Biological activities of four essential oils against Anopheles gambiae in Burkina Faso and their in vitro inhibition of acetylcholinesterase

The control of malaria is still a challenge partly due to mosquito’s resistance to current available insecticides. The aim of this work was to evaluate the ovicidal, larvicidal and repellent activities of Lantana camara, Hyptis suaveolens, Hyptis spicigera and Ocimum canum essential oils against  Anopheles gambiae s.l.  according to the World Health Organization standard method. The in vitro acetylcholinesterase inhibition activity of these oils was also evaluated. The repellent effect using the method of “separated arms” was evaluated. Lantana camara oil was more effective on both eggs and larvae. The LD50 and LD90 values observed in this oil solution were respectively 53.59 and 170.89 ppm on eggs whereas LD50 and LD90 were 61 and 125 ppm respectively on larvae. All oils exhibited repellent activities against adult mosquitoes. The most effective repellent was the oil of Hyptis suaveolens with a 50% efficacy dose value of 67 ppm. The highest  cetylcholinesterase inhibitory activity was observed with O. canum and H. suaveolens essential oils which IC50 was 0.21 and 0.55 μg/ml respectively. Results suggest that these essential oils have a potential for vector control and can be considered as a source of natural and ecofriendly substances for malaria vector control.Keywords: Anopheles gambiae s.l., malaria, essential oil, acetylcholinesterase, insecticidal activity

Examining the human infectious reservoir for Plasmodium falciparum malaria in areas of differing transmission intensity.

A detailed understanding of the human infectious reservoir is essential for improving malaria transmission-reducing interventions. Here we report a multi-regional assessment of population-wide malaria transmission potential based on 1209 mosquito feeding assays in endemic areas of Burkina Faso and Kenya. Across both sites, we identified 39 infectious individuals. In high endemicity settings, infectious individuals were identifiable by research-grade microscopy (92.6%; 25/27), whilst one of three infectious individuals in the lowest endemicity setting was detected by molecular techniques alone. The percentages of infected mosquitoes in the different surveys ranged from 0.05 (4/7716) to 1.6% (121/7749), and correlate positively with transmission intensity. We also estimated exposure to malaria vectors through genetic matching of blood from 1094 wild-caught bloodfed mosquitoes with that of humans resident in the same houses. Although adults transmitted fewer parasites to mosquitoes than children, they received more mosquito bites, thus balancing their contribution to the infectious reservoir

Parametric Subtypes in ABEL

Several problems arise when parametric subtypes are used in ABEL. This paper deals with subtype parameters, the disjointness relation and the generation of prole sets, extended to handle type parameters properly. I show how more type-information can be obtained syntactically by studying the proles of the parametric type generators. 1 Introduction For an introduction to ABEL (Abstraction Building Experimental Language), refer to [DO91] and a more recent paper [DO95]. 1.1 Types and Subtypes Each type T in ABEL has an associated attribute V T , where V T is the value set of T . There are two kinds of subtypes in ABEL; syntactic and semantic ones. Syntactic subtypes and the main type itself are dened simultaneously. Example 1 type Int by Neg,Zero,Pos with NPos = Neg+Zero and Nat = Pos+Zero and Nzro = Neg+Pos == module func 0 : \Gamma! Zero - - zero func S : Nat \Gamma! Pos - - successor func N : Pos \Gamma! Neg - - negation one-one genbas 0,S ,N - - generator basis endm..