Studies on antibody levels during vaccination of rhesus monkeys against Plasmodium knowlesi.

established during the disease in four previously healthy adults and one child with a mononucleosis-like disease without a positive heterophil agglutination test. No antibodies were demonstrable in the first sample from three patients. The disease was characterized by protracted fever and absence of tonsillitis. Enlargement of the lymph nodes was seen in only one patient. The tests for liver function gave abnormal results in all the cases. Leucocytosis, relative and absolute lymphocytosis, and the appearance of abundant atypical lymphocytes were features of the haernatological pattern. No significant rise of the C.F. antibody titre to the cytomegalovirus was demonstrable in a single case among 19 patients suffering from infectious mononucleosis with a positive heterophil agglutination test or among 130 patients with various acute infectious diseases. A high titre, however, was found in two patients with infectious mononucleosis, there being a significant decrease of the titre later, after the disease was over, and in two patients of the control material, both of whom had a chronic debilitating disease in addition to their acute infection.