This book is a translation by F. K. Plous of the Proceedings of the 4th Conference on Natural Nidality of Diseases in Kazakhstan and the Republics of Middle Asia, held in the Institute of Zoology at Alma-Ata, Kazakhstan, U.S.S.R. on 15–20 September 1959. It begins, appropriately, with a concise review of the scope of the subject by Academician E. N. Pavlovsky, who began a long series of important contributions to the ecology of the zoonoses in 1939 and was the first to use the word “nidality” in this context. Among other ideas, Pavlovsky discusses the possibility that viruses are altered by natural transmission sequences through various hosts. He also pays tribute to workers in other parts of the world and is especially complimentary to Czech and Chinese workers for their methodical contributions. The second contribution is also a review by I. G. Galuzo.