Jock Mahoney jumped into the Klong River, the dirtiest river in the world, and caught tertiary malaria and amoebic dysentery.
He was deathly sick; he couldn't eat. His lungs filled up with fluid and he developed pneumonia while filming Tarzan's 3 Challenges.

TARZAN'S 3 CHALLENGES (1963)
Cast; Jock Mahoney (Tarzan), Woody Strode, Tsu Kobayashi, Earl Cameron, Jimmy Jamal, Salah Jamal, Anthony Chinn, Robert Hu, Christopher Carlos, Ricky Der. Directed by Robert Day; Screenplay by Robert Day and Bernie Giler. PLOT: The spiritual leader of an oriental country is dying. The leader's evil brother Khan is plotting to prevent Kashi, the youthful heir, from assuming his rightful position. Tarzan is summoned to protect Kashi and, in doing so, he must face Khan in three tests of strength. The final test is a sword fight which takes place on a wide-mesh net stretched over cauldrons of boiling oil. Jeweled elephants lead grand processions, and a thousand girls perform the "dance of the candles".