A miracidium trap for use in flowing water

Abstract

Three types of trap were designed, each of simple construction and with solid walls, to enhance the opportunities for contact between laboratory-reared sentinel snails and schistosome miracidia in running water. In field trials conducted under appropriate conditions, snails exposed to the traps (20 per trap) had an infection rate of 3·7%, compared with 0·5% for snails exposed in standard mosquito gauze bags (ten per bag). Irrespective of the type of cage used (trap or bag), a three-fold improvement in infection rate resulted when the same total number of snails was exposed in groups of only five per unit. These results thus indicate ways of increasing sentinel snail infection rates without a corresponding increase in work load.