Name the host when first premiere is august 3, 2007
CREATE TABLE "table1_1597866_3" (
  "country" text,
  "name" text,
  "host" text,
  "channel" text,
  "first_premiere" text,
  "regular_judge" text,
  "seasons" real
);
SELECT "host" FROM "table1_1597866_3" WHERE "first_premiere"='August 3, 2007';