Pyrethroid and DDT resistance of Anopheles gambiae s.s. (Diptera: Culicidae) in five agricultural ecosystems from Côte-d'Ivoire

The promotion of pyrethroid impregnated bednets among the populations is a major activity of the National Malaria Vector Control Programs in African tropical countries. However pyrethroid resistance in Anopheles gambiae, a major malaria vector, has been observed in several parts of C?te-d'Ivoire since 1993. As insecticides used in agriculture against pests are frequently considered as important factors responsible for resistance in malaria vectors, we have evaluated insecticide resistance of An. gambiae populations taking into account the main crops cultivated in C?te-d'Ivoire. Five areas were selected according to the use of insecticide either in agriculture or for domestic purposes: a urban area where vegetables and rice are main crops, a rural rice growing area, a rural area of coffee/cocoa production, a rural area of fruit farming and a rural area without any use of agricultural insecticide. Susceptibility tests were carried out using WHO diagnostic test kits. About 6500 females of An. gambiae were exposed to insecticide impregnated papers (permethrin 1%, deltamethrin 0.05%, DDT 4%) for one hour. Results confirmed that both mortality rates and knockdown time analysis were important to study the resistance data. By using mortality rates, populations of An. gambiae were found to be resistant to pyrethroids and DDT in four of the five areas. Resistance was the highest in urban area, lower in fruit and coffee/cocoa areas and at low level in rice growing area. An. gambiae from area without agricultural treatment was found susceptible to pyrethroids but slightly resistant to DDT A significant increase of knockdown time was observed in all areas with the 3 insecticides. These results agreed with previous studies showing that kdr mutation was the main resistance mechanism to pyrethroids in An. gambiae populations in C?te-d'Ivoire. They also agreed with knockdown time which is an early indicator of resistance development for the population in area without agricultural treatment. In this population the frequency of homozygous resistant individuals was probably too low to have a significant decrease of mortality rates to pyrethroids.     

Zwei neue Filarien (s. l.), Eufilaria delicata spec. nov. und Ornithofilaria böhmi spec. nov. aus der Misteldrossel,Turdus viscivorus L.

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The aggressive cycle of Anopheles gambiae s.s. inside houses and malaria transmission in the Bouake region (C?te d'Ivoire). Value of using impregnated mosquito nets]

The biting indoor cycle of Anopheles gambiae s.s. was studied in a rural zone near Bouaké from 6 pm to 6 am. The cycle was characterized by a peak between midnight and 1 am (n = 19,181). The parturity rate of biting females regularly increased from 6 pm until 3 am, then remained at a high level up to 6 am (n = 14,239). Infected bites were observed from 7 pm to 6 am with a maximum between 0 and 3 am, and 96.7% of them were obtained between 11 pm and 4 am (n = 219). It appears that malaria transmission occurs essentially at the moment when villagers are in bed. The correct use of impregnated bed nets may thus greatly reduce malaria transmission.     

Pathologie osseuse et insuffisance rénale. Actualités sur les explorations biologiques

This paper deals with the interpretation of parathyroid hormone assays in case of renal failure and use of bone remodeling markers for patients undergoing hemodialysis or transplantation.     

Total immunoglobulin E levels and dengue infection on San Andrés Island, Colombia.

An evaluation of total immunoglobulin E (IgE) and dengue serostatus in 168 subjects from San Andrés Island, Colombia, revealed altered levels of IgE in 89% of the population. IgE levels were higher in patients with a history of dengue or with a current secondary or current primary infection than in subjects with no exposure (P = 0. 01). Dengue infection accounted for 23% of the variation in IgE levels.