[Effect of temephos on the acetylcholinesterase activity of the brain of Tilapia guineensis. 1: Experimental study at operative doses].

After having exposed during 10 minutes the Tilapia guineensis to a concentration of 0,05 mg/l of temephos (concentration of a larvicide used for the field test), the authors note a lowering of the acetylcholinesterastic activity of the brain to an order of 25%. The return to a normal activity is achieved within 20 to 25 days. A new exposure, happening one week after the first, provokes a further lowering before the return to a normal value. The authors question themselves on the consequences of these chemical attacks repeated on a weekly basis during antilarval treatments in the struggle against the onchocercose.