IMPACT OF COMBINED LARGE-SCALE IVERMECTIN DISTRIBUTION AND VECTOR CONTROL ON TRANSMISSION OF ONCHOCERCA-VOLVULUS IN THE NIGER BASIN, GUINEA

As part of the WHO Onchocerciasis Control Programme in West Africa (OC P), the attack phase of operations in the Niger basin in Guinea began in 1989 with the simultaneous use of ivermectin and vector control. La rvicide applications coupled with annual large-scale ivermectin distri bution have greatly reduced blackfly infectivity (by 78.8% for the num ber of infective larvae per 1000 parous flies). The combination of vec tor control and ivermectin has permitted excellent control of transmis sion. in the original OCP area, it took 6-8 years of vector control al one to obtain an equivalent decrease in blackfly infectivity. Far the same number of flies caught, transmission was much higher in areas whe re ivermectin had not been distributed. The combined use of ivermectin and vector control has opened up new prospects for carrying out OCP o perations with, notably, the possibility of reducing larviciding opera tions.