Programa mundial de la OMS para la vigilancia de vectores resistentes a los plaguicidas / A WHO global programme for monitoring vector resistance to pesticides

Este trabajo describe el programa de vigilancia de vectores resistentes a los plaguicidas y su establecimiento. Resume, a intervalos de cinco años desde 1956, los datos de base computarizados y la acumulación de especies de vectores que han adquirido resistencia, así como datos extraídos de los informes del Comité de Expertos a partir de 1947. También examina los problemas y dificultades del programa y las soluciones proyectadas.

Programa mundial de la OMS para la vigilancia de vectores resistentes a los plaguicidas / A WHO global programme for monitoring vector resistance to pesticides

Este trabajo describe el programa de vigilancia de vectores resistentes a los plaguicidas y su establecimiento. Resume, a intervalos de cinco años desde 1956, los datos de base computarizados y la acumulación de especies de vectores que han adquirido resistencia, así como datos extraídos de los informes del Comité de Expertos a partir de 1947. También examina los problemas y dificultades del programa y las soluciones proyectadas

Programa mundial de la OMS para la vigilancia de vectores resistentes a los plaguicidas / A WHO global programme for monitoring vector resistance to pesticides

Este trabajo describe el programa de vigilancia de vectores resistentes a los plaguicidas y su establecimiento. Resume, a intervalos de cinco anos desde 1956, los datos de base computarizados y la acumulacion de especies de vectores que han adquirido resistencia, asi como datos extraidos de los informes del Comité de Expertos a partir de 1947. Tambien examina los problemas y dificultades del programa y las soluciones proyectadas

A WHO global programme for monitoring vector resistance to pesticides.

This paper describes the programme for monitoring vector resistance to pesticides and how it was established. It presents a summary of the computer baseline data and the cumulative number of vector species developing resistance at intervals of 5 years, starting in 1956, as well as information derived from Expert Committee reports dating back to 1947. The problems and concerns of the programme and envisaged solutions are also discussed.

A WHO global programme for monitoring vector resistance to pesticides

This paper describes the programme for monitoring vector resistance to pesticides and how it was established. It presents a summary of the computer baseline data and the cumulative number of vector species developing resistance at intervals of 5 years, starting in 1956, as well as information derived from Expert Committee reports dating back to 1947. The problems and concerns of the programme and envisaged solutions are also discussed

Assessment of insecticidal impact on the malaria mosquito's vectorial capacity, from data on the man-biting rate and age-composition.

The reduction in average age of a vector population after application of a residual insecticide is commonly interpreted under the implicit assumption that the vector population is uniformly exposed to the insecticide. This assumption maximizes the calculated impact of the insecticide on the vectorial capacity. An alternative assumption, namely that the vector population is composed of two subpopulations, one endophilic and exposed, the other exophilic and not exposed, leads to a much smaller calculated impact of insecticide on the vectorial capacity. This is illustrated with data collected before and after application of propoxur in the Garki District, Kano State, Nigeria. These data were also used to estimate, on the one hand, before spraying, the proportion of blood meals taken by Anopheles gambiae s.l. on man that are followed by rest indoors, and on the other hand, after spraying, the proportion exposed after the first blood meal, according to the model of non-uniform exposure; the two estimates agree fairly well. The discussion compares the models of uniform and non-uniform exposure in terms of plausibility and concludes that the latter is more realistic. It is therefore prudent to take it into account when evaluating the impact of insecticides on the transmission of malaria.

The impact of propoxur on Anopheles gambiae s.1. and some other anopheline populations, and its relationship with some pre-spraying variables.

A significant and stable difference in the residual night-biting collection (NBC, observed/expected) of A. gambiae s.l. was observed among different villages of the West African savannah when sprayed for 2 years with propoxur. The residual mosquito density of a given village was positively associated with some of its pre-spraying characteristics: the NBC/PSC (pyrethrum spray collections) ratio, the median biting hour, and possibly the proportion of species B. It was not significantly associated with several other pre-spraying characteristics (absolute mosquito density, the ratios between NBC indoors and NBC outdoors, between ETC (exit-trap collections) and PSC, between fed and gravid in the PSC or ETC, between males and females in the PSC), and was not associated with variations in recorded coverage, with latitude, or with distance from unsprayed villages.In a comparison between A. gambiae s.l., A. funestus, and A. pharoensis, the residual NBC (observed/expected) was positively associated with the pre-spraying NBC/PSC ratio, and was negatively associated with the median biting hour.The pre-spraying NBC/PSC ratio thus appears to be a predictor of the variation, between villages or species, in the reduction of the NBC by residual spraying, and may assist in forecasting the effect of a residual insecticide. The limitations of any absolute prediction must, however, be kept in mind.

Malaria vectorial capacity of a population of Anopheles gambiae: an exercise in epidemiological entomology.

In order to assess the factors of malaria vectorial capacity and the daily reproduction rate, separate consideration is given to data from Kankiya, Northern Nigeria, concerning the incidence of vector-man contact (the man-biting rate), the vector's expectation of infective life, as reflected by the proportion of parous mosquitos under certain conditions, and the vector's man-biting habit, comprising the frequency of feeding and the human blood index. The main difficulty in the assessment of each of these factors was shown to be that of representative and adequate sampling, especially in a sprayed area. In order to compensate for deficiencies in the Kankiya data, especially with regard to the daily and cyclic survival-rates, the gonotrophic cycle and the effective sporogonic period, more complete published data on an Anopheles gambiae population in East Africa were examined, and extrapolations were made from these data in spite of the consequential risks involved.The results of the analysis show that the spraying of an area with DDT reduced the malaria vectorial capacity of Anopheles gambiae sp. B (the main vector of Plasmodium falciparum in the area) by an over-all factor of about 23 times. Nevertheless the basic reproduction rate of the disease is estimated to have averaged slightly over 20 in the sprayed area during the 6 months of the main transmission season. This is consistent with an observed recovery in the parasite rate, which had been reduced to a very low level by regular mass drug administration through the preceding dry season.The analysis was a tentative exercise in "epidemiological entomology" and it is suggested that in the postgraduate teaching of tropical hygiene, the epidemiological approach to entomology should be preferred to the classical morphological-bionomical approach.