response field assays using 50mg of the synthetic pheromone captured a mean 4.8 (95% C.L.: 3.91, 5.80) to 6.3 (95% C.L.: 3.24, 12.11) times more vectors (female Lu . longipalpis ) than using 10mg of synthetic pheromone. The intervention reduced household female vector abundance by 59% (C.L.: 48.7, 66.7%) (IRR = 0.41) estimated by the cross-sectional community study, and by 70% (C.L.: 56.7%, 78.8%) estimated by the longitudinal sentinel study. Similar reductions in male Lu . longipalpis were observed. Beneficial spill-over intervention effects were also observed at nearby untreated households with a mean reduction of 24% (95% C.L.: 0.050%, 39.8%) in female vectors. The spill-over effect in untreated houses was 44% (95% C.L.: 29.7%, 56.1%) as effective as the intervention in pheromone-treated houses. Ownership of chickens increased the intervention effects in both treated and untreated houses, attributed to the suspected synergistic attraction of the synthetic pheromone and chicken kairomones. The variation in IRR between study blocks was not associated with inter-household distances, household densities, or coverage (proportion of total households treated). Conclusions The study confirms the entomological efficacy of the lure-and-kill method to reduce the abundance of this important sand fly vector in treated and untreated homesteads. The outcomes were achieved by low coverage and using only 1–2% of the quantity of insecticide as normally required for IRS, indicating the potential cost-effectiveness of this method. Implications for programmatic deployment of this vector control method are discussed.

Objective Failure to control domestic Triatoma infestans in the Chaco is attributed to vulnerable adobe construction, which provides vector refuges and diminishes insecticide contact. We conducted a pilot to test the impact of housing improvement plus indoor residual spraying (IRS) on house infestation and vector abundance in a rural community in the Bolivian Chaco. Methods The intervention included three arms: housing improvement + IRS [HI], assisted IRS [AS] in which the team helped to clear the house pre-IRS and routine IRS [RS]. HI used locally available materials, traditional construction techniques and community participation. Vector parameters were assessed by Timed Manual Capture for 2 person-hours per house at baseline and medians of 114, 173, 314, 389 and 445 days post-IRS-1. A second IRS round was applied at a median of 314 days post-IRS-1. Results Post-intervention infestation indices and abundance fell in all three arms. The mean odds of infestation was 0.29 (95% CL 0.124, 0.684) in the HI relative to the RS arm. No difference was observed between AS and RS. Vector abundance was reduced by a mean 44% (24.8, 58.0) in HI compared to RS, with no difference between AS and RS. Median delivered insecticide concentrations per house were lower than the target of 50 mg/m(2) in >90% of houses in all arms. Conclusion Housing improvement using local materials and community participation is a promising strategy to improve IRS effectiveness in the Bolivian Chaco. A larger trial is needed to quantify the impact on reinfestation over time.

Background Indoor residual spraying (IRS) of insecticides is a key method to reduce vector transmission of Trypanosoma cruzi , causing Chagas disease in a large part of South America. However, the successes of IRS in the Gran Chaco region straddling Bolivia, Argentina, and Paraguay, have not equalled those in other Southern Cone countries. Aims This study evaluated routine IRS practices and insecticide quality control in a typical endemic community in the Bolivian Chaco. Methods Alpha-cypermethrin active ingredient (a.i.) captured onto filter papers fitted to sprayed wall surfaces, and in prepared spray tank solutions, were measured using an adapted Insecticide Quantification Kit (IQK™) validated against HPLC quantification methods. The data were analysed by mixed-effects negative binomial regression models to examine the delivered insecticide a.i. concentrations on filter papers in relation to the sprayed wall heights, spray coverage rates (surface area / spray time [m 2 /min]), and observed/expected spray rate ratios. Variations between health workers and householders’ compliance to empty houses for IRS delivery were also evaluated. Sedimentation rates of alpha-cypermethrin a.i. post-mixing of prepared spray tanks were quantified in the laboratory. Results Substantial variations were observed in the alpha-cypermethrin a.i. concentrations delivered; only 10.4% (50/480) of filter papers and 8.8% (5/57) of houses received the target concentration of 50 mg ± 20% a.i./m 2 . The delivered concentrations were not related to those in the matched spray tank solutions. The sedimentation of alpha-cypermethrin a.i. in the surface solution of prepared spray tanks was rapid post-mixing, resulting in a linear 3.3% loss of a.i. content per minute and 49% loss after 15 min. Only 7.5% (6/80) of houses were sprayed at the WHO recommended rate of 19 m 2 /min (± 10%), whereas 77.5% (62/80) were sprayed at a lower than expected rate. The median a.i. concentration delivered to houses was not significantly associated with the observed spray coverage rate. Householder compliance did not significantly influence either the spray coverage rates or the median alpha-cypermethrin a.i. concentrations delivered to houses. Conclusions Suboptimal delivery of IRS is partially attributable to the insecticide physical characteristics and the need for revision of insecticide delivery methods, which includes training of IRS teams and community education to encourage compliance. The IQK™ is a necessary field-friendly tool to improve IRS quality and to facilitate health worker training and decision-making by Chagas disease vector control managers. Graphical Abstract

Objective To evaluate the efficacy of a synthetic sex-aggregation pheromone of the sand fly vector Lu. longipalpis, co-located with residual insecticide, to reduce the infection incidence of Leishmania infantum in the canine reservoir. Methods A stratified cluster randomised trial was designed to detect a 50% reduction in canine incident infection after 24 months in 42 recruited clusters, randomly assigned to one of three intervention arms (14 cluster each): synthetic pheromone + insecticide, insecticide-impregnated dog collars, or placebo control. Infection incidence was measured by seroconversion to anti-Leishmania serum antibody, Leishmania parasite detection and canine tissue parasite loads. Changes in relative Lu. longipalpis abundance within households were measured by setting three CDC light traps per household. Results A total 1,454 seronegative dogs were followed-up for a median 15.2 (95% C.I.s: 14.6, 16.2) months per cluster. The pheromone + insecticide intervention provided 13% (95% C.I. 0%, 44.0%) protection against anti-Leishmania antibody seroconversion, 52% (95% C.I. 6.2%, 74·9%) against parasite infection, reduced tissue parasite loads by 53% (95% C.I. 5.4%, 76.7%), and reduced household female sand fly abundance by 49% (95% C.I. 8.2%, 71.3%). Variation in the efficacy against seroconversion varied between trial strata. Equivalent protection attributed to the impregnated-collars were 36% (95% C.I. 14.4%, 51.8%), 23% (95% C.I. 0%, 57·5%), 48% (95% C.I. 0%, 73.4%) and 43% (95% C.I. 0%, 67.9%), respectively. Comparison of the two interventions showed no statistically consistent differences in their efficacies; however, the errors were broad for all outcomes. Reductions in sand fly numbers were predominant where insecticide was located (chicken and dog sleeping sites), with no evidence of insecticide-induced repellence onto humans or dogs. Conclusion The synthetic pheromone co-located with insecticide provides protection particularly against canine L. infantum parasite transmission and sand fly vector abundance. The effect estimates are not dissimilar to those of the insecticide-impregnated collars, which are documented to reduce canine infection incidence, human infection and clinical VL disease incidence, in different global regions. The trialled novel lure-and-kill approach is a low-cost potential vector control tool against ZVL in the Americas.

Background: Screening for Trypanosoma cruzi infection was performed amongst children in a rural community in the Bolivian Chaco, an area known for high prevalence. The force of infection (FOI) was estimated. Methods: A total of 423 children attending the local school were screened using the Chagas Detect Plus (CDP) rapid test (InBios International, Inc.). CDP-positive specimens were further tested by indirect haemagglutination assay (IHA) and Wiener Recombinante v3.0 ELISA. A catalytic model was used to estimate FOI. Results: Confirmed seroprevalence was 0.22, rising steeply with age. The mean age of seropositive individuals was 13 years. The calculated specificity of the rapid test was 91.9%. The annual incidence estimated from the FOI was 0.021. Conclusions: This study demonstrates persistent transmission and continuing high levels of T. cruzi infection in the Bolivian Chaco, and highlights the practicality of school-based screening. (C) 2019 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.

Despite large-scale reductions in Chagas disease prevalence across Central and South America, Trypanosoma cruzi infection remains a considerable public health problem in the Gran Chaco region where vector-borne transmission persists. In these communities, peridomestic animals are major blood-meal sources for triatomines, and household presence of infected dogs increases T. cruzi transmission risk for humans. To address the pressing need for field-friendly, complementary methods to reduce triatomine infestation and interrupt T. cruzi transmission, this study evaluated the systemic activity of three commercial, oral, single dose insecticides Fluralaner (Bravecto®), Afoxolaner (NexGard®) and Spinosad (Comfortis®) in canine feed-through assays against Triatoma infestans, the principal domestic vector species in the Southern Cone of South America.

The aim of this study was to describe the phlebotomine sand fly fauna and its respective ecological indexes in risk zones of cutaneous leishmaniasis (CL). The study was carried out in the Municipality of Santarém, Pará State, Brazil. From the total of 102 records of CL patients in 2010 and 2011, infected with different Leishmania species, 31 were selected. Kernel density analysis was performed. CDC light traps were placed (6 p.m.-6 a.m., three nights, height of 1.5 m) in the identified risk zones (indoors, chicken sheds and surrounding forest) in two occasions: rainy and dry seasons of 2012. Shannon traps were installed in the forest during 3 h (7 p.m.-9 p.m., one night). Shannon (H'), Pielou (J') and Dominance (D) indexes were calculated and two spatial clusters (SC) of CL, SC1 (urban-rural) and SC2 (rural farm), were identified. Phlebotomines were sampled in SC1 (243) and SC2 (174). In the whole sample (417) there were 24 species of 10 genera, but only 12 species were found in both risk zones. Ecological indexes varied widely (H' = 0.5-1.72; J = 0.44-0.78; D = 0.46-0.91). The highest D values in the forest (≥ 0.75) were associated to Psychodopygus complexus during both seasons in SC1 and Psychodopygus davisi during the rainy season in SC2. Other CL vectors were identified in smaller frequence. A great diversity of phlebotomine species was described in each risk zone. The CL vectors sampled were well-matched with the Leishmania species infecting the patients. The epidemiological importance of dominant species may vary with climatic seasons and risk zones in Santarém.