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Valerio L.,University of Rome La Sapienza | Valerio L.,University of California at Davis | Facchinelli L.,University of California at Davis | Ramsey J.M.,Centro Regional Of Investigacion En Salud Publica | And 2 more authors.
American Journal of Tropical Medicine and Hygiene | Year: 2012

Most Aedes aegypti dispersal studies have focused on females because of their central role in dengue virus transmission. Only a few mark-release- recapture (MRR) studies provided insights into male Ae. aegypti dispersal. To fill this knowledge gap, we conducted five male Ae. aegypti MRR experiments in a coastal village in southern Mexico. Small and large male cohorts were marked with fluorescent dusts, released outside buildings, and recaptures were carried out by using backpack aspirators. Recapture rates ranged between 0.35% and 6.55% and median distance traveled was 12-166 meters. A statistically significant difference in median distance traveled with large males dispersing farther than small ones was detected only in one experiment (MRR5: U = 3.5, P < 0.01). Male dispersal data will be useful for constructing and estimating parameter values and validating models that will be used to plan the most effective release strategies for genetically modified male Ae. aegypti. Copyright © 2012 by The American Society of Tropical Medicine and Hygiene.


Marina C.F.,Centro Regional Of Investigacion En Salud Publica | Bond J.G.,Centro Regional Of Investigacion En Salud Publica | Casas M.,Centro Regional Of Investigacion En Salud Publica | Munoz J.,Centro Regional Of Investigacion En Salud Publica | And 3 more authors.
Pest Management Science | Year: 2011

Background: Field trials were conducted during the wet and dry seasons in periurban and semi-rural cemeteries in southern Mexico to determine the efficacy of a suspension concentrate formulation of spinosad (Tracer 480SC) on the inhibition of development of Aedes albopictus L. and Ae. aegypti Skuse. For this, oviposition traps were treated with spinosad (1 or 5 mg L-1), Bacillus thuringiensis israelensis (Bti, VectoBac 12AS), a sustained release formulation of temephos and a water control. Results: Ae. albopictus was subordinate to Ae. aegypti during the dry season, but became dominant or codominant during the wet season at both sites. The two species could not be differentiated in field counts on oviposition traps. Mean numbers of larvae + pupae of Aedes spp. in Bti-treated containers were similar to the control at both sites during both seasons. The duration of complete absence of aquatic stages varied from 5 to 13 weeks for the spinosad treatments and from 6 to 9 weeks for the temephos treatment, depending on site, season and product concentration. Predatory Toxorhynchites theobaldi Dyar and Knab suffered low mortality in control and Bti treatments, but high mortality in spinosad and temephos treatments. Egg counts and percentage of egg hatch of Aedes spp. increased significantly between the dry and wet seasons, but significant treatment differences were not detected. Conclusion: Temephos granules and a suspension concentrate formulation of spinosad were both highly effective larvicides against Ae. aegypti and Ae. albopictus. These compounds merit detailed evaluation for inclusion in integrated control programs targeted at Ae. aegypti and Ae. albopictus in regions where they represent important vectors of human diseases. © 2010 Society of Chemical Industry.


Kautz T.F.,University of Texas Medical Branch | Diaz-Gonzalez E.E.,Autonomous University of Nuevo León | Erasmus J.H.,University of Texas Medical Branch | Malo-Garcia I.R.,Centro Regional Of Investigacion En Salud Publica | And 9 more authors.
Emerging Infectious Diseases | Year: 2015

Since chikungunya virus (CHIKV) was introduced into the Americas in 2013, its geographic distribution has rapidly expanded. Of 119 serum samples collected in 2014 from febrile patients in southern Mexico, 79% were positive for CHIKV or IgM against CHIKV. Sequencing results confirmed CHIKV strains closely related to Caribbean isolates. © 2015, Centers for Disease Control and Prevention (CDC). All rights reserved.


Marina C.F.,Centro Regional Of Investigacion En Salud Publica | Bond J.G.,Centro Regional Of Investigacion En Salud Publica | Munoz J.,Centro Regional Of Investigacion En Salud Publica | Valle J.,ECOSUR | And 2 more authors.
Parasites and Vectors | Year: 2014

Background: The larvicidal efficacy of the naturally derived insecticide spinosad, for control of immature stages of Anopheles albimanus and associated culicids, was compared to that of synthetic and biological larvicides. Effects on non-target insects were also determined. Methods. A field trial was performed in replicated temporary pools during the rainy season, in southern Mexico. Pools were treated with 10 ppm a.i. spinosad (Tracer 480SC), Bti granules applied at 2 kg/ha (VectoBac WDG, ABG-6511), and 100 ml/ha temephos (50 EC), or an untreated control. Numbers of immature mosquitoes, and aquatic insects in pools were monitored for 20 weeks. Results: Samples of immature mosquitoes comprised approximately 10% An. albimanus, 70% Culex spp. (mostly Cx. melanoconion and Cx. coronator) and 20% Uranotaenia lowii. The most effective larvicides were spinosad and temephos that eliminated An. albimanus in 16 out of 20 post-treatment samples, or 9 weeks of continuous control of immature stages, respectively. These larvicides resulted in 15 and 5 weeks of elimination of Culex spp., respectively, or 20 and 4 weeks of continuous elimination of U. lowii, respectively. Bti treatment provided little consistent control. Aquatic insects were recorded comprising 3 orders, 20 families, 40 genera and 44 species. Shannon diversity index values (H') for aquatic insects were highest in the control (0.997) and Bti (0.974) treatments, intermediate in the spinosad treatment (0.638) and lowest in the temephos treatment (0.520). Severely affected non-target insects in the spinosad and temephos treated pools were predatory Coleoptera, Hemiptera and Odonata, which in the case of spinosad was likely due to the high concentration applied. Bti had little effect on aquatic insects. Conclusions: The spinosad treatment retained larvicidal activity for markedly longer than expected. Spinosad is likely to be an effective tool for control of anopheline and other pool-breeding mosquitoes in tropical regions. Non-target effects of spinosad on aquatic insects merit further study, but were likely related to the concentration of the product used. © 2014 Marina et al.; licensee BioMed Central Ltd.


The leishmaniasis is a complex disease system, caused by the protozoan parasite Leishmania and transmitted to humans by the vector Lutzomyia spp. Since it is listed as a neglected disease according to the World Health Organization, the aim of this study was to determine the current and future niche of cutaneous and visceral leishmaniasis in the Neotropical region. We built the ecological niche model (ENM) of cutaneous (N= 2 910 occurrences) and visceral (N= 851 occurrences) leishmaniasis using MaxEnt algorithm. Nine bioclimatic variables (BIO1, BIO4, BIO5, BIO6, BIO7, BIO12, BIO13, BIO14, BIO15 (downloaded from the Worldclim) and disease occurrences data were used for the construction of ENM for three periods (current, 2050 and 2070) and four climate change scenarios (RCP 2.6, 4.5, 6.0 y 8.5). We analyzed the number of pixels occupied, identity niche, modified niche (stable, loss, and gain) and seasonality. Our analyses indicated the expansion for cutaneous leishmaniasis (CL), a comparison for visceral leishmaniasis (VL). We rejected the null hypothesis of niche identity between CL and VL with Hellinger’s index = 0.91 (0.92-0.98) and Schoener’s Index = 0.67 (0.85-1.00) but with an overlap niche of 56.3 %. The differences between the two leishmaniasis types were detected in relation to RCP scenarios and niche shifts (area gained / loss). Seasonality was more important for CL. We provided a current picture of CL and VL distributions and the predicted distributional changes associated to different climate change scenarios for the Neotropical region. We can anticipate that increasing range is likely although it will depend locally on the future trends in weather seasonality. © 2016 Universidad de Costa Rica. All Rights Reserved.


Estrada J.L.T.,Centro Regional Of Investigacion En Salud Publica | Delgado S.M.R.,Centro Regional Of Investigacion En Salud Publica | Takken W.,Wageningen University
Journal of the American Mosquito Control Association | Year: 2013

We determined the behavioral response of Aedes aegypti females to volatile compounds collected in indoor primary school classrooms. Volatiles were collected from classrooms from 0800 through 1030 h and 1130 through 1400 h in urban and rural schools in Tapachula, Chiapas, Mexico. Female responses to volatiles were assessed in a Y-tube olfactometer. Chemical compounds were identified using gas chromatography-mass spectrometer analysis. Volatiles from both schools were attractive when compared against their control. When such volatiles were compared, those from the rural school were more attractive than the ones from the urban school. Chromatographic profiles were similar between schools; however, the rural school showed more compounds. Attraction of Ae. aegypti females toward volatiles of primary school classrooms might increase dengue transmission probabilities in those sites. © 2013 by The American Mosquito Control Association, Inc.


Contreras-Moreno F.M.,Juarez Autonomous University of Tabasco | De La Cruz-Felix K.,Centro Regional Of Investigacion En Salud Publica | Bello-Gutierrez J.,Juarez Autonomous University of Tabasco | Hidalgo-Mihart M.G.,Juarez Autonomous University of Tabasco
Therya | Year: 2016

The brocket deer (Mazama temama and M. pandora) are two of the Mexican tropical deer with great importance for subsistence and sport hunters. Brocket deer are considered species with preference for pristine habitats conserved, however at the landscape level, factors such as hunting pressure could influence the presence and abundance of these species. Campeche, is the only Mexican state where it has been authorized the exploitation of the brocket deer for sport hunting. This hunting pressure along with the intense subsistence hunting that occurs in Campeche, could have important effects on the conservation of the species. Establishing what factors determine the presence of the species at the landscape level is essential to elaborate comprehensive management plans of these species to allow their long-term conservation. The aim of this study was to determine the habitat variables at the landscape level that influence the brocket deer presence in the central-western area of Campeche State in Mexico. The study area in the state of Campeche (19° 15′ N, -91° 20′ W) was divided into six study regions (Chekubul-Cristalina; Chenkan; Chicbul-Km 74; Pixtún-Felipe Carrillo Puerto, Miguel Colorado; Centenario-La Rigueña) following the main paved road of the area and according to the conservation level of the natural ecosystems, presence of flooded areas, and intensity of the human activities where we determine the presence of brocket deer. We searched for brocket deer tracks along 263 transects of 500 m each. The tracks were identified to genus only. The presence/absence of brocket deer in the transects was combined with variables of human and natural origin of the study area in a geographical information system. We use principal component analysis and a logistic regression to determine the relationship between variables and the presence/absence of the brocket deer. We were not able to distinguish by their tracks the two potentially distributed species of brocket deer in the area. Due to this constraint, we did not perform a distinction between both species and all the observed tracks were classified as brocket deer. We found that brocket deer were present only in three of the six studied regions: Miguel Colorado (21.3 % transect had brocket deer presence), Centenario-La Rigueña (20.4 %) and Chenkan (1.7 %). The principal component analysis indicated that the variables determining the presence of brocket deer were, the percentage of preserved forest and distance to pastures, positively associated, while livestock density was negative. The best model obtained by the logistic regression showed that the presence of brocket deer increased when the percentage of preserved forests around transect is increased, while decreasing with increasing livestock density. The presence of conserved forests favors the presence of brocket deer in the study area, while a higher density of cattle decreases the probability of detection. The few records of brocket deer in flooded zones in this study and the lack of detection of the species in previous studies, suggests that these flooded ecosystems may not be suitable for brocket deer, which would have a strong impact on their known distributional range. Finding that brocket deer are present mainly in preserved sites indicates the species could be subject to an intense population reduction in the study area due to the continued habitat loss. The results suggest that before granting authorizations for sport hunting in this region, it is necessary to make accurate estimates of the population distribution and abundance of the species in the region. © 2016 Asociación Mexicana de Mastozoología.


Pozo-Aguilar J.O.,National Autonomous University of Mexico | Monroy-Martinez V.,National Autonomous University of Mexico | Diaz D.,National Autonomous University of Mexico | Barrios-Palacios J.,National Autonomous University of Mexico | And 4 more authors.
Parasites and Vectors | Year: 2014

Background: Dengue fever (DF) is the most prevalent arthropod-borne viral disease affecting humans. The World Health Organization (WHO) proposed a revised classification in 2009 to enable the more effective identification of cases of severe dengue (SD). This was designed primarily as a clinical tool, but it also enables cases of SD to be differentiated into three specific subcategories (severe vascular leakage, severe bleeding, and severe organ dysfunction). However, no study has addressed whether this classification has advantage in estimating factors associated with the progression of disease severity or dengue pathogenesis. We evaluate in a dengue outbreak associated risk factors that could contribute to the development of SD according to the 2009 WHO classification. Methods: A prospective cross-sectional study was performed during an epidemic of dengue in 2009 in Chiapas, Mexico. Data were analyzed for host and viral factors associated with dengue cases, using the 1997 and 2009 WHO classifications. The cost-benefit ratio (CBR) was also estimated. Results: The sensitivity in the 1997 WHO classification for determining SD was 75%, and the specificity was 97.7%. For the 2009 scheme, these were 100% and 81.1%, respectively. The 2009 classification showed a higher benefit (537%) with a lower cost (10.2%) than the 1997 WHO scheme. A secondary antibody response was strongly associated with SD. Early viral load was higher in cases of SD than in those with DF. Logistic regression analysis identified predictive SD factors (secondary infection, disease phase, viral load) within the 2009 classification. However, within the 1997 scheme it was not possible to differentiate risk factors between DF and dengue hemorrhagic fever or dengue shock syndrome. The critical clinical stage for determining SD progression was the transition from fever to defervescence in which plasma leakage can occur. Conclusions: The clinical phenotype of SD is influenced by the host (secondary response) and viral factors (viral load). The 2009 WHO classification showed greater sensitivity to identify SD in real time. Timely identification of SD enables accurate early decisions, allowing proper management of health resources for the benefit of patients at risk for SD. This is possible based on the 2009 WHO classification. © 2014 Pozo-Aguilar et al.; licensee BioMed Central.


PubMed | Centro Regional Of Investigacion En Salud Publica
Type: Journal Article | Journal: Journal of the American Mosquito Control Association | Year: 2013

We determined the behavioral response of Aedes aegypti females to volatile compounds collected in indoor primary school classrooms. Volatiles were collected from classrooms from 0800 through 1030 h and 1130 through 1400 h in urban and rural schools in Tapachula, Chiapas, Mexico. Female responses to volatiles were assessed in a Y-tube olfactometer. Chemical compounds were identified using gas chromatography-mass spectrometer analysis. Volatiles from both schools were attractive when compared against their control. When such volatiles were compared, those from the rural school were more attractive than the ones from the urban school. Chromatographic profiles were similar between schools; however, the rural school showed more compounds. Attraction of Ae. aegypti females toward volatiles of primary school classrooms might increase dengue transmission probabilities in those sites.


PubMed | National Autonomous University of Mexico, Centro Regional Of Investigacion En Salud Publica and University of Santa María in Ecuador
Type: | Journal: Parasites & vectors | Year: 2015

Dengue fever (DF) is the most prevalent arthropod-borne viral disease affecting humans. The World Health Organization (WHO) proposed a revised classification in 2009 to enable the more effective identification of cases of severe dengue (SD). This was designed primarily as a clinical tool, but it also enables cases of SD to be differentiated into three specific subcategories (severe vascular leakage, severe bleeding, and severe organ dysfunction). However, no study has addressed whether this classification has advantage in estimating factors associated with the progression of disease severity or dengue pathogenesis. We evaluate in a dengue outbreak associated risk factors that could contribute to the development of SD according to the 2009 WHO classification.A prospective cross-sectional study was performed during an epidemic of dengue in 2009 in Chiapas, Mexico. Data were analyzed for host and viral factors associated with dengue cases, using the 1997 and 2009 WHO classifications. The cost-benefit ratio (CBR) was also estimated.The sensitivity in the 1997 WHO classification for determining SD was 75%, and the specificity was 97.7%. For the 2009 scheme, these were 100% and 81.1%, respectively. The 2009 classification showed a higher benefit (537%) with a lower cost (10.2%) than the 1997 WHO scheme. A secondary antibody response was strongly associated with SD. Early viral load was higher in cases of SD than in those with DF. Logistic regression analysis identified predictive SD factors (secondary infection, disease phase, viral load) within the 2009 classification. However, within the 1997 scheme it was not possible to differentiate risk factors between DF and dengue hemorrhagic fever or dengue shock syndrome. The critical clinical stage for determining SD progression was the transition from fever to defervescence in which plasma leakage can occur.The clinical phenotype of SD is influenced by the host (secondary response) and viral factors (viral load). The 2009 WHO classification showed greater sensitivity to identify SD in real time. Timely identification of SD enables accurate early decisions, allowing proper management of health resources for the benefit of patients at risk for SD. This is possible based on the 2009 WHO classification.

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