Cable News Network today will announce a major push into Africa, with new distribution deals for its international service in five countries across the continent.Agreements in Nigeria, Ghana, Kenya, Zambia and Uganda will increase the CNN Intl. reach in sub-Saharan Africa from 700,000 homes to 10.5 million by June. The biggest single deal is in Nigeria, where CNN Intl. will be rebroadcast on a 24-hour basis to 7 million households via a new UHF transmission system operated by Osam Associates and Nigerian Telecom. Kenya Television Network has signed to rebroadccast CNN Intl. for 12 hours daily, reaching 1.5 million homes. The Ghana Broadcasting Co. has already started retransmitting the CNN Intl. signal for up to 24 hours a day to 350,000 homes in the capital city, Accra. Zambia National Broadcasting Corp. will broadcast up to 12 hours of CNN Intl. on Saturdays and Sundays, reaching 300,000 homes. In Uganda, Cablesat Television is transmitting the service up to 14 hours a day to more than 40,000 househbolds in the capital, Kampala.