RESUMEN
The way in which vectors distribute themselves amongst their hosts has important epidemiological consequences. While the role played by active host choice is largely unquestioned, current knowledge relates mostly to the innate response of vectors towards stimuli signalling the presence or quality of their hosts. Many of those cues, however, can be unpredictable, and therefore prevent the incorporation of the appropriate response into the vector's behavioural repertoire unless some sort of associative learning is possible. We performed a wide range of laboratory experiments to test the learning abilities of the mosquito, Aedes aegypti. Mosquitoes were exposed to choice procedures in (1) an olfactomenter and (2) a 'visual arena'. Our goal was to determine whether the mosquitoes were able to associate unconditional stimuli (blood feeding, human breath, vibration and electrical shock) with particular odours (citral, carvone, citronella oil and eugenol) and visual patterns (horizontal or vertical black bars) to which they had been previously observed to be responsive. We found no evidence supporting the hypothesis that associative learning abilities are present in adult Ae. aegypti. We discuss the possibilities that the assays employed were either inappropriate or insufficient to detect associative learning, or that associative learning is not possible in this species.
Asunto(s)
Aedes/fisiología , Aprendizaje por Asociación/fisiología , Conducta Animal/fisiología , Insectos Vectores/fisiología , Animales , Conducta de Elección/fisiología , Femenino , Interacciones Huésped-Parásitos , Masculino , Estimulación Física/métodosRESUMEN
The way in which vectors distribute themselves amongst their hosts has important epidemiological consequences. While the role played by active host choice is largely unquestioned, current knowledge relates mostly to the innate response of vectors towards stimuli signalling the presence or quality of their hosts. Many of those cues, however, can be unpredictable, and therefore prevent the incorporation of the appropriate response into the vector's behavioural repertoire unless some sort of associative learning is possible. We performed a wide range of laboratory experiments to test the learning abilities of the mosquito, Aedes aegypti. Mosquitoes were exposed to choice procedures in (1) an olfactomenter and (2) a 'visual arena'. Our goal was to determine whether the mosquitoes were able to associate unconditional stimuli (blood feeding, human breath, vibration and electrical shock) with particular odours (citral, carvone, citronella oil and eugenol) and visual patterns (horizontal or vertical black bars) to which they had been previously observed to be responsive. We found no evidence supporting the hypothesis that associative learning abilities are present in adult Ae. aegypti. We discuss the possibilities that the assays employed were either inappropriate or insufficient to detect associative learning, or that associative learning is not possible in this species
Asunto(s)
Animales , Masculino , Femenino , Aedes , Aprendizaje por Asociación , Conducta Animal , Insectos Vectores , Conducta de Elección , Interacciones Huésped-Parásitos , Estimulación FísicaRESUMEN
Acute otitis media (AOM) has been associated with respiratory syncytial virus (RSV) infection; AOM develops in up to one third of children with RSV illness. A masked multicenter trial used an immune globulin enriched with RSV-neutralizing antibodies (RSVIG) to prevent RSV infection of the lower respiratory tract in 249 children with either bronchopulmonary dysplasia, congenital heart disease, or prematurity. To determine whether monthly RSVIG therapy might decrease the incidence of AOM, we retrospectively analyzed the records of 109 children in two of the centers. RSVIG was administered during RSV season of a high dose of 750 mg/kg monthly or a low dose of 150 mg/kg monthly; control children received no RSVIG. Children were examined for AOM by masked observers using pneumatic otoscopy. No difference in sex, race, underlying diagnosis, number of persons in the home, exposure to smoking, or atopy was found between groups studied. In recipients of high doses of RSVIG, significantly less AOM developed per season than in control children (mean episodes, 0.15 vs 0.78; p = 0.003), and fewer episodes of RSV-related AOM occurred (0 vs 5; p = 0.047). Low doses of RSVIG did not have a clinically significant impact. High doses of RSVIG appeared to have a significant impact on preventing AOM (both RSV- and non-RSV-related AOM) in these-high risk populations. This finding may have important implications in the development of improved preventive modalities for AOM.