Treaties and other international acts series. 2157. Health and sanitation, cooperative program in Uruguay, agreement between United States and Uruguay, modifying and extending agreement of Oct. 1 and Nov. 1, 1943, effected by exchange of notes signed Montevideo Apr. 8 and 23. 1946, entered into force Apr. 23, 1946, operative Jan. 1, 1947: and exchange of letters signed Montevideo Apr. 9 and 11, 1946.