This 9th edition of Topley and Wilson builds on its undisputed reputation as the world's definitive reference on microbiology. The text has been extended to six volumes to accommodate the vast amount of new information. General principles, previously covered in a single volume, are now incorporated in relevant chapters throughout the volumes. The coverage includes every class of pathogens: viruses, bacteria, fungi, and parasites, including the helminths. Most of the material has been completely rewritten and deals with individual topics in greater depth. For the first time, coverage of mycology and parasitic protozoa is provided in two additional volumes, taking account of their importance in public health. The quality of the illustrations has been considerably improved, and many of them are now reproduced in color. Extensive referencing is provided throughout, and a cumulative index is put together in a separate volume. Genuinely exhaustive, Topley and Wilson is now also completely international. Each of the five volumes has both. British and an American editor, and the 340 contributors are drawn from research centers from around the world. The Ninth Edition is over 2/3 bigger than its predecessor.