The Soviet Union said that the number of people inflicted with AIDS in the last six months has risen sharply to about 200 foreigners and 30 Soviet citizens. Figures released last summer had placed the number of known cases at 130, with 19 of them Soviets. The Tass news agency said most of the 200 foreigners now confirmed to be carrying AIDS are from Africa. Many African students study in the Soviet Union. “Sex with foreigners was found to be the main route by which the infection . . . spread” in the country, the official news agency said. “Several cases involved Soviet women who were married to, or were going to marry, foreigners,” it added.