Cost-effective control of plant disease when epidemiological knowledge is incomplete: modelling Bahia bark scaling of citrus.

A spatially-explicit, stochastic model is developed for Bahia bark scaling, a threat to citrus production in north-eastern Brazil, and is used to assess epidemiological principles underlying the cost-effectiveness of disease control strategies. The model is fitted via Markov chain Monte Carlo with data augmentation to snapshots of disease spread derived from a previously-reported multi-year experiment. Goodness-of-fit tests strongly supported the fit of the model, even though the detailed etiology of the disease is unknown and was not explicitly included in the model. Key epidemiological parameters including the infection rate, incubation period and scale of dispersal are estimated from the spread data. This allows us to scale-up the experimental results to predict the effect of the level of initial inoculum on disease progression in a typically-sized citrus grove. The efficacies of two cultural control measures are assessed: altering the spacing of host plants, and roguing symptomatic trees. Reducing planting density can slow disease spread significantly if the distance between hosts is sufficiently large. However, low density groves have fewer plants per hectare. The optimum density of productive plants is therefore recovered at an intermediate host spacing. Roguing, even when detection of symptomatic plants is imperfect, can lead to very effective control. However, scouting for disease symptoms incurs a cost. We use the model to balance the cost of scouting against the number of plants lost to disease, and show how to determine a roguing schedule that optimises profit. The trade-offs underlying the two optima we identify-the optimal host spacing and the optimal roguing schedule-are applicable to many pathosystems. Our work demonstrates how a carefully parameterised mathematical model can be used to find these optima. It also illustrates how mathematical models can be used in even this most challenging of situations in which the underlying epidemiology is ill-understood.FFL was funded via a CNPq Fellowship (Brazil's National Council for Scientific and Technological Development, see http://memoria.cnpq.br/english/cnpq/index.htm). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Gravidez na adolescência: perfil sócio-demográfico e comportamental de uma população da periferia de São Paulo, Brasil Teenage pregnancy: behavioral and socio-demographic profile of an urban Brazilian population

Com objetivo de identificar o perfil sócio-demográfico e comportamental de gestantes adolescentes, foram entrevistadas mil adolescentes, admitidas entre 24 de julho de 2001 e 27 de novembro de 2002, em um hospital municipal de São Paulo, Brasil, correspondendo a 24,3% das internações para resolução da gestação. Setenta (7%) adolescentes foram admitidas para curetagem pós-abortamento e 930 (93%), para parturição, com idade média de 17 &plusmn; 1,5 anos. A maioria (72,4%) residia próximo ao hospital e 93% pertenciam às classes econômicas C, D e E. Na época da parturição, 627 (67,3%) adolescentes não estudavam. Apenas 23,7% das adolescentes faziam uso de método contraceptivo, 81,2% não tinham planejado a gestação e 80,1% eram primigestas. Dos partos, 67,4% foram vaginais. Dos bebês, 13,3% foram pré-termo e 15, 9%, baixo peso. Durante a gestação, o consumo referido de tabaco, de álcool e de drogas ilícitas foi, respectivamente de 17,3%, 2,8% e 1,7%. Conclui-se que gravidez na adolescência é um fenômeno complexo, associado a fatores econômicos, educacionais e comportamentais, precipitando problemas decorrentes da maternidade precoce. O presente estudo fornece subsídios para políticas públicas de saúde, visando a prevenir a gravidez na adolescência.<br>To identify the socio-demographic behavioral profile of low-income pregnant teenagers, 1,000 adolescents admitted to a Brazilian public maternity hospital from July 24, 2001, to November 27, 2002, were interviewed. Socio-demographic and behavioral variables were assessed through a questionnaire. Over the 492 days of the study, 24.3% of admissions were adolescents (930 for childbirth and 70 for miscarriage). Mean maternal age was 17 years. Most teenagers (72.9%) lived near the hospital. 930 (93%) belonged to socioeconomic classes C, D, and E. School dropout was identified in 67.3% of the total. 80.1% of the subjects were giving birth for the first time. 81.2% had not planned the pregnancy, and 23.8% had been using some contraceptive method. 67.4% had vaginal deliveries. Some 13.3% of the newborns were premature and 15.9% had low birth weight. 17.3% of these adolescent mothers reported smoking during pregnancy, with 2.8% reporting alcohol and 1.7% illicit drugs. Teenage pregnancy is a complex phenomenon associated with various economic, educational, and behavioral factors. The study provides importance references for public policies to prevent teenage pregnancy

Avaliação do efeito da cafeína no teste vestibular Evaluation of the caffeine effect in the vestibular test

Há controvérsias sobre a interferência da cafeína no teste vestibular. O café é a fonte mais rica em cafeína. Enquanto em alguns serviços os pacientes são orientados a suspender a ingestão de café 24 a 48 horas antes da realização do teste, outros não consideram necessária a suspensão da ingestão dessa bebida. OBJETIVO: Avaliar o efeito da cafeína no resultado do teste vestibular. FORMA DE ESTUDO: clínico com coorte transversal. MATERIAL E MÉTODO: Estudo comparativo, transversal, pareado. O teste vestibular foi realizado em duplicidade, com intervalo máximo de cinco dias entre um e outro exame. No primeiro teste, os pacientes foram orientados a não ingerir café 24 horas antes do exame; no segundo teste, os pacientes foram orientados a beber café como de costume. Todos os participantes tinham indicação clínica de se submeter ao teste vestibular e tinham o hábito de tomar café. RESULTADOS: Participaram do estudo 19 mulheres com idade média de 49,5 anos. O consumo médio de café foi de três xícaras por dia. As queixas de ansiedade e cefaléia foram associadas ao teste realizado com suspensão do café. Não houve diferença estatisticamente significante nos resultados dos exames realizados com e sem ingestão de café. CONCLUSÃO: A ingestão moderada de café não interferiu no resultado do teste vestibular. Considerando ser recomendável que o paciente esteja tranqüilo ao se submeter ao teste vestibular e que a meia-vida da cafeína é de apenas seis horas, sugerimos que a orientação para a suspensão súbita e completa da ingestão moderada de café antes do teste vestibular para os indivíduos habituados à ingestão diária seja reavaliada.<br>Exist controversy about the interference of the caffeine in the vestibular test. Coffee is the richest source of caffeine. While in some services, the patients were orient to suspend the ingestion of caffeine 24 to 48 hours before the vestibular test, other not consider the suspension of this drink necessary. AIM: To evaluate the effect of caffeine in the vestibular test result. STUDY DESIGN: clinical with transversal cohort. MATERIAL AND METHOD: Seccional and matched research. The vestibular test was performed twice in the same patient, with five days interval between the exams. In the first test, the patient did not drink coffee 24 hours before the exam; in the second, the patient drunk coffee as usual. All of the participants had clinical indication for vestibular test and were used to drinking coffee. RESULTS: Nineteen women, medium age of 49,5 years, participated. The average coffee consumption was three cups per day. The complaints of anxiety and headache were associated with the submission to the vestibular test without coffee. The exams were not statistically different comparing the results of the tests performed with and without the coffee ingestion. CONCLUSION: The moderate ingestion of coffee was not shown to interfere in the results of the vestibular test. Considering that it is recommended that the patient be calm to be submitted to the vestibular test and that the half-life of the caffeine is only of six hours, we suggest that the orientation of complete and abrupt drinking coffee suspension of moderate dose before the vestibular test for the individuals used to daily drinking coffee be reevaluated