El Niño Southern Oscillation (ENSO) effects on local weather, arboviral diseases, and dynamics of managed and unmanaged populations of Aedes aegypti (Diptera: Culicidae) in Puerto Rico.

We investigated the effects of interannual El Niño Southern Oscillation (ENSO) events on local weather, Aedes aegypti populations, and combined cases of dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV) viruses in 2 communities with mass mosquito trapping and 2 communities without mosquito control in southern Puerto Rico (2013-2019). Gravid adult Ae. aegypti populations were monitored weekly using Autocidal Gravid Ovitraps (AGO traps). Managing Ae. aegypti populations was done using 3 AGO traps per home in most homes. There were drought conditions in 2014-2015 concurrent with the emergence of a strong El Niño (2014-2016), wetter conditions during La Niña (2016-2018), a major hurricane (2017), and a weaker El Niño (2018-2019). The main factor explaining differences in Ae. aegypti abundance across sites was mass trapping. Populations of Ae. aegypti reached maximum seasonal values during the wetter and warmer months of the year when arbovirus epidemics occurred. El Niño was significantly associated with severe droughts that did not impact the populations of Ae. aegypti. Arbovirus cases at the municipality level were positively correlated with lagged values (5-12 mo.) of the Oceanic El Niño Index (ONI), droughts, and abundance of Ae. aegypti. The onset of strong El Niño conditions in Puerto Rico may be useful as an early warning signal for arboviral epidemics in areas where the abundance of Ae. aegypti exceeds the mosquito density threshold value.

Soft topographical patterns trigger a stiffness-dependent cellular response to contact guidance.

Topographical patterns are a powerful tool to study directional migration. Grooved substrates have been extensively used as in vitro models of aligned extracellular matrix fibers because they induce cell elongation, alignment, and migration through a phenomenon known as contact guidance. This process, which involves the orientation of focal adhesions, F-actin, and microtubule cytoskeleton along the direction of the grooves, has been primarily studied on hard materials of non-physiological stiffness. But how it unfolds when the stiffness of the grooves varies within the physiological range is less known. Here we show that substrate stiffness modulates the cellular response to topographical contact guidance. We find that for fibroblasts, while focal adhesions and actin respond to topography independently of the stiffness, microtubules show a stiffness-dependent response that regulates contact guidance. On the other hand, both clusters and single breast carcinoma epithelial cells display stiffness-dependent contact guidance, leading to more directional and efficient migration when increasing substrate stiffness. These results suggest that both matrix stiffening and alignment of extracellular matrix fibers cooperate during directional cell migration, and that the outcome differs between cell types depending on how they organize their cytoskeletons.

Surveillance and Control of Culex quinquefasciatus Using Autocidal Gravid Ovitraps.

We monitored trap captures of Culex quinquefasciatus using an interrupted time-series study to determine if autocidal gravid ovitraps (AGO traps) were useful to control the population of this mosquito species in a community in southern Puerto Rico. Data for this report came from a previous study in which we used mass trapping to control Aedes aegypti, resulting in a significant 79% reduction in numbers of this species. The AGO traps used to monitor and control Ae. aegypti also captured numerous Cx. quinquefasciatus. Culex quinquefasciatus was monitored in surveillance AGO traps from October 2011 to February 2013, followed by a mosquito control intervention from February 2013 to June 2014. Optimal captures of this mosquito occurred on the 2nd wk after the traps were set or serviced, which happened every 8 wk. Changes in collection numbers of Cx. quinquefasciatus were positively correlated with rainfall and showed oscillations every 8 wk, as revealed by sample autocorrelation analyses. Culex quinquefasciatus was attracted to and captured by AGO traps, so mass trapping caused a significant but moderate reduction of the local population (31.2%) in comparison with previous results for Ae. aegypti, possibly resulting from female mosquitoes flying in from outside of the study area and decreased attraction to the traps past the 2nd wk of trap servicing. Because Ae. aegypti and Cx. quinquefasciatus are frequently established in urban areas, mass trapping to control the former has some impact on Cx. quinquefasciatus. Control of the latter could be improved by locating and treating its aquatic habitats within and around the community.

Cemeteries as sources of Aedes aegypti and other mosquito species in southeastern Puerto Rico.

OBJECTIVE: To investigate the presence and abundance of mosquito species in containers found in different types of cemeteries in Puerto Rico to assess their importance and make control recommendations. METHODS: We conducted surveys of containers with water in 16 cemeteries in southeastern Puerto Rico to detect the presence of larvae and pupae of Aedes aegypti and other mosquitoes; to identify the most common and productive containers and to study their variation in relation to the type of cemetery. RESULTS: The most common containers with water were flowerpots, followed in abundance by a variety of discarded containers and open tombs. We found a positive relationship between density of containers with water and rainfall. There was a rich community of mosquito species developing in containers of the inspected cemeteries: nine mosquito species belonging to four genera with Ae. aegypti and Ae. mediovittatus being the most frequent and abundant. We sampled 13 cement-type cemeteries, 2 mixed and only 1 lawn cemetery, consequently, we could not draw any conclusion regarding container productivity and cemetery type. CONCLUSIONS: Surveyed cemeteries were important sources of Ae. aegypti and other mosquitoes in flowerpots, discarded containers and open tombs. We recommend conducting further studies to establish how frequently inspections should occur; and mosquito control by emptying aquatic habitats and larviciding to reduce mosquito productivity and protect workers and visitors from mosquito bites and possible transmission of arboviruses.

Multi-Year Mass-Trapping With Autocidal Gravid Ovitraps has Limited Influence on Insecticide Susceptibility in Aedes aegypti (Diptera: Culicidae) From Puerto Rico.

Mass-trapping has been used to control outbreaks of Aedes aegypti (Linnaeus) (Diptera: Culicidae) in Puerto Rico since 2011. We investigated the effect of multi-year, insecticide-free mass trapping had on the insecticide susceptibility profile of Ae. aegypti. Eggs collected in southern Puerto Rico were used to generate F1 populations that were tested for susceptibility to permethrin, sumethrin, bifenthrin, deltamethrin, and malathion according to CDC bottle bioassays protocols. All populations of Ae. aegypti were resistant to the synthetic pyrethroids and mosquitoes from two locations were partially resistant to malathion. Population genetic analysis, using a double digest restriction sites associated DNA sequencing (ddRADseq) approach, indicated a large amount of migration between study sites effectively homogenizing the mosquito populations. Mass-trapping using noninsecticidal autocidal gravid ovitraps did not restore susceptibility to five active ingredients that are found in commercial insecticides. Migration between communities was high and would have brought outside alleles, including resistant alleles to the treatment communities. Further investigation suggests that household use of commercially available insecticide products may continue to select for resistance in absence of public health space spraying of insecticides.

Improving the Safety and Acceptability of Autocidal Gravid Ovitraps (AGO Traps).

Gravid traps that collect eggs or adult mosquitoes use color, size, or volume as well as water or plant infusions as attractants. Biorational larvicides have been used to prevent these devices from producing adult mosquitoes within the traps. Results from field assays on the use of several biorational larvicides for various mosquito species have provided mixed results in terms of increased, neutral, or reduced attraction. We investigated the use of Bacillus thuringiensis var. israelensis, spinosad, and novaluron in field assays in Puerto Rico to evaluate the behavioral response of Aedes aegypti and Culex spp. to autocidal gravid ovitraps (AGO traps). The purpose of the study was to increase the safety of these traps by preventing accidental release of adult mosquitoes when traps are opened or damaged. We also investigated whether trap color (blue, green, terracotta) that may be more amenable for use by residents in their properties induced a similar attraction response to the original black trap color. We found that the use of biorational larvicides did not significantly change the behavioral attraction of these mosquito species to AGO traps. For Ae. aegypti, green traps yielded the lowest captures while black, terracotta, and blue produced similar higher yields. Culex spp. in black traps showed significantly higher captures compared with other colors. These results suggest that black, terracotta, or blue AGO traps can be used for the surveillance and control of Ae. aegypti.

Role of Abandoned and Vacant Houses on Aedes aegypti Productivity.

The control of container Aedes species by house inspections usually achieves insufficient coverage and impact because a percentage of residents are absent and some residents refuse inspections and treatments. In addition, another fraction of the buildings may be uninhabited, such as those for rent or sale, or abandoned. Although the productivity of Aedes aegypti has been investigated in abandoned lots, less is known about the importance of uninhabited buildings. We investigated Ae. aegypti pupal productivity in inhabited, vacant, and abandoned houses and its interaction with socioeconomic levels (SELs). We found pupae in containers of 386 houses (66 abandoned, 62 vacant, and 258 inhabited) in 19 neighborhoods in southern Puerto Rico from May to August 2017. Using a generalized linear model, we found a significant interaction between the status of the house (abandoned, vacant, and inhabited) and SELs (low, medium) on Ae. aegypti pupal abundance. More pupae were found in abandoned and inhabited houses of low SELs. The lowest productivity was found in vacant houses, regardless of the SEL. Most containers producing Ae. aegypti in low-SEL houses were discarded on backyards, whereas in medium SELs, most productivity came from containers in use. Septic tanks producing Ae. aegypti were found only in houses of low SELs, where most emerging mosquitoes came from inhabited houses. We did not find any pupae of Ae. aegypti on roofs. These results indicate that proper yard management could significantly reduce the production of Ae. aegypti and the risk of dengue infections in low-SEL neighborhoods.

Microfabrication of poly(acrylamide) hydrogels with independently controlled topography and stiffness.

The stiffness and topography of a cell's extracellular matrix (ECM) are physical cues that play a key role in regulating processes that determine cellular fate and function. While substrate stiffness can dictate cell differentiation lineage, migration, and self-organization, topographical features can change the cell's differentiation profile or migration ability. Although both physical cues are present and intrinsic to the native tissues in vivo, in vitro studies have been hampered by the lack of technological set-ups that would be compatible with cell culture and characterization. In vitro studies therefore either focused on screening stiffness effects in cells cultured on flat substrates or on determining topography effects in cells cultured onto hard materials. Here, we present a reliable, microfabrication method to obtain well defined topographical structures of micrometer size (5-10 µm) on soft polyacrylamide hydrogels with tunable mechanical stiffness (3-145 kPa) that closely mimic the in vivo situation. Topographically microstructured polyacrylamide hydrogels are polymerized by capillary force lithography using flexible materials as molds. The topographical microstructures are resistant to swelling, can be conformally functionalized by ECM proteins and sustain the growth of cell lines (fibroblasts and myoblasts) and primary cells (mouse intestinal epithelial cells). Our method can independently control stiffness and topography, which allows to individually assess the contribution of each physical cue to cell response or to explore potential synergistic effects. We anticipate that our fabrication method will be of great utility in tissue engineering and biophysics, especially for applications where the use of complex in vivo-like environments is of paramount importance.

Factors Modulating Captures of Gravid Aedes aegypti Females.

To improve detection and assessment of Aedes aegypti abundance, we investigated whether microhabitat factors of the location of autocidal gravid ovitraps (AGO traps) influenced captures of gravid females in 2 locations in southern Puerto Rico. One location had been under vector control for several years using mass AGO trapping (intervention site), where Ae. aegypti abundance was several times lower than in the other study site without mosquito control (nonintervention site). We observed 10 environmental factors describing trap microhabitat location, and monitored water volume and minimum, maximum, and average temperature in AGO traps. Air temperature, relative humidity, and rainfall were recorded at each site. We conducted a hot-spot analysis of AGO traps to understand whether trap captures were influenced by the local abundance of mosquitoes rather than or in addition to trap microhabitat factors. AGO traps were classified using a 2-step cluster analysis based on attributes of trap microhabitats, water temperature, and water volume. Captures of female Ae. aegypti in each cluster per site were compared between resulting clusters to determine whether trap microhabitat factors defining the clusters were associated with trap captures. Trap captures in both study sites were mostly correlated with captures in nearby traps regardless of trap microhabitat factors, possibly reflecting the influence of the spatial aggregation of mosquitoes coming from nearby aquatic habitats or the concentration of dispersing adults. These results indicated that AGO traps can be located at places that can be easily reached during periodic inspections, such as in front of houses, without much regard to local microhabitat conditions.

Autocidal gravid ovitraps protect humans from chikungunya virus infection by reducing Aedes aegypti mosquito populations.

BACKGROUND: Public health responses to outbreaks of dengue, chikungunya, and Zika virus have been stymied by the inability to control the primary vector, Aedes aegypti mosquitos. Consequently, the need for novel approaches to Aedes vector control is urgent. Placement of three autocidal gravid ovitraps (AGO traps) in ~85% of homes in a community was previously shown to sustainably reduce the density of female Ae. aegypti by >80%. Following the introduction of chikungunya virus (CHIKV) to Puerto Rico, we conducted a seroprevalence survey to estimate the prevalence of CHIKV infection in communities with and without AGO traps and evaluate their effect on reducing CHIKV transmission. METHODS AND FINDINGS: Multivariate models that calculated adjusted prevalence ratios (aPR) showed that among 175 and 152 residents of communities with and without AGO traps, respectively, an estimated 26.1% and 43.8% had been infected with CHIKV (aPR = 0.50, 95% CI: 0.37-0.91). After stratification by time spent in their community, protection from CHIKV infection was strongest among residents who reported spending many or all weekly daytime hours in their community:10.3% seropositive in communities with AGO traps vs. 48.7% in communities without (PR = 0.21, 95% CI: 0.11-0.41). The age-adjusted rate of fever with arthralgia attributable to CHIKV infection was 58% (95% CI: 46-66%). The monthly number of CHIKV-infected mosquitos and symptomatic residents were diminished in communities with AGO traps compared to those without. CONCLUSIONS: These findings indicate that AGO traps are an effective tool that protects humans from infection with a virus transmitted by Ae. aegypti mosquitos. Future studies should evaluate their protective effectiveness in large, urban communities.

Impacts of Hurricanes Irma and Maria on Aedes aegypti Populations, Aquatic Habitats, and Mosquito Infections with Dengue, Chikungunya, and Zika Viruses in Puerto Rico.

Puerto Rico was severely impacted by Hurricanes Irma and Maria in September 2017. The island has been endemic for dengue viruses (DENV) and recently suffered epidemics of chikungunya (CHIKV 2014) and Zika (ZIKV 2016) viruses. Although severe storms tend to increase the number of vector and nuisance mosquitoes, we do not know how they influence Aedes aegypti populations and arboviral transmission. We compared the abundance of female Ae. aegypti in autocidal gravid ovitraps (AGO traps), container habitats, and presence of RNA of DENV, CHIKV, and ZIKV in this vector before and after the hurricanes in Caguas city and in four communities in southern Puerto Rico. Two of these communities were under vector control using mass AGO trapping and the other two nearby communities were not. We also investigated mosquito species composition and relative abundance (females/trap) using Biogents traps (BG-2 traps) in 59 sites in metropolitan San Juan city after the hurricanes. Mosquitoes sharply increased 5 weeks after Hurricane Maria. Ensuing abundance of Ae. aegypti was higher in Caguas and in one of the southern communities without vector control. Aedes aegypti did not significantly change in the two areas with vector control. The most abundant mosquitoes among the 26 species identified in San Juan were Culex (Melanoconion) spp., Culex quinquefasciatus, Culex nigripalpus, and Ae. aegypti. No arboviruses were detected in Ae. aegypti following the hurricanes, in contrast with observations from the previous year, so that the potential for Aedes-borne arboviral outbreaks following the storms in 2017 was low.

Citywide Control of Aedes aegypti (Diptera: Culicidae) during the 2016 Zika Epidemic by Integrating Community Awareness, Education, Source Reduction, Larvicides, and Mass Mosquito Trapping.

This investigation was initiated to control Aedes aegypti and Zika virus transmission in Caguas City, Puerto Rico, during the 2016 epidemic using Integrated Vector Management (IVM), which included community awareness and education, source reduction, larviciding, and mass-trapping with autocidal gravid ovitraps (AGO). The epidemic peaked in August to October 2016 and waned after April 2017. There was a preintervention period in October/November 2016 and IVM lasted until August 2017. The area under treatment (23.1 km2) had 61,511 inhabitants and 25,363 buildings. The city was divided into eight even clusters and treated following a cluster randomized stepped-wedge design. We analyzed pools of female Ae. aegypti adults for RNA detection of dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV) viruses using 360 surveillance AGO traps every week. Rainfall, temperature, and relative humidity were monitored in each cluster. Mosquito density significantly changed (generalized linear mixed model; F8, 14,588 = 296; P < 0.001) from 8.0 ± 0.1 females per trap per week before the intervention to 2.1 ± 0.04 after the percentage of buildings treated with traps was 60% and to 1.4 ± 0.04 when coverage was above 80%. Out of a total 12,081 mosquito pools, there were 1 DENV-, 7 CHIKV-, and 49 ZIKV-positive pools from October 2016 to March 2017. Afterward, we found only one positive pool of DENV in July 2017. This investigation demonstrated that it was possible to scale up effective Ae. aegypti control to a medium-size city through IVM that included mass trapping of gravid Ae. aegypti females.

Integrated vector control of Aedes aegypti mosquitoes around target houses.

BACKGROUND: The developing fetuses of pregnant women are at high risk of developing serious birth defects following Zika virus infections. We applied an Integrated Vector Control (IVC) approach using source reduction, larviciding, and mass trapping with non-insecticidal sticky traps to protect targeted houses by reducing the density of female Aedes aegypti mosquitoes. METHODS: We tested the hypothesis that Ae. aegypti density could be reduced to below three female mosquitoes/trap/week around a target house in the center of a circular area with a 150 m radius using IVC. Two non-adjacent areas within the same neighbourhood were selected and randomly designated as the treatment or control areas. Sentinel Autocidal Gravid Ovitraps (SAGO traps) were placed in each study area and were sampled weekly from May to November, during the 2016 Zika epidemic in Puerto Rico. The experimental design was longitudinal with pre-and post-IVC treatment observations between treatment and control areas, and a partial cross-over design, where IVC was applied to the original control area after 2 months to determine if Ae. aegypti density converged to levels observed in the treatment area. Pools of female Ae. aegypti mosquitoes were analyzed by RT-PCR to detect Zika, dengue and chikungunya virus RNA. RESULTS: Overall, pre-treatment mosquito densities in the inner (0-50 m; 15.6 mosquitoes/trap/week), intermediate (50-100 m; 18.1) and outer rings (100-150 m; 15.6) were reduced after treatment to 2.8, 4.1, and 4.3 in the inner, middle, and outer rings, respectively. Density at the target house in the treatment area changed from 27.7 mosquitoes/trap/week before IVC to 2.1 after IVC (92.4% reduction), whereas after treating the original control area (cross-over) density changed from 22.4 to 3.5 (84.3% reduction). Vector reductions were sustained in both areas after IVC. Zika virus was detected in Ae. aegypti, but the low incidence of the virus precluded assessing the impact of IVC on Zika transmission during the study. CONCLUSIONS: Applying IVC to circular areas that were surrounded by untreated areas significantly decreased the number of mosquitoes around target houses located in the center. Gravid Ae. aegypti females in the center of the 150 m areas fell below threshold levels that possibly protect against novel invading arboviruses, such as chikungunya and Zika.

Differences in Prevalence of Symptomatic Zika Virus Infection, by Age and Sex-Puerto Rico, 2016.

Background: During the outbreak of Zika virus (ZIKV) disease in Puerto Rico in 2016, nonpregnant women aged 20-39 years were disproportionately identified with ZIKV disease. We used household-based cluster investigations to determine whether this disparity was associated with age- or sex-dependent differences in the rate of ZIKV infection or reported symptoms. Methods: Participation was offered to residents of households within a 100-m radius of the residences of a convenience sample of 19 laboratory-confirmed ZIKV disease cases. Participants answered a questionnaire and provided specimens for diagnostic testing by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). Results: Among 367 study participants, 114 (31.1%) were laboratory positive for ZIKV infection, of whom 30% reported a recent illness (defined as self-reported rash or arthralgia) attributable to ZIKV infection. Age and sex were not associated with ZIKV infection. Female sex (adjusted prevalence ratio [aPR], 2.28; 95% confidence interval [CI], 1.40, 3.67), age <40 years (aPR, 2.39; 95% CI, 1.55, 3.70), and asthma (aPR, 1.63; 95% CI, 1.12, 2.37) were independently associated with symptomatic infection. Conclusions: Although neither female sex nor age were associated with an increased prevalence of ZIKV infection, both were associated with symptomatic infection. Further investigation to identify a potential mechanism of age- and sex-dependent differences in reporting symptomatic ZIKV infection is warranted.

Salinomycin kills cancer stem cells by sequestering iron in lysosomes.

Cancer stem cells (CSCs) represent a subset of cells within tumours that exhibit self-renewal properties and the capacity to seed tumours. CSCs are typically refractory to conventional treatments and have been associated to metastasis and relapse. Salinomycin operates as a selective agent against CSCs through mechanisms that remain elusive. Here, we provide evidence that a synthetic derivative of salinomycin, which we named ironomycin (AM5), exhibits a more potent and selective activity against breast CSCs in vitro and in vivo, by accumulating and sequestering iron in lysosomes. In response to the ensuing cytoplasmic depletion of iron, cells triggered the degradation of ferritin in lysosomes, leading to further iron loading in this organelle. Iron-mediated production of reactive oxygen species promoted lysosomal membrane permeabilization, activating a cell death pathway consistent with ferroptosis. These findings reveal the prevalence of iron homeostasis in breast CSCs, pointing towards iron and iron-mediated processes as potential targets against these cells.

Impact of Autocidal Gravid Ovitraps on Chikungunya Virus Incidence in Aedes aegypti (Diptera: Culicidae) in Areas With and Without Traps.

Puerto Rico detected the first confirmed case of chikungunya virus (CHIKV) in May 2014 and the virus rapidly spread throughout the island. The invasion of CHIKV allowed us to observe Aedes aegypti (L.) densities, infection rates, and impact of vector control in urban areas using CDC autocidal gravid ovitraps (AGO traps) for mosquito control over several years. Because local mosquitoes can only get the virus from infectious residents, detecting the presence of virus in mosquitoes functions as a proxy for the presence of virus in people. We monitored the incidence of CHIKV in gravid females of Ae. aegypti in four neighborhoods-two with three AGO traps per home in most homes and two nearby neighborhoods without AGO mosquito control traps. Monitoring of mosquito density took place weekly using sentinel AGO traps from June to December 2014. In all, 1,334 pools of female Ae. aegypti (23,329 individuals) were processed by real-time reverse transcription PCR to identify CHIKV and DENV RNA. Density of Ae. aegypti females was 10.5 times lower (91%) in the two areas with AGO control traps during the study. Ten times (90.9%) more CHIKV-positive pools were identified in the nonintervention areas (50/55 pools) than in intervention areas (5/55). We found a significant linear relationship between the number of positive pools and both density of Ae. aegypti and vector index (average number of expected infected mosquitoes per trap per week). Temporal and spatial patterns of positive CHIKV pools suggested limited virus circulation in areas with AGO traps.

Operational Aspects of the Centers for Disease Control and Prevention Autocidal Gravid Ovitrap.

Dengue viruses cause hundreds of millions of infections every year in tropical and subtropical countries. Unfortunately, there is not a single universal vector control method capable of suppressing Aedes aegypti (L.) populations. Amongst novel control tools or approaches are various types of traps targeting gravid females or their eggs. Here, we provide details of the operational use of the Centers for Disease Control and Prevention autocidal gravid ovitrap (CDC-AGO trap) for the surveillance and control of Ae. aegypti. Adult mosquitoes were monitored every week in 2 isolated neighborhoods treated with 3 AGO traps per house in 85% of houses and in 2 reference neighborhoods without control traps. Between March 2013 and April 2015 we serviced the AGO traps 14 times in each community (every 2 months). Common trap problems were absent or broken trap tops (1-1.5%), flooded (0.1-0.7%) or dry (0.5-1.3%) traps, and missing (0.3-0.8%) or vandalized (0.5-1.4%) traps. Most traps kept a volume of infusion between 45% and 97% of their original volume (10 liters). Nontarget organisms captured in AGO traps were mostly small flies, and to a lesser extent ants, cockroaches, grasshoppers, butterflies, dragonflies, and lizards. Trap coverage ranged between 83% and 87% of houses in both communities throughout the study. We interpret such high levels of trap retention over time as an expression of acceptance by the community.

Reduced Incidence of Chikungunya Virus Infection in Communities with Ongoing Aedes Aegypti Mosquito Trap Intervention Studies - Salinas and Guayama, Puerto Rico, November 2015-February 2016.

Aedes species mosquitoes transmit chikungunya virus, as well as dengue and Zika viruses, and bite most often during the day.* Infectious mosquito bites frequently occur in and around homes (1,2). Caribbean countries first reported local transmission of chikungunya virus in December 2013, and soon after, chikungunya virus spread throughout the Americas (3). Puerto Rico reported its first laboratory-positive chikungunya case in May 2014 (4), and subsequently identified approximately 29,000 suspected cases throughout the island by the end of 2015.(†) Because conventional vector control approaches often fail to result in effective and sustainable prevention of infection with viruses transmitted by Aedes mosquitoes (5), and to improve surveillance of mosquito population densities, CDC developed an Autocidal Gravid Ovitrap (AGO) (6) to attract and capture the female Aedes aegypti mosquitoes responsible for transmission of infectious agents to humans (Figure). The AGO trap is a simple, low-cost device that requires no use of pesticides and no servicing for an extended period of time (6).

Binational Dengue Outbreak Along the United States-Mexico Border - Yuma County, Arizona, and Sonora, Mexico, 2014.

Dengue is an acute febrile illness caused by any of four dengue virus types (DENV-1-4). DENVs are transmitted by mosquitos of the genus Aedes (1) and are endemic throughout the tropics (2). In 2010, an estimated 390 million DENV infections occurred worldwide (2). During 2007-2013, a total of three to 10 dengue cases were reported annually in Arizona and all were travel-associated. During September-December 2014, coincident with a dengue outbreak in Sonora, Mexico, 93 travel-associated dengue cases were reported in Arizona residents; 70 (75%) cases were among residents of Yuma County, which borders San Luis Río Colorado, Sonora, Mexico. San Luis Río Colorado reported its first case of locally acquired dengue in September 2014. To investigate the temporal relationship of the dengue outbreaks in Yuma County and San Luis Río Colorado and compare patient characteristics and signs and symptoms, passive surveillance data from both locations were analyzed. In addition, household-based cluster investigations were conducted near the residences of reported dengue cases in Yuma County to identify unreported cases and assess risk for local transmission. Surveillance data identified 52 locally acquired cases (21% hospitalized) in San Luis Río Colorado and 70 travel-associated cases (66% hospitalized) in Yuma County with illness onset during September-December 2014. Among 194 persons who participated in the cluster investigations in Yuma County, 152 (78%) traveled to Mexico at least monthly during the preceding 3 months. Four (2%) of 161 Yuma County residents who provided serum samples for diagnostic testing during cluster investigations had detectable DENV immunoglobulin M (IgM); one reported a recent febrile illness, and all four had traveled to Mexico during the preceding 3 months. Entomologic assessments among 105 households revealed 24 water containers per 100 houses colonized by Ae. aegypti. Frequent travel to Mexico and Ae. aegypti colonization indicate risk for local transmission of DENV in Yuma County. Public health officials in Sonora and Arizona should continue to collaborate on dengue surveillance and educate the public regarding mosquito abatement and avoidance practices. Clinicians evaluating patients from the U.S.-Mexico border region should consider dengue in patients with acute febrile illness and report suspected cases to public health authorities.

Evaluation of Household Bleach as an Ovicide for the Control of Aedes aegypti.

Accumulations of dormant eggs in container habitats allow Aedes aegypti populations to survive harsh environmental conditions and may frustrate control interventions directed at larval and adult life stages. While sodium hypochlorite solutions (NaOCl) have long been recognized as ovicides for use against dengue vectors, the susceptibility of eggs to spray applications has not been robustly evaluated on substrate materials representative of the most frequently utilized artificial container habitats. Experiments were performed under controlled and natural conditions by applying dilutions of household bleach (52.5 ppt NaOCl) as a spray to eggs on plastic, rubber, and concrete surfaces, with and without a smectite clay thickener. Laboratory assays identified the minimum NaOCl concentrations required to eliminate eggs on plastic (10 ppt), rubber (20 ppt) and concrete (20 ppt) surfaces. Addition of smectite clay reduced the minimum effective concentration to 10 ppt NaOCl for all 3 substrates. A minimum exposure period of 24 h was required to completely eliminate egg viability on concrete surfaces, even at the highest NaOCl concentration (52.5 ppt). Field experiments verified that spray application of a 1∶3 dilution of household bleach mixed with smectite clay can reduce egg hatching by ≥ 99% in shaded and sun-exposed plastic containers. Similarly, 4∶1 dilution of household bleach (with or without smectite clay) eliminated ≥ 98% of eggs from concrete surfaces in outdoor, water-filled drums. In this study, we propose a practical, effective and safe strategy for using household bleach to eliminate Ae. aegypti eggs in a range of artificial container habitats.