For over 30 years I have been engaged as a parasitolo­ nitz, Springer-Verlag, Heidelberg, was arranged in the pres­ gist in research on endemic diseases in our land. However, ence of Professor Jusatz. lt was indeed a great honor for I have been somewhat dissatisfied within my heart of me, but I also felt a very heavy responsibility; how to set hearts from the point of view of a medical person. Most of up the scheme, how to collect the materials, how to di­ gest, analyze and compile them in accordance with the us, myself included, handle disease sectionally, not comprehensively. Clinicians pay more attention to finding ef­ original goals. I frankly confess to realizing how limited fective drugs, medical scientists concentrate more effort my knowledge was at the same time. Poor editing would on clarifying pathologic etiology, and public health work­ result in dishonor not only to myself, but to my country ers are more concerned with environmental sanitation. as well. Now at this juncture, the point of editing, I am filled Thus, most of us generally neglect to search out the with deep emotion. In spite of limited time and knowl­ causal relation of a certain disease. For a disease to be established various factors must be involved: agent, ecolo­ edge, this manuscript will be prepared for edition at all gy, hosts, carriers, transmitters, habits, geographic and events.