Dr Chapman, who has been working of coccidiosis throughout his distinguished 40-year career, had been invited to give the Milton Y. Dendy Keynote Address.

He said that the first key paper on the topic was published in Poultry Science in 1948, describing the use of sulphaquinoxaline for the control of coccidiosis in chickens. This paper was to have profound implications as this forms the basis for the way we treat the disease to this day, he added.

Dr Chapman went on to acknowledge the great contribution to our knowledge of the coccidiosis control made by the pioneers in this field, John P. Delaplane and Leland C. Grumbles of Texas A&M University.

There were objections to the use of medications, even at that time, he said. The importance of allowing the birds to develop immunity to the Eimeria parasites was also recognised at this stage.

The first conference of coccidiosis in poultry was held in 1949, while the heyday of synthetic drug discovery followed soon afterwards in the 1950s to the 1970s, Dr Chapman said.

He continued by outlining the various modes of action proposed for the anticoccidial drugs, and explained what he called "the extraordinary ability of Eimeria for adapt and develop resistance". It is this ability of the parasites that has been the focus of much of the research on coccidiosis control ever since.

Looking to the future, Dr Chapman sees continued success with rotation programmes involving both drugs and vaccines although he stressed the need too for high standards of management to control coccidiosis successfully as long as broilers are raised on the floor.