ABSTRACT
The dynamics of the control of Aedes (Stegomyia) aegypti Linnaeus, (Diptera, Culicidae) by Bacillus thuringiensis var israelensis has been related with the temperature, density and concentration of the insecticide. A mathematical model for biological control of Aedes aegypti with Bacillus thuringiensis var israelensis (Bti) was constructed by using data from the literature regarding the biology of the vector. The life cycle was described by differential equations. Lethal concentrations (LC50 and LC95) of Bti were determined in the laboratory under different experimental conditions. Temperature, colony, larvae density and bioinsecticide concentration presented marked differences in the analysis of the whole set of variables; although when analyzed individually, only the temperature and concentration showed changes. The simulations indicated an inverse relationship between temperature and mosquito population, nonetheless, faster growth of populations is reached at higher temperatures. As conclusion, the model suggests the use of integrated control strategies for immature and adult mosquitoes in order to achieve a reduction of Aedes aegypti.
Foi elaborado um modelo matemático do controle biológico de Aedes aegypti com foco em Bacillus thuringiensis var israelensis (Bti). Na construção do modelo foram utilizados dados da literatura sobre a biologia do vetor, no qual o ciclo de vida foi descrito através de equações diferenciais. As concentrações letais (CL50 e CL95) do Bti foram determinadas no laboratório sob diferentes condições experimentais. As variáveis temperatura, colônia, densidade de larvas e concentração do bioinseticida acusaram diferenças significativas quando analisadas no modelo geral, porém quando analisadas individualmente, apenas a temperatura e concentração apresentaram diferenças. As simulações do modelo indicam que a temperatura afeta inversamente a produção de indivíduos e que os pontos máximos de produção de mosquitos são atingidos mais rápido a temperaturas maiores. Concluímos, com a simulação do modelo, que estratégias integradas de controle de imaturos e adultos devem ser utilizadas para atingir redução expressiva da população de Aedes aegypti.
Subject(s)
Animals , Male , Female , Aedes , Insecticides , Models, Theoretical , Pest Control, Biological , Temperature , Population DensityABSTRACT
OBJETIVOS: Se presenta un modelo de simulación que muestra la dinámica de depredación de Mesocyclops spp., sobre Aedes aegypti MÉTODOS: Representado por cuatro ecuaciones diferenciales: H'(t), cantidad de huevos; L'(t), cantidad de larvas; A'(t), cantidad de adultos y C'(t), cantidad de copépodos. Inicialmente las ecuaciones son del tipo clásico presa-depredador, según Lotka y Volterra. Posteriormente se modifica en un sistema con respuesta funcional para invertebrados, según Holling. RESULTADOS: El primer sistema controla y estabiliza la población de mosquitos, el segundo muestra que los copepodos son inefectivos como controladores. CONCLUSIONES: Se reconoce la necesidad de estudiar sistemas presa depredador (mosquitos - copepodos) con trabajos que integren pruebas de laboratorio y de campo. Solo así será posible establecer la validez en el uso de estos últimos como controladores biológicos efectivos de mosquitos.
Subject(s)
Animals , Aedes , Models, Statistical , Mosquito Control/statistics & numerical data , Crustacea/parasitology , Dengue/transmission , Yellow Fever/transmissionABSTRACT
OBJECTIVE: To identify the beliefs and knowledge of a group of rural physicians on the dietary management of children under five years of age, with acute diarrhea. Physicians' dietary management was compared with that recommended by the World Health Organization. MATERIAL AND METHODS: A cognitive anthropology study was carried out from July to December 1998, on ten physicians that care for the infant population ascribed to Hospital Rural IMSS-Solidaridad of San Juanito Bocoyna, Chihuahua, Mexico. Data were collected through focus groups, case vignettes, free listing, pile sorting, and a semi-structured questionnaire, and then cross-referred. RESULTS: The physicians recognized the negative impact of diarrhea on the nutritional state of the child, but not all of them evaluated this state. Prevailing interventions were antibiotic therapy, fluid management, and feeding recommendations. Among the latter, the most consistent were breastfeeding, delayed feeding, and gradual feeding. CONCLUSIONS: The obtained information is in conflict with WHO's recommendations, specially with that of sustained feeding.
Subject(s)
Adult , Child, Preschool , Humans , Infant , Middle Aged , Diarrhea , Physicians/psychology , Breast Feeding , Case-Control Studies , Knowledge , Culture , Diarrhea, Infantile , Diet , Infant Food , Nutrition Disorders , Case Management , Dehydration/prevention & control , Practice Guidelines as Topic , Acute Disease , Fluid Therapy , World Health OrganizationABSTRACT
Background. The association between gallstone disease (gallstones or cholecystectomy) and plasma lipids was evaluated in 2,089 subject who attended a private health care facility in Mexico city from august 1991 to August 1992. Methods. All participants provided data on their sociodemographic status, non-insulin dependent diabetes mellitus diagnoses, alcohol consumption, and smoking habits; women also gave data regarding their obstetric-gynecologic histories. Ultrasounds of the liver and biliary tract were performed. Cholesterol levels, high-density lipoproteins cholesterol, and triglyceride plasma concentration were determined. Results. This study shows a strong inverse association between gallstone disease and plasma cholesterol concentration, with OR = 0.61 (95 percent CI = 0.42-0.89) in the category of 181-239 mg/dL, and OR = 0.49 (95 percent CI 0.32-0.77) in the group of 240 mg/dL or more, when compared to 180 mg/dL or less, after adjusting for the following risk factors; gender, age, and body mass index. Conclusions. These results suggest an increment in the catabolic pool of cholesterol, reflected in lower levels of plasm cholesterol in subjects with gallstone disease
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Cholelithiasis/blood , Cholesterol/blood , Cholecystectomy , Retrospective StudiesABSTRACT
Se estudiaron a 27 hombres y 17 mujeres colombianas con edad promedio de 41ñ16 años, que sufrían de úlcera duodenal activa. Luego de un diagnóstico clínico y endoscópico se inició tratamiento con Famotidina 40 mg en dosis única al acostarse durante un máximo de 8 semanas y se midieron los parámetros de eficacia clínica, con control de síntomas gastrointestinales y seguridad del medicamento. El 90.2 por ciento de las úlceras estaban completamente cicatrizadas al cabo de 8 semanas de terapia y el 9.8 por ciento restante había, en general, mostrado una mejoría aceptable. El dolor diurno y nocturno y demás síntomas gastrointestinales desaparecieron significativamente durante el tratamiento. La eficacia global fue calificada como excelente o buena en el 95 por ciento de los casos tanto por los investigadores como por los pacientes. No hubo reporte de efectos colaterales clínicos o de laboratorio de importancia