Laboratory evaluation of Vectobac as against Aedes aegypti in Monterrey,Nuevo León,Mexico

Intensive use of the organophosphate insecticide malathion against adults and temephos against larvae of Aedes aegypti in Mexico over the past 30 years has led to problems requiring the use of new larvicides. Toward this objective, Bacillus thuringiensis var. israelensis (Bti), a target-specific and environmentally safer control agent, was evaluated. Laboratory bioassays were done to determine the susceptibility of 2nd- and 3rd-stage larvae of Ae. aegypti to Vectobac 12 AS (aqueous suspension, 600 ITU/mg). A median lethal concentration of 0.0104 ppm and a 95% lethal concentration of 0.18 ppm were determined after 24 h of exposure to the agent. The values obtained were adjusted for field application and were further tested in the field by the State of Nuevo León, Mexico Vector Control Program. Suspensions of Bti were poured into pipe-water trucks and transferred to domestic 200-gal metal water drums. Larval populations were reduced during a 2-week study period. However, residents complained about a fine dusty film on the water surface. Nevertheless, these results are promising for future Bti field applications.     

Spatial distribution of the larval indices of Aedes aegypti in Guadalupe,Nuevo León,Mexico, with circular distribution analysis

A census of all outdoor larval breeding sites (951) present in 361 dwellings in a neighborhood of Guadalupe in northeastern Mexico was conducted in October 1997 to determine larval indices of Aedes aegypti, and their relationship to human population density and vegetation type. Here we present a method that allows finding the direction and extrapolar flight range of vectors, as parameters in the dynamics of dengue transmission. By using circular statistics applied to each block of data, ranges (quartiles) were computed for larval index type, adult-child (a/c) relationship, and vegetation. Eight angles between 37 and 300 degrees were used. Circular distribution was determined by using mean angle (a) and argument (r) from the sum of ranges for each variable. Arguments corresponding to the mean angle of house (260 degrees), recipient (265 degrees), and Breteau (247 degrees) indices were 0.2321, 0.2331, and 0.2225, respectively. In addition, arguments for the mean angle of herbaceous (277 degrees), shrub (318 degrees), and arboreal (333 degrees) vegetation were 0.2589, 0.1984, and 0.2367, respectively, and the 3 were located in the 4th quadrant. The a/c relationship was in 282 degrees, with an argument of 0.2466, which indicates that in this neighborhood in southern Guadalupe, both the human population density and the larval indices were higher than in other areas.     

Heart transplant in Monterrey, Nuevo León

Heart failure constantly increases its incidence and prevalence in our society, it was imperative to start a heart transplant program to improve the survival rates of patients with end stages of the disease. Legal issues made impossible to transplant patients out of Mexico City until recent years. Even with an acute hemodynamic and clinic improvement after the transplant, these patients frequently develop complications such as graft rejection or opportunistic infections due to the immunosuppressive schemes increasing the morbidity and mortality of the procedure. In the present article we report the experience acquired with 65 heart transplant patients from 4 transplant programs in Monterrey, Nuevo Leon, one of them from the socialized system and the other three from private hospitals. Our program not only has successfully transplanted patients with advanced age but, for the first time in Latin America we have transplanted patients assisted with the ambulatory Thoratec TLC II system. Even that we have faced obstacles like a newly started donation culture in our population and limited resources, our patient's survival rate push us to continue working with these very ill population.     

Climate and the superimposed distribution of Aedes aegypti and Aedes albopictus on infestation of São Paulo State,Brazil

OBJECTIVE: To study the influence of climatic factors and superimposed distribution of Aedes aegypti and Aedes albopictus populations on their geographic dispersal in the state of S?o Paulo. METHODS: Data from government agencies on Ae. aegypti and Ae. albopictus foci and their distribution throughout counties of the state of S?o Paulo year by year, from 1985 to 1995, were obtained. Temperatures and rainfall data were also collected. Two indicators were used: infestation and rate. RESULTS AND CONCLUSIONS: The analysis indicated that the lower the temperature, the slower the geographic dispersal of Ae. aegypti population. This factor predominantly influenced the macro regional dispersal patterns of the species in the state of S?o Paulo. There was no clear influence of temperature on the dispersal of Ae. albopictus. The influence of rainfall on dispersal patterns was seen only for Ae. aegypti in a state area. No influence was detected on the prior presence of Ae. albopictus on the establishment of Ae. aegypti.     

Daily oviposition activity of Aedes aegypti in Orán, Argentina

The study aimed to determinate the maximum daily peak of Aedes aegypti oviposition in the city of Oran, northwestern Argentina. Biweekly samplings were taken between November 2006 and February 2007 (spring-summer). The city was divided into three areas (north, center, and south) and households were randomly selected. Two ovitraps were placed outdoors in the selected houses. Ovitraps were replaced every four hours, from morning (8 a.m.) to late afternoon (8 p.m.). The largest number of eggs was recorded between 4 p.m. and 8 p.m. (81%). These findings enhance our understanding of the vector and thus its control such as spraying during the hours of peak oviposition activity.     

Occurrence of Aedes albopictus in the state of Pará, Brazil

It is first reported the detection of Aedes (Stg) albopictus mosquitoes in state of Par , Brazil, in the urban area of Medicil ndia, a municipality far 90 km from Altamira, where 42 adult mosquitoes were baited using human attraction. All mosquitoes were pooled and inoculated into C6/36 and suckling mice in attempts for virus isolation. No virus was isolated. The occurrence of Aedes albopictus in urban areas of the Amazon region is of concern since dengue and yellow fever viruses are endemic in the Amazon and thus there is a potential risk for this mosquito species to become infected with both viruses.     

Aedes albopictus in bromeliads of anthropic environment in São Paulo State, Brazil

OBJECTIVE: Aedes albopictus populations can breed in several kinds of containers, and its presence has also been reported in Bromeliaceae. The purpose of this study was to evaluate the epidemiological importance of the Bromeliaceae plants as potential breeding sites of Aedes albopictus and to document the associated Culicidae entomofauna found in this micro-habitat. METHODS: Collections of Culicidae larvae were carried out fortnightly in aquatic content of bromeliads during 1998 and 1999. Collections took place in urban and periurban areas of Ilhabela island and periurban area of Ilha Comprida island, Brazil. RESULTS: A total of 26,647 Culicidae larvae were collected at both study sites, 14,575 in the urban area and 10,987 in the periurban area of Ilhabela and the remaining 1,085 in the periurban area of Ilha Comprida. There was no statistical difference between the amount of larvae collected in urban and periurban areas of Ilhabela. Regarding the Ae. albopictus, there was found a higher frequency and amount of larvae in the urban area of Ilhabela, followed by the periurban area in the same site, whereas in the periurban area of Ilha Comprida, its presence was considered accidental, since it was reported only in the first three months. CONCLUSIONS: The results show that bromeliads, largely used in landscaping, may contribute to the spread of Ae. albopictus. The presence of this species in domesticated and domiciled bromeliads allows us to suggest that the Culicidae larva is part of the regional fauna and facilitate the contact between humans and etiological agents of the natural ecosystem.     

First report of Aedes (Stegomyia) albopictus in the state of Ceará, Brazil

For the first time, the occurrence of Aedes (Stegomyia) albopictus in an urban area of the city of Fortaleza, Northeastern, Brazil, is reported. From January to July 2005, ovitraps were used to collect eggs from Aedes spp., which were kept under laboratory conditions to develop into the adult phase. The resultant mosquitoes were identified and subjected to dengue virus isolation tests. Thirteen specimens of Aedes albopictus, all females, were identified. No dengue virus was isolated in any of the mosquito pools. Even though Aedes albopictus has not been incriminated in Brazilian dengue outbreaks, the possibility of dengue virus transmission by these mosquitoes cannot be dismissed.     

Aedes albopictus seasonality in a protected area in the city of São Paulo, Brazil

The study had the objective of assessing the seasonality of Aedes albopictus and the impact of environmental factors on breeding sites in a protected urban area. Immature individuals were collected through fluid aspiration from nine tree holes, in the Ecological Park of Tietê in the city of S?o Paulo, Southern Brazil, from 2001 to 2002. The index of positivity and number of individuals results were as follows: positivity x precipitation (rho=0.69, p<0.001), positivity x temperature (rho=0.35, p<0.001), number of individuals x precipitation (rho=0.29, p<0.001) and number of individuals x temperature (rho=0.13, p<0.05). These correlations suggest rainfalls had greater impact than temperature.     

Changes in susceptibility of Aedes aegypti to organophosphates in municipalities in the state of São Paulo, Brazil

Baseline data on susceptibility of Aedes aegypti to organophosphates detected alterations in cities of the state of S. Paulo, Brazil     

Association of Arsenic and Metals with Concentrations of 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D among Adolescents in Torreón,Mexico

Background: Limited data suggest that lead (Pb), cadmium (Cd), and uranium (U) may disrupt vitamin D metabolism and inhibit production of 1,25-dihydroxyvitamin D [1,25(OH)₂D], the active vitamin D metabolite, from 25-hydroxyvitamin D [25(OH)D] in the kidney.Objectives: We evaluated the association between blood lead (BPb) and urine arsenic (As), Cd, molybdenum (Mo), thallium (Tl), and U with markers of vitamin D metabolism [25(OH)D and 1,25(OH)₂D].Methods: We conducted a cross-sectional study of 512 adolescents in Torreón, a town in Mexico with a Pb smelter near residential areas. BPb was measured using atomic absorption spectrometry. Urine As, Cd, Mo, Tl, and U were measured using inductively coupled plasma mass spectrometry. Serum 25(OH)D and 1,25(OH)₂D were measured using a chemiluminescent immunoassay and a radioimmunoassay, respectively. Multivariable linear models with vitamin D markers as the outcome were used to estimate associations of BPb and creatinine-corrected urine As and metal concentrations with serum vitamin D concentrations, controlling for age, sex, adiposity, smoking, socioeconomic status, and time outdoors.Results: Serum 25(OH)D was positively associated with urine Mo and Tl [1.5 (95% CI: 0.4, 2.6) and 1.2 (95% CI: 0.3, 2.1) ng/mL higher with a doubling of exposure, respectively]. Serum 1,25(OH)₂D was positively associated with urine As and U [3.4 (95% CI: 0.9, 5.9) and 2.2 (95% CI: 0.7, 3.7) pg/mL higher, respectively], with little change in associations after additional adjustment for serum 25(OH)D. Pb and Cd were not associated with 25(OH)D or 1,25(OH)₂D concentrations.Conclusions: Overall, our findings did not support a negative effect of As or metal exposures on serum 1,25(OH)₂D concentrations. Additional research is needed to confirm positive associations between serum 1,25(OH)₂D and urine U and As concentrations and to clarify potential underlying mechanisms.Citation: Zamoiski RD, Guallar E, García-Vargas GG, Rothenberg SJ, Resnick C, Rubio Andrade M, Steuerwald AJ, Parsons PJ, Weaver VM, Navas-Acien A, Silbergeld EK. 2014. Association of arsenic and metals with concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D among adolescents in Torreón, Mexico. Environ Health Perspect 122:1233–1238; http://dx.doi.org/10.1289/ehp.1307861     

Pupal surveys for Aedes aegypti surveillance and potential targeted control in residential areas of Mérida, México

A mosquito larval-pupal survey was conducted in 1,160 households of the Mexican city of Mérida during the rainy season of 2003 to determine their differential productivity for Aedes aegypti. Larvae and pupae were detected in 15 broad categories of container types. All breeding sites were found in the patios (backyards) and were potentially rain filled. Ae. aegypti pupae were produced from all categories of breeding site, and no single container type was predominately responsible for pupal production. The most productive buckets comprised 42% of the pupae-positive containers and provided 34% of the total pupae collected. Pupal production in buckets, together with plastic rubbish, pet dishes and basins, utensils for cooking and washing, tires, and flowerpots, accounted for almost 87% of pupal production. However, the most important pupal producers had low infestation indices for immature forms, illustrating that the use of positive-container indices can underestimate the importance of certain breeding sites. Overall, 40% of containers that were observed harboring Ae. aegypti pupae were classified as disposable. The remaining containers were considered useful, although some were seldom used. The discussion focuses on the potential utility of the pupal survey for targeting control, and its resulting pupae-per-person entomological indicator, both for comparison with a theoretical threshold for dengue transmission and for targeting vector control in this Mexican city.     

Association between arsenic exposure and behavior among first-graders from Torreón, Mexico

Previous studies suggest adverse effects of arsenic exposure on children’s cognitive function. In this study, we examined the potential association between arsenic exposure and children’s behavior. Five hundred and twenty-six children, 6–7 years old, living near a metal foundry in Torreón, Mexico, participated in the study. Arsenic exposure was measured as total urinary arsenic (UAs) and arsenic metabolites—monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) concentrations. Children’s behavior was assessed by Conners Behavior Rating Scales for parents and teachers. The median (interquartile range) concentrations of UAs, MMA and DMA were 55.2 (39.7), 6.7 (5.9) and 39.3 (28.5) μg/L, respectively. The mean behavior scores from parent and teacher ratings were within the clinically normal range (T<65). The relationship between behavior and urinary arsenic was modeled in linear and logistic regression models, with UAs, MMA and DMA tested in separate models and entered as quartiles. No significant association was found between any measure of urinary arsenic and parent ratings of behavior. However, higher UAs was modestly associated with higher scores on the Oppositional, Cognitive Problems and ADHD sub-scales of the teacher ratings; a dose–response relationship was not established between UAs quartiles and behavior. Higher urinary DMA was associated with higher ratings on the Oppositional, Cognitive Problems and ADHD Index by teachers. The associations between UAs and behavior became statistically non-significant after adjustment for the Peabody Picture Vocabulary Test scores, suggesting that the harmful effects of arsenic on behavior may be secondary to arsenic-induced cognitive deficits. These data suggest a potential adverse association between arsenic and children’s behavior and indicate a need to further study the effects of arsenic and arsenic metabolites on neurobehavioral outcomes in children.