Conus-sting is a syndrome produced by the sting of marine snails belonging to the genus Conus. These snails are predacious and feed on their prey (fishes, snails and polychaetes) by means of shooting a radular tooth into the victim. The radular tooth, which is hollow and harpoon-like in shape and charged with venom, is ejected from the tip of a tapering proboscis lengthened from the mouth (rostrum).
More than 55 cases of Conus-sting including 21 fatalities have been recorded in tropical Indo-Pacific (16 cases including 7 fatalities in Japan) as of Aug. 1982. The majority of fatal case are caused by C. geographus although about 20 species of Conus are reported to have stung humans. The fatality rate of C. geographus stings is 66.7% in the world and 55.3% in Japan. The main symptoms induced by C. geographus' venom (CGV) are paralysis of voluntary muscles and death caused by hindrances of respiration. No cardiac disfunction was observed.
In considering possible therapy for the Conus-sting syndrome in humans, the effect of ligation of an extremity at the part proximal from the site injected with CGV was examined using mice. The crude CGV used was obtained by squeezing the venom duct of the living snail, and was stored in a deep freezer until use. The ligation was performed for 30 minutes as follows: A) Ligation at the distal end of a thigh just before injection with CGV in 1.54-3.84×LD1h (Lethal dose within 1 hour) into a leg; B) Ligation at the ankle joint 10 seconds after injection of CGV in 1.0-2.5×LD1h into the sole of a foot; C) Ligation at the distal end of a thigh various times (10, 30, 60, 180, 240 and 300 seconds) after injection with CGV in 1.54×LD1h into the sole of a foot. In this experiment, the LD1h of dried crude CGV for mice corresponds to 1.3mg/kg into a thigh or leg and about 2.0mg/kg into the sole. The symptoms caused by these doses of CGV were crying, due to severe pain at the time of the injection, excitement, fatigue, ataxia in gait, clonic convulsions on every voluntary muscle (continues to death), breathing disorders (irregular, convulsive and finally standstill) and death within 1 hour. In the control group injected with a dose of. 1.5×LD1h or more without ligation, death came within 10 minutes.
As a result, in all the cases accompanied by ligation, except one that was ligated 5 minutes after injection with CGV, lifesaving or lifepreservation was successful. Especially, in the case of mice injected with CGV in the foot area, death could be completely prevented and the mice recovered without any physical signs, when the thigh was ligated within 3 minutes after injection of 1.5×LD1h or just before the injection of 3.84×LD1h. Ligation in these cases has a larger significance than in cases of snakebites by species with necrotic venom because Conus-sting is not accompanied by organic changes such as necrosis. Ligation is therefore considered to be the most effective primary treatment of Conus-sting due to C. geographus in humans as well.
