Community-serving research addressing climate change impacts on vector-borne diseases.

The impacts of climate change on vector-borne diseases are uneven across human populations. This pattern reflects the effect of changing environments on the biology of transmission, which is also modulated by social and other inequities. These disparities are also linked to research outcomes that could be translated into tools for transmission reduction, but are not necessarily actionable in the communities where transmission occurs. The transmission of vector-borne diseases could be averted by developing research that is both hypothesis-driven and community-serving for populations affected by climate change, where local communities interact as equal partners with scientists, developing and implementing research projects with the aim of improving community health. In this Personal View, we share five principles that have guided our research practice to serve the needs of communities affected by vector-borne diseases.

Spatiotemporal Analysis of Malaria Transmission in the Autonomous Indigenous Regions of Panama, Central America, 2015-2022.

Despite ongoing efforts for elimination, malaria continues to be a major public health problem in the Republic of Panama. For effective elimination, it is key that malaria foci and areas of high transmission are identified in a timely manner. Here, we study malaria transmission records for the 2015-2022 period, a time when cases have increased by a factor of ten. Using several methods to study spatial and spatiotemporal malaria confirmed case clusters at the level of localities, including LISA and scan, we found that cases are clustered across indigenous villages located within the autonomous indigenous regions of Ngäbe-Buglé, Guna Yala, and Embera, with the latter on the eastern border of Panama (with Colombia). We discuss the different factors that might be shaping the marked increase in malaria transmission associated with these clusters, which include an inflow of malaria-exposed migrating populations hoping to reach the USA, insufficient health services, and the lack of culturally sensitive actionable tools to reduce malaria exposure among the ethnically diverse and impoverished indigenous populations of Panama.

Chemical control of medically important arthropods in Panama: A systematic literature review of historical efforts.

Vector-borne diseases are a major source of morbidity in Panama. Herein, we describe historical usage patterns of synthetic insecticides to control arthropod disease vectors in this country. We examine the influence of interventions by vector control programs on the emergence of insecticide resistance. Chemical control has traditionally focused on two mosquito species: Anopheles albimanus, a major regional malaria vector, and Aedes aegypti, a historical vector of yellow fever, and current vector of dengue, chikungunya, and Zika. Countrywide populations of An. albimanus depict hyperirritability to organochlorine insecticides administered by indoor residual spraying, although they appear susceptible to these insecticides in bioassays settings, as well as to organophosphate and carbamate insecticides in field tests. Populations of Ae. aegypti show resistance to pyrethroids, particularly in areas near Panama City, but the spread of resistance remains unknown in Ae. aegypti and Aedes albopictus. A One Health approach is needed in Panama to pinpoint the insecticide resistance mechanisms including the frequency of knockdown mutations and behavioral plasticity in populations of Anopheles and Aedes mosquitoes. This information is necessary to guide the sustainable implementation of chemical control strategies and the use of modern vector control technologies such as genetically modified mosquitoes, and endosymbiont Wolbachia-based biological control.

Results of intrastromal corneal ring implantation in advanced keratoconus With the aim of postpoing or avoiding corneal transplantation.

PURPOSE: To evaluate the safety and efficacy of the surgery of intracorneal ring segment implantation with 320° of arc (320-ICRS) in patients with advanced keratoconus stage IV and maximum keratometry (Kmax) above 60 D. METHODS: A prospective, interventional case series study evaluating 25 eyes of 19 patients with keratoconus stage IV and Kmax > 60D in which 320-ICRS were implanted using VisuMax® femtosecond. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometric values (mean - mean-K, flat - K1, and steep - K2), maximum keratometry (Kmax), tomographic astigmatism, refractive astigmatism and asphericity (Q) were assessed preoperatively and at 3, 6 and 12 months after the procedure. RESULTS: The UDVA improved from 1.03 ± 0.28 LogMAR (20/200) to 0.54 ± 0.21 LogMAR (20/60), (p < 0.001), the CDVA (with glasses) improved from 0.63 ± 0.29 LogMAR (20/80) to 0.31 ± 0.16 LogMAR (20/40),(p = 0.004), K1 reduced from 54.41 ± 4.46 D to 49.36 ± 4.11 D (p < 0.001), K2 reduced from 61.15 ± 4.37 D to 53.715 ± 4.05 D, (p < 0.001), mean-K reduced from 57.55 ± 4,17 D to 51.44 ± 3,94 D (p < 0.001), Kmax reduced from 69.80 ± 8.20 D to 63.43 ± 6.31 D (p < 0.001) and asphericity (Q) changed from -1.57 ± 0.35 to -0.77 ± 0.56 (p < 0.001). A total of 89.9% patients reached BCVA wearing scleral contact lens  0.2 LogMAR(20/25). CONCLUSION: 320-ICRS to treat advanced keratoconus appears to be an efficacious and safe procedure, being a surgical alternative to delay or even prevent corneal transplantation.

Trypanosoma cruzi infection in dogs along the US-Mexico border: R0 changes with vector species composition.

Infection with Trypanosoma cruzi, etiological agent of Chagas disease, is common in US government working dogs along the US-Mexico border. This 3145 km long border comprises four states: Texas (TX), New Mexico (NM), Arizona (AZ) and California (CA) with diverse ecosystems and several triatomine (a.k.a., kissing bug) species, primary vectors of T. cruzi in this region. The kissing bug (Heteroptera: Reduviidae) community ranging from CA to TX includes Triatoma protracta (Uhler), Triatoma recurva (Stål) and Triatoma rubida (Uhler) and becomes dominated by Triatoma gerstaeckeri Stål in TX. Here, we ask if T. cruzi infection dynamics in dogs varies along this border region, potentially reflecting changes in vector species and their vectorial capacity. Using reversible catalytic models of infection, where seropositivity can be lost, we estimated an R0 (Estimate ± S.E.) of 1.192 ± 0.084 for TX and NM. In contrast, seropositivity decayed to zero as dogs aged in AZ and CA. These results suggest that dogs are likely infected by T. cruzi during their training in western TX, with a force of infection large enough for keeping R0 above 1, i.e., the disease endemically established, in TX and NM. In AZ and CA, a lower force of infection, probably associated with different vector species communities and associated vectorial capacity and/or different lineages of T. cruzi, results in dogs decreasing their seropositivity with age.

Ecological predictors of mosquito population and arbovirus transmission synchrony estimates.

Quantifying synchrony in species population fluctuations and determining its driving factors can inform multiple aspects of ecological and epidemiological research and policy decisions. We examined seasonal mosquito and arbovirus surveillance data collected in Connecticut, United States from 2001 to 2020 to quantify spatial relationships in 19 mosquito species and 7 arboviruses timeseries accounting for environmental factors such as climate and land cover characteristics. We determined that mosquito collections, on average, were significantly correlated up to 10 km though highly variable among the examined species. Few arboviruses displayed any synchrony and significant maximum correlated distances never exceeded 5 km. After accounting for distance, mixed effects models showed that mosquito or arbovirus identity explained more variance in synchrony estimates than climate or land cover factors. Correlated mosquito collections up to 10-20 km suggest that mosquito control operations for nuisance and disease vectors alike must expand treatment zones to regional scales for operations to have population-level impacts. Species identity matters as well, and some mosquito species will require much larger treatment zones than others. The much shorter correlated detection distances for arboviruses reinforce the notion that focal-level processes drive vector-borne pathogen transmission dynamics and risk of spillover into human populations.

When might host heterogeneity drive the evolution of asymptomatic, pandemic coronaviruses?

Controlling many infectious diseases, including SARS-Coronavirus-2 (SARS-CoV-2), requires surveillance followed by isolation, contact-tracing and quarantining. These interventions often begin by identifying symptomatic individuals. However, actively removing pathogen strains causing symptomatic infections may inadvertently select for strains less likely to cause symptomatic infections. Moreover, a pathogen's fitness landscape is structured around a heterogeneous host pool; uneven surveillance efforts and distinct transmission risks across host classes can meaningfully alter selection pressures. Here, we explore this interplay between evolution caused by disease control efforts and the evolutionary consequences of host heterogeneity. Using an evolutionary epidemiology model parameterized for coronaviruses, we show that intense symptoms-driven disease control selects for asymptomatic strains, particularly when these efforts are applied unevenly across host groups. Under these conditions, increasing quarantine efforts have diverging effects. If isolation alone cannot eradicate, intensive quarantine efforts combined with uneven detections of asymptomatic infections (e.g., via neglect of some host classes) can favor the evolution of asymptomatic strains. We further show how, when intervention intensity depends on the prevalence of symptomatic infections, higher removal efforts (and isolating symptomatic cases in particular) more readily select for asymptomatic strains than when these efforts do not depend on prevalence. The selection pressures on pathogens caused by isolation and quarantining likely lie between the extremes of no intervention and thoroughly successful eradication. Thus, analyzing how different public health responses can select for asymptomatic pathogen strains is critical for identifying disease suppression efforts that can effectively manage emerging infectious diseases. Supplementary Information: The online version contains supplementary material available at 10.1007/s11071-022-07548-7.

Land reversion and zoonotic spillover risk.

Deforestation alters wildlife communities and modifies human-wildlife interactions, often increasing zoonotic spillover potential. When deforested land reverts to forest, species composition differences between primary and regenerating (secondary) forest could alter spillover risk trajectory. We develop a mathematical model of land-use change, where habitats differ in their relative spillover risk, to understand how land reversion influences spillover risk. We apply this framework to scenarios where spillover risk is higher in deforested land than mature forest, reflecting higher relative abundance of highly competent species and/or increased human-wildlife encounters, and where regenerating forest has either very low or high spillover risk. We find the forest regeneration rate, the spillover risk of regenerating forest relative to deforested land, and how rapidly regenerating forest regains attributes of mature forest determine landscape-level spillover risk. When regenerating forest has a much lower spillover risk than deforested land, reversion lowers cumulative spillover risk, but instaneous spillover risk peaks earlier. However, when spillover risk is high in regenerating and cleared habitats, landscape-level spillover risk remains high, especially when cleared land is rapidly abandoned then slowly regenerates to mature forest. These results suggest that proactive wildlife management and awareness of human exposure risk in regenerating forests could be important tools for spillover mitigation.

Bess Beetle (Coleoptera: Passalidae) Species Composition Across the Altitudinal Gradient of Montecristo National Park, El Salvador.

Bess beetle species tend to be endemic and are useful indicators for the designation of conservation areas. However, little is known about the diversity and distribution of these beetles in El Salvador. Here, we present results from a study testing if species segregated along the altitudinal gradient of Montecristo National Park, El Salvador. The survey was done between September and December 2015. Beetles were collected at nine transects from three ecosystems, which included cloud, mixed-pine, and dry forests that occur along the altitudinal gradient of Montecristo. We sampled a total of 696 trees, finding 79 galleries of bess beetles, belonging to 13 species, which included: Arrox agassizi (Kaup), Chondrocephalus granulifrons (Bates), Chondrocephalus sp., Chondrocephalus salvadorae (Schuster), Heliscus eclipticus (Truqui), Odontotaenius striatopunctatus (Percheron), Ogyges politus (Hincks), Oileus sargi (Kaup), Passalus punctatostriatus Percheron, Passalus punctiger Lepeletier & Audinet-Serville, Verres hageni Kaup, Vindex sculptilis Bates, and Chondrocephalus gemmae Reyes-Castillo & Castillo which is a new species record for El Salvador. We found that species segregated by altitude, with the highest species richness observed in the cloud forest (n = 6), followed by the dry (n = 5) and mixed pine-oak (n = 4) forests. Most species were randomly associated with different tree species trunks, with the exception of V. hageni which was associated with trunks of Cecropia sp. Loefl. (Rosales: Urticaceae), and P. punctastriatus and P. punctiger which were associated with trunks of Cordia alliodora (Ruiz & Pav.) Oken (Boraginales: Boraginaceae). Our results show that species segregate by habitat, as only two species (C. gemmae and H. eclipticus) were found in more than one ecosystem.

Anopheles albimanus (Diptera: Culicidae) Ensemble Distribution Modeling: Applications for Malaria Elimination.

In the absence of entomological information, tools for predicting Anopheles spp. presence can help evaluate the entomological risk of malaria transmission. Here, we illustrate how species distribution models (SDM) could quantify potential dominant vector species presence in malaria elimination settings. We fitted a 250 m resolution ensemble SDM for Anopheles albimanus Wiedemann. The ensemble SDM included predictions based on seven different algorithms, 110 occurrence records and 70 model projections. SDM covariates included nine environmental variables that were selected based on their importance from an original set of 28 layers that included remotely and spatially interpolated locally measured variables for the land surface of Costa Rica. Goodness of fit for the ensemble SDM was very high, with a minimum AUC of 0.79. We used the resulting ensemble SDM to evaluate differences in habitat suitability (HS) between commercial plantations and surrounding landscapes, finding a higher HS in pineapple and oil palm plantations, suggestive of An. albimanus presence, than in surrounding landscapes. The ensemble SDM suggested a low HS for An. albimanus at the presumed epicenter of malaria transmission during 2018-2019 in Costa Rica, yet this vector was likely present at the two main towns also affected by the epidemic. Our results illustrate how ensemble SDMs in malaria elimination settings can provide information that could help to improve vector surveillance and control.

Trade, uneven development and people in motion: Used territories and the initial spread of COVID-19 in Mesoamerica and the Caribbean.

Mesoamerica and the Caribbean form a region comprised by middle- and low-income countries affected by the COVID-19 pandemic differently. Here, we ask whether the spread of COVID-19, measured using early epidemic growth rates (r), reproduction numbers (R t ), accumulated cases, and deaths, is influenced by how the 'used territories' across the regions have been differently shaped by uneven development, human movement and trade differences. Using an econometric approach, we found that trade openness increased cases and deaths, while the number of international cities connected at main airports increased r, cases and deaths. Similarly, increases in concentration of imports, a sign of uneven development, coincided with increases in early epidemic growth and deaths. These results suggest that countries whose used territory was defined by a less uneven development were less likely to show exacerbated COVID-19 patterns of transmission. Health outcomes were worst in more trade-dependent countries, even after controlling for the impact of transmission prevention and mitigation policies, highlighting how structural effects of economic integration in used territories were associated with the initial COVID-19 spread in Mesoamerica and the Caribbean.

Plasmodium vivax Genetic Diversity in Panama: Challenges for Malaria Elimination in Mesoamerica.

Panama and all nations within the Mesoamerican region have committed to eliminate malaria within this decade. With more than 90% of the malaria cases in this region caused by Plasmodium vivax, an efficient national/regional elimination plan must include a comprehensive study of this parasite's genetic diversity. Here, we retrospectively analyzed P. vivax genetic diversity in autochthonous and imported field isolates collected in different endemic regions in Panama from 2007 to 2020, using highly polymorphic markers (csp, msp-1, and msp-3α). We did the analysis using molecular techniques that are cost-effective for malaria molecular surveillance within Mesoamerica. Thus, we used molecular analyses that are feasible for malaria molecular surveillance within the region, and that can provide useful information for policy and decision making about malaria elimination. We also evaluated if haplotypes established by combining the genotypes found in these genes were associated with relevant epidemiological variables and showed structure across the transmission foci that have been observed in Panama. Ten different haplotypes were identified, some of them strongly associated with geographical origin, age, and collection year. Phylogenetic analysis of csp (central repeat domain) revealed that both major variant types (vk210 and vk247) were circulating in Panama. Variant vk247 was restricted to the eastern endemic regions, while vk210 was predominant (77.3%) and widespread, displaying higher diversity (14 alleles) and geographically biased alleles. The regional implications of these molecular findings for the control of P. vivax malaria to achieve elimination across Mesoamerica are discussed.

Aedes albopictus and Aedes flavopictus (Diptera: Culicidae) pre-imaginal abundance patterns are associated with different environmental factors along an altitudinal gradient.

Aedes (Stegomyia) albopictus (Skuse) is a major global invasive mosquito species that, in Japan, co-occurs with Aedes (Stegomyia) flavopictus Yamada, a closely related species recently intercepted in Europe. Here, we present results of a detailed 25-month long study where we biweekly sampled pupae and fourth instar larvae of these two species from ovitraps set along Mt. Konpira, Nagasaki, Japan. This setting allowed us to ask whether these species had different responses to changes in environmental variables along the altitudinal gradient of an urban hill. We found that spatially Ae. albopictus abundance decreased, while Ae. flavopictus abundance increased, the further away from urban land. Ae. flavopictus also was more abundant than Ae. albopictus in locations with homogenous vegetation growth with a high mean Enhanced Vegetation Index (EVI), platykurtic EVI, and low SD in canopy cover, while Ae. albopictus was more abundant than Ae. flavopictus in areas with more variable (high SD) canopy cover. Moreover, Ae. flavopictus abundance negatively impacted the spatial abundance of Ae. albopictus. Temporally we found that Ae. flavopictus was more likely to be present in Mt. Konpira at lower temperatures than Ae. albopictus. Our results suggest that spatial and temporal abundance patterns of these two mosquito species are partially driven by their different response to environmental factors.

Modeling the association between Aedes aegypti ovitrap egg counts, multi-scale remotely sensed environmental data and arboviral cases at Puntarenas, Costa Rica (2017-2018).

Problems with vector surveillance are a major barrier for the effective control of vector-borne disease transmission through Latin America. Here, we present results from a 80-week longitudinal study where Aedes aegypti (L.) (Diptera: Culicidae) ovitraps were monitored weekly at 92 locations in Puntarenas, a coastal city in Costa Rica with syndemic Zika, chikungunya and dengue transmission. We used separate models to investigate the association of either Ae. aegypti-borne arboviral cases or Ae. aegypti egg counts with remotely sensed environmental variables. We also evaluated whether Ae. aegypti-borne arboviral cases were associated with Ae. aegypti egg counts. Using cross-correlation and time series modeling, we found that arboviral cases were not significantly associated with Ae. aegypti egg counts. Through model selection we found that cases had a non-linear response to multi-scale (1-km and 30-m resolution) measurements of temperature standard deviation (SD) with a lag of up to 4 weeks, while simultaneously increasing with finely-grained NDVI (30-m resolution). Meanwhile, median ovitrap Ae. aegypti egg counts increased, and respectively decreased, with temperature SD (1-km resolution) and EVI (30-m resolution) with a lag of 6 weeks. A synchrony analysis showed that egg counts had a travelling wave pattern, with synchrony showing cyclic changes with distance, a pattern not observed in remotely sensed data with 30-m and 10-m resolution. Spatially, using generalized additive models, we found that eggs were more abundant at locations with higher temperatures and where EVI was leptokurtic during the study period. Our results suggest that, in Puntarenas, remotely sensed environmental variables are associated with both Ae. aegypti-borne arbovirus transmission and Ae. aegypti egg counts from ovitraps.

Plasmodium falciparum Genetic Diversity in Panamá Based on glurp, msp-1 and msp-2 Genes: Implications for Malaria Elimination in Mesoamerica.

Panamá, together with all the nations in Mesoamerica, has committed to eliminate malaria from the region by 2020. As these countries approach malaria elimination and local transmission decreases, an active molecular surveillance to identify genotypes circulating along the border areas is particularly needed to accurately infer infection origin, drug resistance and disease propagation patterns in the region. This study evaluated the genetic diversity and allele frequencies of msp-1, msp-2 and glurp genes using different molecular analyses (nested PCR, PCR-restriction fragment length polymorphism (RFLP) and sequencing) from 106 autochthonous and imported P. falciparum isolates collected from different endemic areas in Panamá between 2003 and 2019. We also explored if P. falciparum genotypes assessed with these molecular markers were associated with relevant malaria epidemiological parameters using a multiple correspondence analysis. A strong association of certain local haplotypes with their geographic distribution in endemic areas, but also with parasite load and presence of gametocytes, was evidenced. Few multiclonal infections and low genetic diversity among locally transmitted P. falciparum samples were detected, consequent with the low transmission intensity of this parasite in Panamá, a pattern likely to be extended across Mesoamerica. In addition, several imported cases were genetically dissimilar to local infections and representative of more diverse extra-continental lineages.

Clinical and Immunological Features of Human Leishmania (L.) infantum-Infection, Novel Insights Honduras, Central America.

Leishmania (Leishmania) infantum is the etiological agent of both American visceral leishmaniasis (AVL) and non-ulcerated cutaneous leishmaniasis (NUCL) in Honduras. Although AVL is the most severe clinical form of infection, recent studies have shown that human immune response to parasite infection can result in a clinical-immunological spectrum. The overall prevalence rate of infection and clinical-immunological profiles of the L. (L.) infantum infection in Amapala municipality, South Honduras was determined. We examined 576 individuals with diagnosis based on combined ELISA (IgG/IgM) and DTH assays. We also used genus-specific kDNA PCR and Hsp70 PCR-RFLP for NUCL cases. Clinical evaluation found 82% asymptomatic and 18% symptomatic individuals. All symptomatic cases (n = 104) showing NUCL were positive for parasites. We identified L. (L.) infantum species in 100% of the skin lesion scrapings and in 90% of the blood samples from NUCL cases studied. A total of 320 asymptomatic individuals were exposed (ELISA+ and/or DTH+), providing an overall L. (L.) infantum prevalence of 73.6%. Clinical, parasitological, and immunological evaluations suggest seven infection profiles, three asymptomatic and four symptomatic. This represents the first report on clinical and immunological features of human L. (L.) infantum-infection in Amapala municipality, Honduras.

Long-term transmission patterns and public health policies leading to malaria elimination in Panamá.

BACKGROUND: The present study provides a countrywide perspective of the malaria situation in Panamá over a long-term framework, with the purpose of identifying historical malaria resurgence events and their potential causes. METHODS: A descriptive-ecological study was conducted by analysing demographic and epidemiological annual malaria time series data in Panamá (1884-2019) using several data sources. Malaria intensity indicators were calculated during the study period. The effects of El Niño Southern Oscillation on malaria transmission were also analysed using a retrospective analysis of malaria cases between 1957 and 2019. RESULTS: Several factors were identified responsible for malaria resurgence in Panamá, mostly related with Malaria Control Programme weakening. During the past 20 years (2000-2019) malaria has progressively increased in prevalence within indigenous settlements, with a predominance of male cases and a high proportion (15% of total cases) in children less than 5 years old. During this period, a significant and increasing proportion of the Plasmodium falciparum cases were imported. Retrospective analysis (1957-2019) evidenced that ENSO had a significant impact on malaria transmission dynamics in Panamá. CONCLUSIONS: Data analysis confirmed that although authorities have been successful in focalizing malaria transmission in the country, there are still neglected issues to be solved and important intercultural barriers that need to be addressed in order to achieve elimination of the disease by 2022. This information will be useful for targeting strategies by the National Malaria Elimination Programme.

Synchrony of globally invasive Aedes spp. immature mosquitoes along an urban altitudinal gradient in their native range.

Mosquito-borne infections often have concerted peaks, or are synchronous, across landscapes. This phenomenon might be driven by vector responses to similar environmental conditions that synchronize their abundance. While adult mosquito populations can be synchronous over spatial scales ranging from a few meters to a few kilometers, little to nothing is known about immature mosquito synchrony, including its relationship with mosquito colonization and persistence in larval habitats. Here, we present results from a 2-yearlong synchrony study in co-occurring populations of Aedes (Stegomyia) albopictus (Skuse), Aedes (Stegomyia) flavopictus Yamada and Aedes (Finlaya) japonicus japonicus (Theobald), three invasive mosquito species, along an urban altitudinal gradient in Japan. We found that Ae. albopictus was asynchronous while Ae. flavopictus and Ae. j. japonicus had synchrony that, respectively, tracked geographic and altitudinal patterns of temperature correlation. Spatially, Ae. albopictus was more persistent at hotter locations near urban land use, while Ae. j. japonicus and Ae. flavopictus increasingly persisted farther away from urban land. Temporally, Ae. albopicus and Ae. flavopictus decreased the proportion of colonized habitats following variable rainfall, while Ae. j. japonicus increased with vegetation growth and leptokurtic temperatures. Our results support the hypothesis that immature mosquito synchrony is autonomous from dispersal and driven by common environmental conditions.

Health policy impacts on malaria transmission in Costa Rica.

Costa Rica is near malaria elimination. This achievement has followed shifts in malaria health policy. Here, we evaluate the impacts that different health policies have had on malaria transmission in Costa Rica from 1913 to 2018. We identified regime shifts and used regression models to measure the impact of different health policies on malaria transmission in Costa Rica using annual case records. We found that vector control and prophylactic treatments were associated with a 50% malaria case reduction in 1929-1931 compared with 1913-1928. DDT introduction in 1946 was associated with an increase in annual malaria case reduction from 7.6% (1942-1946) to 26.4% (1947-1952). The 2006 introduction of 7-day supervised chloroquine and primaquine treatments was the most effective health policy between 1957 and 2018, reducing annual malaria cases by 98% (2009-2018) when compared with 1957-1968. We also found that effective malaria reduction policies have been sensitive to natural catastrophes and extreme climatic events, both of which have increased malaria transmission in Costa Rica. Currently, outbreaks follow malaria importation into vulnerable areas of Costa Rica. This highlights the need to timely diagnose and treat malaria, while improving living standards, in the affected areas.

Dispersal of female and male Aedes aegypti from discarded container habitats using a stable isotope mark-capture study design in South Texas.

Aedes aegypti is the main vector of arboviral diseases such as dengue, chikungunya and Zika. A key feature for disease transmission modeling and vector control planning is adult mosquito dispersal. We studied Ae aegypti adult dispersal by conducting a mark-capture study of naturally occurring Ae. aegypti from discarded containers found along a canal that divided two residential communities in Donna, Texas, USA. Stable isotopes were used to enrich containers with either 13C or 15N. Adult mosquitoes were collected outdoors in the yards of households throughout the communities with BG Sentinel 2 traps during a 12-week period. Marked mosquito pools with stable isotopes were used to estimate the mean distance travelled using three different approaches (Net, Strip or Circular) and the probability of detecting an isotopically marked adult at different distances from the larval habitat of origin. We consistently observed, using the three approaches that male (Net: 220 m, Strip: 255 m, Circular: 250 m) Ae. aegypti dispersed further in comparison to gravid (Net: 135 m, Strip: 176 m, Circular: 189 m) and unfed females (Net: 192 m, Strip: 213 m, Circular: 198 m). We also observed that marked male capture probability slightly increased with distance, while, for both unfed and gravid females, such probability decreased with distance. Using a unique study design documenting adult dispersal from natural larval habitat, our results suggest that Ae. aegypti adults disperse longer distances than previously reported. These results may help guide local vector control authorities in their fight against Ae. aegypti and the diseases it transmits, suggesting coverage of 200 m for the use of insecticides and innovative vector control tools.