Prevalencia y riesgo de malformación congénita en mujeres gestantes expuestas a plaguicidas. en el Hospital Regional de Ica, Perú / Prevalence and risk of pregnant women in congenital malformation exposed to pesticides. Regional Hospital Ica, Peru

Objetivo: Determinar la prevalencia y asociación entre exposición a plaguicidas antes y durante el primer trimestre de la gestación y el riesgo de malformación congénita. Material y métodos: Estudio observacional, transversal retrospectivo, analítico de casos y controles. Los casos (n = 57) se seleccionaron por muestreo no probabilístico y los controles (n= 114) por muestreo aleatorio simple de una población hospitalaria de la Región Ica, durante el periodo de 3 años comprendido entre el 1 de enero del 2005 al 31 de diciembre del 2007. Los casos, se definieron como neonatos con malformaciones congénitas y los controles, recién nacidos sin malformaciones. Se consideró exposición a cualquier contacto con plaguicidas. Se evaluaron otros factores de riesgo conocidos para malformación congénita: in gesta de medicamentos, drogadicción, alcoholismo y anemia materna severa, como factores de confusión. Resultados: Se reportaron 26 malformaciones de la cara, boca y paladar, 11 del sistema cardiovascular, 11 de las extremidades, 7 del sistema genitourinario, 6 del sistema nervioso central y 12 otras malformaciones. Las gestantes expuestas tuvieron un alto riesgo de procrear hijos malformados OR 2,85 (IC 95% 1,46 ­ 5,54 p < 0,05). Los riesgos más elevados a malformaciones fueron: exposición por acudir a campos fumigados OR: 3,82 (IC 95% 1,92 ­ 7,60 p< 0,05) y vivir cerca de campos fumigados OR: 3,07 (IC 95% 1,59 ­ 5,92 p < 0.05) . Conclusiones: Se muestra evidencia epidemiológica de la relación causal entre exposición a plaguicidas y malformaciones congénitas en una muestra de mujeres gestantes en el hospital regional de Ica. (AU)

Objective: To determine the prevalence and association between pesticide exposure before and during the first trimester of pregnancy and the risk of congenital malformation in the systems: cardiovascular, genitourinary, central nervous malformations of the face, mouth, palate and limbs. . Materials and Methods: Observational, transversal retrospective analytical case-control study. The cases (n = 57) were selected by non-probability sampling and controls (n = 114) by simple random sampling from a hospital population of Ica region during the three years period from 1 January 2005 to 31 December 2007. The cases were defined as infants with congenital malformations and controls infants without malformations. Exposures to any contact with pesticides are considered. In quest of drugs, drug addiction, alcoholism and severe maternal anemia, as confounding factors: other known risk factors for congenital malformation they were evaluated. Results: 26 were reported defects of the face, mouth and palate, cardiovascular system 11, 11 of the limbs 7 of the genitourinary system, central nervous system 6 and 12 other malformations. Exposed pregnant women had a higher risk of bearing children malformed OR 2,85 (95% CI 1,46 to 5,54 p < 0,05). The highest risk of malformations were fumigated exposure attend camps OR : 3,82 ( 95% CI 1,92 to 7,60 p < 0,05 ), living near sprayed fields OR : 3,07 ( IC 95 % 1,59 to 5,92 p < 0,05) and living with a spouse working in fields sprayed OR: 2,40 (95% CI 1,21 to 4,78 p<0,05). Conclusions: Epidemiological evidence of a causal relationship between pesticide exposure and birth defects. (AU)

Effects of piperonyl butoxide on the toxicity of the organophosphate temephos and the role of esterases in the insecticide resistance of Aedes aegypti

Introduction The effects of piperonyl butoxide (PBO) on the toxicity of the organophosphate temephos (TE) and the role of esterases in the resistance of Aedes aegypti to this insecticide were evaluated. Methods A. aegypti L4 larvae susceptible and resistant to TE were pre-treated with PBO solutions in acetone at concentrations of 0.125, 0.25, 0.5, 1, and 2% for 24h and subsequently exposed to a diagnostic concentration of 0.02mg/L aqueous TE solution. The esterase activity of the larvae extracts pre-treated with varying PBO concentrations and exposed to TE for three time periods was determined. Results At concentrations of 0.25, 0.5, 1, and 2%, PBO showed a significant synergistic effect with TE toxicity. High levels of esterase activity were associated with the survival of A. aegypti L4 larvae exposed to TE only. Conclusions The results of the biochemical assays suggest that PBO has a significant inhibitory effect on the total esterase activity in A. aegypti larvae. .

Control of mosquito vectors of tropical infectious diseases: (2) pyrethroid susceptibility of Aedes aegypti ( l) collected from different sites in Thailand.

Four strains (SS, BS, A and B) of Aedes aegypti collected from different sites in Bangkok and at different times were examined for their pyrethroid susceptibility. Mosquito coils containing dl, d-T80-allethrin, d, d-T-prallethrin and methoxymethyl-tetrafluorobenzyl tetramethyl-cyclopropanecarboxylate (K-3050) with or without a synergist were tested by the 25 m3 semi-field test method. One strain (SS) was the most susceptible with KT50 values of about < 30 minutes for all mosquito coils, while the other three strains (BS, A and B) were found to be around 10 to 20 times more tolerant to pyrethroids than the SS strain. A similar tendency for the pyrethroid susceptibility of the four strains was obtained with tests by topical application method. In field efficacy tests, mosquito coils with d, d-T-prallethrin 0.20% plus N-(2-ethylhexyl)bicycle-[2,2,1]- hept-5- ene-2,3-dicarboxyimide as a synergist exhibited a repellent effect of about 85%, while those with K-3050 0.10% plus the synergist exhibited a greater repellent effect of about 90%. In contrast, the repellent effect of commercial dl, d-T80-allethrin 0.20% coils was as low as about 50%. The d, d-T-prallethrin and K-3050 coils with the synergist were confirmed to be highly effective in repelling Ae. aegypti.

Efficacy of piperonyl butoxide (PBO) as a synergist with deltamethrin on five species of mosquitoes.

Development of insecticide resistance has been a challenging problem for a long time and new solutions are yet to emerge. In this regard, the use of synergist with the insecticide is thought to play a key role in reducing the resistance levels. Present study demonstrates the efficacy of PBO with deltamethrin against the field collected mosquito larvae of five species of Aedes, Anopheles and Culexfrom in and around Mysore.

Ultra low volume aerosol application of deltacide (deltamethrin 0.5% w/v, S-bioallethrin 0.71% w/v & piperonyl butoxide 8.9% w/v) against mosquitoes.

BACKGROUND & OBJECTIVE: Insecticide in the form of space spray as an ultra low volume (ULV) aerosol are used during epidemics of vector borne diseases. Deltacide, a formulation comprising of three chemicals viz., deltamethrin 0.5 per cent w/v, S-bio-allethrin 0.71 per cent w/v and piperonyl butoxide 8.9 per cent w/v is suitable for ULV application. As this combination is found to be effective in preventing resistance development tackling the population, which had already developed resistance and cause immediate mortality, its synergistic effect was tested in Peet Grady chamber, against three species of mosquitoes, viz., Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. METHODS: Blood fed females were exposed to ULV application of deltacide in a Peet Grady chamber at four dosages viz., 0.005, 0.01, 0.02 and 0.04 ml/m2 and examined for knockdown activity at 10 min interval for 60 min. Thereafter, the mosquitoes were removed from the chamber and maintained in another room having controlled temperature (28+/-2 degrees C) and humidity (60-75%) and observed for recovery, if any, and the per cent knockdown was calculated. Mortality rate after 24 h of holding period was also determined from moribund and dead adults. RESULTS: Pairwise comparison showed that the effect of deltacide spray varied significantly (P<0.001) among the three species tested. The effectiveness was significantly higher in Ae. aegypti, when compared with that of Cx. quiquefasciatus (P<0.001) and An. stephensi (P<0.05). However, there was no significant difference in the efficacy of deltacide between Cx. quiquefasciatus and An. stephensi. All species of mosquitoes became inactive i.e., knocked down completely within 60 min of exposure at all the dosages tested and mortality observed was 100 per cent after 24 h of exposure. INTERPRETATION & CONCLUSION: Deltacide when tested in the form of ULV cold aerosol, the dosage 0.01 ml/m2 was effective against both Ae. aegypti, and An. stephensi, and 0.02 ml/m2 against Cx. quiquefasciatus, causing 100 per cent mortality. The efficacy of ULV application of deltacide against vector mosquitoes needs to be assessed under field conditions.

Susceptibility of Aedes aegypti larvae to temephos and Bacillus thuringiensis var israelensis in integrated control

A susceptibilidade de larvas de Aedes aegypti coletadas no campo foi avaliada em termos do tempo letal mediano (TL50) e da mortalidade final, quando tratadas com temephos, Bacilus thuringiensis var israelensis ou misturas desses dois agentes. As larvas de terceiro estádio mostraram-se mais susceptíveis ao patógeno do que aquelas no início ou no fim do quarto estádio. A sobrevivência de alguns indivíduos aos tratamentois com temephos permite sugerir a possibilidaqde de resistência. Foi detectada a existência de sinergismo temporal, quando larvas no início do quarto estádio foram tratadas com as misturas do Bti com o temephos. A possibilidade do tratamento integrado é comentada