Saul Lozano

Centers for Disease Control and Prevention | CDC · Division of Vector-Borne Diseases

We describe a novel software application (QCal) that was developed for calculation of dose-response curves in insecticide resistance bioassays. QCal uses a logistic regression model to generate values for lethal dose/knockdown dose based on data from a bioassay entered into the application user interface. The application can be freely distributed t...

México has cities (e.g., México City and Puebla City) located at elevations > 2,000 m and above the elevation ceiling, below which local climates allow the dengue virus mosquito vector Aedes aegypti to proliferate. Climate warming could raise this ceiling and place high-elevation cities at risk for dengue virus transmission. To assess the elevation...

The rapid expansion of Zika virus (ZIKV), following the recent outbreaks of Chikungunya virus, overwhelmed the public health infrastructure in many countries and alarmed many in the scientific community. Aedes aegypti (L.) (Diptera: Culicidae) and Aedes albopictus (Skuse) (Diptera: Culicidae) have previously been incriminated as the vectors of thes...

The United States experienced local transmission of West Nile Virus (WNV) for the first time in 1999, and Zika Virus (ZIKV) in 2016. These introductions captured the public’s attention in varying degrees. The research presented here analyzes the disproportional perception of ZIKV risk compared to WNV transmission risk, by the public and vector cont...

Among disease vectors, Aedes aegypti (L.) (Diptera: Culicidae) is one of the most insidious species in the world. The disease burden created by this species has dramatically increased in the past 50 years, and during this time countries have relied on pesticides for control and prevention of viruses borne by Ae. aegypti. The small number of availab...

Organophosphate insecticides are widely used for adult mosquito control. Although proven effective in reducing mosquito populations and limiting arbovirus transmission, public concern exists regarding potential human health effects associated with organophosphate exposure. The aim of this scoping review was to describe any reported human health con...

Pyrethroid resistance in Aedes aegypti has become widespread after almost two decades of frequent applications to reduce the transmission of mosquito-borne diseases. Because few insecticide classes are available for public health use, insecticide resistance management (IRM) is proposed as a strategy to retain their use. A key hypothesis of IRM assu...

Pyrethroid resistance in Aedes aegypti has become widespread after almost two decades of frequent applications to reduce the transmission of mosquito-borne diseases. Because few insecticide classes are available for public health use, insecticide resistance management (IRM) is proposed as a strategy to retain their use. A key hypothesis of IRM assu...

Background Insecticide use continues as the main strategy to control Aedes aegypti, the vector of dengue, Zika, chikungunya, and yellow fever. In the city of Tapachula, Mexico, mosquito control programs switched from pyrethroids to organophosphates for outdoor spatial spraying in 2013. Additionally, the spraying scheme switched from total coverage...

Pyrethroids are one of the few classes of insecticides available to control Aedes aegypti, the major vector of dengue, chikungunya, and Zika viruses. Unfortunately, evolving mechanisms of pyrethroid resistance in mosquito populations threaten our ability to control disease outbreaks. Two common pyrethroid resistance mechanisms occur in Ae. aegypti:...

Aedes aegypti is a major vector of Zika, dengue, and other arboviruses. Permethrin adulticidal spraying, which targets the voltage-gated sodium channel (VGSC), is commonly done to reduce local mosquito populations and protect humans from exposure to arbovirus pathogens transmitted by this dangerous pest. Permethrin resistance, however, is a growing...

Aedes aegypti is the major vector of a number of arboviruses that cause disease in humans. Without vaccines or pharmaceuticals, pyrethroid insecticides remain the major tool for public health protection. Pyrethroid resistance is now widespread. Replacement substitutions in the voltage‐gated sodium channel (vgsc) that reduce the stability of pyrethr...

Association mapping of factors that condition pyrethroid resistance in Aedes aegypti has consistently identified genes in multiple functional groups. Toward better understanding of the mechanisms involved, we examined high throughput sequencing data (HTS) from two Aedes aegypti aegypti collections from Merida, Yucatan, Mexico treated with either pe...

Sequencing details for all libraries. Number of reads aligned to reference, percent trimmed reads mapped to reference, number of variant sites per chromosome, ratio of sites per aligned nucleotide * 1000. (XLSX)

χ2 contingency values for all collections in the high association set (n = 1053). Genes are arranged in order of their physical position. Genes in the top ten percent of all common genes are highlighted in gray, those with predicted motoneuron synaptic function are highlighted in pink, and predicted transcriptional regulators are highlighted in gre...

CHL- and NVY-silenced mosquitoes show increased susceptibility to permethrin. Mosquitoes were injected with phosphate-buffered saline (PBS, n = 109), βGal-dsRNA (n = 113), chl-dsRNA (n = 172), nvy-dsRNA (n = 129) or left untreated (n = 136). At 3 dpt, each replicate was subjected to ~1.5 ug permethrin in a CDC bottle assay; knockdown was recorded a...

Primers used in gene silencing and qRT-PCR. (XLSX)

Aedes aegypti is the primary urban mosquito vector of viruses causing dengue, Zika and chikungunya fevers –for which vaccines and effective pharmaceuticals are still lacking. Current strategies to suppress arbovirus outbreaks include removal of larval-breeding sites and insecticide treatment of larval and adult populations. Insecticidal control of...

Background: Some populations of West African Aedes aegypti, the dengue and zika vector, are reproductively incompatible; our earlier study showed that divergence and rearrangements of genes on chromosome 1, which bears the sex locus (M), may be involved. We also previously described a proposed cryptic subspecies SenAae (PK10, Senegal) that had man...

Globally, malaria remains one of the most important vector-borne diseases despite the extensive use of vector control, including indoor residual spraying (IRS) and insecticide-treated nets (ITNs). These control methods target endophagic vectors, whereas some malaria vectors, such as Anopheles arabiensis, preferentially feed outdoors on cattle, maki...

Kdr mutations in the mosquito's voltage-gated sodium channel were characterized as a result of the observed neuronal sensitivity as caused by resistance to DDT and pyrethroids. To determine the frequency of the L1014F kdr mutation, we analized a total of 415 Culex quinquefasciatus (Diptera: Culicidae) from 16 populations in Northeastern Mexico. We...

The L1014F mutation in the voltage-sodium channel gene has been associated with resistance to DDT and pyrethroids in various arthropod species including mosquitoes. We determined the frequency of the L1014F kdr mutation in 16 field populations of Culex quinquefasciatus from Northeastern Mexico collected between 2008 and 2013. The L1014F was present...

AbstractThe mosquito virus vector Aedes (Ae.) aegypti exploits a wide range of containers as sites for egg laying and development of the immature life stages, yet the approaches for modeling meteorologically sensitive container water dynamics have been limited. This study introduces the Water Height and Temperature in Container Habitats Energy Mode...

Background: Although vector control strategies, such as insecticide-treated bed nets (ITNs) and indoor residual spraying (IRS) have been effective in Kenya the transmission of malaria continues to afflict western Kenya. This residual transmission is driven in part by Anopheles arabiensis, known for its opportunistic blood feeding behaviour and pro...

Author Summary Constant use of pyrethroid insecticides has driven mosquito populations to develop resistance. In Aedes aegypti , the primary mosquito vector of dengue, yellow Fever, and chikungunya viruses, pyrethroid resistance is primarily associated with mutations in the voltage-gated sodium channel protein. One mutation occurs in codon 1,016 a...

Background: Ivermectin has been proposed as a novel malaria transmission control tool based on its insecticidal properties and unique route of acquisition through human blood. To maximize ivermectin's effect and identify potential resistance/tolerance mechanisms, it is important to understand its effect on mosquito physiology and potential to shif...

Hematophagous arthropods on many taxa are know to feed on livestock including cattle. Many of these insect transmit vector-borne diseases. Malaria and visceral leishmaniasis (VL) represent two such diseases that result in nearly one million fatalities each year. Since 2009 our research in India and Kenya has focused on the use of systemic insectici...

Chemical insecticides are effective for controlling Lutzomyia and Phlebotomus sand fly (Diptera: Psychodidae) vectors of Leishmania parasites. However, repeated use of certain insecticides has led to tolerance and resistance. The objective of this study was to determine lethal concentrations (LCs) and lethal exposure times (LTs) to assess levels of...

Thesis (Ph.D.)--Colorado State University, 2005. Includes bibliographical references.

The mosquito Aedes aegypti is the major vector of the four serotypes of dengue virus (DENV1-4). Previous studies have shown that Ae. aegypti in Mexico have a high effective migration rate and that gene flow occurs among populations that are up to 150 km apart. Since 2000, pyrethroids have been widely used for suppression of Ae. aegypti in cities in...

The mosquito Aedes aegypti is the major vector of the four serotypes of dengue virus (DENV1-4). Previous studies have shown that Ae. aegypti in Mexico have a high effective migration rate and that gene flow occurs among populations that are up to 150 km apart. Since 2000, pyrethroids have been widely used for suppression of Ae. aegypti in cities in...

It is challenging to develop comprehensive, consistent, analyzable requirements models for evolving requirements. This is particularly critical for certain highly interactive types of socio-technical systems that involve a wide range of stakeholders with disparate backgrounds; system success is often dependent on how well local social constraints a...

[ES]Tanto el cambio global como el cambio climático están impactando de manera directa en la presencia y abundancia de vectores transmisores de enfermedades; esta hipótesis debe ser contrastada con datos climatológicos, entomológicos y sociales a fin de poder establecer escenarios de actuación o riesgo ante la presencia del vector. El dengue es la...

We examined temporal changes in the abundance of the mosquitoes Aedes (Stegomyia) aegypti (L.) and Aedes (Ochlerotatus) epactius Dyar & Knab from June to October 2012 in one reference community at lower elevation (Rio Blanco; ≈1,270 m) and three high-elevation communities (Acultzingo, Maltrata, and Puebla City; 1,670‐2,150 m) in Veracruz and Puebla...

Using a geographic transect in Central Mexico, with an elevation/climate gradient, but uniformity in socio-economic conditions among study sites, this study evaluates the applicability of three widely-used remote sensing (RS) products to link weather conditions with the local abundance of the dengue virus mosquito vector, Aedes aegypti (Ae. aegypti...

The mosquito Aedes (Stegomyia) aegypti (L.), which occurs widely in the subtropics and tropics, is the primary urban vector of dengue and yellow fever viruses, and an important vector of chikungunya virus. There is substantial interest in how climate change may impact the bionomics and pathogen transmission potential of this mosquito. This Forum ar...

The potential effects leading to geographical expansion in areas at risk of infectious diseases are among the important concerns linked to the discussion of climate change. Associations reported in the literature suggest the possibility of monitoring climate related environmental variables to estimate abundance of some vectors of disease agents. Si...

Dengue viruses circulate between mosquito vectors and humans, causing an estimated 300-million dengue infections annually. In the last decade, the Americas have experienced a dramatic increase in severe disease cases (dengue hemorrhagic fever), with devastating public health consequences. Of particular concern is the potential for the expansion of...

Capture of surveillance data on mobile devices and rapid transfer of such data from these devices into an electronic database or data management and decision support systems promote timely data analyses and public health response during disease outbreaks. Mobile data capture is used increasingly for malaria surveillance and holds great promise for...

The home, or domicile, is the principal environment for transmission of dengue virus (DENV) between humans and mosquito vectors. Community-wide distribution of insecticide-treated curtains (ITCs), mimicking vector control program-driven interventions, has shown promise to reduce DENV infections. We conducted a Casa Segura consumer product intervent...

Ontologies, which are made up by standardized and defined controlled vocabulary terms and their interrelationships, are comprehensive and readily searchable repositories for knowledge in a given domain. The Open Biomedical Ontologies (OBO) Foundry was initiated in 2001 with the aims of becoming an "umbrella" for life-science ontologies and promotin...

This dataset was created with the "dengue decision support system" (now the Case Report Form) software. The data, aggregated by epidemiological week and neighborhood, was provided by the Ministry of Health of Yucatan and the Universidad Autonoma de Yucatan

We collected mosquito immatures from artificial containers during 2010-2011 from 26 communities, ranging in size from small rural communities to large urban centers, located in different parts of Yucatán State in southeastern México. The arbovirus vector Aedes (Stegomyia) aegypti was collected from all 26 examined communities, and nine of the commu...

We report on the collection ofimmatures of Aedes (Ochlerotatus) epactius Dyar & Knab from artificial containers during July through September 2011 in 12 communities located along an elevation and climate gradient extending from sea level in Veracruz State to high elevations (>2,000 m) in Veracruz and Puebla States, México. Ae. epactius was collecte...

Novel, low-cost approaches to improving prevention and control of vector-borne diseases, such as mosquito-borne dengue and malaria, are needed in resource-constrained environments. We developed an application to support the use of cell phones for field capture and rapid transfer of mosquito vector surveillance data to a central database. The use of...

TO THE EDITOR: We collected Asian tiger mosquitoes, Aedes albopictus (Skuse), in Cancun in the Yucatan Peninsula of Mexico in September 2011. This mosquito is a nuisance biter of humans and a vector of numerous arboviruses, including those causing dengue, yellow fever, and chikungunya (1).

We analyzed 790 Aedes aegypti from 14 localities of Mexico in 2009 to update information on the frequency of the Ile1016 allele in the voltage-gated sodium channel gene that confers resistance to pyrethroids and DDT. The Ile1016 mutation was present in all 17 collections, and was close to fixation in Acapulco (frequency = 0.97), Iguala (0.93), and...

Entomological surveillance relating to dengue is peculiar in that the immature stages (larvae and pupae) of key dengue virus vectors, especially Aedes aegypti, exploit a wide range of containers (e.g., water storage containers, tires, bottles, cans, etc.) that accumulate in the peridomestic environment as development sites (Focks, 2003). This has l...

During 2007-2010, we examined which container types in Mérida, México, are most productive for Aedes aegypti (L.) immatures. Surveys for mosquito immatures followed routine surveillance methodology and container type classifications used by Servicios de Salud de Yucatán. Our main findings were that (1) small and larger discarded containers that ser...

Emerging information technologies present new opportunities to reduce the burden of malaria, dengue and other infectious diseases. For example, use of a data management system software package can help disease control programs to better manage and analyze their data, and thus enhances their ability to carry out continuous surveillance, monitor inte...

Novel control strategies are essential to reduce vector-borne diseases. Empowering individual home owners to complement and enhance governmental control efforts is an attractive and innovative approach for vector control. A “Casa Segura” study was conducted in Merida, Mexico to determine if individual home owners could utilize insecticide treated c...

Vector-borne diseases are resurgent throughout the world. There are critical needs to develop novel approaches and strategies and improved public health capacity to prevent and control these diseases. Dengue is an archetypical resurging and emerging disease. At the Arthropod-Borne and Infectious Diseases Laboratory, we are investigating novel strat...

Background: Aedes aegypti, the 'yellow fever mosquito', is the primary vector to humans of dengue and yellow fever flaviviruses (DENV, YFV), and is a known vector of the chikungunya alphavirus (CV). Because vaccines are not yet available for DENV or CV or are inadequately distributed in developing countries (YFV), management of Ae. aegypti remains...

Translation of the Abstract into Spanish by Saul Lozano-Fuentes (0.03 MB DOC)

Aedes triseriatus mosquitoes transovarially transmit (TOT) La Crosse virus (LACV) to their offspring with minimal damage to infected ovaries. Ae. triseriatus inhibitor of apoptosis 1 (AtIAP1) is a candidate gene conditioning the ability to vertically transmit LACV. AtIAP1 was amplified and sequenced in adult mosquitoes reared from field-collected e...

The aims of this review paper are to 1) provide an overview of how mapping and spatial and space-time modeling approaches have been used to date to visualize and analyze mosquito vector and epidemiologic data for dengue; and 2) discuss the potential for these approaches to be included as routine activities in operational vector and dengue control p...

Aedes aegypti is the main mosquito vector of the four serotypes of dengue virus (DENV). Previous population genetic and vector competence studies have demonstrated substantial genetic structure and major differences in the ability to transmit dengue viruses in Ae. aegypti populations in Mexico. Population genetic studies revealed that the intersect...

We determined abundance of Aedes aegypti mosquitoes and presence of dengue virus (DENV) in females collected from premises of laboratory-confirmed dengue patients over a 12-month period (March 2007 to February 2008) in Merida, Mexico. Backpack aspiration from 880 premises produced 1,836 females and 1,292 males indoors (predominantly from bedrooms)...

Background: Aedes aegypti, the 'yellow fever mosquito', is the primary vector to humans of dengue and yellow fever flaviviruses (DENV, YFV), and is a known vector of the chikungunya alphavirus (CV). Because vaccines are not yet available for DENV or CV or are inadequately distributed in developing countries (YFV), management of Ae. aegypti remains...

In the absence of a vaccine for use in humans against West Nile virus (WNV), mosquito control and personal protection against mosquito bites are the only measures available to prevent disease. Improved spatial targeting is desirable for costly mosquito and WNV surveillance and control schemes. We used a multivariate regression modeling approach to...

Novel, inexpensive solutions are needed for improved management of vector-borne and other diseases in resource-poor environments. Emerging free software providing access to satellite imagery and simple editing tools (e.g. Google Earth) complement existing geographic information system (GIS) software and provide new opportunities for: (i) strengthen...

OBJECTIVE: Novel, inexpensive solutions are needed for improved management of vector-borne and other diseases in resource-poor environments. Emerging free software providing access to satellite imagery and simple editing tools (e.g. Google EarthTM) complement existing geographic information system (GIS) software and provide new opportunities for: (...

OBJECTIVE As part of a Dengue Decision Support System project funded by the Innovative Vector Control Consortium, we used satellite imagery and mapping tools freely available through Google Earth to: 1) generate data for basic city structure that could be imported into a Geographic Information System (GIS); and 2) serve as the spatial underpinning...

The "Office du Niger" in the Niono District of Mali oversees irrigation from a dam on the Niger River -- the largest irrigation project in Mali. The facility was first built in 1932, and now irrigates more than 55,000 hectares for rice. A large reservoir in the center of the area provides water throughout the year through a water-control system. Th...

Models predicting the spatial spread of dengue epidemics can facilitate national and regional vector control resource allocation and be used to detect hot-spots with high priority for emergency vector control within individual cities. As part of the Dengue Decision Support System project, which is funded by the Innovative Vector Control Consortium,...

Potential insecticide-resistance mechanisms were studied with the use of biochemical assays in Aedes aegypti (L.) collected from 5 municipalities representing the north part of Quintana Roo: Benito Juarez, Cozumel, Isla Mujeres, Lazaro Cardenas, and Solidaridad. The activities of alpha and beta esterases, mixed-function oxidases (MFO), glutathione-...

Evidence suggests that midgut trypsins in Aedes aegypti condition the mosquito's ability to become infected with the dengue-2 flavivirus (DEN2). The activity of early trypsin protein peaks approximately 3 h after blood feeding and then drops within a few hours. We use association mapping to test the hypothesis that segregating sites in early trypsi...

A discriminating dose for permethrin for Aedes aegypti from Baja California, Mexico was determined, and was used to select individuals. Mosquitoes were collected from four different municipalities located in the north and south end of the Baja California Peninsula. Individuals were chosen for further study based on their similar response to the ins...

A population genetic analysis was conducted among 20 Aedes aegypti collections from 19 cities along the south Pacific coast in the Mexican states of Guerrero, Oaxaca, and Chiapas and in Coatepeque, Guatemala. Genetic variation was scored at 131 random amplified polymorphic DNA loci. The amount of genetic differentiation among collections was approx...

A population genetic analysis of Aedes aegypti was conducted among 38 collections from throughout coastal regions of Mexico. Multiple collections were made within 5 cities to examine local patterns of gene flow. Single-strand conformation polymorphism analysis was used to screen for variation in a 387-bp region of the Nicotinamide Adenine Dinucleot...

The spatial and temporal distributions of dengue fever cases in Guadalupe, Nuevo Leon, Mexico, were analyzed using a geographic information system (GIS). Data were obtained from the Secretary of Health of Nuevo Leon and mapped for the Municipality of Guadalupe, NL, using CARTALINX and IDRISI programs. Confirmed cases of dengue (689) occurred mostly...