The onchocerciasis focus at Kinsuka/Kinshasa (Republic of Zaire) in 1985

Abstract

The entomological aspect of the onchocerciasis focus at Kinsuka/Kinshasa has not been studied since vector control was carried out in 1948. As in 1940, larvae of Simulium damnosums. 1. are located in the arm of the Zaire River flowing between Mimosa Island and the Zairian bank. They are, however, scarce. Cytotaxonomic studies showed that the S. squamosum group was the only member of the S. damnosumcomplex present in the region of Kinshasa.

Physico-chemical analysis of the water at breeding sites determined that S. squamosum larvae develop in neutral or acid water with a conductivity of less than 50 µmhos cm⁻¹ and a low concentration of dissolved salts. Longitudinal study showed that the ‘annual biting rate’ (ABR) and the ‘annual transmission potential’ (ATP) fluctuate from 2406–5999 bites man⁻¹ year⁻¹ and from 120–236 infective larvae man⁻¹ year⁻¹ respectively. The low transmission rate at Kinsuka is mainly due to the low level of the biting population occurring during the main river rising. The increase in Kinsuka's population has reinforced this situation by ‘diluting’ the parasite in the human reservoir.