[Effects of various disinfectants on the development and survival possibilities of the pre-parasitic stages of Ostertagia ostertagi, Cooperia oncophora and Ascaris suum].

Eleven disinfectants varying in chemical composition and containing active chlorine, phenol, cresol, sodium or potassium hydroxide, quaternary ammonium compounds, glutaraldehydes or paraformaldehyde were tested for their lethal effect on eggs and infective larvae of Ostertagia ostertagi and Cooperia oncophora and non-embryonated and embryonated eggs of Ascaris suum. Suspensions of all tested stages were mixed with the disinfectants in the concentrations recommended by the manufacturer and with double concentrations during the recommended period of exposure or for 24 hours. Survival of eggs of O. ostertagi and C. oncophora was evaluated by incubation for 24 hours at 20 degrees C of thoroughly washed, treated eggs followed by microscopic examination and differentiation into developed or undeveloped eggs. Survival of non-embryonated eggs of A. suum was measured by incubation for thirty days at 30 degrees C of thoroughly washed, treated eggs followed by microscopic examination of their development. Survival after treatment of infective larvae of O. ostertagi and C. oncophora and of embryonated eggs of A. suum was determined by the motility of the larvae. When 90 per cent of killing was considered to be effective, then none of the disinfectants was effective against the eggs of O. ostertagi or the two types of A. suum. Eggs of C. oncophora were killed by phenols, and infective larvae of O. ostertagi and C. oncophora were killed by sodium hydroxide.