Effects of Bacillus Thuringiensis var., israelensis and Bacillus Sphaericus Mosquito Biolarvicides on incidences of Malaria in selected areas of Lusaka Urban District, Zambia
A Kandyata
Ministry of Health, National Malaria Control Centre
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.