Effects of Bacillus Thuringiensis var., israelensis and Bacillus Sphaericus Mosquito Biolarvicides on incidences of Malaria in selected areas of Lusaka Urban District, Zambia

Abstract

Effects of spraying the mosquito biolarvicides Bacillus thuringiensis var. israelensis (Bti) and Bacillus sphaericus (Bs) over freshwater bodies in four selected areas of Lusaka urban district, on incidences of malaria in the areas were investigated. Incidences of malaria prior to and after larviciding of the study areas were determined by reviewing and analyzing health centre records of laboratory-confirmed positive malaria cases in the study areas prior to and after larviciding. There were relatively higher incidences of malaria cases in all study areas prior to larviciding. Malaria cases dropped drastically by 53-72 % immediately after larviciding in all study areas. However, though numerically very small percent-wise, there were observed marked rises in incidences of positive diagnosed malaria cases in Chelstone study area by the second month. Three study areas; Chainda, Mtendere and Ng'ombe showed continued decline or had slight rises in the incidences of malaria two months after larviciding. Possible reasons for the observed slight rises in incidence in the areas were; importation of malaria by travellers from outside the Lusaka urban district. The deployment of Bti and Bs larvicides in the context of integrated vector management is likely to have long term impacts on incidences of malaria in Zambia.