this account of the conduct of the similium control scheme at abuja , northern nigeria , over the period 1956-66 shows that , by larvicide treatment of some 160 km of rivers with ddt in the early wet season , the simulium damnosum density has been reduced by about 90 % of its precontrol level each year over an area of more than 3000 km ( 2 ) .a skin-snip survey , in which 6748 persons were examined ( of whom 5700 lived within the controlled area and 1048 in a comparison area ) during 1966 , indicates that there has been no obvious decrease in prevalence of onchocerciasis , particularly among children born since the commencement of the scheme , that could be attributed solely to the effects of the control measures , although there are indications that a drop in severity of infection has been achieved .
C0027361
persons
C0008059
children