CONTROL OF SCHISTOSOMIASIS BY ROTIFER EMISSIONS

SCHISTOSOMIASIS, CAUSED BY PARASITIC FLATWORMS LIVING IN THE MESENTERIC/VESICAL VEINS, IS THE SECOND MOST IMPORTANT INFECTIOUS DISEASE OF MAN. PRODUCING CHRONIC ILLNESS, IT SPREADS WITH INCREASING DEMANDS FOR WATER AND INTENSIFIED IRRIGATION IN DEVELOPING COUNTRIES. IT IS A MAJOR CONTRIBU-TOR TO THE HIGH LEVEL OF MORBIDITY AND MORTALITY IN ENDEMIC AREAS, MOLLUSCICIDING, SANITARY ENGINEERING AND CHEMOTHERAPY HAVE NOT BEEN ABLE TO KEEP THE DISEASED IN CHECK. ADDITIONAL CONTROL MEASURES ARE NEEDED. ONE SUCH APPROACH INVOLVES BIOLOGICAL INTERFERENCE WITH DISEASE TRANSMISSION IN THE FIELD. TO SOME EXTENT INTERFERENCE WITH TRANSMISSION OCCURSNATURALLY: BY PREDATION OF CERCARIAE, MIRACIDIA AND SNAILS BY CERTAIN, FISH, PRAWNS, ANNELIDS, TURBELLARIA AND CARNI- VOROUS PLANTS. A NEW APPROACH TO REDUCING TRANSMISSION DEPENDS ON IMMIBILI-ZATION OF CERCARAIAE, THE LARVAL WHICH INFECTS MAN BY PENE- TRATING INTACT SKIN. IN THE LABORATORY A WATERSOLUBLE FAC -TOR EMITTED BY A SYMBIOTIC ROTIFER SPECIES COLONIZING VEC- TOR SNAILS DOES THIS BY PARALYZING THE CERCARIAE AND THUS REDUCING THEIR CAPACITY TO EMERGE FROM SNAILS AND TO INFECT MAN. PHASE I OBJECTIVES ARE TO: FRACTIONATE THIS ANTICERCARIAL ROTIFER FACTOR IN WATER FORM CLONED CULTURES OF ROTIFER; ISOLATE AND PURIFY THE ACTIVE FRACTION(S); AND CHARACTERIZE AND DEFINE IT CHEMICALLY AND STRUCTURALLY.