Yellow fever is a mosquito-borne viral disease found in some parts of Africa and South America, and travellers to those regions are required to be vaccinated to prevent infection.
"The players did not complete in time the health procedures related to the yellow fever vaccine, which is required to enter Angola," the AFA said in a statement.
World champions Argentina, who have already secured their spot at next year's World Cup in the United States, Mexico and Canada, face Angola in Luanda.