Indirect fluorescent antibody test for detection of occult malaria in blood donors

THUS IT IS IMPORTANT TO HAVE A SIMPLE AND EFFECTIVE TEST FOR DETERMINING WHETHER BLOOD DONORS ARE INFECTED WITH MALARIA. TEN CASES OF TRANSFUSION-INDUCED MALARIA INVOLVING 110 DONORS IN THE U.S. WERE INVESTIGATED. ALL OF THE AVAILABLE DONORS WERE CONTACTED AND CASE HISTORIES OBTAINED. SERUM SAMPLES AND BLOOD SLIDES WERE COLLECTED FROM 47 DONORS MOST SUSPECT FROM THEIR HISTORIES. MALARIA ANTIBODY WAS DETECTED BY THE INDIRECT FLUORESCENT ANTIBODY TEST IN ONE DONOR FROM EACH OF THE NINE CASES. IN EIGHT CASES, THE DONOR"S HIGHEST ANTIBODY TITER WAS WITH THE INFECTING SPECIES OF MALARIA. IN THREE CASES, THE POSITIVE DONOR WAS PROVEN TO BE INFECTED. THIS WAS ESTABLISHED BY POSITIVE BLOOD FILMS, BONE MARROW SMEARS, OR SUB-INOCULATION OF BLOOD INTO A HUMAN VOLUNTEER. IN THE OTHER SIX CASES, THE PRESENCE OF MALARIAL ANTIBODY WAS THE ONLY EVIDENCE OF MALARIA INFECTION FOUND IN THE BLOOD DONORS INVOLVED. ONE CASE WAS NOT RESOLVED BY SEROLOGY, BECAUSE TWO HIGHLY SUSPECT DONORS WERE NOT AVAILABLE FOR TESTING. TO DECREASE THE THREAT OF TRANSFUSION-INDUCED MALARIAL, EITHER HIGH-RISK GROUPS MUST BE ELIMINATED FROM DONOR POOLS OR SOME DEPENDABLE MEANS OF MALARIA DETECTION MUST BE EMPLOYED AT THE TIME OF BLOOD DONATION. THE IFA TEST, ALTHOUGH IT IS NOT RAPID, CAN BE USED TO SCREEN THE DONOR POOL BY ELIMINATING ONLY THOSE INDIVIDUALS WITH A POSITIVE MALARIA ANTIBODY RESPONSE. IT MAY ALSO BE USEFUL IN MALARIA ERADICATION PROGRAMS TO DETECT OCCULT INFECTIONS WHICH CONSTANTLY THREATEN TO RESTORE AN ACTIVE MALARIA TRANSMISSION CYCLE.